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Thin Films and Nanoparticles of the Photoactive-Cobalt Iron Prussian Blue Analogue

Permanent Link: http://ufdc.ufl.edu/UFE0021664/00001

Material Information

Title: Thin Films and Nanoparticles of the Photoactive-Cobalt Iron Prussian Blue Analogue
Physical Description: 1 online resource (129 p.)
Language: english
Creator: Frye, Franz A
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2007

Subjects

Subjects / Keywords: films, nanoparticles, photomagnetic, prussian
Chemistry -- Dissertations, Academic -- UF
Genre: Chemistry thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Thin films and nanoparticles of the photomagnetic AjCo4Fe(CN)6l ?nH2O cobalt iron Prussian blue analogue were studied. The cobalt iron analogue has a persistent metastable excited state accessible at low temperatures using photoexcitation to convert diamagnetic metal pairs to ferrimagnetic metal pairs through a charge transfer and spin crossover event. The integration of the photoinducible material into devices will require depositing material at an interface. The formation of films and functionalized nanoparticles are possible methods for placing material at an interface. Thin films and nanoparticles may have properties different than the bulk material. Specifically, the size or dimensional restriction of the cobalt iron analogue changes the magnetic properties normally observed in the bulk. Thin films were generated using a sequential adsorption method. The cobalt iron analogue films were characterized using scanning electron and atomic force microcopy, infrared spectrometry, and elemental analysis. A unique photoinduced decrease in magnetism is observed in the cobalt iron analogue film. The photoinduced behavior is dependent on the thickness of the film and the strength of the applied magnetic field. This behavior is qualitatively explained by considering the dipolar field generated by the quasi two-dimensional organization of ordered primordial ferrimagnetic material in the film. The anisotropic photoinduced behavior was changed by the incorporation of a higher magnetic ordering nickel chromium analogue into the cobalt iron analogue film. Individual behaviors of the different analogues were observed in the same film. The individual behaviors of the analogues were suppressed by modifying the deposition sequence. When a cobalt iron analogue layer was placed between two nickel chromium layers the anisotropic photoinduced magnetic behavior observed was the exact opposite of the cobalt iron film. Photomagnetic nanoparticles of the cobalt iron analogue were generated using both aqueous reactions and oil water emulsion reactions containing surface modifiers to restrict the particle growth. Nanoparticles were characterized using transmission electron microcopy, infrared spectrometry, and elemental analysis. Nanoparticles with diameters ?10 nm follow Curie-like magnetic signals, where as larger nanoparticles have bulk like magnetic signals. Evidence that the surface of the nanoparticles is locked in diamagnetic metal pairs was also observed.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Franz A Frye.
Thesis: Thesis (Ph.D.)--University of Florida, 2007.
Local: Adviser: Talham, Daniel R.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2007
System ID: UFE0021664:00001

Permanent Link: http://ufdc.ufl.edu/UFE0021664/00001

Material Information

Title: Thin Films and Nanoparticles of the Photoactive-Cobalt Iron Prussian Blue Analogue
Physical Description: 1 online resource (129 p.)
Language: english
Creator: Frye, Franz A
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2007

Subjects

Subjects / Keywords: films, nanoparticles, photomagnetic, prussian
Chemistry -- Dissertations, Academic -- UF
Genre: Chemistry thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Thin films and nanoparticles of the photomagnetic AjCo4Fe(CN)6l ?nH2O cobalt iron Prussian blue analogue were studied. The cobalt iron analogue has a persistent metastable excited state accessible at low temperatures using photoexcitation to convert diamagnetic metal pairs to ferrimagnetic metal pairs through a charge transfer and spin crossover event. The integration of the photoinducible material into devices will require depositing material at an interface. The formation of films and functionalized nanoparticles are possible methods for placing material at an interface. Thin films and nanoparticles may have properties different than the bulk material. Specifically, the size or dimensional restriction of the cobalt iron analogue changes the magnetic properties normally observed in the bulk. Thin films were generated using a sequential adsorption method. The cobalt iron analogue films were characterized using scanning electron and atomic force microcopy, infrared spectrometry, and elemental analysis. A unique photoinduced decrease in magnetism is observed in the cobalt iron analogue film. The photoinduced behavior is dependent on the thickness of the film and the strength of the applied magnetic field. This behavior is qualitatively explained by considering the dipolar field generated by the quasi two-dimensional organization of ordered primordial ferrimagnetic material in the film. The anisotropic photoinduced behavior was changed by the incorporation of a higher magnetic ordering nickel chromium analogue into the cobalt iron analogue film. Individual behaviors of the different analogues were observed in the same film. The individual behaviors of the analogues were suppressed by modifying the deposition sequence. When a cobalt iron analogue layer was placed between two nickel chromium layers the anisotropic photoinduced magnetic behavior observed was the exact opposite of the cobalt iron film. Photomagnetic nanoparticles of the cobalt iron analogue were generated using both aqueous reactions and oil water emulsion reactions containing surface modifiers to restrict the particle growth. Nanoparticles were characterized using transmission electron microcopy, infrared spectrometry, and elemental analysis. Nanoparticles with diameters ?10 nm follow Curie-like magnetic signals, where as larger nanoparticles have bulk like magnetic signals. Evidence that the surface of the nanoparticles is locked in diamagnetic metal pairs was also observed.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Franz A Frye.
Thesis: Thesis (Ph.D.)--University of Florida, 2007.
Local: Adviser: Talham, Daniel R.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2007
System ID: UFE0021664:00001


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7a0fd5370d6b7dbf2e7c0a7201ac5e2abcb010a6







THIN FILMS AND NANOPARTICLES OF THE PHOTOACTIVE COBALT IRON
PRUSSIAN BLUE ANALOGUE




















By

FRANZ FRYE


A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA

2007



































2007 Franz Frye





























To Tresha, 1, 2, and 3









ACKNOWLEDGMENTS

I have had the aid of numerous people over the years. I begin with those who have aided

me in a scholarly fashion. First I would like to thank my advisor Daniel R. Talham whose

advice, actions and inactions have made me into a better scientist. The members of the Talham

research group have been a constant resource to me throughout the years from the past members

of the group who aided me in the beginning of my graduate career to the current members. In

particular Justin Gardner and Sarah Lane with whom I've had many conversations with on a

variety of topics over the years but also to Justin for being the energy in the lab and to Sarah for

being one of the few other people I've known that is comfortable with not talking for an

afternoon in the lab.

This research project required collaborations with areas out side of chemistry that have

been invaluable to me. Mark W. Meisel and his research group from the department of physics

have been a critical part of this project. All magnetic information on the material presented was

obtained by this group. I would also thank them for their insight in to the magnetic behavior of

the materials as well as their explanations of the physics involved. The graduate students that

have helped over the years from physics are Ju-Hyun Park who was involved in the early portion

of the project and Daniel Pajerowski who has been critical in helping me at end. I've also made

many trips to MAIC for characterization of materials and have been aided by Kerry Siebein not

only by her expert TEM abilities but also her knowledge of other characterization methods.

People not directly contributing to the research have also been beneficial to me over the

years. My friends at the Kung-Fu school and gamming groups over the years have provided

necessary diversion that allowed me to focus in the lab. Keith and Katie also contributed their

scientific insight before graduating. I'd also like to thank Katie Amaral more directly for her









help in proofreading and for her efforts in obtaining an opportunity for me to become involved in

lecturing at UF.

Finally I arrive at those closest to me. I thank my wife Tresha who has been my friend

over the years. Also, I thank my father whose advice on graduate school by recalling his own

experience has shown me that the process has not changed much in 40 years.









TABLE OF CONTENTS

page

A C K N O W L E D G M E N T S .................................................................. ..................................... ....... 4

L IS T O F T A B L E S ................................................................................................. ..................... 9

LIST OF FIGURES ............................................. .. ......... ............ ............... 10

L IST O F A B B R E V IA T IO N S ......................................................................... ...... ............... 14

CHAPTER

1 INTRODUCTION ............................................... ............................. 18

Introduction ...................................................... .................. 18
P ru ssian B lu e .............................................................. ........................ ...................18
Cobalt Iron Prussian Blue A nalogue ....................... ............................................... 19
T h in F ilm s .......................................................................................................................2 1
N anoparticles ....................................................................... ............. .................. 22

2 ANISOTROPIC PHOTOINDUCED MAGNETISM IN THIN FILMS OF THE
PRU SSIAN BLUE ANALOGUE .................. ............................................................. 27

Introduction ...................................................... .................. 27
E x p erim mental Section .............................................................................................................. 2 9
R agents and M aterials........................................................................................ ............ 29
Sample Preparation of AjCok[Fe(CN)6]i *nH20 Thin Films.......................................29
In stru m e n ta tio n ................................................................................................................3 0
Analysis Preparations ............ ............. .. .......... ........................31.... 1
R results ............................................................ ............... .... ..................... 32
Film G generation and Characterization........................................................ ................ 32
M agnetic Behavior with HE Parallel to the Thin Films.............................. ................ 33
A nisotropic Photom agnetic B ehavior......................................................... ................ 34
A lkali C ation D ependence................................................ ............. ............. ................ 35
Field Dependent Magnetic Behavior of 75 nm and 160 nm Films ...............................36
Effect of Film Thickness .................... ................ 36
Tem perature D ependence of the Anisotropy.............................................. ................ 37
Discussion ...................................................... .................. 37
Conclusions ...................................................... .................. 41

3 HETEROGENOUS PRUSSIAN BLUE ANALOGUE FILMS.......................................51

In tro d u c tio n ............................................................................................................................. 5 1
Experimental ............................................................................. 54
R esults............................ .... ...... ...............................................................55
Fast Nickel Chromium Prussian Blue Analogue Film 1 ............................................55


6









Fast H eterogeneous Stacked Film s 2 and 3 ................................................ ................ 56
Fast M ixed H eterogeneous Film 4 ............................................................. ................ 58
Fast H eterogeneous Sandwich ABA Film 5............................................... ................ 58
Slow Heterogeneous Stacked AB Film 6 ................................................... 60
Slow H eterogeneous M ixed Film 7 ................... ........ ........................... .....................60
Magnetic Anisotropy Present in the Nickel Chromium Film.....................................61
Sequence Effects in the Stacked Film s ............................. .................... .....................62
Photoinduced M agnetism in the Stacked Film s ......................................... ................ 62
Magnitude of the Photoeffects in the Heterogeneous Films ......................................63
Anisotropic Photoinduced Magnetism of the Sandwich Films ..................................63
Diminished Photoeffects in Stacked Films.............. ................ .................... 65
Magnetic Behavior of Metal Thin Films Discussed in Literature...............................66
C o n clu sio n s............................................................................................................ ........ .. 6 7

4 SIZE DEPENDENT PHOTOINDUCED MAGNETISM IN RUBIDIUM COBALT
IRON PRUSSIAN BLUE ANALOGUE NANOPARTICLES.........................................79

In tro du ctio n ............................................................................................................ ........ .. 7 9
E x p erim mental S section .............................................................................................................. 80
R eag ents an d M materials ........ ..... ................... ............ ...... ............. .................... 80
Sample Preparation of AjCok[Fe(CN)6]I nH20 Nanoparticles ...............................80
In stru m en tatio n ............................................................................................................... 8 0
Analysis Preparations ..................................... .............................81
R esults................................................... . ..... .... ................ ................... 82
N anoparticle Generation and Characterization .......................................... ................ 82
The IR D ata ............................................................ ..................... 83
M agnetic B behavior of N anoparticles.................. .................................................... 85
Surface E effects in N anoparticles ...................................... ....................... ................ 87
D discussion ..................................................................... ........ ..................... 88
C critical Size of N anoparticles.......................................... ........................ ................ 88
C ore Shell N anoparticles ... ................................................................... ................ 90
C on clu sion ........................................................................................................... ....... .. 9 1

5 ALTERNATE SYNTHESIS OF COBALT IRON PRUSSIAN BLUE ANALOGUE
NANOPARTICLES .................................... ............... 103

Introduction .................................................................................................. 103
Experim ental Section ................................. .. ........... ............... ............... 103
R agents and M aterials................................................. .. ........................ ............... 103
Sample Preparation of AjCok[Fe(CN)6]I nH20 Nanoparticles ............................. 103
In stru m en tatio n .............................................................................................................. 10 4
Analysis preparations ............................. .......... ....................... 104
R esults.................................................. . .... .... ............... .................... 105
Nanoparticle Generation and Characterization ....... ... ..................................... 105
M agnetic B behavior .................................................. .............................................. 106
Tim e D dependent B behavior .................................................................. ............... 107
D discussion .................................................................................................... 108









Em ulsion Synthesis A dvantages................................... ...................... ............... 108
Emulsion Synthesis Disadvantages ...... .............. ............ ..................... 109
Comparison with PVP Nanoparticles...... ........... ........ ..................... 110
Conclusions ................................................ .............................. 111

6 CONCLUSIONS AND FUTURE WORK......................... ......................119

C o n c lu sio n s ........................................................................................................................... 1 1 9
Future W ork .................................................... .................. 119
T h in F ilm s .....................................................................................................................1 2 0
N anoparticles .................................................................................. ........................12 1

L IS T O F R E F E R E N C E S .............................................................................................................12 3

B IO G R A P H IC A L SK E T C H .......................................................................................................129







































8









LIST OF TABLES


Table page

2-1 Thickness and roughness data for films of Rbo.7Co4[Fe(CN)6]3.0 *6H20 ...........................42

3-1 Sum m ary of heterogeneous film s generated................................................. ................ 68

4-1 Summary of the material properties of the four sample sets ........................................92

4-2 Summary of magnetic data for different nanoparticle samples ....................................92

4-3 Calculation based on magnetic data for PVP nanoparticles .........................................92

5-1 Emulsion nanoparticles synthesis and physical data ....... ... ................................... 113









LIST OF FIGURES


Figure page

1-1 Unit cell representation of the ACo"[Fe" (CN)6] -nH20 analogue........................ 25

1-2 Unit cell representation of the Co"i.5[Fe"'(CN)6] 3H20 analogue................................25

1-3 Potential energy diagram of the cobalt iron Prussian blue analogue..............................26

2-1 The sequential adsorptions m ethod............................................................... ................ 43

2-2 Thickness vs. number of cycles for the slow growth, and fast growth, sequential
adsorptions deposition m ethods......................................... ........................ ................ 43

2-3 SEM im ages of fast m ethod film s.......................................... ....................... ............... 44

2-4 SEM im ages of slow m ethod film s.................................................................. ............... 44

2-5 Room temperature FT-IR ATR spectra of a 160 nm film ............................................45

2-6 Plots of fc and zfc DC magnetization of a 160 nm thick film parallel to HE = 200 G
in dark and photoinduced (light) states......................................................... ................ 45

2-7 Plots of fc and zfc DC magnetization of a 160 nm thick film perpendicular to
HE = 200 G in dark and photoinduced (light) states ..................................... ................ 46

2-8 Anisotropy in the photoinduced magnetization of a 75 nm film of
R bo.7C o4[Fe(CN )6]3.0 *6H 20 ................................................................... ............... 46

2-9 Change in magnetization for a 86 nm film of Ko.5Co4[Fe(CN)6]3.2 *4.8H20
perpendicular to H E of 200 G at 5 K ............................................................. ................ 47

2-10 Rubidium ion concentration dependence of the photoinduced magnetization of 75
cycle slow cobalt iron Prussian blue analogue film s .................................... ................ 47

2-11 Applied field dependence of the photoinduced magnetization with HE perpendicular
to the plane of the film ..................................... ........ .................... 48

2-12 The field dependent magnetization of a 160 nm film of Rbo.7Co4[Fe(CN)6]3.0o 6H20 ......48

2-13 Thickness dependence of the photoinduced magnetization in cobalt iron Prussian
blue analogue thin films with HE perpendicular to the film plane................................49

2-14 Photoinduced magnetism of a 160 nm film of Rbo.7Co4[Fe(CN)6]3.0 *6H20 at 20 K
w ith H E = 200 G perpendicular to the film ................................................... ................ 49

2-15 The photoinduced magnetism in a quasi-two-dimensional film of cobalt iron
Prussian blue analogue ......................... ...................... .. ............... 50









3-1 Schematic of the heterogeneous Prussian blue analogue thin film generated using the
sequential adsorption m ethod .......................................... .......................... ................ 69

3-2 Schematic of the magnetic layer exchange interactions likely to exist in samples of
heterogeneou s fi lm s ................................................... ............................................... 69

3-3 Schematic of the different heterogeneous films generated...........................................69

3-4 Magnetic susceptibility vs. temperature plot of a 75 nm nickel chromium Prussian
blue analogue thin film .................................... ............................. 70

3-5 The ac susceptibility data of the slow film of the nickel chromium Prussian blue
an alogu e ......................................................................................................... . ....... .. 7 0

3-6 The dc magnetic susceptibility verses temperature fc (*), zfc (o) of the stacked AB
heterogeneous Prussian blue analogue.......................................................... ................ 71

3-7 Photoinduced magnetization of a 75 nm nickel chromium Prussian blue analogue
film under a 75 nm cobalt iron Prussian blue analogue film ........................................71

3-8 Photoinduced magnetization of a 75 nm cobalt iron Prussian blue analogue film
under a 75 nm nickel chromium Prussian blue analogue BA.......................................72

3-9 The dc magnetic susceptibility fc zfc versus temperature plot of a mixed film ..............72

3-10 Photoinduced magnetism of a mixed cobalt iron nickel chromium Prussian blue
analogue fast film ......... .... ................. .. ........... .............. ............... 73

3-11 Photoinduced magnetization of a sandwich film nickel chromium, cobalt iron, nickel
chrom ium Prussian blue analogue ....................................... ...................... ................ 73

3-12 The dc magnetic susceptibility vs. temperature with H = 100 G perpendicular to a
slow stacked A B film ............. .. .................... .................. ........................ .. ............... 74

3-13 Photoinduced magnetism of a stacked slow AB film .............. .................................... 74

3-14 Magnetic susceptibility vs. temperature with H = 100 G perpendicular to a mixed
slow fi lm .......................................................................................................... ........ .. 7 5

3-15 Photoinduced magnetism of a mixed slow film of cobalt iron and nickel chromium
an alo g u e ......................................................................................................... . ....... .. 7 5

3-16 Schematic of the dipolar field in the ferromagnetic nickel chromium analogue films......76

3-17 Schematic of the magnetic easy axis in the ferromagnetic nickel chromium analogue
present in stacked films...................... ............ ............................. 76

3-18 Change in magnetic susceptibility over time with photoexcitation...............................77









3-19 Schematic of the sandwich film with directions of the applied magnetic field.............. 77

3-20 Schem atic of the stacked AB film ...................................... ....................... ................ 78

4-1 TEM images of cobalt iron Prussian blue analogue ........................................ ............... 93

4-2 SAED pattern of a large agglomerate consisting of over 100 nanoparticles and a
p o w d ere d so lid ................................................................................................................. .. 9 3

4-3 The particle distributions, normalized to the largest bin, versus diameter for the four
samples of cobalt iron Prussian blue analogue particles ..............................................94

4-4 TEM images of cobalt iron Prussian blue analogue nanoparticles and powdered solid
prepared im m ediately after synthesis............................................................ ................ 95

4-5 Absorbance IR spectra of cobalt iron Prussian blue analogue nanoparticles .................95

4-6 Absorbance IR spectra of powdered solid samples ......................................................96

4-7 The temperature dependence of the low field, 100 G, susceptibilities for
n a n o p a rtic le s ................................................................................................................... ... 9 7

4-8 The temperature dependence of the low field, 100 G, susceptibilities for powdered
so lid .......................................................................................................... ........ . ....... 9 8

4-9 The T = 2 K magnetization versus magnetic field sweeps for the two largest sizes of
n a n o p a rtic le s ................................................................................................................... ... 9 9

4-10 The T = 2 K magnetization versus magnetic field sweeps for the two powdered solid
rubidium concentrations... ..................................................................... ............... 100

4-11 The temperature dependence of the ac-susceptibilities for the four samples ...............101

4-12 Core shell behavior m odel .................... ............................................................... 102

5-1 TEM im ages of cobalt iron Prussian blue...................................................... ............... 114

5-2 SAED pattern of an organized region of nanoparticles ........................ ...................114

5-3 The particle length distributions of the four samples are shown ................................115

5-4 The temperature dependence of the low field, 100 G, susceptibilities........................ 116

5-5 The temperature dependence of the low field, 100 G, susceptibilities over time ........117

5-6 IR room temperature absorbance spectra of a 16.7 nm nanoparticle after magnetic
m e a su rm e n ts .................................................................................................................. .. 1 1 7









5-7 TheiR room temperature absorbance spectra of a 10.6 nm nanoparticle sample over
tim e .......................................................................................................... ......... . ....... 1 1 8









LIST OF ABBREVIATIONS


Tc Magnetic ordering temperature

PVP Polyvinylpyrrolidone

K Kelvin

A Alkaline ion

S Spin value

CTIST Charge Transfer Induced Spin Transition

hs High spin

ls low spin

G Gauss

ICP-MS Inductively coupled plasma mass spectrometry

ACS American Chemical Society

DI Deionized

FT-IR Fourier transform infra red

AFM Atomic force microscopy

SEM Scanning electron microscopy

SQUID Superconducting quantum interference device

OD Outer diameter

PET Polyethylphthalate

ATR Attenuated total reflectance

RMS Route mean squared

fc Field cooled

zfc Zero field cooled

HE External applied magnetic field

emu Electromagnetic unit









HD Dipolar field

x Magnetic susceptibility

SAED Selected area electron diffraction

TEM Transmission electron microscopy

EDS Energy dispersive spectroscopy

He Coercive field

FW Formula weight









Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

THIN FILMS AND NANOPARTICLES OF THE PHOTOACTIVE COBALT IRON
PRUSSIAN BLUE ANALOGUE
By

Franz Frye

December 2007

Chair: Daniel R. Talham
Major: Chemistry

Thin films and nanoparticles of the photomagnetic AjCo4[Fe(CN)6]i *nH20 cobalt iron

Prussian blue analogue were studied. The cobalt iron analogue has a persistent metastable

excited state accessible at low temperatures using photoexcitation to convert diamagnetic metal

pairs to ferrimagnetic metal pairs through a charge transfer and spin crossover event. The

integration of the photoinducible material into devices will require depositing material at an

interface. The formation of films and functionalized nanoparticles are possible methods for

placing material at an interface. Thin films and nanoparticles may have properties different than

the bulk material. Specifically, the size or dimensional restriction of the cobalt iron analogue

changes the magnetic properties normally observed in the bulk.

Thin films were generated using a sequential adsorption method. The cobalt iron

analogue films were characterized using scanning electron and atomic force microcopy, infrared

spectrometry, and elemental analysis. A unique photoinduced decrease in magnetism is

observed in the cobalt iron analogue film. The photoinduced behavior is dependent on the

thickness of the film and the strength of the applied magnetic field. This behavior is

qualitatively explained by considering the dipolar field generated by the quasi two-dimensional

organization of ordered primordial ferrimagnetic material in the film.









The anisotropic photoinduced behavior was changed by the incorporation of a higher

magnetic ordering nickel chromium analogue into the cobalt iron analogue film. Individual

behaviors of the different analogues were observed in the same film. The individual behaviors of

the analogues were suppressed by modifying the deposition sequence. When a cobalt iron

analogue layer was placed between two nickel chromium layers the anisotropic photoinduced

magnetic behavior observed was the exact opposite of the cobalt iron film.

Photomagnetic nanoparticles of the cobalt iron analogue were generated using both

aqueous reactions and oil water emulsion reactions containing surface modifiers to restrict the

particle growth. Nanoparticles were characterized using transmission electron microcopy,

infrared spectrometry, and elemental analysis. Nanoparticles with diameters <10 nm follow

Curie-like magnetic signals, where as larger nanoparticles have bulk like magnetic signals.

Evidence that the surface of the nanoparticles is locked in diamagnetic metal pairs was also

observed.









CHAPTER 1
INTRODUCTION

Introduction

Prussian Blue

Prussian blue (FeI"4[Fe"(CN)6]3 *14H20) has been used for three hundred years as a dye.

The magnetic behavior of the solid was first reported in 1928.1 The first crystal structure was

published in 1977,2 supported by neutron data from 1980,3 showed that Prussian blue is a face-

centered cubic network of iron(III) ions bridged to ferrocyanide ions. More recent studies have

shown that Prussian blue displays interesting electrochromic phenomena that have been

investigated using electrochemical methods.4'5 The medical field has also found a use for

Prussian blue as a heavy metal contaminant remover in biological systems.6 7 Prussian blue and

its analogues have been investigated for their hydrogen storage potential8 and their peroxide

sensing abilities.9'10 Prussian blue has a long-range ferromagnetic ordering temperature of

5.6 K.11 This ordering warranted further studies of Prussian blue as a molecular-based magnet.

When one or more of the iron atoms in Prussian blue are replaced by other transition

metals, the compound is considered a Prussian blue analogue. Two properties of Prussian blue

analogues have generated a great deal of research interest in the last few years and have been

reviewed.12'13 The first is the high magnetic ordering (Tc) of several of the analogues. A few of

the Prussian blue analogues with high Tc values that have been synthesized to date are:

CsNi[Cr(CN)6] *2H2014 and CsMn[Cr(CN)6] *H2015 with a Tc values near 90 K;

Cs2Ni[V(CN)6] with a Tc value of 125 K;16 Cri.5[Cr(CN)6] *5H20 with a Tc value of 240 K;17

and Ko.0o8V""/[Cr(CN)6] *0.79(SO4)0.058*0.93H20 with a Tc value of 372 K.18 The combination

of different third row transition metals and multiple oxidation states has led to a number of









Prussian blue analogues with differing Tc values. Another interesting behavior in a Prussian

blue analogue is the photoinduced magnetization of the cobalt iron Prussian blue analogue.

Cobalt Iron Prussian Blue Analogue

Since the discovery of photoinduced magnetism in the cobalt iron Prussian blue analogue

by Hashimoto and coworkers in 1996,19 extensive research has been done on the powdered solid

form of the analogue.20-41 During aqueous synthesis of Prussian blue analogues the product of

the reaction is a polycrystalline suspension of sub-micrometer sized crystallites that when

isolated from solution form a powdered solid. The cobalt iron Prussian blue analogue

ACo"[Fe" (CN)6] ,nH20, where A is an alkali metal, and the cobalt and iron cations form a face-

centered cubic network bridged by cyanide ions with the alkali metal incorporated into the

tetrahedral holes. (Figure 1-1) The magnetic behavior of the cobalt iron Prussian blue analogue

can be tuned by altering the alkali metal concentration available during synthesis.29'35

Compounds with little to no alkali metal achieve charge balance by incorporating a number of

ferricyanide vacancies in the lattice resulting in an empirical formula of

Co".5[Fe111(CN)6] *3H20. (Figure 1-2) Each cobalt ion has an average of two water molecules

in its coordination sphere that fill the vacancy left by the ferricyanide anion, leading to cobalt

ions that are in a weak ligand field and high spin state. The cobalt ion spin is S = 3/2 and is

ferrimagmetically coupled to the iron S = V2. If an abundance of alkali metals are available

during synthesis, the charge is balanced by trapping available alkali cations into the lattice,

giving an empirical formula of ACo111[Fe11(CN)6]. In this lattice, four alkali metal ions are held

in the tetrahedral holes of each unit cell and the lattice is complete. The result is a rigid structure

with cobalt ions surrounded by six cyanide nitrogens causing a strong ligand field, placing the

cobalt in the low spin state. The low spin state of the cobalt coupled with a charge transfer to the

iron from the cobalt results in empty eg c anti-bonding orbitals in the cobalt ion. This









depopulation of the cobalt eg orbitals cause a lattice contraction of 0.40 A, compared to a

complex with no alkali cation. In this complex, the iron and cobalt are low spin d6 metals, and

diamagnetic.23 Both of these systems will maintain the spin state and magnetic properties when

cooled to 50 K.35

The use of an intermediate amount of alkali metal results in a compound that is between

these two extremes with a unit cell formula of A2Col4[Fe"l(CN)613.33 *4H20. There are alkali

metal ions in the interstitial holes, but there are still ferricyanide vacancies to achieve charge

balance. Each cobalt ion has an average of one water coordinating to it, lowering the octahedral

splitting (Ao) so that room temperature thermal energy allows for the population of the eg orbitals

of the cobalt. This results in magnetic behavior similar to a complex without alkali ions. When

the complex with partially filled vacancies is cooled from room temperature to 50 K the

magnetization decreases. This complex has been described as a CTIST, (charge transfer induced

spin transition) material.35'41 The type of alkali cation present affects the behavior of this change.

The analogues with sodium cations show very dramatic changes in magnetism over a narrow

temperature range as well as wide hysteresis in their warming curves that are attributed to

cooperative effects in the lattice. The larger cations exhibit more gradual decreases in

magnetism and narrow hysteresis. When the magnetism decreases, a charge transfer from the

Col" to the Fe"l' occurs along with a spin crossover of cobalt. The result is a complex that

transitions from a Fe"l' S = 2, Co" S = 3/2 ferrimagnetic pair to a Fell S = 0, Co"l' S = 0

diamagnetic pair.23'25'35 After the transition, the network behaves similar to a solid with no

ferricyanide vacancies. The network retains a small amount of ferrimagnetic material referred to

as non-switchable pairs or primordial spins. This primordial material displays magnetic behavior

similar to a complex without alkali ions even at low temperatures.









The other interesting property of the cobalt iron Prussian blue analogue is the

photoinduced magnetism. The elemental composition and ligand field strength around the cobalt

must be similar to that in the CTIST material. At temperatures below 20 K, the predominately

diamagnetic Co"l', Fell material may be photoexcited using 600 nm light and converted to the

ferrimagnetic Co"1, Fe"l' species, thereby increasing the magnetization. This excited material is

now in a long-lived, meta-stable excited state, which will decay slowly over several days. The

process is reversible by irradiation with 450 nm light or by thermal treatment of the sample to a

temperature of 100 K, both of which allow the complex to relax to the diamagnetic state.19'20

The photomagnetic effect of the cobalt iron Prussian blue analogue can be explained with

the aid of a potential energy versus internuclear distance diagram.23'25'35 (Figure 1-3) At low

temperatures, photoexcitation (light) provides the energy required to cause the charge transfer.

This high energy Fell' Co" Is pair relaxes back to the diamagnetic state by another charge transfer

or to the ferrimagnetic state through a spin crossover event at the cobalt. If the system is

continually photoexcited, all the photoswitchable diamagnetic material will be converted to

ferrimagnetic material. At low temperatures, this ferrimagnetic material is trapped in the excited

spin state by a potential energy barrier too large to be overcome by thermal energy, causing the

long-lived metastable excited state that has been reported for this compound.

Thin Films

Application of these exciting materials would likely require the formation of

homogeneous thin films and the development of methods for depositing material on solid

supports. Prussian blue and its analogues will not wet a surface well, and instead they form

insoluble microcrystalline powder samples. This property makes the formation of homogenous

films difficult. The most common method of generating Prussian blue films and their analogues

is the electrochemical method42-48. Other methods include dip-coating or spin casting of









colloidal solutions,42'49 adsorption onto sol-gel films,50'51 adsorption at Langmuir monolayers,52-59

and sequential adsorptions 60-67 onto modified surfaces.

Prussian blue films generated by electrochemical methods have demonstrated the ability

to form homogenous films, however the solid support employed needs to be a smooth

conducting surface, which excludes the use of the porous supports and polymers that would be

necessary to investigate the photomagnetic properties of the film. Dip-coating or spin casting of

colloidal solutions will offer the ability to use solid supports not available with electrochemical

methods, but fine thickness control is lost and films generated in this manner have heterogeneous

structures. Adsorption at a Langmuir monolayer provides for a uniform single layer of Prussian

blue, but requires separating the layers by the amphiphilic molecule on the surface. Of the

remaining adsorption techniques, the sequential adsorption method offers the advantages of

homogeneous film generation, availability of different solid supports, fine thickness control, and

the ability to easily tailor the composition of the film generated. Previous researchers using the

sequential adsorption method have developed dense, defect free films of the cobalt iron Prussian

blue analogue necessary for their ion transport research.63 Adaptations to this method need to be

made because previous studies of the powder samples of the cobalt iron Prussian blue analogue

indicate a need for the defects in order to observe photoinduced magnetic phenomenon.25'28'35

Nanoparticles

Another form in which the cobalt iron Prussian blue analogue could have a potential

application is with nanoparticles. The preparation of discrete photomagnetic nanoparticles

would be very exciting for applications in memory devices. Nanoparticles of Prussian blue and

analogues have been reported by other researchers,68-78 but very few have reported any

photoinduced magnetism.79'80 The formation of nanoparticles of Prussian blue and its analogues









happens easily. The aqueous reaction of the two component ions causes a colloidal suspension

of particles.

Methods of isolating the nanoparticles and restricting their growth involve coating the

particles with substrates to prevent aggregation. One substrate used is the water-soluble polymer

polyvinylpyrrolidone (PVP).71,72 The PVP is dissolved in the cationic metal solution where the

polymer interacts with the metal ion. When the anionic cyanometalate is added to the solution,

the Prussian blue analogue forms and the polymer coats the outside of the particle. Particle size

can be controlled by varying the amount of polymer added, with smaller particles resulting from

higher concentrations of polymer. Another method of controlling the size of the particle is to

control the size of the reactor.70'73 By using reaction mixture ratios of water and cyclohexane,

the size of the water droplets in the solution can be controlled. The addition of a protecting

polymer (Igepal) is still used in this case and is later replaced with an octadecylamine. The

principle is to generate a nanoparticle then prevent the particle from aggregating.

In the following chapters, a detailed report of the different uses of Prussian blue

analogues will be given. First, the formation and unique anisotropic magnetic behavior of the

cobalt iron Prussian blue analogue in thin films is discussed. The anisotropic behavior shows

that the magnetic properties of the cobalt iron analogue are different from the powdered solid

when the material is confined to a quasi-two-dimensional network. A discussion of the

incorporation of a higher Tc nickel chromium Prussian blue analogue into the film follows.

Again, anisotropic behavior was observed in the film and was not reported in the powdered solid.

In addition, the combination of cobalt iron and nickel chromium analogues in the same film,

magnetic behavior different than the cobalt iron film was observed. The focus of this

dissertation will then shift to two different methods of generating nanoparticles of the cobalt iron









Prussian blue analogue and the size dependent magnetic behavior of the particles. The final

chapters show that photomagnetic nanoparticles can be synthesized and that the powdered solid

behavior observed can be suppressed by restricting the size of the nanoparticle, a

superparamagnetic size limit of 10 nm was established for the PVP nanoparticles. The emulsion

nanoparticles appear to have a larger superparamagnetic limit. Below this size, few photoeffects

are seen in the particles. Data suggests that the surfaces of the nanoparticles are locked in the

low spin state and the core material is photoactive.





















Figure 1-1. Unit cell representation of the ACo[Fe"1(CN)6] nH20 analogue. Prussian blue
analogues form a face centered cubic network of divalent and trivalent metals bridged
by cyanide ligands with alkali ions in the tetrahedral holes of the network.


Figure 1-2. Unit cell representation of the Co".5[Fe"'(CN)6] 3H20 analogue. Prussian blue
analogues achieve charge balance by incorporating alkali cation into the network or
by leaving ferricyanide vacancies.










Fe(III)-CN-Co(II) Is




Fe(III)-CN-Co(II)hs

Fe(II)-CN-Co(III) Is
Internuclear distance


Figure 1-3. Potential energy diagram of the cobalt iron Prussian blue analogue. At low
temperatures the lowest energy state is the diamagnetic state. Excitation causes a
charge transfer to a high energy state that relaxes back to the diamagnetic state or to
the ferrimagnetic state by a spin crossover event. The system is then trapped in the
ferrimagnetic state by an energy barrier in a long-lived metastable excited state.23









CHAPTER 2
ANISOTROPIC PHOTOINDUCED MAGNETISM IN THIN FILMS OF THE PRUSSIAN
BLUE ANALOGUE

Introduction

Photoinduced magnetism in the cobalt iron Prussian blue analogue,

AjCok[Fe(CN)6]I *nH20, was discovered by Hashimoto and coworkers in 1996,19 and

subsequently studied by several groups.22,23,25,26,35'40 Diamagnetic Co"' (Is)-FeI" pairs may be

photoexcited to a long-lived metastable ferrimagnetic Co"1 (hs)-FeI"' state through a charge

transfer and spin crossover event, increasing the magnetism. Although still a low-temperature

phenomenon, many potential applications of this exciting class of materials will require

fabrication of thin films. The research is part of an ongoing study62'64-67'81-84 of the

AjCok[Fe(CN)6]I *nH20 system with the goal of developing fabrication methods for thin films of

molecule-based magnetic materials. Investigation of the magnetic and photomagnetic properties

of AjCok[Fe(CN)6]I *nH20 showed that, in addition to the magnetic and photomagnetic

phenomena present in powdered solids, the thin films exhibit a new phenomenon, a

photoinduced decrease in magnetization for a specific orientation of the film in the applied

magnetic field.65 The photomagnetic response of the thin films is anisotropic, increasing in one

orientation and decreasing in the other, when the externally applied magnetic field is less than

1.5 kG and the temperature is below the magnetic ordering temperature. This finding was

previously communicated65 and we proposed a model for the anisotropic behavior that depends

on the influence of residual magnetic moments in the film before photoexcitation. In this chapter

a complete study of the fabrication and magnetic behavior of thin films of

AjCok[Fe(CN)6]I *nH20 including thorough investigations of the parameters that determine the

photoinduced magnetic behavior is presented. These observations are used to qualitatively

validate the proposed mechanism for the novel thin film behavior.









Compounds of the family AjCok[Fe(CN)6]I *nH20 with partial [Fe(CN)6]3- vacancies have

been shown to exhibit Charge Transfer Induced Spin Transition (CTIST).35 When this complex

is cooled from room temperature to 50 K, there is a charge transfer from the Co"l to the Fe."'

along with a spin crossover event for the cobalt ion, while the iron remains low spin.

Specifically, regions of the compound transition from ferrimagnetic Co"1 (S = 3/2), Fe"l' (S = /2) to

diamagnetic Coll' (S = 0), Fell (S = 0) resulting in a decrease in magnetism. However, the

transition is not complete. Local heterogeneity in the distribution of ferricyanide vacancies cause

some of material to remain in the ferrimagnetic state. This component of the material is referred

to as non-switchable pairs, or primordial spins,65 and undergoes magnetic ordering near 20 K.

The ColI(ls)-Fe" pairs of the diamagnetic compound may be photoexcited using visible

light and converted back to the ferrimagnetic Col(hs)-Fe"' pairs, thereby increasing the

magnetization 9'22'25'35 and placing the material in a long-lived, metastable state. The process is

reversible by thermal treatment allowing the photoexcited states to relax to the diamagnetic

state.23

Methods of generating films and coatings of Prussian blue and its analogues include

electrochemical methods,42-48 dip-coating or spin casting of colloidal solutions,42'49 and

adsorption onto sol-gel films.50'51 Routes to films with nanoscale thickness include synthesis of

cyanometallate monolayers81'82 and adsorption of the cyanometallate at Langmuir

monolayers,54'55 and charged amphiphiles.5259 One of these methods by Einaga and coworkers58

reports anisotropy in a cobalt iron Prussian blue analogue film. However, no photoinduced

decrease was observed. Films of intermediate, submicrometer, thickness can be prepared by

synthesizing the cyanometallate directly on surfaces by sequential adsorptions of the constituent

ions.60-63'65-67 The sequential adsorption approach affords fine thickness control of homogeneous









films on a variety of different solid supports and the ability to easily tailor the chemical

composition of the film. Sequential adsorption techniques were used to produce the films

described in this study.

Experimental Section

Reagents and Materials

All reagents were purchased from Sigma-Aldrich or Fisher Scientific and used without

further purification. Trace metal grade nitric acid was used for inductively coupled plasma mass

spectrometry (ICP-MS) experiments, all other reagents were ACS grade. Deionized (DI) water

(18 MQ) was used for all experiments. Melinex, a polyethylene terephthalate polymer

535/380 gauge was obtained from DuPont Teijin films.

Sample Preparation of AjCok[Fe(CN)6] *nH20 Thin Films

Rbo.7Co4[Fe(CN)613.o '6H20. Slow growth.63 A sheet of Melinex was placed in a 5 mM

aqueous solution of cobalt(II) nitrate for 60 seconds. The film was rinsed with DI water, then

rinsed with methanol and dried with a stream of nitrogen. The film was then placed in a solution

containing 20 mM potassium ferricyanide and 0.12 mM rubidium nitrate for 60 seconds. The

film was rinsed with DI water, then rinsed with methanol and dried with a stream of nitrogen to

complete one cycle. The process was repeated for 5, 10, 20, 40, or 75 cycles to generate films of

varied thickness. Metal content was determined by ICP-MS using a 40 cycle film with resultant

metal percentages of Rb 3.2, Co 12.7, and Fe 9.0.

Rb2.3Co4[Fe(CN)613.i 5.4H20. Slow growth. The method was similar to the one

described above except a potassium ferricyanide solution containing 12 mM rubidium nitrate

was used. The film was rinsed with DI water and methanol then dried. Both 40 and 75

deposition cycle films were generated. Metal content was determined by ICP-MS using a 40

cycle film with resultant metal percentages of Rb 10.6, Co 12.4, and Fe 8.9.









Ko.sCo4[Fe(CN)613.2 *4.8H20. Slow growth. The method was similar to the one described

above except a potassium ferricyanide solution containing 12 mM potassium nitrate was used.

Both 40 and 75 deposition cycle films were generated. Metal content was determined by

ICP-MS using a 40 cycle film with resultant metal percentages of K 0.37, Co 4.5, and Fe 3.4.

Rbo.7Co4[Fe(CN)613.0 61120. Fast growth.65 A hydrophilic solid support, such as silicon

or Melinex was used as a solid support. The solid support was quickly immersed 5 times in a

5 mM aqueous solution of cobalt(II) nitrate. The excess solution was drained, and the solid

support was quickly immersed 5 times in an aqueous solution of 20 mM potassium ferricyanide

and 12 mM rubidium nitrate. The solid support was then rinsed with DI water. This process was

repeated 1, 5, 10, 20 or 40 times to generate films of increasing thickness. After deposition, the

film was rinsed with methanol and dried under vacuum. Metal content was determined by

ICP-MS using a 40 cycle film with resultant metal percentages of Rb 3.2, Co 12.7, and Fe 9.0.

Instrumentation

The elemental analyses were performed by ICP-MS on a Thermo-Finnigan Element-2

spectrometer. FTIR spectra were recorded using a Nicolet 6700 spectrometer. Atomic force

microscopy (AFM) measurements were performed using a Digital Instruments multimode

scanning probe microscope. Scanning electron microscopy (SEM) images were obtained using a

Hitachi S-4000 FE-SEM. Magnetic measurements were made by the University of Florida

Department of Physics using a Quantum Design MPMS XL superconducting quantum

interference device (SQUID) magnetometer. A bundle of 10 optical fibers, 270 [tm O.D. (Ocean

Optics Model 200) was used to introduce light, from a room-temperature, halogen-light source,

of 1-2 mW power into the SQUID magnetometer for photoinduced experiments.85









Analysis Preparations

Melinex supports were cut to 8 cm x 2.5 cm and cleaned using methanol. For

transmission FT-IR ATR experiments, 20 cycles of material were deposited using the fast

method, the film was then pressed against a silicon ATR crystal, and the spectra was obtained.

ICP-MS samples of 40 cycle films were prepared by digesting the thin film and Melinex in 2 mL

of boiling, concentrated sulfuric acid for 4 hours, resulting in a black liquid. Concentrated nitric

acid (0.5 mL) was then added dropwise, before diluting the mixture to 100 mL with DI water.

The samples were compared to matrix matched metal blends between 1 ppm and 1 ppb. The

resultant concentrations were normalized to a unit cell formula AjCo4[Fe(CN)6]i 'nH20 by fixing

4 cobalt ions per unit cell. The unit cell formula will then provide the formula used to determine

the molar mass of the analogue. The water content is assumed to be H20 molecules coordinated

to the cobalt and was determined by the number of ferricyanide vacancies, specifically,

n = 6(4-1). Using AFM, thickness and roughness data were obtained by averaging the

measurements of five different 4 tm2 scans. Thickness was determined by investigating the

height difference between the average thickness of the film and the solid support. The root mean

squared (RMS) average of height deviations taken from the mean data plane is used to express

roughness. For magnetic measurements the samples were cut into squares (-10.5 mm2) and

stacked, with the surfaces parallel, into a polyethylene sample holder. Background contributions

of the container and Melinex were measured separately and subtracted from the raw data. The

change in magnetization is expressed as the magnetization of the sample after the time of the

initial photoexcitation minus the magnetization at time 0. (AM = M(t) M(t=0))









Results


Film Generation and Characterization

All films were generated by sequentially adsorbing Co2+ and [Fe(CN)6]3- from aqueous

solution, adapting procedures previously described 60,61,63,65 for Prussian blue films and other

Prussian blue analogues. (Figure 2-1) The process is related to the often described layer-by-layer

deposition of polyelectrolytes, utilizing coordinate covalent bonds instead of purely electrostatic

interactions within the resulting film. The thickness can be tuned by adjusting the number of

deposition cycles, and films can be fabricated over large surface areas using a variety of solid

supports. This last point becomes important because transparent diamagnetic solid supports are

needed for photomagnetic experiments. Standard glass or silicon supports can still be used for

other chemical and spectroscopic analyses without detectable changes in film composition or

quality.

Deposition normally begins by adsorption of ions to a charged surface. For the Melinex

supports, the surface charge results from a nitrogen-containing, adhesion-promoting coating

placed on the surface by the manufacturer. It takes several deposition cycles to achieve complete

surface coverage. Our group previously demonstrated that homogeneous surface coverage can

be achieved for a thin film by first modifying the surface with a cyanometallate monolayer,

prepared using Langmuir-Blodgett methods.62'82 However, the studies described herein utilize

thicker (50-300 nm) films so the template layer is not needed.

During a deposition cycle, the solid support was first immersed in an aqueous solution

containing Co2 ions, followed by immersion in a solution containing A+ and [Fe(CN)6]3- ions.

The process can be controlled to alter the rate of deposition, and two methods, referred to here as

slow and fast, were used to generate films. In the slow method, the substrate is rinsed between

changing solutions, limiting the amount of material deposited during each cycle. For the fast









method, substrates were immersed in both solutions before rinsing, resulting in a film that

developed quickly. Film thickness, measured using AFM, increases with number of cycles for

both methods (Figure 2-2).

The surface topology of the films can be compared with SEM. (Figures 2-3 and 2-4)

After only one cycle of the fast method, the substrate is still visible, indicating that uniform

coverage is not yet achieved. It takes five cycles to completely cover the substrate with powder-

like features. The surface morphology is retained as the film develops beyond 5 cycles (Figure

2-3). Using the slow method, complete coverage is not obtained until 20 cycles, at which point

the films show similar morphology to those of comparable thickness generated with the fast

method. Complete surface coverage is achieved between 30 and 50 nm of thickness for both

methods. Surface roughness measurements confirm the SEM observations (Table 2-1).

All films are light pink, with uniform coloration over the surface of the substrate. Room

temperature IR spectra, shown in Figure 2-5 for a 160 nm film, display two cyanide stretching

bands, a sharp peak at 2169 cm-1, attributed to cyanide bridging Col(hs)-FeI", and a broader peak

centered at 2110 cm-1, attributed to cyanide bridging Col"(ls)-Fe" with a shoulder at 2085 cm-1

attributed to the cyanide bridging CoI(hs)-Fe". The energy of these stretches agrees with

previously reported data for powdered solids23 of similar rubidium concentrations confirming the

targeted material is deposited on the surface.

Magnetic Behavior with HE Parallel to the Thin Films

The thin films exhibit magnetic behavior similar to powder samples, when the plane of

the film is oriented parallel to the external magnetic field, HE. Temperature dependent zero-

field-cooled (zfc) and field-cooled (fc) measurements from 5 K to 30 K were performed with the

film plane parallel to HE = 200 G, and data from a 160 nm film are shown in Figure 2-6. An

apparent Tc, defined here as the temperature at which the magnetization begins to increase, is









near 15 K. The fc and zfc magnetizations bifurcate near 9 K, and there is a maximum in zfc

magnetization at T ~ 7 K. Upon photoexcitation, Tc increases to 18 K and the peak temperature

in zfc magnetization shifts to T ~ 9.5 K. (Figure 2-6)

The magnetic response is consistent with the reported behavior of powder samples of

cobalt iron Prussian blue analogues.23'25'58 The dark state response is attributed to glassy

behavior86'87 of disordered interacting clusters of ferrimagnetically ordered Col(hs)-FeI"' regions

that have not undergone charge transfer and spin crossover demagnetization upon cooling. With

illumination, some diamagnetic pairs that did undergo spin crossover upon cooling are switched

to the Col(hs)-FeI"' state, causing an increase of the concentration and size of ferrimagnetic

clusters. The result is enhanced magnetization, and also an increase in blocking temperature,

defined as the temperature at which the fc and zfc plots bifurcate, from 9 K to 11 K due to larger

size or increased concentration of domains.85

Anisotropic Photomagnetic Behavior

With the planes of the films oriented perpendicular to the applied magnetic field, the

photoeffects are different. The temperature dependent fc and zfc measurements from 5 K to

30 K with HE = 200 G perpendicular to the same 160 nm film shown in Figure 2-6, are shown in

Figure 2-7 for both the light and dark states. The dark state data are essentially the same as in

the parallel orientation. In addition, upon photoexcitation, the Tc of 16 K increases to 18 K, and

there is also an increase in the blocking temperature shifting from 10 K to 11 K. These trends

are similar to the ones observed for HE parallel to the film. However, the magnetization of the

photoinduced (light) sample is now lower than the dark sample. In other words, there is a

photoinduced decrease in magnetization.

The anisotropic photoinduced response of the thin films is more clearly illustrated by

plotting the time dependent change of the magnetization upon irradiation with visible light.









Figure 2-8 shows the magnetization versus time at 5 K, with HE = 200 G in both orientations, for

a 75 nm thick film. Upon irradiation, the magnetization of the film increases by 4 emuG/cm3

when oriented parallel to HE = 200 G, and decreases by 2 emuG/cm3 when perpendicular to the

same HE.

Alkali Cation Dependence

Photoinduced magnetism in the cobalt iron Prussian blue is not restricted to Rb+

analogues, but has also been reported in Na K+, and Cs+ salts.19'22'23'25'29'35'46 Other thin film

compositions were therefore investigated to determine if the anisotropy seen for the Rb+

analogues depends on chemical formula. A potassium containing film with formula

Ko.sCo4[Fe(CN)6]3.2 *4.8 H20 was generated. The time dependent change in magnetization of an

86 nm film at 5 K is shown in Figure 2-9 when HE = 200 G and is perpendicular to the film. As

for the Rb+ films, a photoinduced decrease in magnetization was observed, indicating that the

anisotropic photoresponse is not alkali cation specific.

Increasing the concentration of alkali ions in the interstitial sites of powdered solids of

cobalt iron Prussian blue analogues leads to fewer ferricyanide vacancies and increases the

average ligand field strength around the cobalt.25'35 The increased ligand field strength hinders

the temperature dependent spin crossover, eliminating the presence of photoswitchable pairs and,

therefore, any photoinduced change in magnetism. Figure 2-10 compares the time dependent

photoinduced magnetization of slow 75 cycle films (86 nm) with different Rb+ ion content,

Rbo.7Co4[Fe(CN)6]3.0 *6 H20, and Rb2.3Co4[Fe(CN)6]3.1 *5.4 H20. Figure 2-10B shows

photoinduced magnetism of the Rb2.3 film. On this scale thermal effects are clear and correspond

to an increase in temperature of 0.7 K. The beginning of illumination causes an increase in

temperature and corresponding decrease in magnetization of the film. When the illumination

ceases after 1 hour the sample cools and an increase in magnetization is observed. The slope of









the data before and after illumination is attributed to the glassy nature of the film. As for

powdered solids, there is little photoinduced change in magnetization for thin films with higher

alkali ion content.

Field Dependent Magnetic Behavior of 75 nm and 160 nm Films

The effect of the external magnetic field strength on the photoinduced decrease in

magnetism was explored by comparing the time dependent change in magnetization in external

fields of HE = 200 G and 5 kG. Data for 75 nm and 160 nm films oriented perpendicular to HE

are presented in Figure 2-11. Whereas the films show a photoinduced decrease of magnetization

for HE = 200 G, both samples show a photoinduced increase in magnetization when HE is

increased to 5 kG.

The observation that the increase or decrease of photoinduced magnetization is related to

the strength of HE, suggests that there should be a field for which no photoinduced change in

magnetism is observed. To look for this transition, the field dependent magnetization of a

160 nm film was measured at 5 K for both the dark state and saturation light state. (Figure 2-12)

As shown in the figure insert when the HE is around 1.5 kG, the photoinduced magnetization

becomes greater relative to the dark state magnetization, so a photoinduced increase in

magnetization is expected for fields greater than 1.5 kG. Below 1.5 kG, the magnetization of the

photoinduced state is less than the dark state, so a photoinduced decrease in magnetization is

observed.

Effect of Film Thickness

The photoinduced decrease in magnetism is not observed for powdered solids but only in

continuous thin films, so the influence of film thickness was investigated by taking advantage of

the ability to control the thickness of the films with the sequential adsorption process. The

photomagnetic response of four films, with thicknesses of 51, 75, 160 and 300 nm, were









measured at T = 5 K with HE = 200 G applied perpendicular to the plane of the films.

(Figure 2-13) The 51, 75, and 160 nm films all show a photoinduced decrease. However, for the

300 nm film, a photoinduced increase in magnetization is observed. In addition, the magnitude

of the effect varies as the thickness changes. At first, the magnitude of the decrease becomes

larger as films become thicker. However, by the time the film is 160 nm thick, the magnitude of

the photoinduced decrease has diminished. By 300 nm, the effect is reversed, and a

photoinduced increase is observed.

Temperature Dependence of the Anisotropy

Magnetic data in Figures 2-8 through 2-13 were obtained at 5 K, below the onset of

ferrimagnetic ordering of the magnetic domains. Above the ordering temperature,

photoswitchable pairs are still present because the charge transfer/spin crossover state persists

until much higher temperatures, nominally up to 200 K. To determine if the photoinduced

decrease is a property of the ordered state, the photoresponse was studied above the ordering

temperature of a film that was previously shown to exhibit a photoinduced decrease at 5 K. The

time dependent response of the 160 nm film studied in Figure 2-13 was then measured at 20 K.

(Figure 2-14) Above the ordering temperature, the 160 nm film displays a photoinduced

increase in magnetism. The result shows that the photoinduced decrease in magnetism is a

property of the film below the ordering temperature.

Discussion

Cobalt iron Prussian blue analogue films prepared using sequential adsorption methods

exhibit several properties typical of the more extensively studied powdered solids. With

appropriate composition, a fraction of the material in the films undergoes charge transfer and

spin crossover and the residual high spin fraction orders giving a ferrimagnetic state at low

temperature. The low temperature magnetic properties are consistent with cluster spin glass









behavior, which also characterizes the known powdered solids. Upon photoexcitation, Tc

increases, as does the blocking temperature, indications that the size or concentration of

magnetic domains in the sample increases. With the film oriented parallel to the magnetic field,

photoexcitation yields an increase in magnetization. Compositions that exhibit these

photoeffects in powdered solids also show them in thin films. These observations indicate that

the microscopic mechanism by which the magnetization changes with light is the same in the

films as was seen before with the powdered solids. However, the photoresponse of the films is

anisotropic. The photoinduced increase in magnetism seen when the film is oriented parallel to

the magnetic field becomes a photoinduced decrease when the film is oriented perpendicular.

An orientation dependent photoinduced decrease is never seen in the powdered solids. Initial

attempts to attribute the anisotropic behavior to chemical anisotropy using room and low

temperature have been unsuccessful. Better methods of detecting chemical anisotropy in films

are discussed in future works in chapter 6.

The anisotropic photoeffects are influenced by a number of factors. The first is the

increase in field strength; by increasing HE to ~1.5 kG, when HE is perpendicular to the film, the

photoinduced decrease in magnetization becomes a photoinduced increase as HE becomes

greater. Film thickness also plays an important role. As films become thicker, the photoinduced

decrease diminishes and, by 300 nm, becomes a photoinduced increase like in the parallel

orientation and the analogous powdered solids. Furthermore, the photoinduced decrease is only

observed below the ferrimagnetic ordering temperature. At 20 K, a photoinduced increase is

observed. Taken together, these observations suggest that the requirements for observing a

photoinduced decrease in magnetization include the presence of ordered magnetic domains, thin

film organization, and low applied magnetic field strength.









The behavior in the thin films can be explained by considering the influence of the

dipolar field (HD) emanating from magnetic domains present in the dark state film.65 The

photoswitchable component of the films consists of diamagnetic Col"(ls)-Fe" pairs that

underwent charge transfer and spin crossover upon cooling. Also present is residual high spin

material that undergoes ferrimagnetic ordering at low temperature, generating magnetic domains.

With respect to photoinduced effects, these domains can be considered primordial moments.

With an applied field perpendicular to the film, these primordial moments will align along HE.

The primordial moments themselves will generate a magnetic field that will oppose HE in the

plane of the film. Therefore, proximal photoinducible regions in the plane of the film will

experience both HE and an opposing HD (Figure 2-15). When HE is small, the photoswitchable

pairs generate moments that align with HD, against HE, and a photoinduced decrease in

magnetization is observed.

The proposed mechanism is consistent with the observations made upon changing

different experimental parameters. For example, if HE is increased such that HE > HD, the new

photoinduced moments align with HE, and a photoinduced increase in magnetism is observed, as

reported in Figure 2-11. The data from Figure 2-12 show that a HE of 1.5 kG will transition from

a photoinduced decrease to a photoinduced increase. This indicates that the HD generated for the

160 nm film is approximately 1.5 kG.

The proposed dipolar field model also accounts for why the photoinduced decrease is

observed in thin films and not for the bulk powders. The quasi-two-dimensional arrangement of

the primordial moments is necessary for the photoswitchable pairs to experience internal fields

that predominately oppose the applied field. The photoswitchable pairs must be in the plane

perpendicular to the net magnetic dipole moment of the ordered domains to experience HD









antiparallel to HE. Such an arrangement exists in a thin film. On the other hand, in the bulk,

photoswitchable pairs can be surrounded by primordial moments in all directions, effectively

canceling the influence of these internal dipolar fields, so they respond to HE upon

photoexcitation. For the films studied in Figure 2-13, the transition from quasi-two-dimensional

to bulk-like is observed. Thinner films exhibit a photoinduced decrease in magnetization, while

the effect is diminished for thicker films. For the films studied here, the transition to three-

dimensional behavior begins for thicknesses greater than 75 nm, suggesting that the important

interaction length is of this order. By 300 nm, bulk-like behavior is seen.

The proposed dipolar field model requires the presence of ordered primordial moments,

which explains why the photoinduced decrease is only observed below the ordering temperature.

Above the ordering temperature, the local moments of the residual high spin fraction are not

ordered, resulting in a random arrangement of HD in the sample, allowing the photoinduced

moments to follow HE and increasing magnetization.

Einaga and coworkers58 reported anisotropic behavior in cobalt iron Prussian blue

analogue films generated using exfoliated clay and didodecyldimethylammonium bromide as the

charged surface to form the layer. Although the magnetic behavior was anisotropic, no

photoinduced decrease was reported. In this case the cobalt iron layers were clearly isolated in

the z-direction by the semectite clay and didodecyldimethylammonium bromide used to form the

film. The in-plane structure was composed of a disordered arrangement of wire or rodlike

structures 4 A thick. This arrangement yields networks that are structurally anisotropic88 and

gives rise to a magnetic easy axis in the plane of the film. The intrinsic disorder of the clay-

based films causes a decrease in the resulting HD and allows HE to dominate the magnetic

behavior during photoinduced experiments. This arrangement is significantly different from our









system, which at the molecular level is continuous in three-dimensions and contains no structural

anisotropy or easy axis. The anisotropy in our system is a result of the HD from the primordial

spins influencing the proximal diamagnetic material during photoexcitation.

Conclusions

Cobalt iron Prussian blue analogue films prepared using sequential adsorption methods

exhibit several properties typical of the more extensively studied powdered solids. These

observations indicate that the microscopic mechanism by which the magnetization changes with

light is the same in the films as with the powdered solids. However, unlike previously studied

bulk solids, the photoresponse of the films is anisotropic. The photoinduced increase in

magnetism seen when the film is oriented parallel to the magnetic field becomes a photoinduced

decrease when the film is oriented perpendicular to the magnetic field.

The anisotropic photoeffects are influenced by field strength, film thickness and

temperature. The behavior in the thin films can be explained qualitatively by considering the

influence of the dipolar field emanating from primordial magnetic domains present in the dark

state film. The ability to direct a photoinduced magnetic increase or decrease affords another

level of control only available in thin films of the cobalt iron Prussian blue analogue and may be

useful in potential device applications of this class of material.









Table 2-1. Thickness and roughness data for films of Rbo.7Co4[Fe(CN)6]3.0 *6H20
Number of cycles Average RMS roughness

thickness (nm)

(nm)

slow method

20 34 3 12

40 71 + 15 22

75 86 3 37

fast method

5 51 8 17

10 75 20 23

20 160 30 62

40 300+ 30 100

Average thickness of the AFM scans and the average thickness standard deviation are reported.
Surface roughness is expressed as root mean squared (RMS) average of height deviations taken
from the mean data plane.




















A,Co,[Fe(CN),], nH 0


Figure 2-1. The sequential adsorptions method showing the deposition of cationic and anionic
building blocks to form the cobalt iron Prussian blue analogue. Adapted from
Polyhedron 2007, 26, 2273.84


300 -

S 200

S100 -




0 20 40 60 80
Number of Cycles
Figure 2-2. Thickness vs. number of cycles for the slow growth, (*), and fast growth, (m),
sequential adsorptions deposition methods used to generate thin films of the cobalt
iron Prussian blue analogue. Error bars represent the average thickness standard
deviation. Adapted from Polyhedron 2007, 26, 2273.84























Figure 2-3. The SEM images of fast method films, a-e, with thicknesses of 21 nm, 51 nm,
75 nm, 160 nm, and 300 nm, respectively. A 1 [tm scale bar is shown in each image.
The deposition method develops a continuous film after 5 cycles (b). The surface
morphology is retained as the film develops beyond 5 cycles. Adapted from
Polyhedron 2007, 26, 2273.84


Figure 2-4. The SEM images of slow method films, a-c, with thicknesses 22 nm, 34 nm, and
71 nm, respectively. A 1 [tm scale bar is shown in each image. Uniform coverage is
achieved after 20 cycles (b); less material is deposited by the slow method when
compared to the fast method. Slow films show roughness and surface coverage
similar to fast films of similar thicknesses. Adapted from Polyhedron 2007, 26.84






















2200 2100


Wavenumbers (cm-1)
Figure 2-5. Room temperature FT-IR ATR spectra of a 160 nm film on Melinex. A sharp peak
at 2169 cm-1 is attributed to the Co"(hs)-NC-Fe"' bridging cyanide stretch and the
broad peak centered at 2110 cm-1 is attributed to the Col"(ls)-NC-Fe" bridging
cyanide stretch with a shoulder at 2085 cm-1 attributed to the cyanide bridging
Col(hs)-FeI". IR bands are similar to those found in powder samples containing Rb+
ion.


30


20

10
C)


T (K)
Figure 2-6. Plots of fc and zfc DC magnetization of a 160 nm thick film parallel to HE = 200 G
in dark and photoinduced (light) states.


HE parallel to film
A fc light
e v zfc light
0 fc dark
zfc dark


2000












- 15

10

I 5

0


I I a I I
0 10 20 30
T (K)
Figure 2-7. Plots of fc and zfc DC magnetization of a 160 nm thick film perpendicular to
HE = 200 G in dark and photoinduced (light) states.


0 20 40 60
Time (min)
Figure 2-8. Anisotropy in the photoinduced magnetization of a 75 nm film of
Rbo.7Co4[Fe(CN)6]3.0 *6H20, measured at 5 K with the measuring field of 200 G
oriented parallel and perpendicular to the film. The time axis is relative to the point
the light is applied. The relative change of magnetization AM = M(t) M(t=0) is
shown.


HE perpendicular to film -

\, fc dark
zfc dark

0: oo 0 fc light
* o< "o o zfc light
0o 8 C
0 SC3
80l









0.00


-0.05

| -0.10

I -0.15

-0.20

-0.25


I i
Light on







I
*
*
*
*


I


Time (min)
Figure 2-9. Change in magnetization for a 86 nm film of Ko.5Co4[Fe(CN)613.2 *4.8H20
perpendicular to HE of 200 G at 5 K. A photoinduced decrease in magnetization is
observed. The time axis is relative to the point the light is applied. The relative
change of magnetization AM = M(t) M(t=0) is shown.


Trne (nin)


Figure 2-10. (A) Rubidium ion concentration dependence of the photoinduced magnetization of
75 cycle slow cobalt iron Prussian blue analogue films, (A)
Rb2.3Co4[Fe(CN)6]3.1 *5.4H20, and (m) Rbo.7Co4[Fe(CN)6]3.0 *6H20. Films with
higher rubidium concentration do not experience a photoinduced decrease in
magnetism. The time axis is relative to the point the light is applied. The relative
change of magnetization AM = M(t) M(t=0) is shown. (B) The Rb2.3 film plotted
on a relative change of magnetization of 10-3 emuG/cm3. Thermal effects of heating
approximately 0.7 K and glassy behavior dominate the data.
















H E = 5 kG



HE = 200 G

-2
0 20 40
Time (min)

Figure 2-11. Applied field dependence of the photoinduced magnetization with HE
perpendicular to the plane of the film. Data for a 75 nm of film
Rbo.7Co4[Fe(CN)6]3.0 *6H20 measured with HE = 200 G (e) and 5 kG (o) and a 160
nm film Rbo.7Co4[Fe(CN)6]3.0 6H20 with HE = 200 G (m) and 5 kG (o) are shown.
The time axis is relative to the point the light is applied. The relative change of
magnetization AM = M(t) M(t=0) is shown.



150* o o

0
100 .o


20
50 2

0
0 1 2
00 H(kG)

H (kG)
Figure 2-12. The field dependent magnetization of a 160 nm film of Rbo.7Co4[Fe(CN)6]3.0 *6H20
was measured at 5 K with the magnetic field perpendicular to the field. At a HE
-1.5 kG no difference in magnetization is observed between the dark state (.) and the
photoinduced state (o).Adapted from Ju-Hyun Park's dissertation.85













S I '+++I+ 1 UU 11111
1 o 51 nm
-1 0


'75 nm
< -2 .Light on


0 20 40 60
Time (min)
Figure 2-13. Thickness dependence of the photoinduced magnetization in cobalt iron Prussian
blue analogue thin films with HE perpendicular to the film plane. The films less than
160 nm thick show a decrease in magnetization upon illumination. As films become
thicker, the photoinduced effect becomes an increase in magnetization, similar to that
of bulk powder samples. The relative change of magnetization AM = M(t) M(t=0)
is shown with photoexcitation ending at 60 min.


0.25


0.20


0.15


0 20 40
Time (Min)
Figure 2-14. Photoinduced magnetism of a 160 nm film of Rbo.7Co4[Fe(CN)6]3.0 o6H20 at 20 K
with HE = 200 G perpendicular to the film. The light is applied at t = 0 min and
discontinued at t = 40 min. Above the onset of ferrimagnetic ordering, there is a
photoinduced increase in magnetism.










Dark (Below Tc) HE Film
,A *% ,,,, .




Light
HDHE



tti* Primordial 0 Photoinduced
CoFe CoFe

Figure 2-15. The photoinduced magnetism in a quasi-two-dimensional film of cobalt iron
Prussian blue analogue. The direction of the induced moments will depend on the
vector sum of the dipolar field (HD) from the primordial moments and the applied
magnetic field (HE). Adapted from Polyhedron 2007, 26.84











CHAPTER 3
HETEROGENOUS PRUSSIAN BLUE ANALOGUE FILMS

Introduction

The preceding chapter showed the use of the sequential adsorption method to generate

thin films of the cobalt iron Prussian blue analogue in a controlled manner. Taking advantage of

the vast number of metals that can be bridged by cyanide ligands allows for films that

incorporate more than two metals, possibly incorporating properties of different analogues in the

same film. The cobalt iron Prussian blue analogue incorporates the desirable trait of

photomagnetic response. Other Prussian blue analogues display magnetic ordering at higher

temperatures. Combinations of analogues can be incorporated in the same film in a regular

manner by varying the component solutions used in the sequential adsorption method.

The nickel chromium Prussian blue analogue shows a higher magnetic ordering

temperature (Tc) in bulk samples with temperatures ranging from 75 K, in the absence of any

charge balancing alkali ion, to 90 K, for compositions with the maximum number of alkali ions

incorporated.14 Prussian blue analogues with higher Tc have been reported, but all contain

vanadium(II)16 or chromium(II),17'18 both are unstable in aqueous solutions. The nickel

chromium Prussian blue analogue was selected as the second component for the heterogeneous

film to test for changes in photomagnetic effects following work included in Ju-Hyun Park's

dissertation8 5

The sequential adsorption method has been shown to generate quasi-two-dimensional

films of Prussian blue analogues. The thickness of the film is controlled by changing the number

of deposition cycles.84 A new material could be introduced simply by changing the ions

dissolved in the solution during the sequential adsorption method, provided the new ions are









capable of attaching to the material already existing on the support. By changing the component

solution at regular intervals, heterogeneous films of Prussian blue analogues can be developed.

(Figure 3-1)

At low temperatures, the cobalt iron Prussian blue analogue is diamagnetic except for

primordial spins.65 In theory, a cobalt iron layer sandwiched between two nickel chromium

layers separates the nickel chromium Prussian blue analogue layers, there by supressing

magnetic ordering in the Z direction. (Figure 3-2) If the layers are to be continuous in the plane

of the film and sufficiently thin to be two-dimensional in nature then a decrease in Tc for the

nickel chromium Prussian blue analogue is observed.89 The structural order of the film is

maintained as the sequential adsorption method builds each layer on top of the last, using the

trivalent hexacyanometalate moieties to bridge divalent metals. With photoexcitation, the cobalt

iron Prussian blue analogue is expected to participate in magnetic exchange and will allow

magnetic communication between the isolated quasi-two-dimensional layers of the nickel

chromium Prussian blue analogue. The increase in magnetism comes from two sources. The

increase is partly due to the excitation of the cobalt iron Prussian blue analogue into the meta-

stable state through charge transfer and spin crossover processes. The second source of the

increased magnetism is due to the increase in magnetic exchange between the isolated layers of

the nickel chromium Prussian blue analogue. Depending on the sign (ferromagnetic or anti-

ferromgnetic) of the coupling, the interaction between the two different Prussian blue analogue

layers may increase or decrease the net magnetization of the film and, consequently, may shift

the Tc accordingly.

Initial investigations of a 20 cycle nickel chromium analogue film that have not been

published else where have been conducted. Spin glass behavior was observed in the dc









susceptibility data conducted at varying fields with the plane of the film perpendicular to the

applied magnetic field. The zfc maximum shifts temperature with different applied magnetic

fields. (Figure 3-3) The Tc and spin glass behavior corresponded with the expected behavior

that was similar to the powdered solid.

For these experiments, different sequential adsorption deposition combinations were

utilized. (Figure 3-4) The fast method from chapter two was used to generate a film of nickel

chromium Prussian blue analogue to determine the individual properties of the film. The nickel

chromium analogue will be termed the A layer and the cobalt iron analogue the B layer. Then a

film containing a layer of cobalt iron Prussian blue analogue on top of a nickel chromium

Prussian blue analogue was generated (stacked AB film). Also, a film where the solutions were

alternated after every deposition cycle was generated (mixed film). The slow method from

chapter two was used to generate films comparable to the fast films. Finally, a film with a layer

of cobalt iron Prussian blue analogue between two layers of nickel chromium Prussian blue

analogue was generated using the fast method (sandwich ABA film).

The magnetic and photomagnetic behavior of the different deposition methods oriented

parallel and perpendicular to the applied magnetic field is the subject of this chapter. The

magnetic behavior of the nickel chromium Prussian blue analogue film was compared to the

reported powdered solid.14 Magnetic anisotropy was observed indicating that there was a

magnetic easy axis in the plane of the film. When the two different analogues were stacked on

top of one another in an AB or BA manner, the magnetic behavior was the sum of the behaviors

of the individual layers in the same film. As the layers were mixed to prevent any regions of a

continuous A or B layers developing, all the properties of the individual A or B layers were lost.

In the final ABA sandwich deposition arrangement, magnetic properties were observed in the









films that were different from the sum of the component films, indicating an interaction between

the different layers.

Experimental

Materials and instrumentation described in chapter two have been used for the films

discussed here. The sequential adsorption fast method was used to generate films. The

procedure was the same as the cobalt iron Prussian blue analogue film and the same

concentrations of Co(N03)2 *6H20, K3[Fe(CN)6] and RbNO3 were used for the solutions. To

provide Ni2 10. mM Ni(N03)2 *6H20 was used. Solutions of 10. mM K3[Cr(CN)6] mixed with

12.5 mM RbNO3 were used to provide [Cr(CN)6]3- and Rb+. A nickel chromium Prussian blue

analogue film was developed (film 1) by alternating 10 depositions between the Ni2+ and

[Cr(CN)6]3- solutions and rinsing after each cycle to build a film. To create a stacked AB film

(film 2), 10 deposition cycles of nickel chromium Prussian blue analogue were deposited, and 10

cycles of cobalt iron Prussian blue analogue film were then added. The deposition order was

then reversed BA film (film 3). A mixed film (film 4) was generated using the fast method

alternating between the two analogues with rinsing in between each analogue set of solutions for

a total of 20 cycles. The final fast film, a sandwich ABA film (film 5), was created by depositing

10 cycles of nickel chromium Prussian blue analogue followed by 10 cycles of cobalt iron

Prussian blue analogue and finally by another 10 cycles of of the nickel chromium analogue.

Attempts were made, that will not be reported, to tune the thickness of each layer by

adjusting the number of deposition cycles before changing analogues. In all cases the behavior

was similar to the stacked film if more than five cycles were deposited. After five deposition

cycles complete coverage is achieved. However, the layer spacing appeared to be too great to

change the ordering temperature of the nickel chromium analogue as was the original goal. For

films with less than five cycles of deposition before the solutions were changed, the magnetic









behavior was similar to the mixed film, resulting in a film that appeared to be random at the

molecular level.

The sequential adsorption slow method was also used to generate films. The procedure

was the same as the cobalt iron Prussian blue analogue film, rinsing after 1 minute of immersion

in each solution, mentioned in chapter two. To reduce the amount of Rb ion adsorbed onto the

Prussian blue analogue, the rubidium concentration used was only 0.12 mM. The first slow film

created (film 6) had 40 cycles of nickel chromium Prussian blue analogue followed by 40 cycles

of cobalt iron Prussian blue analogue stacked AB. Film 7 alternated analogues every deposition

cycle forming a mixed film. A short hand method of communicating the film structure will be

employed. The first analogue deposited will be the first letter with the number (n) of cycles as a

subscript then the second letter with n cycles will be indicated. The sequential deposition

method used will be given as a superscript outside the brackets fast (f) or slow (s), finally the

total number of repeats will be indicated as a subscript. [AnBn]xt The methods used, fast or slow,

and film type is summarized in Table 3-1.

Results

Fast Nickel Chromium Prussian Blue Analogue Film 1

First, the magnetic properties of a film of nickel chromium Prussian blue were

determined. The Talham group has previously reported that a nickel chromium Prussian blue

analogue thin films can be generated using a surface modified with a two-dimensional metal

cyanide grid,62 however the fast and slow method do not employ such a template. A Melinex

substrate was cleaned with methanol and quickly immersed five times in a Ni2+ aqueous solution

and then immersed five times in a [Cr(CN)6]3- and Rb+ solution and was rinsed with deionized

water after every cycle. The process was repeated 10 times, resulting in a gray film deposited on

the substrate. [Alo0]f Magnetism versus temperature measurements were taken with the film









oriented parallel and perpendicular to the applied magnetic field for fc = 100 G and zfc

temperature sweeps. The film showed a Tc z 70 K, which is lower than the ordering

temperatures reported for a powdered solid14 and for a thicker 20 cycle film where Tc z 80 K 85

(Figure 3-5). On the other hand, Tc z 70 K is consistent with the results reported for the

templated films.62 The magnetic response was also anisotropic and is not observed in previous

work.

Fast Heterogeneous Stacked Films 2 and 3

The first film that combined the two different Prussian blue analogues was a film with

one interface between the two Prussian blue analogue regions. Each region had a nominal

thickness of 75 nm based on data from chapter two. The nickel chromium Prussian blue

analogue was deposited first using the fast method, followed by the cobalt iron Prussian blue

analogue [AioBio] f. Magnetic susceptibility versus temperature was examined with the film

parallel to an applied field of 100 G. Two separate ordering temperatures were observed. The

first one near 70 K and is attributed to the nickel chromium Prussian blue analogue. The second

ordering transition near 15 K is attributed to the cobalt iron Prussian blue analogue. This film

showed a bifurcation near 35 K that is typically seen with the nickel chromium Prussian blue

analogue powdered solid samples in a field of 100 G. (Figure 3-6).

The photomagnetic properties of the film were also investigated in the parallel and

perpendicular orientations relative to the applied magnetic field. At 5 K, the magnetic

susceptibility over time was measured at 100 G, shown with photoexcitation of the sample in

Figure 3-7. A photoinduced increase is observed in both directions, although the effect is much

weaker in the perpendicular direction. The increase in the parallel direction was

2.5 x 107 emu G/cm2 but was 0.2 x 107 emu G/cm2 in the perpendicular direction. The decrease









in magnetism attributed to heating of the sample from the light is readily observed in the plot of

the perpendicular orientation.

The stacked AB film 2 showed that the two separate behaviors demonstrated by the

single-component films can exist in a single film. The nickel chromium Prussian blue analogue

still showed a Tc of 70 K and the cobalt iron Prussian blue analogue displayed its own ordering

transition and photomagnetic behavior. The film exhibited a photoinduced increase in

magnetization over time in both orientations. The photoinduced increase is different than the

photoinduced decrease in the perpendicular direction observed in cobalt iron films of similar

thickness reported in chapter two.

The order of the deposition of the analogues was then switched [B1oA1o]fl. The cobalt

iron Prussian blue analogue was deposited first and covered with the nickel chromium Prussian

blue analogue. The photomagnetic properties of the film were investigated in the parallel and

perpendicular orientation relative to the applied magnetic field. At 5 K, the magnetic

susceptibility over time was measured at 100 G, shown with photoexcitation of the sample in

Figure 3-8. The photoincrease in the parallel direction was easily detectable and a change of

0.4 x 10 emu G/cm2 was observed. On the other hand, although magnetic changes consistent

with sample heating from the light were observed in the perpendicular direction, a persistent

increase in magnetism was not detected. The absolute magnetic susceptibility was higher during

the BA deposition arrangement compared to the AB arrangement, however the magnitude of the

photoinduced magnetization was lower indicating that more nickel chromium analogue had been

deposited on the film. The reduced magnitude of the photomagnetism indicates that less cobalt

iron analogue was deposited or the photoeffect of the cobalt iron was attenuated by the nickel

chromium.









Fast Mixed Heterogeneous Film 4

After observing the characteristic behavior of the nickel chromium Prussian blue

analogue and the cobalt iron Prussian blue analogue in a film with one interface, a mixed

heterogeneous film was deposited by alternating the analogues in each deposition cycle for a

total of 20 cycles [A1Bi]'fo. The fast method has been shown to deposit an average of 8 nm per

cycle. The surface coating produced by the fast method is far from uniform. There is a

significant amount of roughness on the surface and coverage is not complete on a single layer as

seen in the SEM image in chapter two. Fast films adsorb to the surface of the solid support in

small islands on the first cycle and with subsequent cycles builds upon the islands to form

complete coverage after five cycles. It is likely that there is mixing at the molecular level when

alternating between analogue solutions. Each cationic solution (Ni2+ or Co2+) can coordinate

with the two anionic species ([Fe(CN)6]3- or [Cr(CN)6]3-) to form four different Prussian blue

analogues: the nickel chromium and cobalt iron analogues that were targeted, and the nickel iron

and cobalt chromium analogues that both order ferromagnetically at 23 K.

Magnetic susceptibility verses temperature with with the film perpendicular to an applied

field of 100 G was measured. There is an increase in magnetic susceptibility with Tc 55 K,

however there was no divergence between fc and zfc data. (Figure 3-9) The film undergoes a

0.4 x 107 emu G/cm2 increase in magnetism when photoexcited perpendicular to the applied

magnetic field. (Figure 3-10) Consequently, it appears that the magnetic behavior of the film

was dominated by the nickel chromium Prussian blue analogue but trace behavior of the cobalt

iron Prussian blue analogue was also present.

Fast Heterogeneous Sandwich ABA Film 5

The final fast heterogeneous film type that was investigated was a sandwich ABA film.

[A1oB10oA1o]f In this film, 10 cycles of nickel chromium Prussian blue analogue was deposited,









followed by 10 cycles of cobalt iron Prussian blue analogue and a final layer of 10 cycles of

nickel chromium Prussian blue analogue. The photomagnetic properties of the film were

investigated in both the parallel and perpendicular orientations relative to the applied magnetic

field. At 5 K, the magnetic susceptibility over time was measured at 100 G, shown with

photoexcitation of the sample in Figure 3-11. When the applied magnetic field was parallel to

the film, there was a photoinduced increase in magnetism for 10 minutes, then an overall

photoinduced decrease in magnetism of 1 x 10- emu G/cm2 was observed. An initial

photoinduced increase followed by an overall photoinduced decrease had not been previously

observed in our films and will be discussed later. A photoinduced increase in magnetism of

7.4 x 107 emu G/cm2 was observed when film 5 was placed perpendicular to the applied

magnetic field. This increase was much larger than any other films reported, indicating that the

covering nickel chromium was not attenuating the cobalt iron layer. When compared to the

cobalt iron 10 cycle 75 nm film in chapter two, the photoinduced increase and decrease are in the

opposite orientations. Also, the value of the photoeffect is an order of magnitude smaller than

observed in the pure cobalt iron film.

To summarize the results presented to this point, fast heterogeneous films provided

evidence that the individual properties of the nickel chromium analogue and cobalt iron Prussian

blue analogue could be observed in the same film. It was also demonstrated that the

photomagnetic properties could be nearly eliminated by generating films without continuous

regions of the separate analogues by alternating the deposition solutions and forming a mixed

film. In an attempt to exercise greater control of the interface the slow method discussed in

chapter two was utilized to deposit layers.









Slow Heterogeneous Stacked AB Film 6

A stacked AB film was produced using the slow method. Film 6 contained a 40 cycle

layer of nickel chromium Prussian blue analogue deposited onto the Melinex substrate followed

by a 40 cycle layer of cobalt iron Prussian blue analogue similar to film 2. [A40B40]s' The

magnetism versus temperature measurements showed an ordering temperature near 70 K.

(Figure 3-12). The film also displayed a photoinduced increase in magnetism of

0.4 x 10-7 emu G/cm2 when perpendicular to HE = 100 G and after irradiation for one hour.

(Figure 3-13) The finite slope before photoexcitation is attributed to the glassy behavior of the

film. The two characteristic behaviors of the different analogues were observed in the same film

with one interface between the two analogues. The same behavior was observed in the fast

Stacked AB film.

Slow Heterogeneous Mixed Film 7

This film contained the maximum number of interfaces. The solutions used to generate

the different Prussian blue analogues were changed after each cycle for a total of 80 cycles.

[A1B1]S40 A decrease in Tc to abort 30 K in the susceptibility versus temperature plot was

observed. (Figure 3-14) The Tc was even lower than the film 4 generated using the fast method.

The slow method appears to achieve greater mixing of the analogues at the molecular level,

causing a corresponding decrease in Tc. The film also underwent a photoinduced increase in

magnetization over time. The effect was small, with only a 0.1 x 10-7 emu G/cm2 change

observed at 5 K after one hour. (Figure 3-15)

Discussion

There are a number of observations that can be made from the data presented regarding

films of the nickel chromium Prussian blue analogues and the heterogeneous films that resulted









when the cobalt iron analogue was added. The magnetic response of the nickel chromium

analogue film is anisotropic. Both the high Tc magnetic ordering of the nickel chromium

analogue and the photoinduced magnetism of the cobalt iron analogue were observed in the

stacked films. When the two different analogues were mixed, the two magnetic behaviors were

suppressed. The photoinduced increase or decrease in magnetism of the cobalt iron analogue

presented in chapter two was different than in the films containing the nickel chromium

analogue. Finally, the largest photoeffect observed in the sandwich film was over one order of

magnitude smaller than the films reported in chapter two.

Magnetic Anisotropy Present in the Nickel Chromium Film

The magnetic susceptibility of the nickel chromium film perpendicular to the applied

magnetic field was one-third of the response when the film was parallel to the applied magnetic

field. This magnetic anisotropy in the film suggests that the nickel chromium analogue film

contains a magnetic easy axis in the plane of the solid support used to build the film (Figure 3-3).

A magnetic easy axis is the direction for which the material has a greater susceptibility to a

magnetic field. The Prussian blue families of compounds are cubic structures and should contain

no structural anisotropy, and this behavior in the films is different from the bulk solid. The

surface of the solid support could be directing the formation of the film, causing the material to

form an easy axis. Another possible cause of the nickel chromium films magnetic anisotropy

could be the magnetic dipolar field generated by the nickel chromium analogue, when in a quasi-

two-dimensional structure. When the film is parallel to the applied magnetic field, all the dipolar

fields align head to tail and are continuous down the surface of the film. When the film is

perpendicular to the external field, the ferromagnetic moments align with the field but they are

only continuous over the thickness of the film, thereby causing a competition between aligning

with the applied magnetic field and ordering in the plane of the film. (Figure 3-16) The









anisotropic behavior from nickel chromium was observed in the later films and accounts for the

different starting magnetic values for the parallel and perpendicular orientations.

Sequence Effects in the Stacked Films

The magnetic behavior of the stacked films changed depending on which analogue was

deposited first. When comparing Figures 3-7 and 3-8, it appeared that the analogue deposited

first has its magnetic properties suppressed. The magnetic susceptibility was much less when the

nickel chromium analogue was deposited first in [A1oBio] f film 2 (Figure 3-7) when compared

to the magnetic susceptibility in [Bo0A10]fl film 3 which had the nickel chromium analogue

deposited second. (Figure 3-8) When the cobalt iron analogue was deposited first, as in film 3

(Figure 3-8), there is a smaller photoeffect compared to film 2 that had cobalt iron deposited

second. (Figure 3-7) The reduction of the first layer's magnetic behavior is explained by

considering the deposition method. The sequential adsorption method required several cycles to

establish a uniform film as known from chapter two. Films of nominally 30 nm are required to

achieve uniform coverage. (Figure 2-3) The first analogue deposited must achieve this coverage

before building a film, but the second analogue was able bind to a surface that has already been

established.

Photoinduced Magnetism in the Stacked Films

When this deposition order is combined with the magnetic easy axis, additional behaviors

of the film are explained. The easy axis continues into the second layer in the stacked films.

There was a large magnetic anisotropy in the dark stacked film 3 [B1oAo10]f when the nickel

chromium analogue was the second layer. This magnetic easy axis could also contribute to the

photoinduced magnetism. In stacked films, the photoinduced increase in the parallel direction

was larger than the increase in the perpendicular direction by an order of magnitude. The

magnetic easy axis and applied field are additive when the film is parallel to the applied









magnetic field. The new photoinduced spins align with the applied magnetic field. The

magnetic easy axis and applied field are orthogonal when the film is perpendicular to the applied

magnetic field causing fewer of the photoinduced spins to align with the applied magnetic field,

which led to a small or null photoinduced effect in the films in the perpendicular orientation.

(Figure 3-17)

Magnitude of the Photoeffects in the Heterogeneous Films

In the stacked films, the photoinduced change in magnetism was different from the

behavior observed in the chapter two cobalt iron films. First, no photoinduced decrease was

observed. All the heterogeneous films contain -75 nm of the cobalt iron analogue based on

chapter two data. Photoinduced increases were observed, however the magnitude of the increase

was small when compared to a 75 nm film of only the cobalt iron analogue. The largest

photoinduced increase reported for the heterogeneous films was in the sandwich [A1oB1oAo10]f

film 5 and was 7.5 x 10i7 emuG/cm2, and is compared to the photoinduced increases of the

stacked films 2 and 3. (Figure 3-18) This result indicates that attenuation of the cobalt iron layer

is not a significant contributor to the suppression ofphotoeffects seen in other films. To

compare the relative strengths of the photoeffects with the lone cobalt iron film it was assumed

that 10 cycles of cobalt iron deposited on a nickel chromium analogue deposited 75 nm of

material. When converted to cm3 the change in magnetism for the sandwich film gives a value

of 0.1 emuG/cm3. The photoinduced decrease reported in chapter two for a 75 nm film

perpendicular was 2 emuG/cm3. There is more than an order of magnitude decrease in the

photoeffects in the heterogeneous films.

Anisotropic Photoinduced Magnetism of the Sandwich Films

The sandwich film 5 has magnetic behavior different from the stacked films 2, 3. The

magnetic susceptibility in the parallel directions is greatest of all the films investigated, reaching









near 120 x 107 emu G/cm2 at 5 K. This result is reasonable as it contains two 75 nm regions of

nickel chromium analogue. The photoinduced behavior of the sandwich film is different than the

stacked films and the simple cobalt iron films. When the sandwich film is parallel to the applied

magnetic field, there is a photoinduced increase for 10 minutes, and then a decrease in

susceptibility is observed resulting in an overall photoinduced decrease. This behavior is

unusual on two counts. It is the first observed behavior of a photoinduced decrease when a film

is parallel to the applied magnetic field. Also, observation that the susceptibility begins to

increase and then decreases has not been previously observed. The gradual initial onset of

magnetization is in contrast to the immediate decrease from heating observed in other films.

Thermal effects are observed at the end of photoexcitation when the light is turned off and there

is an increase in magnetism. A qualitative explanation of the two behaviors comes when the

dipolar fields generated by the nickel chromium layers are considered. The dipolar field of the

ordered nickel chromium layers will penetrate through the mixed region of the interface into the

cobalt iron region. The two dipolar fields interacting with the cobalt iron region give rise to a

photoinduced decrease in magnetism in the parallel direction. (Figure 3-19) The initial increase

in magnetism may be from small areas, in the center of the cobalt iron region, where the

developing photoinduced spin regions are to small to be affected by the nickel chromium dipolar

field, that align with the applied magnetic field these regions reach a maximum and are canceled

by more material influenced by the dipolar field of the nickel chromium or as the cobalt iron

regions increase in size they begin to be affected by the nickel chromium dipolar field and

reverse alignment and order opposed to the applied magnetic field. In the perpendicular

direction, the dipolar field generated by the nickel chromium would influence the photoactive









material in an additive manner, with the applied magnetic field resulting in a larger photoinduced

increase in magnetism. (Figure 3-19)

Diminished Photoeffects in Stacked Films

The primary contribution to the diminished photoeffects in the stacked films would be the

roughness of the interface between the two analogues. Regions between different analogues

would have greater mixing at the molecular level resulting in photomagnetic behavior similar to

a mixed film that has little photoeffects. For stacked film 3 [Bo0A10]if the 10 cycles of cobalt

iron analogue was deposited first and resulted in a film 75 + 20 nm with a roughness of 23 nm as

stated in chapter two. The subsequent deposition of the nickel chromium layer would be on top

of the surface provided by the cobalt iron layer filling in the valleys generating an area of mixed

analogues.

Another explanation for the diminished photoeffects in the stacked films can be achieved

by considering the magnetic fields involved. In chapter two, there were two fields identified to

exist in the film: the applied magnetic field and the dipolar field generated by primordial regions

of cobalt iron Prussian blue analogue. The alignment of the induced spins either parallel or anti-

parallel to the applied magnetic field depends on the relative strength of the two fields. Another

force that influences the directional alignment of the new spins that needs to be considered is the

dipolar field generated by the continuous ferromagnetic nickel chromium analogue. When a

stacked film is parallel to the applied magnetic field, the nickel chromium region will generate a

dipolar field that should align the photoinduced material anti-parallel to the applied magnetic

field. The material proximal to the nickel chromium region should demonstrate the greatest

effect. The material influenced by the nickel chromium dipolar field was a mixed analogue

region and showed poor photoeffects allowing the material in the continuous cobalt iron region

to behave similar to the lone cobalt films. With the film perpendicular to the applied magnetic









field the nickel chromium dipolar fields should average causing the unaffected material to align

anti parallel to the applied field. (Figure 3-20)

Magnetic Behavior of Metal Thin Films Discussed in Literature

To the best of our knowledge there has been no other attempt to combine two different

Prussian blue analogues in the same film. Effects on the magnetic behavior that are inherent

heterogeneous films are expected. A large body of literature is available that focuses on thin

metal films and how those films behave when in contact with another material.90-99 The

literature describes metal films and the magnetic behavior that results. A number of different

effects that cause anisotropy have been discussed and include surface anisotropy, interface

roughness, lattice mismatch, classical dipole interactions, and exchange bias.

The surface anisotropy in the metal films causes an easy axis to be perpendicular to the

plane of the films.90,91,94,95 In our films the easy axis observed is in the plane of the film. Our

films are much thicker than the metal films with surface anisotropies. Surface anisotropy is

related to the surface area of the film and is an important contribution in thin films of less the

five monolayers. Our layer thicknesses are nominally 75 nm or 75 monolayers. The interface

roughness described in the literature is not comparable to our samples. Metal films are almost

atomically smooth and contain step features.97 The roughness in the multiple sequential

adsorption films is much rougher so that the surfaces are not comparable. The interface between

the nickel chromium region and cobalt iron region is best described as a mixed film.

Several behaviors of the metal films do provide insight into our system. The first is a

lattice mismatch. A lattice mismatch is when the unit cells of the film do not align perfectly with

material previously deposited inducing strain and is expected to be a source of anisotropy in

ferromagnetic materials.95 Exchange bias is observed by a shift of the hysteresis loop along the

field axis when a ferromagnetic film is in contact with an antiferromagnetic film.99 The









relevance to our system is not yet know, we have not yet conducted the experiments to detect any

exchange bias. The classical dipole interaction does apply to our system. The dipole interaction

favors interaction in the plane of the film and increases with film thickness to overwhelm surface

effects.90 The dipolar interaction is qualitatively explains the anisotropic behavior observed in

the nickel chromium films.

Conclusions

The synthesis of heterogeneous films containing two different Prussian blue analogues

was achieved. The behaviors of the separate analogues were conserved when regions of

sufficient thickness were deposited. The behaviors of the separate analogues were destroyed

when the analogues were mixed on the molecular level preventing the formation of regions of

pure analogues, resulting in a mixed film. There was evidence of the interactions between the

different regions observed by the photoinduced effects that differed from pure cobalt iron

Prussian blue analogue films.

When the films were oriented perpendicular to the applied magnetic field, a

photoinduced increase or null result was observed in the stacked and sandwich films in contrast

to the photoinduced decrease present in the pure cobalt iron films. The propagation of the

dipolar field from the nickel chromium layer caused another field to influence the photoexcited

material. The direction of the new photoinduced spins is determined by the sum of the applied

magnetic field, the nickel chromium region dipolar field and the dipolar field generated by the

primordial cobalt iron spins.









Table 3-1. Summary of heterogeneous films generated
Film Methoda Film Typeb Number of Cycles Short Hand

1 Fast A 10 [Alo]fl

2 Fast Stacked AB 10/10 [AloBio]fl

3 Fast Stacked BA 10/10 [BioAlofl

4 Fast Mixed 20 [AlBi]flo

5 Fast Sandwich ABA 10/10/10 [AloBioAlo]fl

6 Slow Stacked AB 40/40 [A4oB4o]si

7 Slow Mixed 80 [AiBi]s4o

a. Fast sequential adsorption method rinses between cycles, Slow sequential adsorption rinses
between analogue solutions chapter two.
b. A nickel chromium Prussian blue analogue, B cobalt iron Prussian blue analogue.


















**I Repeat for "X" cycles ...' .*.. ,I Repeat for "X" cycles .*.**


Rb Co,kFe(CN)J1 nHO


I10 x NiCr + 10 x CoFe = ...



Figure 3-1. Schematic of the heterogeneous Prussian blue analogue thin film generated using the
sequential adsorption method.

)CoFe intralayer interactions


interlayer
interactions


CoFe/NiCr interlayer interactions

f N iCr intralayer interactions


Figure 3-2. Schematic of the magnetic layer exchange interactions likely to exist in samples of
heterogeneous films.


2.0 i

1z5. H = 250 G
S]o H= 100G
S H=50G
S10 H =20G
H=5G




0.0

0 50 100
T(K)
Figure 3-3. The dc magnetic susceptibility data with varying field of a slow film of the nickel
chromium Prussian blue analogue. The shifting peak temperature with field is typical
of glassy Prussian blue materials.














Ni-Cr A layer Sandwich
Co-Fe B layer ..................
Jr"


Stacked Mixed
Figure 3-4. Schematic of the different heterogeneous films generated. Stacked films contain
regions of both analogues, Sandwich films place one cobalt iron B layer between two
nickel chromium A layers, mixed films do not form layers of discrete analogues.


60



o 40



S20


I


A ZFC Hparr
"WA A FC Hparr
A A A A ZFCHperp
A A U FC Hperp
A A

H -100 G
A




A


0 20 40 60
T (K)


100


Figure 3-5. Magnetic susceptibility vs. temperature plot of a 75 nm nickel chromium Prussian
blue analogue thin film (film 1). Temperature dependent fc/zfc sweeps of dc
susceptibility the film parallel and perpendicular to an applied magnetic field of
100 G. The magnetic response is anisotropic.


I
















6



4.
3 '

2


0 ..
0 25 50 75 100 125
T (K)



Figure 3-6. The dc magnetic susceptibility verses temperature fc (*), zfc (o) of the stacked AB
heterogeneous Prussian blue analogue film 2 at H = 100 G parallel to the film. A
separate ordering transition is observed for each analogue in the film.


H perpendicular






a 1.8 -




1 7 I I


Time (Hours) Time (Hours)
Figure 3-7. Photoinduced magnetization of a nickel chromium Prussian blue analogue film
under a cobalt iron Prussian blue analogue film, AB film 2, measured at 5 K with the
measuring field of 100 G oriented parallel (left) and perpendicular (right) to the film.
The time axis is relative to the point where the light is applied, and irradiation stopped
at ~1 hour.


6
H parallel

7 -


6
*
*
5 p
*


1. ..... .........


























Time (Hours)


H perpendicular



19.3


*


Time (Hours)


Figure 3-8. Photoinduced magnetization of a cobalt iron Prussian blue analogue film under a
nickel chromium Prussian blue analogue BA film 3, measured at 5 K with the
measuring field of 100 G oriented parallel (left) and perpendicular (right) to the film.
The time axis was relative to the point where the light was applied, and irradiation
stopped at 1 hour.


T (K)
Figure 3-9. The dc magnetic susceptibility fc (*), zfc (o) versus temperature plot of a mixed film
cobalt iron nickel chromium Prussian blue analogue deposited using the fast method
(film 4). The film was parallel to an applied field of 100 G.


H parallel
4




2


*


- I I -


4.





















21.2


21.1


21.0


20.9


20.8


Time (min)

Figure 3-10. Photoinduced magnetism of a mixed cobalt iron nickel chromium Prussian blue
analogue fast film (film 4) at 5 K perpendicular to the applied magnetic field. The
time axis was relative to the point where the light was applied, and irradiation stopped
at 120 min.


Time (Hours)


Time (Hours)


Figure 3-11. Photoinduced magnetization of a sandwich film nickel chromium, cobalt iron,
nickel chromium Prussian blue analogue (film 5), measured at 5 K with the
measuring field of 100 G oriented parallel (left) and perpendicular (right) to the film.
The time axis is relative to the point the light is applied, and irradiation stopped at ~1
hour.


U
U
U
U
U

p p


H parallel



iX-


g g
H perpendicular






I
U
U
U
U
U
U
*
*
*
*























C)
O




2


0 25 50 75 100 125 150
T (K)
Figure 3-12 fc (.), zfc (o) dc magnetic susceptibility vs. temperature with H = 100 G
perpendicular to a slow stacked AB film 6 with one interface between the analogues.


1.8 I


1.6


Time (min.)


Figure 3-13. Photoinduced magnetism of a stacked slow AB film 6 of cobalt iron over nickel
chromium analogue measured at 5 K with the measuring field of 100 G oriented
perpendicular to the film. The time axis is relative to the point the light is applied,
and irradiation stopped at 60 min.


Om
OI
[]




-i D

D

'D
D
=1 U
...


**E --
U
U


..a-

















4


0

0
B

2



0


0


*





DS







20 40 60
T (K)


Figure 3-14. fc (*), zfc (o) magnetic susceptibility vs. temperature with H
perpendicular to a mixed slow film 7.


3.7





3.6



3.5



2


U








U
U
U
U


I


100 G


Time (min.)
Figure 3-15. Photoinduced magnetism of a mixed slow film of cobalt iron and nickel chromium
analogue (film 7) measured at 5 K with the measuring field of 100 G oriented
perpendicular to the film. The time axis is relative to the point where the light is
applied, and irradiation stopped after 60 min.








Dipolar field





Ferromagnetic spin

Ni Cr


t I T t


Easy axis


Applied magnetic field
Figure 3-16. Schematic of the dipolar field in the ferromagnetic nickel chromium analogue
films. When the film is orientated parallel to the applied magnetic field the films
dipolar field, easy axis and the applied field are additive.


*'Co Fe

Ni Cr


Easy axis


St t t t


Applied magnetic field
Figure 3-17. Schematic of the magnetic easy axis in the ferromagnetic nickel chromium
analogue present in stacked films. When the film is orientated parallel to the applied
magnetic field the films magnetic easy axis and the applied field are additive.











6

0 *----6I
0 50




























Applied magnetic field
\












Dipolar field



t

Ferromagnetic spin

'Co Fe (B)

Ni Cr (A)




Easy axis


Applied magnetic field
Figure 3-20. Schematic of the stacked AB film 2 with directions of the applied magnetic field,
nickel chromium dipolar field and easy axis indicated with respect to film orientation.
All three forces contribute to the final direction of the photoinduced spin.









CHAPTER 4
SIZE DEPENDENT PHOTOINDUCED MAGNETISM IN RUBIDIUM COBALT IRON
PRUSSIAN BLUE ANALOGUE NANOPARTICLES

Introduction

A range of compositions of the Prussian blue analogue, AjCok[Fe(CN)6]I *nH20, exhibit

photoinduced magnetism.19-41 At temperatures below 20 K, diamagnetic Co"(l1s)-Fe"

photoswitchable pairs may be photoexcited to ferrimagnetic Con(hs)-Fe"' through a charge

transfer and spin crossover event, increasing magnetization. The metastable excited state is

long-lived and reversible by irradiation or thermal treatment.

Nanoparticles display physical and magnetic properties that could be different from the

bulk material as well as have technical and biophysical applications. Nanoparticles of the cobalt

iron Prussian blue analogue are also of interest in the field of molecular magnetism. The

synthesis of cobalt iron Prussian blue analogue nanoparticles has been reported, although the

photoinduced magnetism was not discussed.70'73 The exception is a study of KjCok[Fe(CN)6]l

fabricated within a silica xerogel. At 5 K and 500 Oe a 9% increase in magnetism was reported

after photoexcitation to saturation.79

The photoinduced magnetism in nanoparticles of RbjCok[Fe(CN)6]I synthesized in the

presence of the polymer polyvinylpyrrolidone (PVP) will be discussed here. These nanoparticles

display magnetic behavior consistent with a cobalt iron Prussian blue analogue powdered solid,

although altered by the restricted particle size. The nanoparticle size variation allowed for the

elucidation of a critical size for bulk like behavior. The photomagnetism and critical size of our

nanoparticles has been previously reported.100'101 Evidence that the surface of the nanoparticle

behaves differently than the core of the nanoparticles has also been observed.









Experimental Section


Reagents and Materials

All reagents were purchased from Sigma-Aldrich or Fisher Scientific and used without

further purification. Trace metal grade nitric acid was used for inductively coupled plasma mass

spectrometry (ICP-MS) experiments, all other reagents were ACS grade. Holey carbon

transmission electron microcopy (TEM) grids were purchased from Ted Pella. Deionized (DI)

water (18 MQ) was used for all experiments.

Sample Preparation of AjCok[Fe(CN)6I. nH20 Nanoparticles

Four sets of nanoparticles were synthesized by modifying the procedure described by

Uemura and coworkers.71'72 A 2.0 mL solution containing both 28.0 mg K3Fe(CN)6 (42 mM)

and 6.8 mg RbNO3 (23 mM) was added dropwise to a series of 8.0 mL solutions containing

30.0 mg Co(N03)2 *6H20 (13 mM) and 1000. mg, 500. mg, 200. mg or 100. mg

polyvinylpyrrolidone (PVP), samples A-D respectively, while stirring rapidly. After 30 minutes

of stirring, the solution was allowed to sit for one week. Powdered solid samples were prepared

as described above without PVP. Samples containing no rubidium were prepared as described

above, omitting the RbNO3 salt.

Instrumentation

The elemental analyses were performed by ICP-MS on a Thermo-Finnigan Element-2

spectrometer. FTIR spectra were recorded using a Nicolet 6700 spectrometer. TEM and

selected area electron diffraction (SAED) were performed on a JOEL 2010F. Magnetic

measurements were made by the University of Florida Department of Physics using a Quantum

Design MPMS XL superconducting quantum interference device (SQUID) magnetometer. A

bundle of 10 optical fibers, 270 pm O.D. (Ocean Optics Model 200) was used to introduce light,









from a room-temperature, halogen-light source, of 1-2 mW power into the SQUID

magnetometer for photoinduced experiments.85

Analysis Preparations

For TEM analysis, a 50.0 [L aliquot of the suspension was diluted 2000 times and

sonicated for 30 minutes then 8.0 [L of the diluted suspension was placed on a holey carbon

TEM grid. To isolate particles, three volumes of acetone were added to the synthesis solution

which was centrifuged to sediment the particles, and then the particles were further washed with

acetone and dried under vacuum. ICP-MS samples were prepared by digesting 5 mg of sample

in 0.4 mL of boiling, concentrated sulfuric acid for 4 hours, resulting in a black liquid.

Concentrated nitric acid (0.5 mL) was then added dropwise, before diluting the mixture to

5.00 mL with DI water. The samples were diluted immediately prior to analysis, and then

compared to matrix matched metal blends between 1 ppm and 1 ppb. The resultant

concentrations were normalized to a unit cell formula AjCo4[Fe(CN)6]i n120 by fixing 4 cobalt

ions per unit cell. The unit cell formula will then provide the formula used to determine the

molar mass of the analogue. The water molecules coordinated to the cobalt were determined by

the number of ferricyanide vacancies, specifically, n = 6(4-1). The unit cell formula was then

used to determine the molar mass of the compounds. The FT-IR spectra of the nanoparticle and

powdered solid samples were obtained by transmission IR using CaF2 salt plates. For magnetic

measurements the samples were mounted to commercial transparent tape and were irradiated

with light from a room-temperature, halogen source by using a homemade probe equipped with a

bundle of optical fibers.85 Background contributions from the holder and tape have been

independently measured and have been subtracted from the data.









Results

Nanoparticle Generation and Characterization

The nanoparticles were generated by adding a solution containing potassium ferricyanide

and rubidium nitrate dropwise to a solution with cobalt(II) nitrate and PVP. After addition the

sample was allowed to sit 1 week, TEM grids of each sample were prepared, and the

nanoparticles were isolated. Representative TEM images are shown. (Figure 4-1) In addition,

SAED of the nanoparticles was compared to SAED of powdered solid samples and to published

powder X-ray diffraction patterns to confirm the structure.25 (Figure 4-2) Using Image J imaging

software,102 the TEM images were analyzed to obtain the particle size distribution, and these data

were fit to a log-normal distribution103 that yielded batches, samples A-D, with different

characteristic diameters of 3.3 ( 0.8), 6.9 ( 2.5), 9.7 ( 2.1), and 13.0 ( 3.2) nm respective to

decreasing amounts of PVP added. (Figure 4-3) The log-normal distribution was used to fit the

smaller nanoparticles that could not fit to a Gaussian function due to the finite size minimum.

The literature preparation of Prussian blue nanoparticles called for a one week aging time

of the nanoparticles. This aging time is an important step in the synthesis of PVP nanoparticles.

Images of all nanoparticle and powdered solid samples prepared immediately after synthesis

displayed size distributions consistent with the smallest set (3 to 5 nm). (Figure 4-4) During the

one week time period the particles increase in size until the growth is inhibited. An important

observation is that the addition of increased amounts of PVP restricts the growth of nanoparticles

during the one week aging of the sample.

Chemical analysis was obtained from a combination of CHN combustion analysis and

ICP-MS. The formulas were determined to be near Rbi.sCo4[Fe(CN)6]3.2 *4.8H20 for samples A-

C and Rbo.9Co4[Fe(CN)6]2.9 *6.6H20 for sample D. Both are in the range of photoactive bulk

cobalt iron Prussian blue analogues22 and are listed in Table 4-1. The cyanide contribution to the









total amount of carbon and nitrogen can be determined by considering that each iron will be

coordinated by six cyanide ligands. To calculate the amount of polymer present, the carbon and

nitrogen contained in the cyanide ligands was subtracted from the CHN data. The remaining

carbon and nitrogen percentages were then normalized to the cobalt in the sample. The ratio of

PVP repeat unit to cobalt was found to be 360, 200, 60, and 20 for samples A-D, respectively,

reflecting the amount of PVP added. The physical properties of the four sample sets are

summarized in Table 4-1. There are three types of water molecules known to exist in the

nanoparticles: the water coordinating to the cobalt which can be inferred by the ferricyanide

vacancies that are included in the formula, water intercalated in the framework of Prussian blue,

and water associated with the PVP. The final two types of water cannot be determined

separately.

The IR Data

There are three different cyanide stretches of interest in the IR spectra. The first of which

is at 2130 cm-1 and is attributed to the diamagnetic Co(ls)-Fe" pair.23 The second is the stretch

at 2160 cm-1 attributed to the ferrimagnetic Col(hs)-Fe"' pair. The third is the stretch at

2085 cm-lattributed to the reduced, paramagnetic Col(hs)-Fe" pair that cannot participate in

photoinduced magnetism of the sample. The intensity of the three different peaks can be

changed by altering the Rb ion concentration and is also affected by the particle size. As the Rb

ion concentration is increased the diamagnetic pair is favored.

IR spectra were obtained using transmission IR of the sample through CaF2 plates at

room temperature. Samples A-C nanoparticles each revealed one peak in the cyanide stretching

at energies region ranging from 2124 cm-1 to 2105 cm-1. (Figure 4-5) This is consistent with

samples containing a combination of the ColI(1s)-Fe" diamagnetic pair23 and the reduced

CoI(hs)-Fe" paramagnetic pair.29 A powdered solid sample with chemical formula









Rbi.sCo4[Fe(CN)6]3.2 *4.8H20 also displayed one peak in the cyanide stretching region at

2121 cm-1. A powdered solid sample with chemical formula Rbo.6Co4[Fe(CN)6]2.9 *6.6H20

displayed two peaks at 2156 and 2105 cm-1. (Figure 4-6) Sample D displayed two different

peaks in the cyanide stretching region: a small sharp peak at 2156 cm-1; and a large broad peak

centered at 2090 cm-1 corresponding to Co"(hs)-Fe"' ferrimagnetic23 and Col(hs)-Fe"

paramagnetic pair. (Figure 4-5) The broad lower energy peak is a result of different

combinations of diamagnetic Col"(ls)-Fe" reported at 2130 cm-1 and paramagnetic Col(hs)-Fe"

reported at 2085 cm-1. The cyanide stretching energies for the nanoparticles are close to the

energies of the powdered solid with similar concentrations.

The Rb ion concentration dependent behavior was studied in the powder samples to make

comparisons to nanoparticles with the same chemical formula. Samples with no Rb show all

three peaks in the cyanide stretching region, with the ferrimagnetic pair at 2165 cm-1dominating

the spectra and the paramagnetic pair at 2085 cm-1 being the next most prominent. As the

concentration of Rb increases, the peak due to the ferrimagnetic pair decreases and the

diamagnetic peak increases, leading to a broad peak that includes both the diamagnetic and

paramagnetic pairs. At even higher concentrations of Rb, the diamagnetic peak is dominant and

the other two peaks have almost disappeared. (Figure 4-6)

The size effects of the nanoparticles on the IR stretching energies are more evident when

samples with no alkali cation are prepared and the ability to resolve the diamagnetic peak and

paramagnetic peak is gained. Nanoparticles and powdered solid samples were synthesized using

the same procedure without rubidium nitrate to target formation of the ferrimagnetic pairs. The

powdered solid sample shows the presence of all three peaks. As the size of the particles

decrease, the ferrimagnetic peak decreases in size and the diamagnetic peak increases. The









increase in diamagnetic material shifts the lower energy peak toward the literature values of the

diamagnetic peak indicating that new paramagnetic pairs are not formed in smaller nanoparticles.

(Figure 4-6)

Two observations about the nanoparticle can be made from the IR data. First smaller

nanoparticles favor the formation of the diamagnetic pairs. Also, the IR data indicates that the

diamagnetic pair bridging cyanide stretch in the nanoparticles is shifted to lower energy.

Literature data reports the diamagnetic pair cyanide stretch at 2130 cm-1.23 The nanoparticles

cyanide stretch ranges between 2125 and 2110 cm1.23 (Figure 4-5) The kinematic effect is often

utilized to explain the shift seen only when the cyanide is bridging one metal on each end. The

restraint in motion results in an increase in stretching energy. The kinematic effect would be

greater in powdered solid samples and reduced in samples with restricted size leading to a lower

energy than the powdered solid.

Magnetic Behavior of Nanoparticles

The temperature dependence of the dc magnetic susceptibilities, X(T), of rubidium

samples A-D are shown in Figure 4-7. The magnetic signals are expressed per mole of Prussian

blue analogue using the corresponding unit cell formula of each sample. (Table 4-2) The dark

state zero field cooled (zfc) data were obtained after cooling in zero applied field from 300 K to

2 K, while the dark state field cooled (fc) data were taken after cooling in 100 G from 300 K to

2 K. The light state was established after field cooling the samples from 300 K to 5 K in 100 G

and subsequently irradiating with light for five hours, which saturated the photoinduced

response. The light state fc data were obtained after cycling the sample to 30 K in 100 G. The

3.3 nm particles (A) followed Curie-like behavior with Tc less than 2 K for the light and dark

run. The Tc of the larger samples 6.9, 9.7 and 13 nm B-D respectively, increased with size from

10 to 13 to 19 K in the dark state. Samples B-D all showed and increase in Tc of 3 K during the









light temperature sweep. (Table 4-2) The same experiments were performed on powdered solid

samples with rubidium ion concentrations of 1.8 and 0.6 for comparison of the nanoparticles to

powdered solid samples. Powdered solid samples prepared using the nanoparticle protocols

show magnetic behavior similar to other powdered solid samples with similar alkali ion

concentrations.20,22 (Figure 4-8)

When comparing the different samples of nanoparticles, the first consideration is the

chemical formula of the particle. The 13 nm particles have a significantly lower amount of

rubidium in each unit cell compared to the other particles. The rubidium balances the charge of

the unit cell. If there were less rubidium, then more ferricyanide vacancies were present, causing

an increased amount of water to coordinate to the cobalt. This keeps more material in the

ferrimagnetic state when the sample is cooled to low temperatures, increasing the magnetic

susceptibility of sample D as shown in Figure 4-8. The 13 nm particles were still able to

undergo photoinduced magnetism; however a larger percentage of the material was locked in a

ferrimagnetic state. The 13 nm particles have similar magnetic behavior to powdered solids with

similar alkali cation concentrations.

All samples show a photoinduced increase in their magnetic signals and the strength of

the change is correlated with the size of the particles. (Table 4-2) The larger particle sizes

display a larger increase in magnetic susceptibilities when photoexcited. The differences between

the fc susceptibilities of the light and dark states, AX = ,gh fark, are plotted in the insets of

Figure 4-7, and finite values can only arise from the photoinduced magnetism.

Magnetizations versus field experiments for all samples were conducted for both the dark

and photoexcited states at 2 K. The full field sweep is shown along with a magnification of the

hysteresis. At full scale, the smaller nanoparticles had no observable difference between light









and dark sweeps with coercive fields (Hc) less than 10 G. Magnetic hysteresis is observed in the

magnetization vs. field (M vs. H) plots for the 9.7 nm and 13 nm particles. The 9.7 nm particle's

Hc increased from 250 G to 330 G with photoexcitation, the 13 nm particles Hc increased from

1000 to 1500 G. (Figure 4-9) A summary of the Hc of the light and dark state samples are

presented in Table 4-2. Magnetization versus field experiments for both the Rbl.8 and Rb0.6

powdered samples are also shown. (Figure 4-10)

The ac magnetic susceptibility versus temperature in the dark state after zero-field-

cooling for all samples was also investigated. The 3.3 nm and 6.9 nm samples of particles

displayed no frequency dependence. The real component of the ac magnetic susceptibility

versus temperature is shown for the 9.7 nm and 13 nm particles. (Figure 4-11) This provides

additional evidence that to 2 K the smaller nanoparticles are non-interacting and follow Curie-

like behavior.

Surface Effects in Nanoparticles

In nanoparticles the amount of surface material becomes a significant fraction of the

material present. The surface may be chemically different than the core material. The percent

core material was calculated by assuming complete unit cells (cobalt and iron are equal) for

cubic nanoparticles. The total number of cobalt atoms was 4n3, with n = number of unit cells on

an edge The surface cobalt atoms were subtracted from the total: 4 corner, 12(n-1) edge, and

6(n-1)(2n-2) face. The remaining cobalt atoms were considered core atoms and divided by the

total to give the percent of core atoms. The 3 nm particles contained 30% core atoms, and the

percentage of core atoms increased quickly with particle size to 63, 73 and 79% for the 7, 10 and

13 nm particles respectively. (Table 4-3)

The magnetization data per unit cell at 7 T was used to determine the amount of

ferrimagnetic material in the samples. First the spin value of the unit cell was determined using









the equation Msat = Ng1BS104 where Msat is the magnetization/mol (emuG/mol) at 7 T, N is

Avogadro's number, g is Lande constant and approximated at 2, [-B is Bohr magneton (9.27 x 10-

21 erg/G), and s is the spin value of the molar formula unit which was set to the unit cell. It was

then assumed that only two types of unit cells were present in the samples, diamagnetic unit cells

and ferrimagnetic unit cells. The average spin value of each samples unit cell was divided by the

calculated spin value of a ferrimagnetic unit cell to determine the percent of ferrimagnetic unit

cells in the sample. In the 3 nm particles only 1% of the unit cells are ferrimagnetic and the rest

of the material is diamagnetic. The 13 nm particle had 62% of the unit cells in the ferrimagnetic

spin state and 79% of the material in the core. For all samples the percentage of ferrimagnetic

material is less than the percent core material indicating that the surfaces of the particles are

diamagnetic. (Table 4-3)

Discussion

The data presented have led to some observations about cobalt iron Prussian blue

analogue nanoparticles. First nanoparticles of the cobalt iron analogue have been synthesized

with the ability to control particle size. The magnetic and photomagnetic behavior of the

nanoparticles evolves with size from non-interacting Curie-like to powdered solid behavior with

increasing particle size. Chemical differences between the surface of the nanoparticles and core

appear to be present.

Critical Size of Nanoparticles

Two main features are seen when considering the evolution of magnetic properties due to

the increasing average size of the separate batches, namely the onset of long-range magnetic

order and an increasing net magnetization. This scaling of magnetization may be linked to an

increased diamagnetic surface to magnetically-active-volume ratio in smaller particle sizes.









At low temperatures, the Fe and high-spin Co ions interact antiferromagnetically, giving

rise to a ferrimagnetic transition at Tc, which is about 24 K for photoinduced powdered solid

samples. For the magnetic data shown in Figures 4-7 and 4-8, the onset of this transition can be

estimated, and these temperatures are listed in Table 4-2. Particles larger than a critical size will

allow domains large enough to approach bulk-like magnetic properties. Conversely, smaller

particles may put limits on allowed domain size, suppressing the ordering temperature.

Microscopically, if the size of the magnetic domains is less than or of the order of the magnetic

coherence length, then a spectrum of Tc values can be expected until the superparamagnetic limit

is achieved.

Consider the magnetic properties of the samples presented in conjunction with the TEM

analysis. The 3.3 nm particles have no observed coercivity and follow Curie-like behavior.

Samples of 6.9 nm and 9.7 nm particles show a combination of Curie-tail and partial ordering

with a reduced Tc (Figure 4-7), as well as finite coercive fields (Table 4-2). Finally, the active

sites in the 13 nm sample are almost entirely ferrimagnetically ordered with the largest coercive

field of all batches presented. In addition, the differences between the fc and zfc data for the

dark state and the ac magnetic susceptibility in the 9.7 nm and 13 nm samples are consistent with

spin glass or cluster glass behavior,23'75 in accord with the presence of large magnetic domains

observed in the bulk samples. These interpretations are consistent with the M versus H

measurements performed at 2 K, where Hc, and remnant magnetization values are observed for

the largest sets of particles but not for the smallest sets of particles. (Figures 4-7 and 4-8, and

Table 4-2) The size dependent behavior is also confirmed by the ac magnetic susceptibility data.

The smaller particles follow the field regardless of the field strength. The larger particles show

frequency dependent temperature shifts in the susceptibility indicating that the larger particles









have sufficient size to order. By making the assumption that the 3 nm particles magnetic

behavior is entirely Curie-like the Curie-like contribution in the other samples can then be

subtracted from the data. Analysis of the data suggests that the superparamagnetic contribution

for each of the four samples of nanoparticles (A-D) is 100%, 90%, 50%, and 10%. The

percentage of superparamagnetic contributions in each sample was than applied to the particle

size histograms. An observation that 90% of sample B, 50% of sample C and 10% of sample D

present in each histogram are particles <10 nm in diameter was made. Consequently, at least

down to 2 K, nanoparticles with sizes below -10 nm are in the superparamagnetic limit.

Core Shell Nanoparticles

Treatment of the data thus far has been made with the assumption that the entire particle

is chemically one species and photoactive in the entire particle. Investigation of the IR data and

saturation magnetization indicate that within a particle there are cobalt iron pairs that have been

rendered diamagnetic and photoinactive.

Using the Msat data in Table 4-3 the following two observations were made. Most of the

material in the nanoparticles are diamagnetic (CoI"(ls)-Fe"). The percentage of ferrimagnetic

(Co"(hs)-FeI") material present in the dark state, primordial spin, increases with particle size

along with the percent of core material suggesting that the surfaces of the nanoparticles are

diamagnetic. IR data also supports the increase in diamagnetic material with a decrease in

particle size. (Figure 4-5, 4-6) Cobalt ions with six strong field ligands have been shown to be

locked in the low spin state. At the surface the nitrogen atoms in the PVP are available to

coordinate to the Co and fill the coordination sphere. The PVP is stronger field ligand then the

displaced water and results in a strong ligand field.

The 13 nm particles have a large fraction of high spin material in the dark state due to the

low concentration of Rb ion in the unit cell. By making the assumption that all the ferrimagnetic









material is in the core of the particle 62% of the material is a cube with an edge length of 11 nm.

The diamagnetic surface is 1 nm thick, which corresponds to the length of one unit cell of

Prussian blue, suggesting that the PVP is only interacting with the surface. (Figure 4-12) A

diamagnetic 1 nm surface on a 3 nm particle would result in only a single unit cell of the 27 total

unit cells, 4%, able to be a ferrimagnetic pair accounting for the low amount of magnetic

material observed in the 3 nm samples.

Conclusion

In conclusion, the synthesizes of four different sizes of RbjCok[Fe(CN)6]1 nH20

nanoparticles protected by PVP was achieved. Each sample of particles is photoinducible, but

the strength of this effect, as well as other global properties, e.g. Tc and Hc, are correlated with

the intrinsic particle size distributions of each sample, and the surface area to volume ratio. The

combination of photoinduced magnetism and nanosized Prussian blue analogue particles with

finite coercive fields is unique and establishes a length scale limit of -10 nm for these properties.

As the size of the nanoparticles decrease, the surface area to volume ratio increases, and

the surfaces of the nanoparticle are diamagnetic. Nanoparticle syntheses without the addition of

Rb ion more clearly showed cyanide stretching behavior that was different than the powdered

solids, which changes with particle size. This effect is confined to the surface of the

nanoparticle.









Table 4-1. Summary of the material properties of the four sample sets
Starting PVP PVP:Co
Sample Starting P Resulting chemical formula PVPCo Diameter (nm)
(mg) ratio
A 1000 Rbl.9Co4[Fe(CN)6]3.2-4.8H20 360 3.3 + 0.8
B 500 Rbi.8Co4[Fe(CN)6]3.2-4.8H20 200 6.9 2.5
C 200 Rbi.7Co4[Fe(CN)6]3.2-4.8H20 60 9.7 + 2.1
D 100 Rb0.9Co4[Fe(CN)6]2.9-6.6H20 20 13.0 + 3.2


Table 4-2. Summary of magnetic data for different nanoparticle samples
dark
x
Diameter (nm) T (K) Tc, (K) H (G) Hh (G) (emu/mol)

3.3 0.8 <2 < 2 < 10 < 10 0.27
6.9 2.5 10 13 15 -30 0.37
9.7 2.1 13 17 250 330 3.7
13.0 3.2 19 22 1000 1500 29
Rbl.8 powder <2 24 < 10 300 1.1
Rb0.6 powder 18 22 540 950 4.8


Tahle 4-3


Ca~lciil~in at o bsed on magnetic, data fbr PVP nanonartic~les


Size Msat Dark Msat Light % ferrimagnetic
(nm) (emuG/mol) (emuG/mol) Dark % core atoms
3.3 484 629 1.0 30.
6.9 3480 3620 7.1 63
9.7 14300 14600 29 73
13. 31700 35000 62 79


























Figure 4-1. The TEM images of cobalt iron Prussian blue analogue with nominal sizes of
(a) 3.3 nm, (b) 6.9 nm, (c) 9.7 nm, (d) 13.0 nm, (e) powdered solid. A 5 nm (a-d) and
50 nm (e) scale bar is shown.


Figure 4-2. The SAED pattern of (a) a large agglomerate consisting of over 100 nanoparticles
and (b) a powdered solid with the 200, 220 and 400 reflections identified.










1.0 -
3.3 (+ 0.8) nm
0.8
0.6
0.4
0.2
0.0 i*
1.0 -
6.9 (+ 2.5) nm
S 0.8 -
0.6
0.4
a 0.2

S 1.0 -
9.7(+ 2.1) nm
s 0.8
| 0.6
^ 0.4
0.2

0.0 :- ,-,
1.0 -
0.8 13.0 (+ 3.2) nm

0.6
0.4
0.2
0.0
0 5 10 15 20

Diameter (nm)


Figure 4-3. The particle distributions, normalized to the largest bin, versus diameter for the four
samples of cobalt iron Prussian blue analogue particles, shown in Table 4-1. The total
number of particles for each distribution, smallest to largest, is 44, 27, 53, and 62,
respectively. The solid lines are the results of log-normal fits that provide the
characteristic diameters shown for each distribution. Adapted from New J Phys.
2007, 9, 222.101






























Figure 4-4. The TEM images of cobalt iron Prussian blue analogue nanoparticles and powdered
solid prepared immediately after synthesis using: (a) 1000 mg PVP: (b) 500 mg PVP:
(c) 200 mg PVP: (d) 100 mg PVP: (e) 0 mg PVP. A 5 nm scale bar is shown. All
sets of particles start out at 3-5 nm in size particle size evolve with the one week
aging of the samples.


2200 2100
Wavenumbers (cm )


2000


2200 2100 1
Wavenumbers (cm )


Figure 4-5. Absorbance IR spectra of cobalt iron Prussian blue analogue nanoparticles from
batches (A-D) and powdered solid (P) samples. Samples A-D are displayed with a
powdered solid sample containing 1.8 rubidium ions per unit cell. Sample D and a
powdered solid (P) with a rubidium concentration of 0.6 ions per unit cell are
displayed at right.


2000
















0 ; 0.



S m I m
2200 2100 1 2000 2200 2100 2000
Wavenumbers (cm ) Wavenumbers (cm )
Figure 4-6. Absorbance IR spectra of powdered solid samples (left) with different
concentrations of rubidium ion. IR of nanoparticles prepared without rubidium (right)
samples (A, D), with powdered solid (P). The powdered solid spectra shows the three
cyanide stretches of interest at 2165 cm-1, 2130 cm-1, and 2085 cm-1 attributed to the
ferrimagnetic, diamagnetic and paramagnetic cobalt iron pairs respectively.
Nanoparticles with no alkali cation show a decrease in ferrimagnetic pairs and an
increase in diamagnetic pairs with size reduction.













0.3 1 003 -. 3.3 nm
O 002 -
0.2 o0

0.1 0 5 10 15 20 25
0.1

0.0 i i ,- 0o0ooo 0oon, o
S0 15 *
o 006.9rnm
0.4 a 010 -
000
0.2 0 5 10 15 20 25

Z 0.0 GD,001oon
1 0 1 1 9.7 nm
4 % Sot .....

2 0 5 10 15 20 25
4O n T (K)



20 2-
30- 6 0- **-


10 0 5 10 15 20 25
0 -- a T(K)

0 5 10 15 20 25 30
T (K)

Figure 4-7. The temperature dependence of the low field, 100 G, susceptibilities are shown for
the zfc dark (+), fc dark (m), and fc light (o) states of each rubidium containing
sample produced. The insets display the differences between the fc light and dark
states. Finite values for this difference can only arise from photoinduced magnetism.
Adapted from New J. Phys. 2007, 9, 222.101

























j O
500

ii.-8.>


Rb0.6


* 8
*
Q


T (K)


Figure 4-8. The temperature dependence of the low field, 100 G, susceptibilities are shown for

the zfc dark (.), fc dark (m), zfc light (o) and fc light (o) states of a
Rbi.8Co4[Fe(CN)6]3.2 *4.8H20 powdered solid and a Rb0.6Co4[Fe(CN)6]2.9 *6.6H20
powdered solid.


[- ] Rbl.8

OD
0
0




0 00

0
Ooooo O O 8


I .


T (K)














4U-
00
O

2 13nm



0 1


t. -20 0

0
-40 -
-5 0 5
H (Tesla)


10 9.7 nm



0



-10
lm .U


H (Tesla)


o 000 0 0




50 U :





-0.04 -0.02 0.00 0.02 0.04

H (Tesla)
U D **
2 -











0 0

C" 0


-2


-0.04 -0.02 0.00 0.02
H (Tesla)


0.04


Figure 4-9. The T = 2 K magnetization versus magnetic field sweeps for the two largest sizes of
nanoparticles, Samples C 9.7 nm and D 13 nm, are shown on the left full sweep, and
on the right hysteresis, for the light (o) and dark (m) states. The He for the light and
dark states for each batch are listed in Table 4-2. Adapted from New J. Phys. 2007, 9,
222.101













10


C

0




-10


-00o00oD00
Rbl.8 ...."""









.1
..... *


-5 0 5

H (Tesla)
"oo OO n 3E[0
*"..""""".
Rb0.6 '









..E ......
-oo 0oD. I


0

SD



o 0
I

no D

Dn
o *



.10 -0.05 0.00 0.05 0.1









u0 0 0
000
o0
D]





H (Tesla



[] iI mmm
] [] 0
[] 0 0


10


-5 0 5 -0.10 -0.05 0.00 0.05 0.10

H (Tesla) H (Tesla)

Figure 4-10. The T = 2 K magnetization versus magnetic field sweeps for the two powdered
solid rubidium concentrations, Rubidium 1.8 and 0.6, are shown on the left for full
sweep, and on the right for hysteresis, for the light (o) and dark (m) states. The He
for the light and dark states for each batch are listed in Table 4-2.


-0


10


5

0
^ 0


S-5

-10











0.2 L 5.. nm

0.1

0.0

-0.1
0.4
.4 6.9 nm

0.2

S0.0

T
1.o 9.7 nm

x 0.5

0.0

15 Tf 13 nm
10

5-
o O*****i

0 5 10 15 20
T(K)

Figure 4-11. The temperature dependence of the ac-susceptibilities are shown for the four
samples. All samples were measured with no applied static field and an alternating
field of 4 G (except for the 13 nm sample, which was measured in 1 G ac). The
frequency dependence was studied at 1 Hz (0), 10 Hz (A), 100 Hz (+), and
1000 Hz (0) for all samples (except for the 13 nm sample, which has an additional
data point at 333 Hz (+)). Adapted from New J. Phys. 2007, 9, 222.101

























13 nm
Figure 4-12. Core shell behavior model theorized in the 13 nm cobalt iron Prussian blue
analogue particle. If the ferrimagnetic material accounts for 62% of the volume of
the nanoparticle, an 11 nm cube can be formed. The remaining 38% of diamagnetic
material surrounding the core is 1 nm thick corresponding to one unit cell edge length
of cobalt iron Prussian blue analogue.









CHAPTER 5
ALTERNATE SYNTHESIS OF COBALT IRON PRUSSIAN BLUE ANALOGUE
NANOPARTICLES

Introduction

In chapter four, the size-dependent magnetization of cobalt iron Prussian blue

analogue nanoparticles was investigated by adapting procedures from Uemura and

Kitagawa.71'72 Yamada et al.73 had reported the synthesis of cobalt iron Prussian blue

analogue nanoparticles that were 5 to 7 nm in length using a reverse micelle protocol. In

chapter four it was determined that small nanoparticles in the size range of 5 to 7 nm do

not show magnetic ordering at 2 K. An attempt to modify the synthesis to generate larger

nanoparticles is presented here.

Experimental Section

Reagents and Materials

All reagents were purchased from Sigma-Aldrich or Fisher Scientific and used

without further purification. Holey carbon transmission electron microcopy (TEM) grids

were purchased from Ted Pella. Deionized (DI) water (18 MQ) was used for all

experiments.

Sample Preparation of AjCok[Fe(CN)6]1 n nH20 Nanoparticles

Four sets of nanoparticles were synthesized by modifying the procedure described

by Yamada et al.73 Three stock solutions were made: 1) 10. mL of 245 mg of

Co(NO3)2 6H20 (84 mM) in DI water, 2) 10. mL of 269 mg K3Fe(CN)6 (82 mM) and

66 mg RbNO3 (45 mM) in DI water, and 3) 10. mL of 1.85 g of Igepal CO520 in

cyclohexane. Emulsions were generated by adding the organic stock solution (3) to each

separate aqueous solution (1,2). The amount of organic solution was varied to control

particle size. Sample A was comprised of 1.0 mL of aqueous and 2 mL of organic stock









solution. Sample B was comprised of 1.0 mL of aqueous and 1.0 mL of organic stock

solution. Sample C was comprised of 1.0 mL of aqueous and 0.50 mL of organic stock

solution. Sample D was comprised of 1.0 mL of aqueous and 0.25 mL of organic stock

solution. Once the emulsions were formed, the rubidium/ferricyanide emulsion was

added to the cobalt emulsion and stirred for four hours. Solid octadecylamine was added

to the emulsions (40. mg to sample A, 20. mg to sample B, 10. mg to sample C, and 5 mg

to sample D). The emulsions were stirred overnight. The emulsions were separated

using methanol and washed several times with water and methanol. The material in the

organic phase was retained and isolated by centrifugation.

Instrumentation

FT-IR spectra were recorded using a Nicolet 6700 spectrometer. TEM, selected

area electron diffraction (SAED) and Energy dispersive spectroscopy (EDS) were

performed on a JOEL 2010F. Magnetic measurements were made by the University of

Florida Department of Physics using a Quantum Design MPMS XL superconducting

quantum interference device (SQUID) magnetometer. A bundle of 10 optical fibers,

270 [tm O.D. (Ocean Optics Model 200) was used to introduce light, from a room-

temperature, halogen-light source, of 1-2 mW power into the SQUID magnetometer for

photoinduced experiments.85

Analysis preparations

For TEM analysis, 5 mg of isolated solid was placed in 1 mL of cyclohexane and

sonicated for 30 minutes. A sample of 10.0 [L of the suspension was placed on a holey

carbon TEM grid. The FT-IR spectra of the nanoparticles were obtained by transmission

IR using NaCl salt plates. For magnetic measurements, the samples were mounted to

commercial transparent tape and were irradiated with light from a room-temperature,









halogen source from a homemade probe equipped with a bundle of optical fibers.74

Background contributions from the holder and tape were independently measured and

were subtracted from the data.

Results

Nanoparticle Generation and Characterization

The nanoparticles were generated by adding a water/cyclohexane emulsion

containing potassium ferricyanide, rubidium nitrate and Igepal to water/cyclohexane

emulsions with cobalt(II) nitrate and Igepal. After four hours of stirring, octadecylamine

was added and the resulting emulsion was stirred overnight. The nanoparticles were then

isolated as a solid and used for experiments. Nanoparticles were placed on TEM grids

for TEM imaging, SAED and EDS. Representative TEM images are shown in

Figure 5-1. In addition, SAED of the nanoparticles was compared to SAED of the

powdered solid samples, PVP nanoparticles, and to published powder X-ray diffraction

patterns to confirm the structure of the nanoparticles.22 (Figure 5-2) Using Image J

imaging software,102 the TEM images were analyzed to obtain the particle size

distribution for 50 particles of samples A-D and these data were fit to a log-normal103

distribution that yielded a characteristic diameter of (A-D) 8.2 ( 0.9), 10.6 ( 0.8),

13.5 ( 1.2), and 16.7 ( 1.1) nm respectively. (Figure 5-3) Chemical analysis was

performed using EDS. The metal ratios of the nanoparticles were obtained and

normalized to four cobalt ions to calculate the unit cell formula. All nanoparticles had

rubidium ion concentrations between 1.5 and 1.8 ions per unit cell and were charged

balanced with ferricyanide complexes. The water content was calculated in the same

manner as the films by considering the amount of ferricyanide vacancies. Table 5-1 lists

the nanoparticles synthesis conditions, chemical formula, and size. Significant amounts









of potassium were also detected by EDS. The amount of potassium per unit cell is also

listed in Table 5-1. The potassium ion is largely present as a contaminant, charge balance

and ferricyanide vacancies indicate that most of the potassium ions are not in the

network.

Magnetic Behavior

The temperature dependence of the dc magnetic susceptibilities, x(T), of the four

samples of particles are shown in Figure 5-4. The magnetic signals are expressed per

gram of each sample. The dark state zero field cooled (zfc) data were obtained after

cooling in zero applied field from 300 K to 2 K, while the dark state field cooled (fc) data

were taken after cooling in 100 G from 300 K to 2 K. The light state was established

after field cooling the samples from 300 K to 5 K in 100 G and subsequent irradiation

with light for five hours that saturated the photoinduced response. The light state fc data

were obtained after cycling the sample to 30 K in 100 G. All particles followed Curie-

like behavior in the dark state. This behavior is typical of powdered solids with higher

alkali cation concentrations.25 A significant increase in Tc from 10 to 14 K and 10 to

20 K with photoexcitation was observed for the 13.5 and 16.7 nm particles respectively.

The 10.6 nm sample showed a small photoinduced increase in magnetic signal. The

strength of the photoinduced change increased in the larger particles and was correlated

with the size of the particles. The larger particle sizes displayed a larger increase in

magnetic susceptibilities when photoexcited. The fc/zfc temperature traces followed the

same path for most of the samples indicating no long-range magnetic ordering was

occurring. For the 16.7 nm particles the photoinduced fc/zfc trace diverges indicating

that long range ordering is occurring.









Time Dependent Behavior

Changing magnetic and chemical behaviors were observed in the nanoparticles

over time. The temperature dependence of the dc magnetic susceptibilities, x(T), of

16.7 nm particles are shown in Figure 5-5. The magnetic signals are expressed per gram

of each sample. The dark state fc data were taken after cooling in 100 G from 300 K to

2 K. The sample was stored at ambient conditions. The measurement was than repeated

twice, once after one day and again after 12 days. There was a decrease in magnetic

susceptibility of the sample over time.

The room temperature FT-IR spectrum of a 16.7 nm sample that had undergone

magnetic measurements was compared to a sample of the same age that had not

undergone magnetic measurements. (Figure 5-6) The two spectra were almost identical,

with a peak consistent with the diamagnetic Co"'(ls)-Fe" pair observed.23 The identical

spectra of the two samples indicates that sample handling and magnetic measurements do

not change the sample. The room temperature FT-IR spectrum of a 10.6 nm sample was

obtained immediately after synthesis (day 1) and compared to a spectrum of the sample

that was 20 days old. (Figure 5-7) The day 1 spectrum displayed a small peak consistent

with the Co"(hs)-Fe"' ferrimagnetic pair at 2160 cm-1 and a major peak at 2095 cm-1 that

was between the energies of the Co"'(ls)-Fe" diamagnetic and Co"(hs)-Fe" paramagnetic

pairs.23 There were also shoulders on the major peak below 2050 cm-1 that are consistent

with a terminal ferrocyanide stretch. After 20 days, the 2160 cm-1 peak diminished and

the major peak broadened and shifted to 2080 cm-1, and the shoulder peaks were also

more evident. The time dependent IR data indicates that the iron is being reduced is

presumably at the surface of the nanoparticles.









Discussion

The emulsion based synthesis of cobalt iron Prussian blue analogue nanoparticles

offers advantages and disadvantages when compared to the aqueous synthesis method

used to produce nanoparticles in chapter four. The primary advantages of the emulsion

synthesis are shorter reaction time, better images and a more mono-dispersed sample set.

Disadvantages to the emulsion synthesis are the potassium contamination and the

decrease in magnetism over time.

Emulsion Synthesis Advantages

For the emulsion synthesis, the nanoparticles formed and were full size in less

than a 24 hour period. When Igepal was used as the surface modifier, the nanoparticle

coating would be less bulky there is a large difference in the formula weights (F.W.) of

the two coatings, Igepal (F.W. 441 amu) and PVP (F.W. -55 kamu). It can be reasoned

that the smaller Igepal particles could achieve a faster formation of nanoparticles for

steric and mixing reasons. The Igepal was then exchanged with the octadecylamine to

provide a surface on which to separate the nanoparticles. This thin coating provided a

small amount of amorphous material that can interfere with imaging of the nanoparticles

resulting in images with better contrast and defined edges. The images of the emulsion

nanoparticles indicated that cubes of material were formed. The nanoparticles also self-

assembled on the TEM grid. Two contributors to the self-assembly were the mono-

dispersity of the nanoparticles and the octadecylamine coating. Particles with regular

size and shape can more easily combine into larger arrangements as frequently seen in

nanoparticles of metal oxides.105'106 The octadecylamine chains interacted with each

other to form larger nanoparticle structures. Measurements were conducted on the inter-

particle spacing, and spaces with averages of 2.1 nm were found when the particles were









in a regular arrangement. This distance is less than the 2.5 nm length of the

octadecylamine, indicating that the chains are likely interdigitated and not normal to the

surface of the particle.

Emulsion Synthesis Disadvantages

The disadvantages of the emulsion synthesis were the presence of potassium ions

and the decay of magnetic properties of the nanoparticles. The presence of this

contamination makes an accurate determination of the chemical formula and surface

coating impossible. The potassium ions are the ferricyanide counter-ions in the synthesis

and combine with the nitrate counter-ions from the cobalt and rubidium. In the aqueous

synthesis of the PVP nanoparticles, the potassium was removed by centrifuging in a

water acetone mixture. The emulsion synthesis used methanol to separate the emulsion

but potassium nitrate has a low solubility in methanol. Attempts were made to remove

the potassium, and although the amount was reduced, all the potassium in the samples

was not eliminated. It is critical to know the concentration of all the alkali ions present

because they can be used for charge balance and thus affect the number of vacancies in

the sample. If the potassium ions are added to the unit cell as part of the formula, the

charge will not balance. Also, powdered solid samples with high concentrations of alkali

ions are known to form diamagnetic cobalt iron pairs that are locked in the low spin

state.25'35 Photomagnetism was observed in the larger nanoparticles. The number of

vacancies was also consistent with photomagnetic material. The lack of charge balance

with potassium, photomagnetism and ferricyanide vacancies all indicate that potassium

was incorporated into the unit cell.

The loss of magnetic susceptibility over time indicates that the nanoparticles were

unstable. Thermal cycling was thought to be a cause of a chemical change in the system.









Room temperature FT-IR showed no differences between a sample that had undergone

three magnetic measurements and a sample that had remained at room temperature.

(Figure 5-6) The nanoparticles did change spin states or oxidation states with time, as

observed by room temperature IR. (Figure 5-7) Over 20 days, the ferrimagnetic pair that

accounts for the primordial spin and photoswitching diminished in the 10.6 nm particle.

Comparison with PVP Nanoparticles

The evolution of magnetic behavior with particle size was partially confirmed

with the emulsion synthesis. A greater photoeffect was observed as the nanoparticles

increase in size. There was an increase in magnetic susceptibility in the 13.5 and 16.7 nm

particles with photoexcitation. The 16.7 nm particles also showed the beginning of long-

range ordering when photoexcited. (Figure 5-4)

The size of the nanoparticle and photeffects do not match when the aqueous PVP

and emulsion methods are compared. For the aqueous PVP nanoparticle synthesis, the

13 nm particles displayed long range magnetic ordering with a Tc of 19 K in the light

state. In the emulsion synthesis, the 13.5 nm particles displayed long range magnetic

ordering with a Tc of 14 K in the light state. The suppressed Tc of the emulsion

nanoparticles indicates that the particles are smaller from a magnetic perspective.

The PVP nanoparticle established a 10 nm size limit where smaller nanoparticles

followed Curie-like behavior and larger particles begin to interact. In the PVP

nanoparticles data was presented suggesting that the shell of the nanoparticle is trapped in

a low spin state. Following the same logic the emulsion nanoparticles could have a

trapped shell that is thicker than the PVP nanoparticles accounting for the apparent

magnetically small size of the emulsion nanoparticles. The emulsion nanoparticles were









larger, yet the magnetic behavior suggested that a smaller amount of material was not

participating in the particle.

One probable cause for the disparate core shell behavior between the two

synthesis methods is the surface coating used, PVP vs. octadecylamine. The emulsion

nanoparticles were more exposed to the environment, coated by -2 nm of

octadecylamine. The octadecylamine could not provide a full surface coating. The

surface of a nanoparticle can be thought of as monolayer of a metal cyanide grid that our

group has worked with previously.62'64'66 Each face-centered square grid would provide

two surface cobalt ions for the octadecylamine to coordinate. The area of the grid unit

cell is -100 A2 the mean molecular area of octadecylamine is 21 A2 per molecule. Even

with the nanoparticles assembled to allow the octadecylamine to interdigitate there is still

16 A2 of free space per surface unit cell. In addition to the chemical effects the

octadecylamine would have at the surface by coordinating to the cobalt the outer shells

would be exposed to the environment. For comparison the average coating of PVP was

between 20-25 nm for the aqueous nanoparticles. The PVP encapsulated the nanoparticle

and only affected the surface, but protected the core from the environment allowing for a

larger photoactive nanoparticle core.

Conclusions

The emulsion-based synthesis of cobalt iron Prussian blue analogue nanoparticles

offers advantages and disadvantages when compared to the aqueous synthesis used to

produce nanoparticles discussed in chapter four. The shorter reaction time, better images

and a more mono-dispersed sample sets are an improvement over the aqueous PVP

nanoparticle synthesis. The disadvantages are the impurities that still need to be removed

from the nanoparticles. The loss of magnetism over time in the particles is of much









greater concern. The suspected cause for the loss of magnetism is the low amount of

protection provided by the octadecylamine for the nanoparticle. The emulsion synthesis

displayed evolving magnetic behavior with particle size. The apparent small magnetic

contribution of the emulsion nanoparticles gives more evidence for nanoparticle surface

behavior that is different from the core of the particle.









Table 5-1. Emulsion nano articles synthesis and physical data
K ion
Present
Water:Present Diameter
Samplecyclohexane Resulting chemical formula (per
cyclohexane (nm)
formula
unit)
A 1 : 2 Rbl.9Co4[Fe(CN)6]3.2-4.8H20 2.2 8.2 0.9
B 1 : 1 Rbl.6Co4[Fe(CN)6]3.1-5.4H20 1.7 10.6 + 0.8
C 2: 1 Rbi.5Co4[Fe(CN)6]3.3-4.2H20 0.8 13.5 + 1.2
D 4 : 1 Rbl.9Co4[Fe(CN)6]3.3-4.2H20 1.1 16.7+ 1.1



































Figure 5-1. The TEM images of cobalt iron Prussian blue (a) 8.2 nm, (b) 10.6 nm, (c)
13.5 nm, (d) 16.7 nm. A 50 nm (a,c,d) and 10 nm (b) scale bar is shown.


Figure 5-2. The SAED pattern of an organized region of nanoparticles with the 200, 220
and 400 reflections identified.













8.2 +0.9 nm 10.6 + 0.8 nm
10
10











0 20

13.5 + 1.2 nm 16.7+1.nm
15



10 10


5



00.. 0
11 12 13 14 15 16 14 15 16 17 18 19 20
Length (nm)

Figure 5-3. The particle length distributions of the four samples are shown. The total
number of particles for each distribution was 50. The solid lines are the results
of log-normal fits that provide the characteristic diameters shown for each
distribution.









4 I J
3 8.6 + 0.9 nm
2



3 10.6 + 0.8 nm





3 13.5 + 1.2 nm






o Op
4 16.7 + 1.1 nm
2 0 l
O S DD
Oo88 g-


T (K)
The temperature dependence of the low field, 100 G, susceptibilities are
shown for the fc dark (m), zfc light (o) and fc light (o) states of each sample
produced. The zfc dark temperature trace follows the fc dark and for the
two smaller samples the zfc light trace follows the fc light and has been
omitted for clarity. The magnetic properties of the nanoparticles evolve
with size toward bulk like behavior.


Figure 5-4.
















-2

J

o
?<


T (K)

Figure 5-5. The temperature dependence of the low field, 100 G, susceptibilities are
shown for the FC dark of a 16.7 nm particle initial ( ), one day (A),
12 days (m). There is a reduction in susceptibilities over time.


2200 2100


2000


Wavenumber (cm 1)

Figure 5-6. The IR room temperature absorbance spectra of a 16.7 nm nanoparticle
sample the same age stored at room temperature (line) and undergone
magnetic measurements (*). There is no change in the room temperature
spectra of the sample attributed to magnetic measurements.


U
I




4mm
*:





m. m
a

U
U
-. n
*p 8'"*'.



















I \
C)\
0 .






2200 2100 2000

Wavenumbers (cm-1)

Figure 5-7. The IR room temperature absorbance spectra of a 10.6 nm nanoparticle
sample obtained on day one (line) and on day 20 (*). As the sample aged the
ferrimagnetic peak at 2160 cm-1 diminishes and the 2095 cm-1 broadens and
shifts to 2080 cm-1. In addition the increase of the terminal ferrocyanide peak
below 2050 cm1 increases with time.











CHAPTER 6
CONCLUSIONS AND FUTURE WORK

Conclusions

In the preceding chapters, a detailed report of the different uses of Prussian blue

analogues was given. First, the formation and unique anisotropic magnetic behavior of the

cobalt iron Prussian blue analogue in thin films was discussed. The anisotropic behavior showed

that the magnetic properties of the cobalt iron analogue are different from the powdered solid

when the material is confined to a quasi-two-dimensional network. The incorporation of a

higher Tc nickel chromium Prussian blue analogue into the film was accomplished. Anisotropic

behavior was observed in the film that was not reported in the powdered solid. In addition, the

two different analogues in the film interacted, causing different magnetic behavior than was

observed in the lone cobalt iron films. Two different methods of generating nanoparticles of the

cobalt iron Prussian blue analogue were investigated. Both sets of nanoparticles displayed size-

dependent magnetic behavior. The final chapters demonstrate that photomagnetic nanoparticles

can be synthesized, but the powdered solid behavior observed can be suppressed by restricting

the size of the nanoparticle, indicating that desirable behavior may not translate into nanoscale

objects from larger systems.

Future Work

No research project is ever finished and more experiments can be done to provide a

deeper understanding of any project. The thin films and nanoparticle projects presented here are

no different. Theories about the behavior of a system continue to be tested and revised.









Thin Films

Most of the understanding of the behavior of the thin films of the Prussian blue analogues

discussed here is based upon the application of a qualitative dipolar field model. This model

provides a basic mechanism for understanding the photoinduced increases or decreases in

magnetism observed in the thin films through the orientation of the film and the dipolar field

relative to the applied magnetic field. The observation of a magnetic easy axis in the nickel

chromium films raises the question of the uniqueness of the axis to the nickel chromium

analogue. Both analogues are cubic and were deposited using a sequential assembly method. If

the easy axis resulted from the solid support effect or early deposition of the cubic networks, the

same axis should be observed in both analogues. There were also other differences in the two

analogues. The nickel chromium analogue is a ferromagnetic system for which changing

oxidation states are not expected when all the material interacts. The cobalt iron analogue is a

ferrimagnetic system for which changing oxidation states are expected. The change in oxidation

states of the cobalt iron analogue gives rise to the photomagnetic behavior observed. The

presence of another photoinduced directing force would cause a re-evaluation of the current

model.

Another study necessary to completely understand the heterogeneous portion of the thin

film project is simultaneous chemical characterization of the two different layers. The current

method employed for elemental characterization is the total digestion of the film and analysis of

the mixed sample. Complete digestion of the sample gives the relative total amount of metals in

the heterogeneous films but gives no location data. Information about the chemical purity and

the mixing region between the layers would bring a greater understanding to the behavior of the

heterogeneous films. Techniques that could probe the surface or sections of the film need to be

investigated. A surface measuring technique such as X-ray photoelectron spectroscopy (XPS)









that can then remove layers of material could be used to profile the metals in the film. Also,

taking cross-sections of the films and using area specific energy dispersive spectroscopy (EDS)

is another alternative for obtaining chemical information on the films related to depth. Another

advantage of depth specific characterization of the chemical environment would give indications

of surface chemical anisotropy that may be present in the films at the interfaces with the air or

solid support that as yet have not been detected. To date another probe that may be able to detect

metal ions in different chemical environments is electron paramagnetic resonance spectroscopy

(EPR). A recurring challenge in the characterization of the films is the low amount of sample

relative to the solid support present. High field EPR would require a sample that contains at least

1019 spins in the sample cavity. A preliminary calculation using one of the 10.6 mm2 sample

chips with a 75 nm thick film of nickel chromium containing 10 spins/ unit cell on both sides

indicates that -1.6 x 1016 spins would be present. The sample thickness could be increased an

order of magnitude but 100 sample chips would still be required to fit into the instruments cavity.

Nanoparticles

The immediate concern for the nanoparticle project is in the area of the surface core

behavior displayed by the nanoparticles. Both synthesis procedures displayed evidence that the

surface of the nanoparticle was different from the photoactive core. The aqueous PVP synthesis

appeared to have a surface effect. Understanding the nature of the interaction of the PVP with

the Prussian blue analogue is necessary to understand the surface effect. In small particles, a

large portion of the cobalt will be at the surface.

Determining the average coordination spheres of the cobalt ions is necessary to determine

the molecules interacting with the cobalt. Keeping in mind that the only diamagnetic cobalt

analogue present in the particle is the octahedral cobalt(III) low spin ion, another future direction









for the nanoparticle project is investigation into the emulsion synthesis. Addressing the

disadvantages of the emulsion may lead to better nanoparticles. The use of counter-ions other

than potassium, such as quaternary ammonium ions, that are not incorporated into the lattice is

one possible method to reduce the potassium contamination of the analogues. The other

modification to the synthesis would be to vary the coating used. The PVP nanoparticles have a

20 nm coating of polymer. The coating appears to provide enough protection for the

nanoparticles to isolate it from the environment but makes imaging and magnetic measurements

more difficult because a only 2-5 % of the material is the Prussian blue analogue. By adding a

bulkier alkyl group after the formation of the nanoparticle, a better surface coating may be

achieved. A more complete surface coating may protect the particles better and lead to a larger

magnetically active core or show damage done to the analogue before the alkyl group is added to

the surface.

Again the mechanism of formation of the nanoparticles is not well understood. In the

literature, some studies used a large excess of organic phase leading to a reverse micelle.73 The

understanding is that two reverse micelles combine, and the particle size is limited by the amount

of material contained in the reverse micelle. In the synthesis presented here there is more

aqueous phase present and the materials are not in reverse micelles. There is too much water

present to form reverse micelles and thus to limit the particle size. A thorough investigation

using other surface modifiers or solvents could be conducted.

The cobalt iron Prussian analogue continues to be the subject of a great deal of research.

The analogue is still being studied in the powdered solid form as well as in thin films and

nanoparticles by us and a great many other researchers.









LIST OF REFERENCES

1. Davidson, D.; Welo, L.A.; J. Phys. Chem. 1928, 32, 1191.

2. BuserH. J.; Schwarzenbach D.; Petter, W.; Ludi. A. Inorg.Chem. 1977, 16, 2704.

3. Day, P,; Herren, F,; Ludi, A,; Gudel, H. U.; Hulliger, F.; Givord, D. Helv. Chim. Acta
1980, 63, 148.

4. Rosseinsky, .D. R.; Glidle, A. J. Electrochem. Soc. 2003, 150, 9.

5. Roger, M.J.; Reynolds, J. R. J. Mat. Chem. 2005, 15, 22.

6. Nigrovi'c V. Phys. Med. and bio. 1965, 10, 81.

7. Stather J. W. Health Phys. 1972, 20, 1.

8. Kaye, S. S.; Long, J. R. J. Am. Chem. Soc 2005, 127, 6506.

9. Karyakin, A. A.; Karyakina, E. E.; Gorton, L. Anal. Chem. 2000, 72, 1720.

10. Dawei, P.; Jinhua, C.; Lihua, N. ; Wenyan, T.; Shouzhuo, Y. Anal. Biochem. 2004, 324,
115.

11. Ito, A.; Suenaga, M.; Ono, K. J. Chem. Phys. 1968, 48, 3597.

12. Dunbar, K. R.; Heintz, R. A. Progress in Inorganic Chemistry. Wiley: New York, 1997.

13. Verdaguer, M.; Girolami, G. Magnetism: Molecules to Materials V ed Wiley-VCH:
Weinheim 2004.

14. Gadet, V.; Mallah, T.; Castro, I.; Verdaguer, M.; Veillet, P. J. Am. Chem. Soc. 1992, 114,
9213.

15. Greibler, W. D.; Babel, D. Naturforsch. 1982, 87b. 832.

16. Entley, W.; Girolami, G. Science 1995, 268, 397.

17. Mallah, T.; Thiebaut, S.; Verdaguer, M.; Veillet, P. Science 1993, 262, 1554.

18. Hatlevik, O.; Buschmann, W.; Zhang, J.; Manson, J.; Miller. J. Adv. Mater. 1999, 11, 914.

19. Sato, O.; lyoda, T.; Fujishima, A.; Hashimoto, K. Science 1996, 272, 704.

20. Sato, O.; Einaga, Y.; lyoda, T.; Fujishima, A.; Hashimoto, K. J. Phys. Chem. B 1997,
101, 3903.

21. Sato, O.; Einaga, Y.; lyoda, T.; Fujishima, A.; Hashimoto, K. J. Electrochem. Soc. 1997,
144, L11.









22. Yoshizawa, K.; Mohri, F.; Nuspl G.; Yamabe, T. J. Phys. Chem. B 1998, 102, 5432.

23. Sato, O.; Einaga, Y.; Fujishima, A.; Hashimoto, K. Inorg. Chem. 1999, 38, 4405.

24. Yokoyama, T.; Kiguchi, M.;Ohta, T.; Sato, O.; Einaga, Y.; Hashimoto, K. Phys. Rev. B
1999, 60, 9340.

25. Bleuzen, A.; Lomenech, C.; Escax, V.; Villain, F.; Varret, F.; Cartier dit Moulin, C.;
Verdaguer, M. J. Am. Chem. Soc. 2000, 122, 6648.

26. Pejakovic, D.; Manson, J.; Miller, J.; Epstein, A. Phys. Rev. Lett. 2000, 85, 1994.

27. Goujon, A.; Roubeau, O.; Varret, F.; Dolbecq, A.; Bleuzen, A.; Verdaguer, M. Eur. Phys.
J. B 2000, 14, 115.

28. Champion, G.; Escax, V.; Cartier dit Moulin, C.; Bleuzen, A.; Villain, F.; Baudelet, F.;
Dartyge, E.; Verdaguer, M. J. Am. Chem. Soc. 2001 123, 12544.

29. Escax, V.; Bleuzen, A.; Cartier dit Moulin, C.; Villain, F.; Goujon, A.; Varret, F.;
Verdaguer, M.; J. Am. Chem. Soc. 2001, 123, 12536.

30. Goujon, A.; Varret, F.; Escax, V.; Bleuzen, A.; Verdaguer, M.; Polyhedron 2001, 20,
1339.

31. Goujon, A.; Varret, F.; Escax, V.; Bleuzen, A.; Verdaguer, M.; Polyhedron 2001, 20,
1347.

32. Kawamoto, T.; Asai, Y.; Abe, S.; Phys. Rev. Lett. 2001, 86, 348.

33. Ng, C.; Ding, J.; Gan, L. J. Solid State Chem. 2001, 156, 400.

34. Ohkoshi, S.; Hashimoto, K. Photochem. Photobiol. C: Photochemistry Reviews 2001, 2,
71.

35. Shimamoto, N.; Ohkoshi, S.; Sato, O.; Hashimoto, K. Inorg. Chem. 2002, 41, 678.

36. Liu, H.; Matsuda, K.; Gu, Z.; Takahashi, K.; Cui, A.; Nakajima, R.; Fujishima, A.; Sato, O.
Phys. Rev. Lett. 2003, 90, 167403

37. Bleuzen, A.; Excax, V.; Ferrier, A.; Villain, F.; Verdaguer, M.; Munsch, P.; Itie, J.-P.
Angew. Chem. Int. Ed., 2004, 43, 3728.

38. Kamiya, M.; Hananwa, M.; Moritomo, Y.; Isobe, Y.;Tateishi, J.; Kato, K.; Nakamura, A.
Phys. Rev. B 2004, 69, 052102.

39. Boukheddanden, K.; Nishino, M.; Miyashita, S.; Varret, F. Phys. Rev. B 2005, 72, 014467.









40. Gawali-Salunke, S.; Varret, F.; Maurin, I.; Enachescu, C.; Malarova, M.; Boukheddanden,
K.; Codjovi, E.; Tokoro, H.; Ohkoshi, S.; Hashimoto, K. J. Phys. Chem. B 2005, 109,
8251.

41. Park, J.-H.; Frye, F. A.; Anderson, N. E.; Pajerowski, D. M.; Huh, Y.-D.; Talham, D. R.;
Meisel, M. W. J. Mag. Magn. Mater. 2007, 310, 1458.

42. Neff, V. J. Electrochem. Soc. 1978, 125, 886.

43. Itaya, K.; Ataka, T.; Toshima, S. J. Am. Chem. Soc, 1982, 104, 4767.

44. Buschmann, W.; Paulson, S. : Wynn, C.; Girtu, M.; Epstien, A.; White, A.; Miller, J.
Chem. Mater. 1988, 10, 1386.

45. Lundgren, C.; Murray, R. Inorg. Chem. 1988, 27, 933.

46. Ohkoshi, S.; Einaga, Y.; Fujishima, A.; Hashimoto, K. J. Electroanal. Chem. 1999, 473,
245.

47. Ivanov, V.; Kaplun, M.; Kondrat'ev, V.; Tikhomirova, A.; Zigel', V.; Yakovleva, S.;
Malev, V. Russ. J Electrochem., 2002, 38, 200.

48. Tacconi, N.; Rajeshwar, K. Chem. Mater. 2003, 15, 3046.

49. Toshima, N.; Liu, K.; Kaneko, M. Chem. Lett. 1990, 485.

50. Honda, K.; Hayashi, H.; Chiba, K. Chem. Lett. 1988, 191.

51. Guo, Y.; Guadalupe, A.; Resto, O.; Fonseca, L.; Weisz, S. Chem. Mater. 1999, 11, 135.

52. Ravaine, S.; Lafuente, C.; Mingotaud, C. Langmuir 1998, 14, 6347.

53. Mingotaud, C.; Lafuente, C.; Amiell, J.; Delhaes, P. Langmuir 1999, 15, 289.

54. Torres, G. Agricole, Chem. Mater. 2002, 14, 4012.

55. Romualdo-Torres, G.; Agricole, B.; Mingotaud, C.; Ravaine, S.; Delhaes, P. Langmuir
2003, 19, 4688

56. T. Yamamoto, Y. Umemura, Sato, O.; Einaga, Y. Chem. Lett. 2004, 33, 500.

57. T. Yamamoto, Y. Umemura, Sato, O.; Einaga, Y. Chem. Mater. 2004, 16, 1195.

58. T. Yamamoto, Y. Umemura, Sato, O.; Einaga, Y. J. Am. Chem. Soc. 2005, 127, 16065.

59. T. Yamamoto, Y. Umemura, Sato, O.; Einaga, Sci. Tec. Adv. Mat. 2006, 7, 134.

60. Millward, R.; Madden, C.; Sutherl, I.; Mortimer, R.; Fletcher, S.; Marken, F. Chem.
Commun. 2001, 1994.









61. Pyrasch, M.; Tieke, B.; Langmuir 117 2001, 117, 7706.

62. Culp, J.; Park, J.-H.; I. Benitez, Huh, Y.-D.; Meisel, M.; Talham, D. Chem. Matter. 2003,
15, 3431.

63. Jin, W.; Toutianoush, A.; Pyrasch, M.; Schnepf, J.; Gottschalk, H.; Rammensee, W.;
Tieke, B. J. Phys. Chem. B 2003, 107, 12062.

64. Park, J.-H.; Huh, Y.-D.; Cizmar, E.; Gamble, S.; Talham, D.; Meisel, M.; J. Magn. Magn.
Mater. 2004, 272-276, 1116.

65. Park, J.-H.; Cizmar, E.; Meisel, M.; Huh, Y.-D.; F. Frye, S. Lane, Talham, D. Appl. Phys.
Lett. 2004, 85, 3797.

66. Culp, J.; Park, J-H,; Frye, F.; Huh, Y-D. Meisel, M.; Talham, D. Coordination Chem. Rev.
2005, 249, 2642.

67. Park, J.-H.; Frye, F.; Lane, S.; Ci2mar, E.; Huh, Y.-D.; Talham, D.; Meisel, M.
Polyhedron 2005, 24, 2355.

68. Vaucher, S,; Li, M.; Mann, S. Angew. Chem. Int. Ed. Engl. 2000, 39, 1793.

69. Ng, C. W.; Ding, J.; Chow, P. Y.; Gan, L. M.; Quek, C. H. J. Appl. Phys. 2000, 87, 6049.

70. Vaucher, S.; Fielden, J.; Li, M.; Dujardin, E.; Mann, S., Nano. Lett. 2002, 2, 225.

71. Uemura, T.; Kitagawa, S. J. Am.Chem. Soc. 2003, 125, 7814.

72. Uemura, T.; Ohba, M.; Kitagawa, S. Inorg. Chem. 2004, 43, 7339

73. Yamada, M.; Arai, M.; Kurihara, M.; Sakamoto, M.; Miyake, M., J. Am. Chem. Soc. 2004,
126, 9482.

74. Johansson, A.; Widenkvist, E.; Lu, J.; Boman, M.; Jansson, U. Nano Lett. 2005, 5, 1603.

75. Xian, Y.; Zhou, Y.; Xian, Y.; Zhou, L.; Wang, H.; Jin, L. Anal. Chim. Acta 2005, 546,
139.

76. Taguchi, M.; Yamada, K.; Suzuki, K.; Sato, O.; Einaga, Y.; Chem. Mater. 2005, 17, 4554.

77. Taguchi, M.; Yagi, I.; Nakagawa, M.; Iyoda, T.; Einaga, Y.; J. Am. Chem. Soc. 2006, 128,
10978

78. Catala, L.; Gloter, A.; Stephan, O.; Rogez, G.; Mallah, T. Chem. Commun. 2006, 1018.

79. Moore, J. G.; Lochner, E. J.; Ramsey, C.; Dalal, N. S.; Stiegman, A. E. Angew. Chem.
2003, 115, 2847.









80. Catala, L.; Mathonire. C.; Gloter, A.; Stephan, O.; Gacoin, T.; Boilot, J.-P.; Mallah, T.
Chem. Commun. 2005, 746.

81. Culp, J. T.; Park, J.-H.; Meisel, M. W.; Talham, D. R. Inorg. Chem. 2003, 42, 2842.

82. Culp, J. T.; Park, J.-H.; Benitez, I. O.; Meisel, M. W.; Talham, D. R. Polyhedron 2003, 22,
2125.

83. Culp, J. T.; Park, J.-H.; Meisel, M. W.; Talham, D. R. Polyhedron 2003, 22, 3059.

84. Frye, F. A.; Pajerowski, D. M.; Lane, S. M.; Anderson, N. E.; Park, J.-H.; Meisel, M. W.;
Talham, D. R. Polyhedron 2007, 26, 2281.

85. Park, J.-H. Ph.D., University of Florida, 2006.

86. Mydosh, J. A. Spin Glasses: An Experimental Introduction. Taylor and Francis: London,
1993.

87. Pejakovic, D. A.; Manson, J. L.; Miller, J. S.; Epstein, A. J. Synth. Met. 2001, 122, 529.

88. Coronado, E.; Delhaes P.; Gatteschi, D.; Miller, J. S. Molecular Mangnetism: From
Molecular Assemblies to the Devices. Klumer Academic Publishers: Boston, 1996.

89. Verdaguer, M.; Bleuzen, A.; Marvaud, V.; Vaissermann, J.; Seuleiman, M.; Desplanches,
C.; Scuiller, A.; Train, C.; Garde, R.; Gelly, G.; Lomenech, C.; Rosenman, I.; Veillet, P.;
Cartier, C.; Villain, F. Coord. Chem. Rev. 1999, 192, 1023.

90. Gay, J. G.; Richter, R. Phys. Rev. Lett. 1986, 56, 2728.

91. Jonker, B.T.; Walker, K.-H.; Kisker, E.; Prinz, G. A.; Carbone C. Phys. Rev. Lett. 1986,
56, 142.

92. Gay, J. G.; Richter, R. J. Appl. Phys. 1987, 61, 3362.

93. Heinrich, B.; Urquhart, K. B.; Arrott, A. S.; Cochran, J. F.; Myrtle, K.; Purcell, S. T. Phys.
Rev. Lett. 1987, 59, 1756.

94. Koon, N. C.; Jonker, B. T.; Volkening F. A.; Krebs, J. J.; Prinz, G. A. Phys. Rev. Lett.
1987, 59, 2463.

95. Chappert, C.; Bruno, P. J. Appl. Phys. 1988, 64, 5736.

96. Stamps, R. L.; Camley, R. E.; Hillerbrands, B.; Giintherodt, G. Phys. Rev. B 1993, 47,
5072.

97. Chuang, D. S.; Ballentine, C. A.; O'Handley R. C. Phys. Rev. B 1994, 49, 15084.

98. Rosenbusch, P.; Lee, J.; Lauhoff, G.; Bland J. A. C. J. Magn. Magn. Mater. 1997, 172, 19.









99. Frey, N. A.; Srinath, S.; Srikanth, H.; Varele, M.; Pennycook, S. Phys. Rev. B 2006,
74, 024420.

100. Frye, F. A.; Pajerowski, D. M.; Anderson, N. E.; Long, J.; Park, J.-H.; Meisel, M. W.;
Talham, D. R.; Polyhedron 2007, 26, 2273.

101. Pajerowski, D. M.; Frye, F. A.; Talham, D. R.; Meisel, M. W. New J. Phys. 2007, 9, 222.

102. Rasband, W.S. and Image J, US National Institutes of Health, Bethesda, MD, USA
(accessed 1 October 2006) online at http://rsb.info.nih.gov/ij/

103. Evans, M.; Hastings, N.; Peacock, B. Statistical Distributions. Wiley: New York, 2000.

104. Carlin, R. Magnetochemistry. Springer-Verlag: New York, 1986.

105. Chen,M.; Liu, J. P.; Sun, S. J. Am. Chem. Soc., 2004, 126, 8394

106. Shevchenko, E. V.; Talapin, D. V.; Murray, C. B.; O'Brien, S. J. Am. Chem. Soc. 2006,
128, 3620.









BIOGRAPHICAL SKETCH

Franz Frye was born in Austria while his father was in a teaching exchange program. He

then moved to and grew up in Franklin, New York while attending Franklin Central School for

K-12 before graduating. My undergraduate education was conducted at Hartwick College with a

research project on soil chemistry overseen by Frank Dunnivant and Meredith Newman. After

graduating from Hartwick he entered industry and worked for several companies over a span of

four years in the areas of environmental regulation, hazardous waste disposal, water testing, and

solution manufacture. He then entered graduate school in 2002 and has been conducting

research on the cobalt iron Prussian blue analogue in the Talham research group at the University

of Florida.





PAGE 1

1 THIN FILMS AND NANOPARTICLES OF THE PHOTOACTIVE COBALT IRON PRUSSIAN BLUE ANALOGUE By FRANZ FRYE A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2007

PAGE 2

2 2007 Franz Frye

PAGE 3

3 To Tresha, 1, 2, and 3

PAGE 4

4 ACKNOWLEDGMENTS I have had the aid of numerous people over th e years. I begin with those who have aided me in a scholarly fashion. First I would like to thank my advisor Daniel R. Talham whose advice, actions and inactions have made me into a better scientist. The members of the Talham research group have been a cons tant resource to me throughout th e years from the past members of the group who aided me in the beginning of my graduate career to the current members. In particular Justin Gardner and Sarah Lane w ith whom Ive had many conversations with on a variety of topics over the years but also to Justin for being the en ergy in the lab and to Sarah for being one of the few other people Ive known that is comfortable with not talking for an afternoon in the lab. This research project required collaborations with areas out side of chemistry that have been invaluable to me. Mark W. Meisel and his research group from the department of physics have been a critical part of th is project. All magnetic informa tion on the material presented was obtained by this group. I would also thank them for their insight in to the magnetic behavior of the materials as well as their explanations of the physics involved. The graduate students that have helped over the years from physics are Ju -Hyun Park who was involved in the early portion of the project and Daniel Pajerowski who has been critical in helping me at end. Ive also made many trips to MAIC for characte rization of materials and have been aided by Kerry Siebein not only by her expert TEM abilities but also her knowledge of othe r characterization methods. People not directly contributing to the research have also been beneficial to me over the years. My friends at the Kung-Fu school and gamming groups over the years have provided necessary diversion that allowed me to focus in the lab. Keith and Katie also contributed their scientific insight before gradua ting. Id also like to thank Kati e Amaral more directly for her

PAGE 5

5 help in proofreading and for her efforts in obtain ing an opportunity for me to become involved in lecturing at UF. Finally I arrive at those closest to me. I thank my wife Tresha who has been my friend over the years. Also, I thank my father whose advice on graduate school by recalling his own experience has shown me that the process has not changed much in 40 years.

PAGE 6

6 TABLE OF CONTENTS page ACKNOWLEDGMENTS...............................................................................................................4 LIST OF TABLES................................................................................................................. ..........9 LIST OF FIGURES................................................................................................................ .......10 LIST OF ABBREVIATIONS........................................................................................................14 CHAPTER 1 INTRODUCTION..................................................................................................................18 Introduction................................................................................................................... ..........18 Prussian Blue.................................................................................................................. .18 Cobalt Iron Prussian Blue Analogue...............................................................................19 Thin Films..................................................................................................................... ..21 Nanoparticles.................................................................................................................. .22 2 ANISOTROPIC PHOTOINDUCED MAGNETISM IN THIN FILMS OF THE PRUSSIAN BLUE ANALOGUE..........................................................................................27 Introduction................................................................................................................... ..........27 Experimental Section........................................................................................................... ...29 Reagents and Materials....................................................................................................29 Sample Preparation of AjCok[Fe(CN)6]l nH2O Thin Films............................................29 Instrumentation................................................................................................................30 Analysis Preparations......................................................................................................31 Results........................................................................................................................ .............32 Film Generation and Characterization.............................................................................32 Magnetic Behavior with HE Parallel to the Thin Films...................................................33 Anisotropic Photomagnetic Behavior..............................................................................34 Alkali Cation Dependence...............................................................................................35 Field Dependent Magnetic Behavior of 75 nm and 160 nm Films.................................36 Effect of Film Thickness.................................................................................................36 Temperature Dependence of the Anisotropy...................................................................37 Discussion..................................................................................................................... ..........37 Conclusions.................................................................................................................... .........41 3 HETEROGENOUS PRUSSIAN BL UE ANALOGUE FILMS.............................................51 Introduction................................................................................................................... ..........51 Experimental................................................................................................................... ........54 Results........................................................................................................................ .............55 Fast Nickel Chromium Prussi an Blue Analogue Film 1.................................................55

PAGE 7

7 Fast Heterogeneous Stacked Films 2 and 3.....................................................................56 Fast Mixed Heterogeneous Film 4..................................................................................58 Fast Heterogeneous Sandwich ABA Film 5....................................................................58 Slow Heterogeneous Stacked AB Film 6........................................................................60 Slow Heterogeneous Mixed Film 7.................................................................................60 Magnetic Anisotropy Present in the Nickel Chromium Film..........................................61 Sequence Effects in the Stacked Films............................................................................62 Photoinduced Magnetism in the Stacked Films..............................................................62 Magnitude of the Photoeffects in the Heterogeneous Films...........................................63 Anisotropic Photoinduced Magneti sm of the Sandwich Films.......................................63 Diminished Photoeffects in Stacked Films......................................................................65 Magnetic Behavior of Metal Thin Films Discussed in Literature...................................66 Conclusions.................................................................................................................... .........67 4 SIZE DEPENDENT PHOTOINDUCED M AGNETISM IN RUBIDIUM COBALT IRON PRUSSIAN BLUE ANALOGUE NANOPARTICLES..............................................79 Introduction................................................................................................................... ..........79 Experimental Section........................................................................................................... ...80 Reagents and Materials....................................................................................................80 Sample Preparation of AjCok[Fe(CN)6]l nH2O Nanoparticles.....................................80 Instrumentation................................................................................................................80 Analysis Preparations......................................................................................................81 Results........................................................................................................................ .............82 Nanoparticle Generation and Characterization...............................................................82 The IR Data.................................................................................................................... .83 Magnetic Behavior of Nanoparticles...............................................................................85 Surface Effects in Nanoparticles.....................................................................................87 Discussion..................................................................................................................... ..........88 Critical Size of Nanoparticles..........................................................................................88 Core Shell Nanoparticles.................................................................................................90 Conclusion..................................................................................................................... .........91 5 ALTERNATE SYNTHESIS OF COBALT IRON PRUSSIAN BLUE ANALOGUE NANOPARTICLES.............................................................................................................103 Introduction................................................................................................................... ........103 Experimental Section........................................................................................................... .103 Reagents and Materials..................................................................................................103 Sample Preparation of AjCok[Fe(CN)6]l nH2O Nanoparticles...................................103 Instrumentation..............................................................................................................104 Analysis preparations....................................................................................................104 Results........................................................................................................................ ...........105 Nanoparticle Generation and Characterization.............................................................105 Magnetic Behavior........................................................................................................106 Time Dependent Behavior.............................................................................................107 Discussion..................................................................................................................... ........108

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8 Emulsion Synthesis Advantages....................................................................................108 Emulsion Synthesis Disadvantages...............................................................................109 Comparison with PVP Nanoparticles............................................................................110 Conclusions.................................................................................................................... .......111 6 CONCLUSIONS AND FUTURE WORK...........................................................................119 Conclusions.................................................................................................................... .......119 Future Work.................................................................................................................... ......119 Thin Films.....................................................................................................................120 Nanoparticles.................................................................................................................121 LIST OF REFERENCES.............................................................................................................123 BIOGRAPHICAL SKETCH.......................................................................................................129

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9 LIST OF TABLES Table page 2-1 Thickness and roughness data for films of Rb0.7Co4[Fe(CN)6]3.0 H2O...........................42 3-1 Summary of heterogeneous films generated......................................................................68 4-1 Summary of the material prope rties of the four sample sets.............................................92 4-2 Summary of magnetic data for different nanoparticle samples.........................................92 4-3 Calculation based on magnetic data for PVP nanoparticles..............................................92 5-1 Emulsion nanoparticles s ynthesis and physical data.......................................................113

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10 LIST OF FIGURES Figure page 1-1 Unit cell representation of the ACoII[FeIII(CN)6] nH2O analogue....................................25 1-2 Unit cell representation of the CoII 1.5[FeIII(CN)6] 3H2O analogue.....................................25 1-3 Potential energy diagram of the cobalt iron Prussian blue analogue.................................26 2-1 The sequential adsorptions method....................................................................................43 2-2 Thickness vs. number of cycles for the slow growth, and fast growth, sequential adsorptions deposition methods.........................................................................................43 2-3 SEM images of fast method films......................................................................................44 2-4 SEM images of slow method films....................................................................................44 2-5 Room temperature FT-IR ATR spectra of a 160 nm film.................................................45 2-6 Plots of fc and zfc DC magnetizati on of a 160 nm thick film parallel to HE = 200 G in dark and photoinduced (light) states..............................................................................45 2-7 Plots of fc and zfc DC magnetization of a 160 nm thick film perpendicular to HE = 200 G in dark and photoinduced (light) states..........................................................46 2-8 Anisotropy in the photoinduced ma gnetization of a 75 nm film of Rb0.7Co4[Fe(CN)6]3.0 H2O...............................................................................................46 2-9 Change in magnetization for a 86 nm film of K0.5Co4[Fe(CN)6]3.2 4.8H2O perpendicular to HE of 200 G at 5 K..................................................................................47 2-10 Rubidium ion concentration dependen ce of the photoinduced magnetization of 75 cycle slow cobalt iron Prussi an blue analogue films.........................................................47 2-11 Applied field dependence of th e photoinduced magnetization with HE perpendicular to the plane of the film....................................................................................................... 48 2-12 The field dependent magnetiz ation of a 160 nm film of Rb0.7Co4[Fe(CN)6]3.0 H2O......48 2-13 Thickness dependence of the photoinduced magnetization in cobalt iron Prussian blue analogue thin films with HE perpendicular to the film plane.....................................49 2-14 Photoinduced magnetism of a 160 nm film of Rb0.7Co4[Fe(CN)6]3.0 H2O at 20 K with HE = 200 G perpendicular to the film........................................................................49 2-15 The photoinduced magnetism in a qua si-two-dimensional film of cobalt iron Prussian blue analogue.......................................................................................................50

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11 3-1 Schematic of the heterogeneous Prussian blue analogue thin film generated using the sequential adsorption method............................................................................................69 3-2 Schematic of the magnetic layer exchange in teractions likely to exist in samples of heterogeneous films...........................................................................................................6 9 3-3 Schematic of the different heterogeneous films generated................................................69 3-4 Magnetic susceptibility vs. temperature pl ot of a 75 nm nickel chromium Prussian blue analogue thin film......................................................................................................70 3-5 The ac susceptibility data of the slow f ilm of the nickel chromium Prussian blue analogue....................................................................................................................... ......70 3-6 The dc magnetic susceptibility verses temperature fc ( ), zfc ( ) of the stacked AB heterogeneous Prussian blue analogue...............................................................................71 3-7 Photoinduced magnetization of a 75 nm ni ckel chromium Prussian blue analogue film under a 75 nm cobalt iron Prussian blue analogue film.............................................71 3-8 Photoinduced magnetization of a 75 nm c obalt iron Prussian blue analogue film under a 75 nm nickel chromium Prussian blue analogue BA............................................72 3-9 The dc magnetic susceptibility fc zfc versus temperature plot of a mixed film..............72 3-10 Photoinduced magnetism of a mixed cobalt iron nickel chromium Prussian blue analogue fast film............................................................................................................. ..73 3-11 Photoinduced magnetization of a sandwich film nickel chromium, cobalt iron, nickel chromium Prussian blue analogue.....................................................................................73 3-12 The dc magnetic susceptibility vs. temp erature with H = 100 G perpendicular to a slow stacked AB film.........................................................................................................74 3-13 Photoinduced magnetism of a stacked slow AB film........................................................74 3-14 Magnetic susceptibility vs. temperatur e with H = 100 G perpendicular to a mixed slow film...................................................................................................................... ......75 3-15 Photoinduced magnetism of a mixed slow f ilm of cobalt iron and nickel chromium analogue....................................................................................................................... ......75 3-16 Schematic of the dipolar field in the fe rromagnetic nickel chromium analogue films......76 3-17 Schematic of the magnetic easy axis in the ferromagnetic nickel chromium analogue present in stacked films......................................................................................................7 6 3-18 Change in magnetic susceptibility over time with photoexcitation...................................77

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12 3-19 Schematic of the sandwich film with di rections of the applied magnetic field.................77 3-20 Schematic of the stacked AB film.....................................................................................78 4-1 TEM images of cobalt iron Prussian blue analogue..........................................................93 4-2 SAED pattern of a large agglomerat e consisting of over 100 nanoparticles and a powdered solid................................................................................................................. ..93 4-3 The particle distributions, normalized to th e largest bin, versus diameter for the four samples of cobalt iron Prussian blue analogue particles....................................................94 4-4 TEM images of cobalt iron Prussian blue analogue nanoparticles and powdered solid prepared immediately after synthesis.................................................................................95 4-5 Absorbance IR spectra of cobalt iron Prussian blue analogue nanoparticles....................95 4-6 Absorbance IR spectra of powdered solid samples...........................................................96 4-7 The temperature dependences of the low field, 100 G, susceptibilities for nanoparticles.................................................................................................................. ....97 4-8 The temperature dependences of the low field, 100 G, suscepti bilities for powdered solid.......................................................................................................................... ..........98 4-9 The T = 2 K magnetization versus magnetic field sweeps for the two largest sizes of nanoparticles.................................................................................................................. ....99 4-10 The T = 2 K magnetization versus magneti c field sweeps for the two powdered solid rubidium concentrations...................................................................................................100 4-11 The temperature dependences of the ac -susceptibilities for the four samples.................101 4-12 Core shell behavior model...............................................................................................10 2 5-1 TEM images of cobalt iron Prussian blue........................................................................114 5-2 SAED pattern of an organi zed region of nanoparticles...................................................114 5-3 The particle length distributions of the four samples are shown.....................................115 5-4 The temperature dependences of th e low field, 100 G, susceptibilities...........................116 5-5 The temperature dependences of the low field, 100 G, susceptibilities over time..........117 5-6 IR room temperature absorbance spectr a of a 16.7 nm nanopart icle after magnetic measurments....................................................................................................................117

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13 5-7 TheIR room temperature absorbance sp ectra of a 10.6 nm nanoparticle sample over time........................................................................................................................... .......118

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14 LIST OF ABBREVIATIONS TC Magnetic ordering temperature PVP Polyvinylpyrrolidone K Kelvin A Alkaline ion S Spin value CTIST Charge Transfer Induced Spin Transition hs High spin ls low spin G Gauss ICP-MS Inductively coupled plasma mass spectrometry ACS American Chemical Society DI Deionized FT-IR Fourier transform infra red AFM Atomic force microscopy SEM Scanning electron microscopy SQUID Superconducting quantum interference device OD Outer diameter PET Polyethylphthalate ATR Attenuated total reflectance RMS Route mean squared fc Field cooled zfc Zero field cooled HE External applied magnetic field emu Electromagnetic unit

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15 HD Dipolar field Magnetic susceptibility SAED Selected area electron diffraction TEM Transmission electron microscopy EDS Energy dispersive spectroscopy HC Coercive field FW Formula weight

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16 Abstract of Dissertation Pres ented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy THIN FILMS AND NANOPARTICLES OF THE PHOTOACTIVE COBALT IRON PRUSSIAN BLUE ANALOGUE By Franz Frye December 2007 Chair: Daniel R. Talham Major: Chemistry Thin films and nanoparticles of the photomagnetic AjCo4[Fe(CN)6]l nH2O cobalt iron Prussian blue analogue were st udied. The cobalt iron analogue has a persistent metastable excited state accessible at low te mperatures using photoexcitation to convert diamagnetic metal pairs to ferrimagnetic metal pairs through a char ge transfer and spin crossover event. The integration of the photoinducible material into devices will require depos iting material at an interface. The formation of films and functi onalized nanoparticles are possible methods for placing material at an interface. Thin films a nd nanoparticles may have properties different than the bulk material. Specifically, the size or dime nsional restriction of the cobalt iron analogue changes the magnetic properties normally observed in the bulk. Thin films were generated using a se quential adsorption method. The cobalt iron analogue films were characterized using scanning electron and atomic force microcopy, infrared spectrometry, and elemental analysis. A uni que photoinduced decrease in magnetism is observed in the cobalt iron analogue film. The photoinduced behavior is dependent on the thickness of the film and the strength of the applied magnetic field. This behavior is qualitatively explained by considering the dipo lar field generated by the quasi two-dimensional organization of ordered pr imordial ferrimagnetic material in the film.

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17 The anisotropic photoinduced behavior wa s changed by the incorporation of a higher magnetic ordering nickel chromium analogue in to the cobalt iron analogue film. Individual behaviors of the different analogu es were observed in the same fi lm. The individual behaviors of the analogues were suppressed by modifying the deposition sequence. When a cobalt iron analogue layer was placed between two nickel chromium layers the an isotropic photoinduced magnetic behavior observed was the ex act opposite of the cobalt iron film. Photomagnetic nanoparticles of the coba lt iron analogue were generated using both aqueous reactions and oil water emulsion reactions containing su rface modifiers to restrict the particle growth. Nanoparticles were charac terized using transmission electron microcopy, infrared spectrometry, and elemental an alysis. Nanoparticles with diameters 10 nm follow Curie-like magnetic signals, where as larger na noparticles have bulk li ke magnetic signals. Evidence that the surface of the nanoparticles is locked in diamagnetic metal pairs was also observed.

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18 CHAPTER 1 INTRODUCTION Introduction Prussian Blue Prussian blue (FeIII 4[FeII(CN)6]3 4H2O) has been used for three hundred years as a dye. The magnetic behavior of the solid was first reported in 1928.1 The first crystal structure was published in 1977,2 supported by neutron data from 1980,3 showed that Prussian blue is a facecentered cubic network of iron(III) ions bridged to ferrocyanide i ons. More recent studies have shown that Prussian blue disp lays interesting electrochrom ic phenomena that have been investigated using electrochemical methods.4,5 The medical field has also found a use for Prussian blue as a heavy metal contam inant remover in biological systems.6,7 Prussian blue and its analogues have been investigated for their hydrogen storage potential8 and their peroxide sensing abilities.9,10 Prussian blue has a long-range fe rromagnetic ordering temperature of 5.6 K.11 This ordering warranted further studies of Pr ussian blue as a molecular-based magnet. When one or more of the iron atoms in Pr ussian blue are repl aced by other transition metals, the compound is considered a Prussian bl ue analogue. Two properties of Prussian blue analogues have generated a great deal of research interest in the last few years and have been reviewed.12,13 The first is the high magnetic ordering (TC) of several of the analogues. A few of the Prussian blue analogues with high TC values that have been synthesized to date are: CsNi[Cr(CN)6] H2O14 and CsMn[Cr(CN)6] H2O15 with a TC values near 90 K; Cs2Ni[V(CN)6] with a TC value of 125 K;16 Cr1.5[Cr(CN)6] H2O with a TC value of 240 K;17 and K0.058VII/III[Cr(CN)6] 0.79(SO4)0.0580.93H2O with a TC value of 372 K.18 The combination of different third row transition metals and mu ltiple oxidation states ha s led to a number of

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19 Prussian blue analogues with differing TC values. Another interesti ng behavior in a Prussian blue analogue is the photoindu ced magnetization of the cobalt iron Prussian blue analogue. Cobalt Iron Prussian Blue Analogue Since the discovery of photoinduced magnetism in the cobalt iron Prussian blue analogue by Hashimoto and coworkers in 1996,19 extensive research has been done on the powdered solid form of the analogue.20-41 During aqueous synthesis of Prus sian blue analogues the product of the reaction is a polycrystalline suspension of sub-micrometer sized crystallites that when isolated from solution form a powdered soli d. The cobalt iron Pru ssian blue analogue ACoII[FeIII(CN)6] nH2O, where A is an alkali metal, and th e cobalt and iron cations form a facecentered cubic network bridged by cyanide ions w ith the alkali metal incorporated into the tetrahedral holes. (Figure 1-1) The magnetic be havior of the cobalt iron Prussian blue analogue can be tuned by altering the alkali metal concentration availa ble during synthesis.29,35 Compounds with little to no alkali metal achieve charge balance by inco rporating a number of ferricyanide vacancies in the lattice resulting in an empirical formula of CoII 1.5[FeIII(CN)6] H2O. (Figure 1-2) Each cobalt ion ha s an average of two water molecules in its coordination sphere that fill the vacancy left by the ferricyanide anion, leading to cobalt ions that are in a weak ligand field and high spin state. The cobalt ion spin is S = 3/2 and is ferrimagmetically coupled to the iron S = If an abundance of alka li metals are available during synthesis, the charge is balanced by trap ping available alkali cations into the lattice, giving an empirical formula of ACoIII[FeII(CN)6]. In this lattice, four alkali metal ions are held in the tetrahedral holes of each unit cell and the latt ice is complete. The result is a rigid structure with cobalt ions surrounded by six cyanide ni trogens causing a strong ligand field, placing the cobalt in the low spin state. The low spin state of the cobalt coupled with a charge transfer to the iron from the cobalt results in empty eg anti-bonding orbitals in the cobalt ion. This

PAGE 20

20 depopulation of the cobalt eg orbitals cause a lattice contra ction of 0.40 compared to a complex with no alkali cation. In this complex, the iron and cobalt are low spin d6 metals, and diamagnetic.23 Both of these systems will maintain th e spin state and magnetic properties when cooled to 50 K.35 The use of an intermediate amount of alkali metal results in a compound that is between these two extremes with a unit cell formula of A2CoII 4[FeIII(CN)6]3.33 H2O. There are alkali metal ions in the interstitial holes, but there are still ferricyanide vacancies to achieve charge balance. Each cobalt ion has an average of one water coordinating to it, lowering the octahedral splitting ( o) so that room temperature thermal en ergy allows for the population of the eg orbitals of the cobalt. This results in magnetic behavior similar to a complex without alkali ions. When the complex with partially filled vacancies is cooled from room temperature to 50 K the magnetization decreases. This complex has been described as a CTIST, (charge transfer induced spin transition) material.35,41 The type of alkali cation present a ffects the behavior of this change. The analogues with sodium ca tions show very dramatic changes in magnetism over a narrow temperature range as well as wi de hysteresis in their warming curves that are attributed to cooperative effects in th e lattice. The larger cations exhibit more gradual decreases in magnetism and narrow hysteresis. When the magne tism decreases, a charge transfer from the CoII to the FeIII occurs along with a spin crossover of cobalt. The result is a complex that transitions from a FeIII S = CoII S = 3/2 ferrimagnetic pair to a FeII S = 0, CoIII S = 0 diamagnetic pair.23,25,35 After the transition, the network behaves similar to a solid with no ferricyanide vacancies. The netw ork retains a small amount of ferrimagnetic material referred to as non-switchable pairs or primordial spins. This primordial material di splays magnetic behavior similar to a complex without alkali i ons even at low temperatures.

PAGE 21

21 The other interesting proper ty of the cobalt iron Prussi an blue analogue is the photoinduced magnetism. The elemental compositi on and ligand field strength around the cobalt must be similar to that in the CTIST material. At temperatures below 20 K, the predominately diamagnetic CoIII, FeII material may be photoexcited using 600 nm light and converted to the ferrimagnetic CoII, FeIII species, thereby increasing the magne tization. This excited material is now in a long-lived, meta-stable excited state, which will decay slowly over several days. The process is reversible by irradiation with 450 nm light or by th ermal treatment of the sample to a temperature of 100 K, both of which allow th e complex to relax to the diamagnetic state.19,20 The photomagnetic effect of the cobalt iron Prus sian blue analogue can be explained with the aid of a potential energy vers us internuclear distance diagram.23,25,35 (Figure 1-3) At low temperatures, photoexcitation (light ) provides the energy required to cause the charge transfer. This high energy FeIII CoII ls pair relaxes back to the diama gnetic state by another charge transfer or to the ferrimagnetic state th rough a spin crossover event at th e cobalt. If the system is continually photoexcited, all the photoswitchabl e diamagnetic material will be converted to ferrimagnetic material. At low temperatures, this ferrimagnetic material is trapped in the excited spin state by a potential ener gy barrier too large to be overc ome by thermal energy, causing the long-lived metastable excited state th at has been reported for this compound. Thin Films Application of these exciting material s would likely requir e the formation of homogeneous thin films and the development of methods for depositing material on solid supports. Prussian blue and its analogues will not wet a surface well, and instead they form insoluble microcrystalline powder samples. Th is property makes the formation of homogenous films difficult. The most common method of ge nerating Prussian blue films and their analogues is the electrochemical method42-48. Other methods include dip-coating or spin casting of

PAGE 22

22 colloidal solutions,42,49 adsorption onto sol-gel films,50,51 adsorption at Langmuir monolayers,52-59 and sequential adsorptions 60-67 onto modified surfaces. Prussian blue films generated by electroche mical methods have demonstrated the ability to form homogenous films, however the so lid support employed needs to be a smooth conducting surface, which excludes the use of the porous supports and polymers that would be necessary to investigate the photomagnetic propertie s of the film. Dip-coating or spin casting of colloidal solutions will offer the ability to use solid supports not availabl e with electrochemical methods, but fine thickness control is lost and f ilms generated in this manner have heterogeneous structures. Adsorption at a Langmuir monolayer provides for a uniform si ngle layer of Prussian blue, but requires separating the layers by th e amphiphilic molecule on the surface. Of the remaining adsorption techniques, the sequential adsorption met hod offers the advantages of homogeneous film generation, availability of diffe rent solid supports, fine thickness control, and the ability to easily tailor the composition of the film generated. Previous researchers using the sequential adsorption method have developed dense, defect free films of the cobalt iron Prussian blue analogue necessary for their ion transport research.63 Adaptations to this method need to be made because previous studies of the powder sa mples of the cobalt iron Prussian blue analogue indicate a need for the defects in orde r to observe photoinduced magnetic phenomenon.25,28,35 Nanoparticles Another form in which the cobalt iron Pr ussian blue analogue c ould have a potential application is with nanoparticles. The prep aration of discrete phot omagnetic nanoparticles would be very exciting for applications in memo ry devices. Nanoparticles of Prussian blue and analogues have been reported by other researchers,68-78 but very few have reported any photoinduced magnetism.79,80 The formation of nanoparticles of Prussian blue and its analogues

PAGE 23

23 happens easily. The aqueous reaction of the tw o component ions causes a colloidal suspension of particles. Methods of isolating the nanoparticles and re stricting their growth involve coating the particles with substrates to prev ent aggregation. One substrate us ed is the water-soluble polymer polyvinylpyrrolidone (PVP).71,72 The PVP is dissolved in the cationic metal solution where the polymer interacts with the metal ion. When the anionic cyanomet alate is added to the solution, the Prussian blue analogue forms and the polymer coats the outside of the particle. Particle size can be controlled by varying the amount of polymer added, with smaller particles resulting from higher concentrations of polymer. Another method of controlling the size of the particle is to control the size of the reactor.70,73 By using reaction mixture ratios of water and cyclohexane, the size of the water droplets in the solution can be controlled. The addition of a protecting polymer (Igepal) is still used in this case and is later replaced with an octadecylamine. The principle is to generate a nanoparticle then prevent the particle from aggregating. In the following chapters, a detailed report of the different uses of Prussian blue analogues will be given. First, the formation a nd unique anisotropic magnetic behavior of the cobalt iron Prussian blue analogue in thin films is discussed. The anisotropic behavior shows that the magnetic properties of the cobalt iron analogue are diffe rent from the powdered solid when the material is confined to a quasitwo-dimensional network. A discussion of the incorporation of a higher TC nickel chromium Prussian blue analogue into the film follows. Again, anisotropic behavior was obs erved in the film and was not reported in the powdered solid. In addition, the combination of cobalt iron and nickel chromium analogue s in the same film, magnetic behavior different than the cobalt iron film was observed. The focus of this dissertation will then shift to two different met hods of generating nanopar ticles of the cobalt iron

PAGE 24

24 Prussian blue analogue and the size dependent ma gnetic behavior of the particles. The final chapters show that photomagnetic nanoparticles ca n be synthesized and th at the powdered solid behavior observed can be suppressed by re stricting the size of the nanoparticle, a superparamagnetic size limit of 10 nm was established for the PV P nanoparticles. The emulsion nanoparticles appear to have a la rger superparamagnetic limit. Below this size, few photoeffects are seen in the particles. Data suggests that the surfaces of the nanoparticles are locked in the low spin state and the core material is photoactive.

PAGE 25

25 Figure 1-1. Unit cell representation of the ACoII[FeIII(CN)6] nH2O analogue. Prussian blue analogues form a face centered cubic network of divalent and trivalent metals bridged by cyanide ligands with alkali ions in the tetrahedral holes of the network. Figure 1-2. Unit cell representation of the CoII 1.5[FeIII(CN)6] 3H2O analogue. Prussian blue analogues achieve charge balance by incorpor ating alkali cation into the network or by leaving ferricyanide vacancies. iron cobalt carbon nitrogen water iron cobalt carbon nitrogen water iron cobalt carbon nitrogen alkali ion iron cobalt carbon nitrogen alkali ion

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26 Figure 1-3. Potential energy diagram of the cobalt iron Prus sian blue analogue. At low temperatures the lowest energy state is th e diamagnetic state. Excitation causes a charge transfer to a high energy state that re laxes back to the diamagnetic state or to the ferrimagnetic state by a spin crossover ev ent. The system is then trapped in the ferrimagnetic state by an energy barrier in a long-lived metast able excited state.23 EnergyInternucleardistance Fe(II)-CN-Co(III) ls Fe(III)-CN-Co(II) ls Fe(III)-CN-Co(II)hs EnergyInternucleardistance Fe(II)-CN-Co(III) ls Fe(III)-CN-Co(II) ls Fe(III)-CN-Co(II)hs

PAGE 27

27 CHAPTER 2 ANISOTROPIC PHOTOINDUCED MAGNETISM IN THIN FILMS OF THE PRUSSIAN BLUE ANALOGUE Introduction Photoinduced magnetism in the co balt iron Prussian blue analogue, AjCok[Fe(CN)6]l nH2O, was discovered by Hashimoto and coworkers in 1996,19 and subsequently studied by several groups.22,23,25,26,35,40 Diamagnetic CoIII (ls)-FeII pairs may be photoexcited to a long-lived metastable ferrimagnetic CoII (hs)-FeIII state through a charge transfer and spin crossover event, increasi ng the magnetism. Although still a low-temperature phenomenon, many potential applica tions of this exciting class of materials will require fabrication of thin films. The research is part of an ongoing study62,64-67,81-84 of the AjCok[Fe(CN)6]l nH2O system with the goal of developing fa brication methods for thin films of molecule-based magnetic materials. Investigatio n of the magnetic and photomagnetic properties of AjCok[Fe(CN)6]l nH2O showed that, in addition to the magnetic and photomagnetic phenomena present in powdered solids, the thin films exhibit a new phenomenon, a photoinduced decrease in magnetization for a speci fic orientation of the film in the applied magnetic field.65 The photomagnetic response of the thin films is anisotropic, increasing in one orientation and decreasing in the other, when th e externally applied magnetic field is less than 1.5 kG and the temperature is below the magne tic ordering temperature. This finding was previously communicated65 and we proposed a model for the an isotropic behavior that depends on the influence of residual magnetic moments in th e film before photoexcitation. In this chapter a complete study of the fabrication and magnetic behavior of thin films of AjCok[Fe(CN)6]l nH2O including thorough investig ations of the parameters that determine the photoinduced magnetic behavior is presented. These observati ons are used to qualitatively validate the proposed mechanism fo r the novel thin film behavior.

PAGE 28

28 Compounds of the family AjCok[Fe(CN)6]l nH2O with partial [Fe(CN)6]3vacancies have been shown to exhibit Charge Transf er Induced Spin Transition (CTIST).35 When this complex is cooled from room temperature to 50 K, there is a charge transfer from the CoII to the FeIII along with a spin crossover event for the c obalt ion, while the iron remains low spin. Specifically, regions of the compoun d transition from ferrimagnetic CoII (S = 3/2), FeIII (S = ) to diamagnetic CoIII (S = 0), FeII (S = 0) resulting in a decrea se in magnetism. However, the transition is not complete. Local heterogeneity in the distributi on of ferricyanide vacancies cause some of material to remain in the ferrimagnetic st ate. This component of the material is referred to as non-switchable pairs, or primordial spins,65 and undergoes magnetic ordering near 20 K. The CoIII(ls)-FeII pairs of the diamagnetic compound may be photoexcited using visible light and converted back to the ferrimagnetic CoII(hs)-FeIII pairs, thereby increasing the magnetization19,22,25,35 and placing the material in a long-lived, metastable state. The process is reversible by thermal treatment allowing the photoexcited states to relax to the diamagnetic state.23 Methods of generating films and coatings of Prussian blue and its analogues include electrochemical methods,42-48 dip-coating or spin casti ng of colloidal solutions,42,49 and adsorption onto sol-gel films.50,51 Routes to films with nanoscale thickness include synthesis of cyanometallate monolayers81,82 and adsorption of the cya nometallate at Langmuir monolayers,54,55 and charged amphiphiles.52-59 One of these methods by Einaga and coworkers58 reports anisotropy in a cobalt iron Prussian blue analogue fi lm. However, no photoinduced decrease was observed. Films of intermediate submicrometer, thickness can be prepared by synthesizing the cyanometallate directly on su rfaces by sequential adsorptions of the constituent ions.60-63,65-67 The sequential adsorption approach afford s fine thickness cont rol of homogeneous

PAGE 29

29 films on a variety of different solid supports and the ability to easily tailor the chemical composition of the film. Sequential adsorpti on techniques were used to produce the films described in this study. Experimental Section Reagents and Materials All reagents were purchased from Sigma-Aldr ich or Fisher Scientific and used without further purification. Trace metal grade nitric acid was used for inductively coupled plasma mass spectrometry (ICP-MS) experiments, all other reag ents were ACS grade. Deionized (DI) water (18 M ) was used for all experiments. Melin ex, a polyethylene terephthalate polymer 535/380 gauge was obtained from DuPont Teijin films. Sample Preparation of AjCok[Fe(CN)6]l nH2O Thin Films Rb0.7Co4[Fe(CN)6]3.0 H2O. Slow growth.63 A sheet of Melinex was placed in a 5 mM aqueous solution of cobalt(II) nitrate for 60 seconds The film was rinsed with DI water, then rinsed with methanol and dried wi th a stream of nitrogen. The f ilm was then placed in a solution containing 20 mM potassium fe rricyanide and 0.12 mM rubidium nitrate for 60 seconds. The film was rinsed with DI water, then rinsed with methanol and dried with a stream of nitrogen to complete one cycle. The process was repeated for 5, 10, 20, 40, or 75 cycles to generate films of varied thickness. Metal content was determined by ICP-MS using a 40 cycle film with resultant metal percentages of Rb 3.2, Co 12.7, and Fe 9.0. Rb2.3Co4[Fe(CN)6]3.1 5.4H2O. Slow growth. The method was similar to the one described above except a potassium ferricyanid e solution containing 12 mM rubidium nitrate was used. The film was rinsed with DI wate r and methanol then dried. Both 40 and 75 deposition cycle films were generated. Meta l content was determined by ICP-MS using a 40 cycle film with resultant metal percentages of Rb 10.6, Co 12.4, and Fe 8.9.

PAGE 30

30 K0.5Co4[Fe(CN)6]3.2 4.8H2O. Slow growth. The method was sim ilar to the one described above except a potassium ferricyanide solution c ontaining 12 mM potassium nitrate was used. Both 40 and 75 deposition cycle films were ge nerated. Metal content was determined by ICP-MS using a 40 cycle film with resultant meta l percentages of K 0.37, Co 4.5, and Fe 3.4. Rb0.7Co4[Fe(CN)6]3.0 H2O. Fast growth.65 A hydrophilic solid suppo rt, such as silicon or Melinex was used as a solid support. The solid support was quickly immersed 5 times in a 5 mM aqueous solution of cobalt(II) nitrate. The excess solution was drained, and the solid support was quickly immersed 5 times in an a queous solution of 20 mM potassium ferricyanide and 12 mM rubidium nitrate. The solid support was then rinsed with DI water. This process was repeated 1, 5, 10, 20 or 40 times to generate fi lms of increasing thickness. After deposition, the film was rinsed with methanol and dried unde r vacuum. Metal content was determined by ICP-MS using a 40 cycle film with resultant meta l percentages of Rb 3.2, Co 12.7, and Fe 9.0. Instrumentation The elemental analyses were performed by ICP-MS on a Thermo-Finnigan Element-2 spectrometer. FTIR spectra were recorded us ing a Nicolet 6700 spectrometer. Atomic force microscopy (AFM) measurements were perfor med using a Digital Instruments multimode scanning probe microscope. Scanning electron mi croscopy (SEM) images were obtained using a Hitachi S-4000 FE-SEM. Magnetic measurements were made by the University of Florida Department of Physics using a Quantu m Design MPMS XL superconducting quantum interference device (SQUID) magnetomete r. A bundle of 10 optical fibers, 270 m O.D. (Ocean Optics Model 200) was used to introduce light, fr om a room-temperature, halogen-light source, of 1~2 mW power into the SQUID ma gnetometer for photoinduced experiments.85

PAGE 31

31 Analysis Preparations Melinex supports were cut to 8 cm x 2.5 cm and cleaned using methanol. For transmission FT-IR ATR experiments, 20 cycl es of material were deposited using the fast method, the film was then presse d against a silicon ATR crystal, and the spectra was obtained. ICP-MS samples of 40 cycle films were prepared by digesting the thin film and Melinex in 2 mL of boiling, concentrated sulfuric acid for 4 hours, resulting in a bl ack liquid. Concentrated nitric acid (0.5 mL) was then added dropwise, before d iluting the mixture to 100 mL with DI water. The samples were compared to matrix matched metal blends between 1 ppm and 1 ppb. The resultant concentrations were normalized to a unit cell formula AjCo4[Fe(CN)6]l nH2O by fixing 4 cobalt ions per unit cell. The unit cell formula will then provide the formula used to determine the molar mass of the analogue. The water content is assumed to be H2O molecules coordinated to the cobalt and was determined by the num ber of ferricyanide vacancies, specifically, n = 6(4-l). Using AFM, thickness and roughne ss data were obtai ned by averaging the measurements of five different 4 m2 scans. Thickness was determined by investigating the height difference between the aver age thickness of the f ilm and the solid support. The root mean squared (RMS) average of height deviations taken from the mean data plane is used to express roughness. For magnetic measurements the samples were cut into squares (~10.5 mm2) and stacked, with the surfaces parallel, into a polye thylene sample holder. Background contributions of the container and Melinex were measured sepa rately and subtracted from the raw data. The change in magnetization is expressed as the magnetization of the sample after the time of the initial photoexcitation minus the magnetization at time 0. ( M = M(t) M(t=0))

PAGE 32

32 Results Film Generation and Characterization All films were generated by sequentially adsorbing Co2+ and [Fe(CN)6]3from aqueous solution, adapting procedur es previously described 60,61,63,65 for Prussian blue films and other Prussian blue analogues. (Figure 2-1) The process is related to the often describe d layer-by-layer deposition of polyelectrolytes, ut ilizing coordinate covalent bonds instead of purely electrostatic interactions within the resulting film. The th ickness can be tuned by adjusting the number of deposition cycles, and films can be fabricated ov er large surface areas us ing a variety of solid supports. This last point becomes important b ecause transparent diama gnetic solid supports are needed for photomagnetic experiments. Standard glass or silicon supports can still be used for other chemical and spectroscopic analyses with out detectable changes in film composition or quality. Deposition normally begins by adsorption of io ns to a charged surface. For the Melinex supports, the surface charge results from a nitr ogen-containing, adhesion-promoting coating placed on the surface by the manufactu rer. It takes several deposition cycles to achieve complete surface coverage. Our group previously demonstr ated that homogeneous surface coverage can be achieved for a thin film by first modifyi ng the surface with a cyanometallate monolayer, prepared using Langmuir-Blodgett methods.62,82 However, the studies described herein utilize thicker (50-300 nm) films so the template layer is not needed. During a deposition cycle, the solid support wa s first immersed in an aqueous solution containing Co2+ ions, followed by immersion in a solution containing A+ and [Fe(CN)6]3ions. The process can be controlled to al ter the rate of deposition, and two methods, referred to here as slow and fast, were used to generate films. In the slow method, the substrate is rinsed between changing solutions, limiting the amount of mate rial deposited during each cycle. For the fast

PAGE 33

33 method, substrates were immersed in both solutio ns before rinsing, resulting in a film that developed quickly. Film thickness, measured us ing AFM, increases with number of cycles for both methods (Figure 2-2). The surface topology of the films can be compar ed with SEM. (Figures 2-3 and 2-4) After only one cycle of the fast method, the substrate is still visible, indicating that uniform coverage is not yet achieved. It takes five cycles to completely cover the substrate with powderlike features. The surface mor phology is retained as the film develops beyond 5 cycles (Figure 2-3). Using the slow method, complete coverage is not obtained until 20 cycles, at which point the films show similar morphology to those of comparable thickness generated with the fast method. Complete surface coverage is achie ved between 30 and 50 nm of thickness for both methods. Surface roughness measurements confirm the SEM observations (Table 2-1). All films are light pink, with uniform coloration over the surface of the substrate. Room temperature IR spectra, shown in Figure 2-5 fo r a 160 nm film, display two cyanide stretching bands, a sharp peak at 2169 cm-1, attributed to cyanide bridging CoII(hs)-FeIII, and a broader peak centered at 2110 cm-1, attributed to cyanide bridging CoIII(ls)-FeII with a shoulder at 2085 cm-1 attributed to the cyanide bridging CoII(hs)-FeII. The energy of these stretches agrees with previously reported data for powdered solids23 of similar rubidium con centrations confirming the targeted material is deposited on the surface. Magnetic Behavior with HE Parallel to the Thin Films The thin films exhibit magnetic behavior similar to powder samples, when the plane of the film is oriented parallel to the external magnetic field, HE. Temperature dependent zerofield-cooled (zfc) and field-cooled (fc) measurem ents from 5 K to 30 K we re performed with the film plane parallel to HE = 200 G, and data from a 160 nm f ilm are shown in Figure 2-6. An apparent TC, defined here as the temperature at whic h the magnetization begins to increase, is

PAGE 34

34 near 15 K. The fc and zfc magnetizations bifurc ate near 9 K, and there is a maximum in zfc magnetization at T ~ 7 K. Upon photoexcitation, TC increases to 18 K and the peak temperature in zfc magnetization shifts to T ~ 9.5 K. (Figure 2-6) The magnetic response is consistent with th e reported behavior of powder samples of cobalt iron Prussian blue analogues.23,25,58 The dark state response is attributed to glassy behavior86,87 of disordered interacting cluste rs of ferrimagnetically ordered CoII(hs)-FeIII regions that have not undergone charge transfer and spin crossover de magnetization upon cooling. With illumination, some diamagnetic pairs that did undergo spin crossover upon cooling are switched to the CoII(hs)-FeIII state, causing an increase of the c oncentration and size of ferrimagnetic clusters. The result is enhanced magnetization, and also an increase in blocking temperature, defined as the temperature at which the fc and zfc plots bifurcate, from 9 K to 11 K due to larger size or increased concentration of domains.85 Anisotropic Photomagnetic Behavior With the planes of the films oriented perp endicular to the applied magnetic field, the photoeffects are different. The te mperature dependent fc and zf c measurements from 5 K to 30 K with HE = 200 G perpendicular to the same 160 nm film shown in Figure 2-6, are shown in Figure 2-7 for both the light and dark states. The dark state data are essentially the same as in the parallel orientation. In addition, upon photoe xcitation, the TC of 16 K increases to 18 K, and there is also an increase in the blocking temper ature shifting from 10 K to 11 K. These trends are similar to the ones observed for HE parallel to the film. However, the magnetization of the photoinduced (light) sample is now lower than th e dark sample. In other words, there is a photoinduced decrease in magnetization. The anisotropic photoinduced re sponse of the thin films is more clearly illustrated by plotting the time dependent change of the ma gnetization upon irradiation with visible light.

PAGE 35

35 Figure 2-8 shows the magnetization versus time at 5 K, with HE = 200 G in both orientations, for a 75 nm thick film. Upon irradiation, the magnetization of the film increases by 4 emuG/cm3 when oriented parallel to HE = 200 G, and decreases by 2 emuG/cm3 when perpendicular to the same HE. Alkali Cation Dependence Photoinduced magnetism in the cobalt iron Pr ussian blue is not restricted to Rb+ analogues, but has also been reported in Na+, K+, and Cs+ salts.19,22,23,25,29,35,46 Other thin film compositions were therefore investigated to determine if the anisotropy seen for the Rb+ analogues depends on chemical formula. A potassium containing film with formula K0.5Co4[Fe(CN)6]3.2 .8 H2O was generated. The time dependent change in magnetization of an 86 nm film at 5 K is shown in Figure 2-9 when HE = 200 G and is perpendicu lar to the film. As for the Rb+ films, a photoinduced decrease in magnetiz ation was observed, indicating that the anisotropic photoresponse is not alkali cation specific. Increasing the concentration of alkali ions in the interstitial sites of powdered solids of cobalt iron Prussian blue analogues leads to fe wer ferricyanide vacancies and increases the average ligand field st rength around the cobalt.25,35 The increased ligand field strength hinders the temperature dependent spin crossover, elimin ating the presence of photoswitchable pairs and, therefore, any photoinduced cha nge in magnetism. Figure 2-10 compares the time dependent photoinduced magnetization of slow 75 cy cle films (86 nm) with different Rb+ ion content, Rb0.7Co4[Fe(CN)6]3.0 H2O, and Rb2.3Co4[Fe(CN)6]3.1 5.4 H2O. Figure 2-10B shows photoinduced magnetism of the Rb2.3 film. On this scale therma l effects are clear and correspond to an increase in temperature of 0.7 K. The beginning of illumination causes an increase in temperature and corresponding decrease in magnetiz ation of the film. When the illumination ceases after 1 hour the sample cools and an increa se in magnetization is observed. The slope of

PAGE 36

36 the data before and after illumination is attributed to the glassy nature of the film. As for powdered solids, there is little photoinduced change in magnetiza tion for thin films with higher alkali ion content. Field Dependent Magnetic Behavi or of 75 nm and 160 nm Films The effect of the external magnetic fi eld strength on the photoinduced decrease in magnetism was explored by comparing the time depe ndent change in magnetization in external fields of HE = 200 G and 5 kG. Data for 75 nm and 160 nm films oriented perpendicular to HE are presented in Figure 2-11. Whereas the fi lms show a photoinduced de crease of magnetization for HE = 200 G, both samples show a photoinduc ed increase in magnetization when HE is increased to 5 kG. The observation that the increa se or decrease of photoinduced magnetization is related to the strength of HE, suggests that there should be a fiel d for which no photoinduced change in magnetism is observed. To look for this tran sition, the field depende nt magnetization of a 160 nm film was measured at 5 K for both the dark state and saturation light state. (Figure 2-12) As shown in the figure insert when the HE is around 1.5 kG, the photoinduced magnetization becomes greater relative to the dark state magnetization, so a photoinduced increase in magnetization is expected for fields greater than 1.5 kG. Below 1.5 kG, the magnetization of the photoinduced state is less than the dark state, so a photoinduced decrea se in magnetization is observed. Effect of Film Thickness The photoinduced decrease in magnetism is not observed for powdered solids but only in continuous thin films, so the influence of film thickness was investigated by taking advantage of the ability to control the thickness of the film s with the sequential adsorption process. The photomagnetic response of four films, with thicknesses of 51, 75, 160 and 300 nm, were

PAGE 37

37 measured at T = 5 K with HE = 200 G applied perpendicular to the plane of the films. (Figure 2-13) The 51, 75, and 160 nm films all show a photoinduced decrease. However, for the 300 nm film, a photoinduced increase in magnetizati on is observed. In addition, the magnitude of the effect varies as the thickness changes. At first, the magnitude of the decrease becomes larger as films become thicker. However, by th e time the film is 160 nm thick, the magnitude of the photoinduced decrease has diminished. By 300 nm, the effect is reversed, and a photoinduced increase is observed. Temperature Dependence of the Anisotropy Magnetic data in Figures 2-8 through 2-13 we re obtained at 5 K, below the onset of ferrimagnetic ordering of the magnetic domai ns. Above the ordering temperature, photoswitchable pairs are still present because the charge transfer/spin crossover state persists until much higher temperatures, nominally up to 200 K. To determine if the photoinduced decrease is a property of the ordered state, the ph otoresponse was studied above the ordering temperature of a film that was previously shown to exhibit a photoinduced decrease at 5 K. The time dependent response of the 160 nm film studied in Figure 2-13 was then measured at 20 K. (Figure 2-14) Above the orde ring temperature, the 160 nm film displays a photoinduced increase in magnetism. The result shows th at the photoinduced decrease in magnetism is a property of the film below the ordering temperature. Discussion Cobalt iron Prussian blue analogue films pr epared using sequential adsorption methods exhibit several properties typica l of the more extensively studied powdered solids. With appropriate composition, a fraction of the materi al in the films undergoes charge transfer and spin crossover and the residual high spin fracti on orders giving a ferri magnetic state at low temperature. The low temperature magnetic proper ties are consistent with cluster spin glass

PAGE 38

38 behavior, which also characterizes the know n powdered solids. Upon photoexcitation, TC increases, as does the blocking temperature, in dications that the size or concentration of magnetic domains in the sample increases. With the film oriented parallel to the magnetic field, photoexcitation yields an increase in magne tization. Compositions that exhibit these photoeffects in powdered solids also show them in thin films. These observations indicate that the microscopic mechanism by which the magnetization changes with light is the same in the films as was seen before with the powdered soli ds. However, the photoresponse of the films is anisotropic. The photoinduced increase in magnetis m seen when the film is oriented parallel to the magnetic field becomes a photoinduced decrease wh en the film is oriented perpendicular. An orientation dependent photoindu ced decrease is never seen in the powdered solids. Initial attempts to attribute the anisotropic behavior to chemical anisotropy using room and low temperature have been unsuccessful. Better met hods of detecting chemical anisotropy in films are discussed in future works in chapter 6. The anisotropic photoeffects are influenced by a number of factors. The first is the increase in field strength; by increasing HE to ~1.5 kG, when HE is perpendicular to the film, the photoinduced decrease in magnetization becomes a photoinduced increase as HE becomes greater. Film thickness also plays an important ro le. As films become thicker, the photoinduced decrease diminishes and, by 300 nm, becomes a photoinduced increase like in the parallel orientation and the analogous powde red solids. Furthermore, the photoinduced decrease is only observed below the ferrimagnetic ordering temper ature. At 20 K, a photoinduced increase is observed. Taken together, these observations suggest that the requirements for observing a photoinduced decrease in magnetization include th e presence of ordered magnetic domains, thin film organization, and low app lied magnetic field strength.

PAGE 39

39 The behavior in the thin films can be e xplained by considering the influence of the dipolar field (HD) emanating from magnetic domains present in the dark state film.65 The photoswitchable component of the films consists of diamagnetic CoIII(ls)-FeII pairs that underwent charge transfer and spin crossover upon cooling. Also present is residual high spin material that undergoes ferrimagnetic ordering at low temperature, generating magnetic domains. With respect to photoinduced effects, these domai ns can be considered primordial moments. With an applied field perpendicular to the f ilm, these primordial moments will align along HE. The primordial moments themselves will generate a magnetic field that will oppose HE in the plane of the film. Therefore, proximal photoindu cible regions in the pl ane of the film will experience both HE and an opposing HD (Figure 2-15). When HE is small, the photoswitchable pairs generate moments that align with HD, against HE, and a photoinduced decrease in magnetization is observed. The proposed mechanism is consistent with the observations made upon changing different experimental parameters. For example, if HE is increased such that HE > HD, the new photoinduced moments align with HE, and a photoinduced increase in magnetism is observed, as reported in Figure 2-11. The data from Figure 2-12 show that a HE of 1.5 kG will transition from a photoinduced decrease to a photoinduced in crease. This indicates that the HD generated for the 160 nm film is approximately 1.5 kG. The proposed dipolar field model also account s for why the photoinduced decrease is observed in thin films and not for the bulk powde rs. The quasi-two-dimensional arrangement of the primordial moments is necessa ry for the photoswitchable pairs to experience internal fields that predominately oppose the applied field. The photoswitchable pairs must be in the plane perpendicular to the net magnetic dipole mome nt of the ordered domains to experience HD

PAGE 40

40 antiparallel to HE. Such an arrangement exists in a thin film. On the other hand, in the bulk, photoswitchable pairs can be surrounded by primor dial moments in all directions, effectively canceling the influence of th ese internal dipolar fiel ds, so they respond to HE upon photoexcitation. For the films studied in Figur e 2-13, the transition from quasi-two-dimensional to bulk-like is observed. Thi nner films exhibit a photoinduced d ecrease in magnetization, while the effect is diminished for thicker films. Fo r the films studied here, the transition to threedimensional behavior begins for thicknesses grea ter than 75 nm, suggesting that the important interaction length is of this order. By 300 nm, bulk-like behavior is seen. The proposed dipolar field model requires th e presence of ordered primordial moments, which explains why the photoinduced decrease is only observed below the or dering temperature. Above the ordering temperature, the local mome nts of the residual high spin fraction are not ordered, resulting in a random arrangement of HD in the sample, allowing the photoinduced moments to follow HE and increasing magnetization. Einaga and coworkers58 reported anisotropic behavior in cobalt iron Prussian blue analogue films generated using exfoliated clay and didodecyldimethylammonium bromide as the charged surface to form the layer. Although the magnetic behavior was anisotropic, no photoinduced decrease was reported. In this case the cobalt iron la yers were clearly isolated in the z-direction by the semectite clay and didodecy ldimethylammonium bromide used to form the film. The in-plane structure was composed of a disordered arrangement of wire or rodlike structures 4 thick. This arrangement yields networks that are structurally anisotropic88 and gives rise to a magnetic easy axis in the plane of the film. The intrinsic disorder of the claybased films causes a decrease in the resulting HD and allows HE to dominate the magnetic behavior during photoinduced experiments. This arrangement is significan tly different from our

PAGE 41

41 system, which at the molecular level is continuous in three-dimensions a nd contains no structural anisotropy or easy axis. The anisotropy in our system is a result of the HD from the primordial spins influencing the proximal diamagne tic material during photoexcitation. Conclusions Cobalt iron Prussian blue analogue films pr epared using sequential adsorption methods exhibit several properties typica l of the more extensively studied powdered solids. These observations indicate that the microscopic m echanism by which the magnetization changes with light is the same in the films as with the powde red solids. However, un like previously studied bulk solids, the photoresponse of the films is anisotropic. The photoinduced increase in magnetism seen when the film is oriented parallel to the magnetic field becomes a photoinduced decrease when the film is oriented perpendicular to the magnetic field. The anisotropic photoeffects are influen ced by field strength, film thickness and temperature. The behavior in the thin films can be explained qualitati vely by considering the influence of the dipolar field emanating from pr imordial magnetic domains present in the dark state film. The ability to di rect a photoinduced magnetic increase or decrease affords another level of control only available in thin films of the c obalt iron Prussian blue analogue and may be useful in potential device applications of this class of material.

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42 Table 2-1. Thickness and r oughness data for films of Rb0.7Co4[Fe(CN)6]3.0 H2O Number of cyclesAverage thickness (nm) RMS roughness (nm) slow method 20 34 3 12 40 71 15 22 75 86 3 37 fast method 5 51 8 17 10 75 20 23 20 160 30 62 40 300 30100 Average thickness of the AFM scans and the averag e thickness standard de viation are reported. Surface roughness is expressed as root mean squa red (RMS) average of height deviations taken from the mean data plane.

PAGE 43

43 Figure 2-1. The sequential adsorptions method showing the deposition of cationic and anionic building blocks to form the cobalt iron Prussian blue analogue. Adapted from Polyhedron 2007, 26, 2273.84 Figure 2-2. Thickness vs. number of cycles for the slow growth, ( ), and fast growth, ( ), sequential adsorptions deposition methods used to generate thin films of the cobalt iron Prussian blue analogue. Error bars represent the average thickness standard deviation. Adapted from Polyhedron 2007, 26, 2273.84 020406080 0 100 200 300 Thickness (nm)Number of Cycles Co FeCoII[FeIII(CN)6]3-and A+ Fe Fe Fe Fe Co Co Co Co Co Repeat for X cycles AjCok[Fe(CN)6]lnH2O Solid support

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44 Figure 2-3. The SEM images of fast method films, a-e, with thic knesses of 21 nm, 51 nm, 75 nm, 160 nm, and 300 nm, respectively. A 1 m scale bar is shown in each image. The deposition method develops a continuous film after 5 cycles (b). The surface morphology is retained as the film de velops beyond 5 cycles. Adapted from Polyhedron 2007, 26, 2273.84 Figure 2-4. The SEM images of slow method films, a-c, with thic knesses 22 nm, 34 nm, and 71 nm, respectively. A 1 m scale bar is shown in each image. Uniform coverage is achieved after 20 cycles (b); less material is deposited by the slow method when compared to the fast method. Slow films show roughness and surface coverage similar to fast films of similar thicknesses. Adapted from Polyhedron 2007, 26.84 a d e c b a d e c b

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45 Figure 2-5. Room temperature FT-IR ATR spectr a of a 160 nm film on Melinex. A sharp peak at 2169 cm-1 is attributed to the CoII(hs)-NC-FeIII bridging cyanide stretch and the broad peak centered at 2110 cm-1 is attributed to the CoIII(ls)-NC-FeII bridging cyanide stretch with a shoulder at 2085 cm-1 attributed to the cyanide bridging CoII(hs)-FeII. IR bands are similar to those found in powder samples containing Rb+ ion. Figure 2-6. Plots of fc and zfc DC magneti zation of a 160 nm thic k film parallel to HE = 200 G in dark and photoinduced (light) states.0102030 0 10 20 30 HE parallel to film fc light zfc light fc dark zfc darkM (emu G/cm3)T (K)220021002000 Absorbance (arb. units)Wavenumbers (cm-1)

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46 Figure 2-7. Plots of fc and zfc DC magnetizat ion of a 160 nm thick film perpendicular to HE = 200 G in dark and photoinduced (light) states. Figure 2-8. Anisotropy in the photoinduced magnetization of a 75 nm film of Rb0.7Co4[Fe(CN)6]3.0 H2O, measured at 5 K with the measuring field of 200 G oriented parallel and perpendicular to the film. The time axis is relative to the point the light is applied. The re lative change of magnetization M = M(t) M(t=0) is shown. 0204060 -2 0 2 4 Light on HE perpendicular HE parallel M (eumG/cm3)Time (min)0204060 -2 0 2 4 Light on HE perpendicular HE parallel M (eumG/cm3)Time (min)0102030 0 5 10 15 20 HE perpendicular to film fc dark zfc dark fc light zfc lightM (emu G/ cm3)T (K)

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47 Figure 2-9. Change in magne tization for a 86 nm film of K0.5Co4[Fe(CN)6]3.2 .8H2O perpendicular to HE of 200 G at 5 K. A photoinduced decrease in magnetization is observed. The time axis is relative to the point the light is applied. The relative change of magnetization M = M(t) M(t=0) is shown. Figure 2-10. (A) Rubidium ion concentration dependence of the photoinduced magnetization of 75 cycle slow cobalt iron Prussian blue analogue films, ( ) Rb2.3Co4[Fe(CN)6]3.1 .4H2O, and ( ) Rb0.7Co4[Fe(CN)6]3.0 H2O. Films with higher rubidium concentration do not experience a photoinduced decrease in magnetism. The time axis is relative to the point the light is applied. The relative change of magnetization M = M(t) M(t=0) is shown. (B) The Rb2.3 film plotted on a relative change of magnetization of 10-3 emuG/cm3. Thermal effects of heating approximately 0.7 K and glassy behavior dominate the data.-20020406080 0 2 4 Time (min) -1 0 M (emuG/cm3) M (10-3emuG/cm3) A B Rb2.3Rb2.3Rb0.7Light on Light off -20020406080 0 2 4 Time (min) -1 0 M (emuG/cm3) M (10-3emuG/cm3) A B Rb2.3Rb2.3Rb0.7Light on Light off 050100 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 Light on M (emu G/cm3)Time (min)050100 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 Light on M (emu G/cm3)Time (min)

PAGE 48

48 Figure 2-11. Applied field dependence of the photoinduced magnetization with HE perpendicular to the plane of the film. Data for a 75 nm of film Rb0.7Co4[Fe(CN)6]3.0 H2O measured with HE = 200 G ( ) and 5 kG ( ) and a 160 nm film Rb0.7Co4[Fe(CN)6]3.0 H2O with HE = 200 G ( ) and 5 kG ( ) are shown. The time axis is relative to the point the lig ht is applied. The relative change of magnetization M = M(t) M(t=0) is shown. Figure 2-12. The field dependent ma gnetization of a 160 nm film of Rb0.7Co4[Fe(CN)6]3.0 H2O was measured at 5 K with the magnetic fiel d perpendicular to the field. At a HE ~1.5 kG no difference in magnetization is obs erved between the dark state () and the photoinduced state ( ).Adapted from Ju-Hyun Parks dissertation.85 0204060 0 50 100 150 M (emu G/cm3)H (kG)0123 0 20 40 M (emu G/cm3)H (kG)0204060 0 50 100 150 M (emu G/cm3)H (kG)0123 0 20 40 M (emu G/cm3)H (kG)-2 -1 0 1 HE = 5 kG HE = 200 G 75 nm 02040 -2 -1 0 1 HE = 5 kG HE = 200 G 160 nm Time (min) M (emuG/ cm3)-2 -1 0 1 HE = 5 kG HE = 200 G 75 nm 02040 -2 -1 0 1 HE = 5 kG HE = 200 G 160 nm Time (min) M (emuG/ cm3)

PAGE 49

49 Figure 2-13. Thickness dependence of the photoi nduced magnetization in cobalt iron Prussian blue analogue thin films with HE perpendicular to the film plane. The films less than 160 nm thick show a decrease in magnetization upon illumination. As films become thicker, the photoinduced effect becomes an increase in magnetizati on, similar to that of bulk powder samples. The re lative change of magnetization M = M(t) M(t=0) is shown with photoexcitation ending at 60 min. Figure 2-14. Photoinduced magne tism of a 160 nm film of Rb0.7Co4[Fe(CN)6]3.0 H2O at 20 K with HE = 200 G perpendicular to the film. Th e light is applied at t = 0 min and discontinued at t = 40 min. Above the ons et of ferrimagnetic ordering, there is a photoinduced increase in magnetism.02040 0.15 0.20 0.25 Light off Light on M (emu G / cm3)Time (Min)0204060 -2 -1 0 Light on 75 nm 51 nm 160 nm 300 nm M (emu G/cm3)Time (min)0204060 -2 -1 0 Light on 75 nm 51 nm 160 nm 300 nm M (emu G/cm3)Time (min)

PAGE 50

50 Figure 2-15. The photoinduced magnetism in a quasi-two-dimensional film of cobalt iron Prussian blue analogue. The direction of the induced moments will depend on the vector sum of the dipolar field (HD) from the primordial moments and the applied magnetic field (HE). Adapted from Polyhedron 2007, 26.84 HEDark (Below Tc) HE-Film HD>HEHDHEHD
PAGE 51

51 CHAPTER 3 HETEROGENOUS PRUSSIAN BL UE ANALOGUE FILMS Introduction The preceding chapter showed the use of the sequential adsorption method to generate thin films of the cobalt iron Prussian blue analog ue in a controlled manner. Taking advantage of the vast number of metals that can be bri dged by cyanide ligands allows for films that incorporate more than two metals possibly incorporating propertie s of different analogues in the same film. The cobalt iron Prussian blue an alogue incorporates the desirable trait of photomagnetic response. Other Prussian blue analogues displa y magnetic ordering at higher temperatures. Combinations of analogues can be incorporated in the same film in a regular manner by varying the component solutions us ed in the sequential adsorption method. The nickel chromium Prussian blue analogue shows a higher magnetic ordering temperature (TC) in bulk samples with temperatures ranging from 75 K, in the absence of any charge balancing alkali ion, to 90 K, for compos itions with the maximum number of alkali ions incorporated.14 Prussian blue anal ogues with higher TC have been reported, but all contain vanadium(II)16 or chromium(II),17,18 both are unstable in aqueous solutions. The nickel chromium Prussian blue analogue was selected as the second component for the heterogeneous film to test for changes in photomagnetic e ffects following work included in Ju-Hyun Parks disseration.85 The sequential adsorption method has been shown to generate quasi-two-dimensional films of Prussian blue analogues. The thickness of the film is controlle d by changing the number of deposition cycles.84 A new material could be intr oduced simply by changing the ions dissolved in the solution duri ng the sequential adsorption met hod, provided the new ions are

PAGE 52

52 capable of attaching to the mate rial already existing on the suppor t. By changing the component solution at regular intervals, hete rogeneous films of Prussian blue analogues can be developed. (Figure 3-1) At low temperatures, the c obalt iron Prussian blue analogue is diamagnetic except for primordial spins.65 In theory, a cobalt iron layer sandw iched between two nickel chromium layers separates the nickel chromium Prussian blue anal ogue layers, there by supressing magnetic ordering in the Z direction. (Figure 3-2) If the layers are to be conti nuous in the plane of the film and sufficiently thin to be twodimensional in nature then a decrease in TC for the nickel chromium Prussian blue analogue is observed.89 The structural order of the film is maintained as the sequential adsorption method bu ilds each layer on top of the last, using the trivalent hexacyanometalate moietie s to bridge divalent metals. With photoexcitation, the cobalt iron Prussian blue analogue is expected to participate in magnetic exchange and will allow magnetic communication between th e isolated quasi-two-dimensi onal layers of the nickel chromium Prussian blue analogue. The increas e in magnetism comes from two sources. The increase is partly due to the excitation of th e cobalt iron Prussian blue analogue into the metastable state through charge transfer and spin crossover processes. The second source of the increased magnetism is due to the increase in ma gnetic exchange between th e isolated layers of the nickel chromium Prussian blue analogue. Depending on the sign (ferromagnetic or antiferromgnetic) of the coupling, the interaction be tween the two different Prussian blue analogue layers may increase or decrease the net magnetiza tion of the film and, consequently, may shift the TC accordingly. Initial investigations of a 20 cycle nickel chromium analogue film that have not been published else where have been conducted. Spin glass behavior wa s observed in the dc

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53 susceptibility data conducted at varying fields wi th the plane of the film perpendicular to the applied magnetic field. The zfc maximum shifts temperature with different applied magnetic fields. (Figure 3-3) The TC and spin glass behavior corresp onded with the expected behavior that was similar to the powdered solid. For these experiments, different sequentia l adsorption deposition combinations were utilized. (Figure 3-4) The fast method from chap ter two was used to generate a film of nickel chromium Prussian blue analogue to determine th e individual properties of the film. The nickel chromium analogue will be termed the A layer and the cobalt iron analogue the B layer. Then a film containing a layer of cobalt iron Prussian blue analogue on top of a nickel chromium Prussian blue analogue was genera ted (stacked AB film). Also, a film where the solutions were alternated after every deposition cycle was generated (mixed film). The slow method from chapter two was used to generate films comparable to the fast films. Finally, a film with a layer of cobalt iron Prussian blue analogue between tw o layers of nickel chromium Prussian blue analogue was generated using the fast method (sandwich ABA film). The magnetic and photomagnetic behavior of the different deposition methods oriented parallel and perpendicular to the applied magneti c field is the subject of this chapter. The magnetic behavior of the nickel chromium Pru ssian blue analogue film was compared to the reported powdered solid.14 Magnetic anisotropy was obser ved indicating that there was a magnetic easy axis in the plane of the film. Wh en the two different analogues were stacked on top of one another in an AB or BA manner, th e magnetic behavior was the sum of the behaviors of the individual layers in the same film. As th e layers were mixed to prevent any regions of a continuous A or B layers developing all the properties of the indivi dual A or B layers were lost. In the final ABA sandwich depos ition arrangement, magnetic prope rties were observed in the

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54 films that were different from the sum of the co mponent films, indicating an interaction between the different layers. Experimental Materials and instrumentation described in chapter two have been used for the films discussed here. The sequential adsorption fast method was used to generate films. The procedure was the same as the cobalt iron Pr ussian blue analogue film and the same concentrations of Co(NO3)2 H2O, K3[Fe(CN)6] and RbNO3 were used for the solutions. To provide Ni2+, 10. mM Ni(NO3)2 H2O was used. Solutions of 10. mM K3[Cr(CN)6] mixed with 12.5 mM RbNO3 were used to provide [Cr(CN)6]3and Rb+. A nickel chromium Prussian blue analogue film was developed (film 1) by alternating 10 depositions between the Ni2+ and [Cr(CN)6]3solutions and rinsing after each cycle to build a film. To create a stacked AB film (film 2), 10 deposition cycles of nickel chromium Prussian blue analogue were deposited, and 10 cycles of cobalt iron Prussian bl ue analogue film were then added. The deposition order was then reversed BA film (film 3). A mixed film (film 4) was generated using the fast method alternating between the two analogue s with rinsing in between each analogue set of solutions for a total of 20 cycles. The final fast film, a sa ndwich ABA film (film 5), was created by depositing 10 cycles of nickel chromium Prussian blue analogue followed by 10 cycles of cobalt iron Prussian blue analogue and fina lly by another 10 cycles of of the nickel chromium analogue. Attempts were made, that will not be reported, to tune the thickness of each layer by adjusting the number of deposition cycles before changing analogues. In all cases the behavior was similar to the stacked film if more than fi ve cycles were deposited After five deposition cycles complete coverage is achieved. However, the layer spacing appeared to be too great to change the ordering temperature of the nickel chromium analogue as was the original goal. For films with less than five cycles of deposition be fore the solutions were changed, the magnetic

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55 behavior was similar to the mixe d film, resulting in a film that appeared to be random at the molecular level. The sequential adsorption slow method was also used to generate films. The procedure was the same as the cobalt iron Prussian blue an alogue film, rinsing afte r 1 minute of immersion in each solution, mentioned in chapter two. To reduce the amount of Rb ion adsorbed onto the Prussian blue analogue, th e rubidium concentration used was only 0.12 mM. The first slow film created (film 6) had 40 cycles of nickel chromi um Prussian blue analog ue followed by 40 cycles of cobalt iron Prussian blue analogue stacked AB Film 7 alternated analogues every deposition cycle forming a mixed film. A short hand method of communicating the film structure will be employed. The first analogue deposit ed will be the first letter with the number (n) of cycles as a subscript then the second letter with n cycles will be indicated. The sequential deposition method used will be given as a superscript outside the brackets fast (f) or slow (s), finally the total number of repeats will be indicated as a subscript. [AnBn]x t The methods used, fast or slow, and film type is summarized in Table 3-1. Results Fast Nickel Chromium Pru ssian Blue Analogue Film 1 First, the magnetic properties of a film of nickel chromium Prussian blue were determined. The Talham group has previously re ported that a nickel ch romium Prussian blue analogue thin films can be generated using a surface modified with a two-dimensional metal cyanide grid,62 however the fast and slow method do not employ such a template. A Melinex substrate was cleaned with methanol a nd quickly immersed five times in a Ni2+ aqueous solution and then immersed five times in a [Cr(CN)6]3and Rb+ solution and was rinsed with deionized water after every cycle. The pr ocess was repeated 10 times, resulting in a gray film deposited on the substrate. [A10]f 1 Magnetism versus temperature measurements were taken with the film

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56 oriented parallel and perpendicular to the applied magnetic field for fc = 100 G and zfc temperature sweeps. The film showed a TC 70 K, which is lower than the ordering temperatures reported for a powdered solid14 and for a thicker 20 cycle film where TC 80 K 85 (Figure 3-5). On the other hand, TC 70 K is consistent with the results reported for the templated films.62 The magnetic response was also anisot ropic and is not obs erved in previous work. Fast Heterogeneous Stacked Films 2 and 3 The first film that combined the two differe nt Prussian blue analogues was a film with one interface between th e two Prussian blue analogue regions. Each region had a nominal thickness of 75 nm based on data from chapter two. The nickel chromium Prussian blue analogue was deposited first using the fast met hod, followed by the cobalt iron Prussian blue analogue [A10B10]f 1. Magnetic susceptibility versus temperature was examined with the film parallel to an applied field of 100 G. Two separate ordering te mperatures were observed. The first one near 70 K and is attributed to the nick el chromium Prussian blue analogue. The second ordering transition near 15 K is at tributed to the cobalt iron Prussi an blue analogue. This film showed a bifurcation near 35 K th at is typically seen with the nickel chromium Prussian blue analogue powdered solid samples in a field of 100 G. (Figure 3-6). The photomagnetic properties of the film were also inve stigated in the parallel and perpendicular orientations rela tive to the applied magnetic fi eld. At 5 K, the magnetic susceptibility over time was measured at 100 G, shown with photoexcitation of the sample in Figure 3-7. A photoinduced increas e is observed in both directions although the effect is much weaker in the perpendicular direction. Th e increase in the parallel direction was 2.5 10-7 emu G/cm2 but was 0.2 10-7 emu G/cm2 in the perpendicular di rection. The decrease

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57 in magnetism attributed to heating of the sample fr om the light is readily observed in the plot of the perpendicular orientation. The stacked AB film 2 showed that the two separate behaviors demonstrated by the single-component films can exist in a single film. The nickel ch romium Prussian blue analogue still showed a TC of 70 K and the cobalt iron Prussian bl ue analogue displayed its own ordering transition and photomagnetic behavior. The film exhibited a photoinduced increase in magnetization over time in both orientations. The photoinduced increase is different than the photoinduced decrease in the perp endicular direction observed in cobalt iron films of similar thickness reported in chapter two. The order of the deposition of th e analogues was then switched [B10A10]f 1. The cobalt iron Prussian blue analogue was deposited first a nd covered with the nickel chromium Prussian blue analogue. The photomagnetic properties of th e film were investigat ed in the parallel and perpendicular orientation rela tive to the applied magnetic field. At 5 K, the magnetic susceptibility over time was measured at 100 G, shown with photoexcitation of the sample in Figure 3-8. The photoincrease in the parallel direction was easily detectable and a change of 0.4 10-7 emu G/cm2 was observed. On the other hand, although magnetic changes consistent with sample heating from the light were observed in the perpendicular direction, a persistent increase in magnetism was not detected. The ab solute magnetic susceptib ility was higher during the BA deposition arrangement compared to the AB arrangement, however the magnitude of the photoinduced magnetization was lower indicating that more nickel chromium analogue had been deposited on the film. The reduced magnitude of the photomagnetism indicates that less cobalt iron analogue was deposited or th e photoeffect of the cobalt iron was attenuated by the nickel chromium.

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58 Fast Mixed Heterogeneous Film 4 After observing the characteris tic behavior of the nickel chromium Prussian blue analogue and the cobalt iron Prussian blue anal ogue in a film with one interface, a mixed heterogeneous film was deposited by alternat ing the analogues in each deposition cycle for a total of 20 cycles [A1B1]f 10. The fast method has been shown to deposit an average of 8 nm per cycle. The surface coating produced by the fast method is far from uniform. There is a significant amount of roughness on the surface and cove rage is not complete on a single layer as seen in the SEM image in chapter two. Fast f ilms adsorb to the surface of the solid support in small islands on the first cycle and with subs equent cycles builds upon the islands to form complete coverage after five cycl es. It is likely that there is mixing at the molecular level when alternating between analogue solution s. Each cationic solution (Ni2+ or Co2+) can coordinate with the two anionic species ([Fe(CN)6]3or [Cr(CN)6]3-) to form four different Prussian blue analogues: the nickel chromium and cobalt iron an alogues that were target ed, and the nickel iron and cobalt chromium analogues that bot h order ferromagnetically at 23 K. Magnetic susceptibility verses temperature with with the film perpendicular to an applied field of 100 G was measured. There is an in crease in magnetic susceptibility with TC 55 K, however there was no divergence between fc and zf c data. (Figure 3-9) The film undergoes a 0.4 10-7 emu G/cm2 increase in magnetism when photoexc ited perpendicular to the applied magnetic field. (Figure 3-10) Consequently, it appears that the magnetic behavior of the film was dominated by the nickel chromium Prussian bl ue analogue but trace be havior of the cobalt iron Prussian blue analo gue was also present. Fast Heterogeneous Sandwich ABA Film 5 The final fast heterogeneous film type that was investigated was a sandwich ABA film. [A10B10A10]f 1 In this film, 10 cycles of nickel chromium Prussian blue analogue was deposited,

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59 followed by 10 cycles of cobalt iron Prussian blue analogue and a final layer of 10 cycles of nickel chromium Prussian blue analogue. Th e photomagnetic properties of the film were investigated in both the parallel and perpendicular orientations relative to the applied magnetic field. At 5 K, the magnetic susceptibility over time was measured at 100 G, shown with photoexcitation of the sample in Figure 3-11. When the applied magnetic field was parallel to the film, there was a photoinduced increase in magnetism for 10 minutes, then an overall photoinduced decrease in magnetism of 1 10-7 emu G/cm2 was observed. An initial photoinduced increase followed by an overall phot oinduced decrease had not been previously observed in our films and will be discussed la ter. A photoinduced increase in magnetism of 7.4 10-7 emu G/cm2 was observed when film 5 was pl aced perpendicular to the applied magnetic field. This increase was much larger than any other films reported, indicating that the covering nickel chromium was not attenuating the cobalt iron layer. When compared to the cobalt iron 10 cycle 75 nm film in chapter two, the photoinduced increase and decrease are in the opposite orientations. Also, the value of the photoe ffect is an order of magnitude smaller than observed in the pure cobalt iron film. To summarize the results presented to th is point, fast heterogeneous films provided evidence that the individual prope rties of the nickel chromium analogue and cobalt iron Prussian blue analogue could be observe d in the same film. It was also demonstrated that the photomagnetic properties could be nearly elim inated by generating films without continuous regions of the separate analogue s by alternating the deposition solutions and forming a mixed film. In an attempt to exercise greater contro l of the interface the sl ow method discussed in chapter two was utilized to deposit layers.

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60 Slow Heterogeneous Stacked AB Film 6 A stacked AB film was produced using the slow method. Film 6 contained a 40 cycle layer of nickel chromium Prussian blue analogue deposited onto the Me linex substrate followed by a 40 cycle layer of cobalt iron Prussian blue analogue similar to film 2. [A40B40]s 1 The magnetism versus temperature measurements show ed an ordering temperature near 70 K. (Figure 3-12). The film also displaye d a photoinduced increase in magnetism of 0.4 10-7 emu G/cm2 when perpendicular to HE = 100 G and after irradiation for one hour. (Figure 3-13) The finite slope be fore photoexcitation is attributed to the glassy behavior of the film. The two characteristic behaviors of the diffe rent analogues were observed in the same film with one interface between the two analogues. Th e same behavior was observed in the fast Stacked AB film. Slow Heterogeneous Mixed Film 7 This film contained the maximum number of interfaces. The solutions used to generate the different Prussian blue analogues were change d after each cycle for a total of 80 cycles. [A1B1]s 40 A decrease in TC to abort 30 K in the susceptibil ity versus temperature plot was observed. (Figure 3-14) The TC was even lower than the film 4 generated using the fast method. The slow method appears to achieve greater mi xing of the analogues at the molecular level, causing a correspondi ng decrease in TC. The film also underwen t a photoinduced increase in magnetization over time. The effect was small, with only a 0.1 10-7 emu G/cm2 change observed at 5 K after one hour. (Figure 3-15) Discussion There are a number of observ ations that can be made from the data presented regarding films of the nickel chro mium Prussian blue analogues and the heterogeneous film s that resulted

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61 when the cobalt iron analogue was added. Th e magnetic response of the nickel chromium analogue film is anisotropic. Both the high TC magnetic ordering of the nickel chromium analogue and the photoinduced magnetism of the cobalt iron analogue were observed in the stacked films. When the two different analogues were mixed, the two magnetic behaviors were suppressed. The photoinduced increase or de crease in magnetism of the cobalt iron analogue presented in chapter two was different than in the films containing the nickel chromium analogue. Finally, the largest pho toeffect observed in the sandwi ch film was over one order of magnitude smaller than the films reported in chapter two. Magnetic Anisotropy Present in the Nickel Chromium Film The magnetic susceptibility of the nickel chromium film perpendicular to the applied magnetic field was one-third of the response when the film was parallel to the applied magnetic field. This magnetic anisotropy in the film s uggests that the nickel chromium analogue film contains a magnetic easy axis in the plane of the so lid support used to build the film (Figure 3-3). A magnetic easy axis is the direction for which the material has a greater susceptibility to a magnetic field. The Prussian blue families of compounds are cubic structures and should contain no structural anisotropy, and this behavior in the films is diffe rent from the bulk solid. The surface of the solid support could be directing the formation of th e film, causing the material to form an easy axis. Another possible cause of the nickel chromium films magnetic anisotropy could be the magnetic dipolar fi eld generated by the nickel chro mium analogue, when in a quasitwo-dimensional structure. When the film is para llel to the applied magnetic field, all the dipolar fields align head to tail and ar e continuous down the surface of the film. When the film is perpendicular to the external field, the ferromagn etic moments align with the field but they are only continuous over the thickness of the film, thereby causing a competition between aligning with the applied magnetic field and ordering in the plane of the film. (Figure 3-16) The

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62 anisotropic behavior from nick el chromium was observed in the later films and accounts for the different starting magnetic values for the parallel and perpendicular orientations. Sequence Effects in the Stacked Films The magnetic behavior of the stacked films changed depending on which analogue was deposited first. When comparing Figures 3-7 and 3-8, it appeared th at the analogue deposited first has its magnetic properties suppressed. The magnetic susceptibility was much less when the nickel chromium analogue was deposited first in [A10B10]f 1 film 2 (Figure 3-7) when compared to the magnetic susceptibility in [B10A10]f 1 film 3 which had the nickel chromium analogue deposited second. (Figure 3-8) When the cobalt iron analogue was deposited first, as in film 3 (Figure 3-8), there is a smalle r photoeffect compared to film 2 that had cobalt iron deposited second. (Figure 3-7) The reduction of the fi rst layers magnetic behavior is explained by considering the deposition method. The sequential adsorption met hod required several cycles to establish a uniform film as known from chapter two. Films of nominally 30 nm are required to achieve uniform coverage. (Figure 2-3) The fi rst analogue deposited must achieve this coverage before building a film, but the s econd analogue was able bind to a surface that has already been established. Photoinduced Magnetism in the Stacked Films When this deposition order is combined with the magnetic easy axis, additional behaviors of the film are explained. The easy axis conti nues into the second layer in the stacked films. There was a large magnetic anisotropy in the dark stacked film 3 [B10A10]f 1 when the nickel chromium analogue was the second layer. This magnetic easy axis could also contribute to the photoinduced magnetism. In stacked films, the phot oinduced increase in th e parallel direction was larger than the increase in the perpendicu lar direction by an or der of magnitude. The magnetic easy axis and applied field are additive when the film is parallel to the applied

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63 magnetic field. The new photoinduced spins a lign with the applied magnetic field. The magnetic easy axis and applied field are orthogonal when the film is perpendicular to the applied magnetic field causing fewer of the photoinduced spin s to align with the applied magnetic field, which led to a small or null photoinduced effect in the films in the perpen dicular orientation. (Figure 3-17) Magnitude of the Photoeffects in the Heterogeneous Films In the stacked films, the photoinduced ch ange in magnetism was different from the behavior observed in the chap ter two cobalt iron films. Firs t, no photoinduced decrease was observed. All the heterogeneous films contain ~75 nm of the cobalt iron analogue based on chapter two data. Photoinduced increases were observed, however the magnitude of the increase was small when compared to a 75 nm film of only the cobalt iron analogue. The largest photoinduced increase reported for the hete rogeneous films was in the sandwich [A10B10A10]f 1 film 5 and was 7.5 10-7 emuG/cm2, and is compared to the photoinduced increases of the stacked films 2 and 3. (Figure 318) This result indicates that atte nuation of the cobalt iron layer is not a significant contributor to the suppression of photoeffects seen in other films. To compare the relative strengths of the photoeffects with the lone c obalt iron film it was assumed that 10 cycles of cobalt iron deposited on a ni ckel chromium analogue deposited 75 nm of material. When converted to cm3 the change in magnetism for the sandwich film gives a value of 0.1 emuG/cm3. The photoinduced decrease reported in chapter two fo r a 75 nm film perpendicular was 2 emuG/cm3. There is more than an order of magnitude decrease in the photoeffects in the heterogeneous films. Anisotropic Photoinduced Magnet ism of the Sandwich Films The sandwich film 5 has magnetic behavior diffe rent from the stacked films 2, 3. The magnetic susceptibility in the parallel directions is greatest of all the f ilms investigated, reaching

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64 near 120 10-7 emu G/cm2 at 5 K. This result is reasonable as it contains two 75 nm regions of nickel chromium analogue. The phot oinduced behavior of the sandwic h film is different than the stacked films and the simple cobalt iron films. When the sandwich film is parallel to the applied magnetic field, there is a photoinduced increas e for 10 minutes, and then a decrease in susceptibility is observed resulting in an ove rall photoinduced decrease. This behavior is unusual on two counts. It is the first observed behavior of a phot oinduced decrease when a film is parallel to the applied magnetic field. Also observation that the su sceptibility begins to increase and then decreases has not been previ ously observed. The gr adual initial onset of magnetization is in contrast to the immediate decr ease from heating observed in other films. Thermal effects are observed at th e end of photoexcitation when the light is turned off and there is an increase in magnetism. A qualitative explanation of the two behaviors comes when the dipolar fields generated by the ni ckel chromium layers are consid ered. The dipolar field of the ordered nickel chromium layers will penetrate through the mixed region of the interface into the cobalt iron region. The two dipolar fields interacting with the c obalt iron region give rise to a photoinduced decrease in magnetism in the parallel di rection. (Figure 3-19) The initial increase in magnetism may be from small areas, in the center of the cobalt iron region, where the developing photoinduced spin regions are to small to be affected by the nickel ch romium dipolar field, that align with the applied magnetic fiel d these regions reach a maximum and are canceled by more material influenced by th e dipolar field of the nickel chromium or as the cobalt iron regions increase in size they begin to be aff ected by the nickel chromium dipolar field and reverse alignment and order opposed to the appl ied magnetic field. In the perpendicular direction, the dipolar field ge nerated by the nickel chromium would influence the photoactive

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65 material in an additive manner, with the applied magnetic field re sulting in a larger photoinduced increase in magnetism. (Figure 3-19) Diminished Photoeffects in Stacked Films The primary contribution to the diminished phot oeffects in the stacked films would be the roughness of the interface between the two analog ues. Regions between different analogues would have greater mixing at the molecular level resulting in photomagnetic behavior similar to a mixed film that has little phot oeffects. For stacked film 3 [B10A10]f 1 the 10 cycles of cobalt iron analogue was deposited first and resulted in a film 75 + 20 nm with a roughness of 23 nm as stated in chapter two. The s ubsequent deposition of the nickel chromium layer would be on top of the surface provided by the c obalt iron layer filling in the valle ys generating an area of mixed analogues. Another explanation for the diminished photoe ffects in the stacked films can be achieved by considering the magnetic fields involved. In chapter two, there were two fields identified to exist in the film: the applied magnetic field and the dipolar field generate d by primordial regions of cobalt iron Prussian blue analogue. The alignm ent of the induced spins either para llel or antiparallel to the applied magnetic field depends on the relative strengt h of the two fields. Another force that influences the directional alignment of the new spins that needs to be considered is the dipolar field generated by the continuous ferro magnetic nickel chromium analogue. When a stacked film is parallel to the applied magnetic fi eld, the nickel chromium region will generate a dipolar field that should align the photoinduced material an ti-parallel to the applied magnetic field. The material proximal to the nickel chromium region should demonstrat e the greatest effect. The material influenced by the nickel chromium dipolar field was a mixed analogue region and showed poor photoeffects allowing the material in the continuous cobalt iron region to behave similar to the lone cobalt films. W ith the film perpendicular to the applied magnetic

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66 field the nickel chromium dipolar fields should average causing the unaffected material to align anti parallel to the applie d field. (Figure 3-20) Magnetic Behavior of Metal Thin Films Discussed in Literature To the best of our knowledge there has been no other attempt to combine two different Prussian blue analogues in the same film. Eff ects on the magnetic behavior that are inherent heterogeneous films are expected. A large body of literature is available that focuses on thin metal films and how those films behave wh en in contact with another material.90-99 The literature describes metal films and the magnetic be havior that results. A number of different effects that cause anisotropy have been disc ussed and include surface anisotropy, interface roughness, lattice mismatch, classical dipol e interactions, and exchange bias. The surface anisotropy in the metal films cause s an easy axis to be perpendicular to the plane of the films.90,91,94,95 In our films the easy axis observed is in the plane of the film. Our films are much thicker than the metal films w ith surface anisotropies. Surface anisotropy is related to the surface area of the film and is an important contri bution in thin films of less the five monolayers. Our layer thicknesses are nominally 75 nm or 75 monolayers. The interface roughness described in the literature is not compar able to our samples. Metal films are almost atomically smooth and contain step features.97 The roughness in the multiple sequential adsorption films is much rougher so that the surfaces are not co mparable. The interface between the nickel chromium region and cobalt iron regi on is best described as a mixed film. Several behaviors of the metal films do provide insight into our system. The first is a lattice mismatch. A lattice mismatch is when the unit cells of the film do not align perfectly with material previously deposited i nducing strain and is expected to be a source of anisotropy in ferromagnetic materials.95 Exchange bias is observed by a shift of the hyste resis loop along the field axis when a ferromagnetic film is in contact with an an tiferromagnetic film.99 The

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67 relevance to our system is not yet know, we have not yet conducted the experiments to detect any exchange bias. The classical dipole interaction do es apply to our system. The dipole interaction favors interaction in the plane of the film and increases with f ilm thickness to overwhelm surface effects.90 The dipolar interaction is qualitatively e xplains the anisotropic behavior observed in the nickel chromium films. Conclusions The synthesis of heterogeneous films cont aining two different Pr ussian blue analogues was achieved. The behaviors of the separate analogues were conserved when regions of sufficient thickness were deposited The behaviors of the separa te analogues were destroyed when the analogues were mixed on the molecular level preventing the form ation of regions of pure analogues, resulting in a mi xed film. There was evidence of the interactions between the different regions observed by the photoinduced effects that differed from pure cobalt iron Prussian blue analogue films. When the films were oriented perpe ndicular to the applied magnetic field, a photoinduced increase or null result was observed in the stacked a nd sandwich films in contrast to the photoinduced decrease pres ent in the pure cobalt iron fi lms. The propagation of the dipolar field from the nickel chromium layer caus ed another field to influence the photoexcited material. The direction of the new photoinduced spins is determined by the sum of the applied magnetic field, the nickel chromium region dipol ar field and the dipolar field generated by the primordial cobalt iron spins.

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68 Table 3-1. Summary of he terogeneous films generated Film Methoda Film Typeb Number of Cycles Short Hand 1 Fast A 10 [A10]f 1 2 Fast Stacked AB 10 /10 [A10B10]f 1 3 Fast Stacked BA 10 /10 [B10A10]f 1 4 Fast Mixed 20 [A1B1]f 10 5 Fast Sandwich ABA 10 /10 /10 [A10B10A10]f 1 6 Slow Stacked AB 40 /40 [A40B40]s 1 7 Slow Mixed 80 [A1B1]s 40 a. Fast sequential adsorption method rinses be tween cycles, Slow sequential adsorption rinses between analogue solutions chapter two. b. A nickel chromium Prussian blue an alogue, B cobalt iron Pru ssian blue analogue.

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69 Figure 3-1. Schematic of the heterogeneous Prussi an blue analogue thin film generated using the sequential adsorption method. Figure 3-2. Schematic of the magnetic layer excha nge interactions likely to exist in samples of heterogeneous films. Figure 3-3. The dc magnetic sus ceptibility data with varying field of a slow film of the nickel chromium Prussian blue analogue. The shifti ng peak temperature with field is typical of glassy Prussian blue materials. 050100 0.0 0.5 1.0 1.5 2.0 M (10-3 emu G / sample)T (K) H = 250 G H = 100 G H = 50 G H = 20 G H = 5 G 050100 0.0 0.5 1.0 1.5 2.0 M (10-3 emu G / sample)T (K) H = 250 G H = 100 G H = 50 G H = 20 G H = 5 G NiCrintralayerinteractions CoFeintralayerinteractions CoFe/NiCrinterlayer interactions interlayer interactions NiCrintralayerinteractions CoFeintralayerinteractions CoFe/NiCrinterlayer interactions interlayer interactions Co Fe CoII[FeIII(CN)6]3-andRb+ Fe Fe Fe Fe Co Co Co Co Co Repeat for XcyclesMelinex RbjCok[Fe(CN)6]lnH2O RbjNik[Cr(CN)6]lnH2O Ni Cr Cr Cr Cr Cr Ni Ni Ni Ni Ni Repeat for XcyclesMelinexNiII[CrIII(CN)6]3-andRb+ 10 x NiCr+ 10 x CoFe= Co Fe CoII[FeIII(CN)6]3-andRb+ Fe Fe Fe Fe Co Co Co Co Co Repeat for XcyclesMelinex Co Fe CoII[FeIII(CN)6]3-andRb+ Fe Fe Fe Fe Co Co Co Co Co Repeat for XcyclesMelinex RbjCok[Fe(CN)6]lnH2O RbjCok[Fe(CN)6]lnH2O RbjNik[Cr(CN)6]lnH2O RbjNik[Cr(CN)6]lnH2O Ni Cr Cr Cr Cr Cr Ni Ni Ni Ni Ni Repeat for XcyclesMelinexNiII[CrIII(CN)6]3-andRb+ Ni Cr Cr Cr Cr Cr Ni Ni Ni Ni Ni Repeat for XcyclesMelinexNiII[CrIII(CN)6]3-andRb+ 10 x NiCr+ 10 x CoFe=

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70 Figure 3-4. Schematic of the di fferent heterogeneous films generated. Stacked films contain regions of both analogues, Sandwich films place one cobalt iron B layer between two nickel chromium A layers, mixed films do not form layers of discrete analogues. Figure 3-5. Magnetic susceptibil ity vs. temperature plot of a 75 nm nickel chromium Prussian blue analogue thin film (film 1). Te mperature dependent fc/zfc sweeps of dc susceptibility the film parallel and perpe ndicular to an applied magnetic field of 100 G. The magnetic response is anisotropic.020406080100 0 20 40 60 ZFC Hparr FC Hparr ZFC Hperp FC Hperp (10-7 emu/cm2)T (K)H = 100 G Stacked Mixed Sandwich Co-Fe B layer Ni-Cr A layer Stacked Mixed Sandwich Co-Fe B layer Ni-Cr A layer

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71 0255075100125 0 1 2 3 4 5 6 7 (10-7 emu /cm2)T (K) Figure 3-6. The dc magnetic sus ceptibility verses temperature fc (), zfc ( ) of the stacked AB heterogeneous Prussian blue analogue film 2 at H = 100 G parallel to the film. A separate ordering transition is obser ved for each analogue in the film. Figure 3-7. Photoinduced magnetiz ation of a nickel chromium Pr ussian blue analogue film under a cobalt iron Prussian blue analogue film AB film 2, measured at 5 K with the measuring field of 100 G oriented parallel (lef t) and perpendicular (r ight) to the film. The time axis is relative to th e point where the light is ap plied, and irradiation stopped at ~1 hour.01 4 5 6 7 8 (10-7 emu/cm2)Time (Hours) 01 1.7 1.8 1.9 2.0 (10-7 emu/cm2)Time ( Hours ) H parallel H perpendicular 01 4 5 6 7 8 (10-7 emu/cm2)Time (Hours) 01 1.7 1.8 1.9 2.0 (10-7 emu/cm2)Time ( Hours ) H parallel H perpendicular

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72 Figure 3-8. Photoinduced magne tization of a cobalt iron Prussi an blue analogue film under a nickel chromium Prussian blue analogue BA film 3, measured at 5 K with the measuring field of 100 G oriented parallel (lef t) and perpendicular (r ight) to the film. The time axis was relative to the point where the light was applied, and irradiation stopped at 1 hour. Figure 3-9. The dc magn etic susceptibility fc (), zfc ( ) versus temperature plot of a mixed film cobalt iron nickel chromium Prussian blue analogue deposited using the fast method (film 4). The film was parallel to an applied field of 100 G. 050100150 0 5 10 15 20 25 (10-7 emu G / cm2)T (K)01 39.0 39.2 39.4 (10-7 emu/cm2)Time (Hours)01 19.2 19.3 19.4 (10-7 emu/cm2)Time (Hours)H parallel H perpendicular 01 39.0 39.2 39.4 (10-7 emu/cm2)Time (Hours)01 19.2 19.3 19.4 (10-7 emu/cm2)Time (Hours)H parallel H perpendicular

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73 Figure 3-10. Photoinduced magnetism of a mixed cobalt iron nickel chro mium Prussian blue analogue fast film (film 4) at 5 K perpendi cular to the applied magnetic field. The time axis was relative to the point where th e light was applied, and irradiation stopped at 120 min. Figure 3-11. Photoinduced magnetization of a sandwich film nickel chromium, cobalt iron, nickel chromium Prussian blue analogue (film 5), measured at 5 K with the measuring field of 100 G oriented parallel (lef t) and perpendicular (r ight) to the film. The time axis is relative to the point the light is applied, and irradiation stopped at ~1 hour.01 18 20 22 24 26 (10-7 emu/cm2)Time (Hours)01 118 119 120 121 (10-7 emu/cm2)Time (Hours)H parallel H perpendicular 01 18 20 22 24 26 (10-7 emu/cm2)Time (Hours)01 118 119 120 121 (10-7 emu/cm2)Time (Hours)H parallel H perpendicular 0100 20.8 20.9 21.0 21.1 21.2 21.3 21.4 (10-7 emu G / cm2)Time (min)

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74 Figure 3-12 fc (), zfc ( ) dc magnetic susceptibility vs. temperature with H = 100 G perpendicular to a slow stacked AB film 6 with one interface between the analogues. Figure 3-13. Photoinduced magnetism of a stacked slow AB film 6 of cobalt iron over nickel chromium analogue measured at 5 K with the measuring field of 100 G oriented perpendicular to the film. The time axis is relative to the point the light is applied, and irradiation stopped at 60 min.050 1.4 1.6 1.8 (10-7 emu G/ cm2)Time (min.)0255075100125150 0 2 4 6 (10-7 emuG/ cm2)T (K)

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75 020406080 0 2 4 (10 -7emu G/ cm2)T (K) Figure 3-14. fc (), zfc ( ) magnetic susceptibility vs. temperature with H = 100 G perpendicular to a mixed slow film 7. Figure 3-15. Photoinduced magnetism of a mixed sl ow film of cobalt iron and nickel chromium analogue (film 7) measured at 5 K with the measuring field of 100 G oriented perpendicular to the film. The time axis is relative to the point where the light is applied, and irradiati on stopped after 60 min. 0100 3.4 3.5 3.6 3.7 (10-7 emu G/ cm2)Time (min.)

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76 Figure 3-16. Schematic of the dipolar field in the ferromagnetic nickel chromium analogue films. When the film is orientated parallel to the applied magnetic field the films dipolar field, easy axis and the applied field are additive. Figure 3-17. Schematic of the magnetic easy axis in the ferromagnetic nickel chromium analogue present in stacked films. When the film is orientated pa rallel to the applied magnetic field the films magnetic easy axis and the applied field are additive. Easy axis Applied magnetic field Co Fe Ni Cr Easy axis Applied magnetic field Co Fe Ni Cr Dipolar field Ferromagnetic spin Easy axis Applied magnetic field Ni Cr Dipolar field Ferromagnetic spin Dipolar field Ferromagnetic spin Easy axis Applied magnetic field Ni Cr

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77 Figure 3-18. Change in magnetic su sceptibility over time with photoe xcitation. The time axis is relative to the start of photoexcitation for the stacked film 2 (), stacked film 3 ( ), and sandwich film 5 ( ) perpendicular to H of 100 G film The photoeffects of the stacked films are small compared to the sandwich film. Figure 3-19. Schematic of the sandwich film 5 w ith directions of the applied magnetic field, nickel chromium dipolar field a nd easy axis indicated with respect to film orientation. All three forces contribute to the final direction of the photoinduced spin. Applied magnetic field Dipolar field Ferromagnetic spin Easy axis Nickel chromium (A) Cobalt iron (B) Applied magnetic field Dipolar field Ferromagnetic spin Dipolar field Ferromagnetic spin Easy axis Nickel chromium (A) Cobalt iron (B) 050 0 2 4 6 8 (10-7emu G/cm2)Time (min)

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78 Figure 3-20. Schematic of the stacked AB film 2 with directions of the applied magnetic field, nickel chromium dipolar field a nd easy axis indicated with respect to film orientation. All three forces contribute to the final direction of the photoinduced spin. Dipolar field Ferromagnetic spin Easy axis Applied magnetic field Co Fe (B) Ni Cr (A) Dipolar field Ferromagnetic spin Dipolar field Ferromagnetic spin Easy axis Applied magnetic field Co Fe (B) Ni Cr (A)

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79 CHAPTER 4 SIZE DEPENDENT PHOTOINDUCED MAGNETISM IN RUBIDIUM COBALT IRON PRUSSIAN BLUE ANALOGUE NANOPARTICLES Introduction A range of compositions of the Prussian blue analogue, AjCok[Fe(CN)6]l nH2O, exhibit photoinduced magnetism.19-41 At temperatures be low 20 K, diamagnetic CoIII(ls)-FeII photoswitchable pairs may be phot oexcited to ferrimagnetic CoII(hs)-FeIII through a charge transfer and spin crossover event, increasing ma gnetization. The metastable excited state is long-lived and reversible by irra diation or thermal treatment. Nanoparticles display physical and magnetic pr operties that could be different from the bulk material as well as have t echnical and biophysical applicati ons. Nanoparticles of the cobalt iron Prussian blue analogue are also of interest in the field of molecular magnetism. The synthesis of cobalt iron Prussian blue analogue nanoparticles has been reported, although the photoinduced magnetism was not discussed.70,73 The exception is a study of KjCok[Fe(CN)6]l fabricated within a silica xerogel. At 5 K a nd 500 Oe a 9% increase in magnetism was reported after photoexcitati on to saturation.79 The photoinduced magnetism in nanoparticles of RbjCok[Fe(CN)6]l synthesized in the presence of the polymer polyvinylpyrrolidone (PVP ) will be discussed here. These nanoparticles display magnetic behavior consistent with a c obalt iron Prussian blue analogue powdered solid, although altered by the restricted particle size. The nanoparticle size variation allowed for the elucidation of a critical size fo r bulk like behavior. The photomagnetism and critical size of our nanoparticles has been previously reported.100,101 Evidence that the surf ace of the nanoparticle behaves differently than the core of th e nanoparticles has also been observed.

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80 Experimental Section Reagents and Materials All reagents were purchased from Sigma-Aldrich or Fisher Scientific and used without further purification. Trace metal grade nitric acid was used for inductively coupled plasma mass spectrometry (ICP-MS) experiments, all other reagents were ACS grade. Holey carbon transmission electron microcopy (TEM) grids were purchased from Ted Pella. Deionized (DI) water (18 M ) was used for all experiments. Sample Preparation of AjCok[Fe(CN)6]l nH2O Nanoparticles Four sets of nanoparticles were synthesi zed by modifying the procedure described by Uemura and coworkers.71,72 A 2.0 mL solution containing both 28.0 mg K3Fe(CN)6 (42 mM) and 6.8 mg RbNO3 (23 mM) was added dropwise to a seri es of 8.0 mL so lutions containing 30.0 mg Co(NO3)2 H2O (13 mM) and 1000. mg, 500. mg, 200. mg or 100. mg polyvinylpyrrolidone (PVP), samples A-D respectivel y, while stirring rapidl y. After 30 minutes of stirring, the solution was allowed to sit for on e week. Powdered solid samples were prepared as described above without PVP. Samples cont aining no rubidium were prepared as described above, omitting the RbNO3 salt. Instrumentation The elemental analyses were performed by ICP-MS on a Thermo-Finnigan Element-2 spectrometer. FTIR spectra were recorded using a Nicole t 6700 spectrometer. TEM and selected area electron diffr action (SAED) were performed on a JOEL 2010F. Magnetic measurements were made by the University of Florida Department of Physics using a Quantum Design MPMS XL superconducting quantum inte rference device (SQUID) magnetometer. A bundle of 10 optical fibers, 270 m O.D. (Ocean Optics Model 200) was used to introduce light,

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81 from a room-temperature, ha logen-light source, of 1~2 mW power into the SQUID magnetometer for photoinduced experiments.85 Analysis Preparations For TEM analysis, a 50.0 L aliquot of the suspension was diluted 2000 times and sonicated for 30 minutes then 8.0 L of the diluted suspension was placed on a holey carbon TEM grid. To isolate particles, three volumes of acetone were added to the synthesis solution which was centrifuged to sediment the particles, a nd then the particles were further washed with acetone and dried under vacuum. ICP-MS samples were prepared by digesting 5 mg of sample in 0.4 mL of boiling, concentrated sulfuric acid for 4 hours, resulting in a black liquid. Concentrated nitric acid (0.5 mL) was then added dropwise, before diluting the mixture to 5.00 mL with DI water. The samples were d iluted immediately prior to analysis, and then compared to matrix matched metal blends between 1 ppm and 1 ppb. The resultant concentrations were normalized to a unit cell formula AjCo4[Fe(CN)6]l nH2O by fixing 4 cobalt ions per unit cell. The unit cell formula will then provide the formula used to determine the molar mass of the analogue. The water molecule s coordinated to the cobalt were determined by the number of ferricyanide vacancies, specifically, n = 6(4-l). The unit cell formula was then used to determine the molar mass of the compoun ds. The FT-IR spectra of the nanoparticle and powdered solid samples were obtai ned by transmission IR using CaF2 salt plates. For magnetic measurements the samples were mounted to comme rcial transparent tape and were irradiated with light from a room-temperature, halogen so urce by using a homemade probe equipped with a bundle of optical fibers.85 Background contributions from the holder and tape have been independently measured and have been subtracted from the data.

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82 Results Nanoparticle Generation and Characterization The nanoparticles were generated by adding a solution containing potassium ferricyanide and rubidium nitrate dropwise to a solution with cobalt(II) nitrate and PV P. After addition the sample was allowed to sit 1 week, TEM grids of each sample were prepared, and the nanoparticles were isolated. Representative TEM im ages are shown. (Figure 4-1) In addition, SAED of the nanoparticles was compared to SAED of powdered solid samples and to published powder X-ray diffraction pattern s to confirm the structure.25 (Figure 4-2) Using Image J imaging software,102 the TEM images were analyzed to obtain th e particle size distribu tion, and these data were fit to a log-normal distribution103 that yielded batches, sa mples A-D, with different characteristic diameters of 3.3 ( 0.8), 6.9 ( 2.5) 9.7 ( 2.1), and 13.0 ( 3.2) nm respective to decreasing amounts of PVP added. (Figure 4-3) The log-normal distribution was used to fit the smaller nanoparticles that could not fit to a Gaussian function due to the finite size minimum. The literature preparation of Prussian blue nanoparticles called for a one week aging time of the nanoparticles. This aging time is an importa nt step in the synthesis of PVP nanoparticles. Images of all nanoparticle and powdered solid samples prepared immedi ately after synthesis displayed size distributions consiste nt with the smallest set (3 to 5 nm). (Figure 4-4) During the one week time period the particles increase in size until the growth is inhibited. An important observation is that the addition of increased amounts of PVP restri cts the growth of nanoparticles during the one week aging of the sample. Chemical analysis was obtained from a combination of CHN co mbustion analysis and ICP-MS. The formulas were determined to be near Rb1.8Co4[Fe(CN)6]3.2 4.8H2O for samples AC and Rb0.9Co4[Fe(CN)6]2.9 6.6H2O for sample D. Both are in the range of photoactive bulk cobalt iron Prussian blue analogues22 and are listed in Table 4-1. The cyanide contribution to the

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83 total amount of carbon and nitrogen can be dete rmined by considering that each iron will be coordinated by six cyanide ligands. To calculate the amount of polymer present, the carbon and nitrogen contained in the cyanide ligands was subtracted from the CHN data. The remaining carbon and nitrogen percentages were then normalized to the cobalt in the sample. The ratio of PVP repeat unit to cobalt was found to be 360, 200, 60, and 20 for samples A-D, respectively, reflecting the amount of PVP added. The physic al properties of the four sample sets are summarized in Table 4-1. There are three t ypes of water molecules known to exist in the nanoparticles: the water coordinating to the coba lt which can be inferred by the ferricyanide vacancies that are included in the formula, water intercalated in the fram ework of Prussian blue, and water associated with the PVP. The fi nal two types of water cannot be determined separately. The IR Data There are three different cyanide stretches of in terest in the IR spectra. The first of which is at 2130 cm-1 and is attributed to the diamagnetic CoIII(ls)-FeII pair.23 The second is the stretch at 2160 cm-1 attributed to the ferrimagnetic CoII(hs)-FeIII pair. The third is the stretch at 2085 cm-1attributed to the reduced, paramagnetic CoII(hs)-FeII pair that cannot participate in photoinduced magnetism of the sample. The inte nsity of the three different peaks can be changed by altering the Rb ion concen tration and is also affected by the particle size. As the Rb ion concentration is increased the diamagnetic pair is favored. IR spectra were obtained using transm ission IR of the sample through CaF2 plates at room temperature. Samples A-C nanoparticles each revealed one peak in the cyanide stretching at energies region ranging from 2124 cm-1 to 2105 cm-1. (Figure 4-5) This is consistent with samples containing a combination of the CoIII(ls)-FeII diamagnetic pair23 and the reduced CoII(hs)-FeII paramagnetic pair.29 A powdered solid sample with chemical formula

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84 Rb1.8Co4[Fe(CN)6]3.2 .8H2O also displayed one peak in th e cyanide stretching region at 2121 cm-1. A powdered solid sample with chemical formula Rb0.6Co4[Fe(CN)6]2.9 .6H2O displayed two peaks at 2156 and 2105 cm-1. (Figure 4-6) Sample D displayed two different peaks in the cyanide stretching regi on: a small sharp peak at 2156 cm-1; and a large broad peak centered at 2090 cm-1 corresponding to CoII(hs)-FeIII ferrimagnetic23 and CoII(hs)-FeII paramagnetic pair. (Figure 4-5) The broad lo wer energy peak is a result of different combinations of diamagnetic CoIII(ls)-FeII reported at 2130 cm-1 and paramagnetic CoII(hs)-FeII reported at 2085 cm-1. The cyanide stretching energies fo r the nanoparticles are close to the energies of the powdered solid with similar concentrations. The Rb ion concentration depe ndent behavior was studied in the powder samples to make comparisons to nanoparticles with the same chemical formula. Samples with no Rb show all three peaks in the cyanide stretching region, with the ferrimagnetic pair at 2165 cm-1dominating the spectra and the paramagnetic pair at 2085 cm-1 being the next most prominent. As the concentration of Rb increases, the peak due to the ferrimagnetic pair decreases and the diamagnetic peak increases, leading to a broa d peak that includes both the diamagnetic and paramagnetic pairs. At even higher concentratio ns of Rb, the diamagnetic peak is dominant and the other two peaks have almost disappeared. (F igure 4-6) The size effects of the nanoparticles on the IR stretching energies ar e more evident when samples with no alkali cation are prepared and th e ability to resolve the diamagnetic peak and paramagnetic peak is gained. Nanoparticles and powdered solid samples we re synthesized using the same procedure without rubidi um nitrate to target formation of the ferrimagnetic pairs. The powdered solid sample shows the presence of all three peaks. As the size of the particles decrease, the ferrimagnetic peak decreases in size and the diamagnetic peak increases. The

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85 increase in diamagnetic material shifts the lower energy peak toward the literature values of the diamagnetic peak indicating that new paramagnetic pairs are not formed in smaller nanoparticles. (Figure 4-6) Two observations about the na noparticle can be made from the IR data. First smaller nanoparticles favor the formation of the diamagnetic pairs. Also, the IR data indicates that the diamagnetic pair bridging cyanide stretch in the nanoparticles is shifted to lower energy. Literature data reports the diama gnetic pair cyanid e stretch at 2130 cm-1.23 The nanoparticles cyanide stretch ranges between 2125 and 2110 cm-1.23 (Figure 4-5) The kinematic effect is often utilized to explain the shift seen only when the cyanide is bridging one metal on each end. The restraint in motion results in an increase in st retching energy. The kinematic effect would be greater in powdered solid samples and reduced in samples with restricted size leading to a lower energy than the powdered solid. Magnetic Behavior of Nanoparticles The temperature dependences of the dc magnetic susceptibilities, (T), of rubidium samples A-D are shown in Figure 4-7. The magne tic signals are expressed per mole of Prussian blue analogue using the correspond ing unit cell formula of each samp le. (Table 4-2) The dark state zero field cooled (zfc) data were obtained after cooling in zero applied field from 300 K to 2 K, while the dark state field cooled (fc) data were taken after cooling in 100 G from 300 K to 2 K. The light state was estab lished after field cooling the sa mples from 300 K to 5 K in 100 G and subsequently irradiating with light for five hours, wh ich saturated the photoinduced response. The light state fc data were obtained after cycling the sample to 30 K in 100 G. The 3.3 nm particles (A) followed Curie-like behavior with TC less than 2 K for the light and dark run. The TC of the larger samples 6.9, 9.7 and 13 nm B-D respectively, increased with size from 10 to 13 to 19 K in the dark state. Samples B-D all showed and increase in TC of 3 K during the

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86 light temperature sweep. (Table 4-2) The sa me experiments were performed on powdered solid samples with rubidium ion concentrations of 1. 8 and 0.6 for comparison of the nanoparticles to powdered solid samples. Powdered solid sample s prepared using the nanoparticle protocols show magnetic behavior similar to other powde red solid samples with similar alkali ion concentrations.20,22 (Figure 4-8) When comparing the different samples of na noparticles, the first consideration is the chemical formula of the particle. The 13 nm particles have a signifi cantly lower amount of rubidium in each unit cell compared to the other pa rticles. The rubidium balances the charge of the unit cell. If there were less rubidium, then more ferricyanide vacancies were present, causing an increased amount of water to coordinate to the cobalt. This keeps more material in the ferrimagnetic state when the sample is cooled to low temperatures, increasing the magnetic susceptibility of sample D as shown in Figure 48. The 13 nm particles were still able to undergo photoinduced magnetism; however a larger pe rcentage of the materi al was locked in a ferrimagnetic state. The 13 nm particles have si milar magnetic behavior to powdered solids with similar alkali cation concentrations. All samples show a photoinduced increase in their magnetic signals and the strength of the change is correlated with the size of the part icles. (Table 4-2) The larger particle sizes display a larger increase in magnetic susceptibi lities when photoexcited. The differences between the fc susceptibilities of the light and dark states, = light fc dark fc are plotted in the insets of Figure 4-7, and finite values can only arise from the photoinduced magnetism. Magnetizations versus field experiments for all samples were conducted for both the dark and photoexcited states at 2 K. The full field sweep is shown along with a magnification of the hysteresis. At full scale, the smaller nanopart icles had no observable difference between light

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87 and dark sweeps with coercive fields (HC) less than 10 G. Magnetic hys teresis is observed in the magnetization vs. field (M vs. H) plots for the 9.7 nm and 13 nm particles. The 9.7 nm particles HC increased from 250 G to 330 G with photoexcitation, the 13 nm particles HC increased from 1000 to 1500 G. (Figure 4-9) A summary of the HC of the light and dark state samples are presented in Table 4-2. Ma gnetization versus field experime nts for both the Rb1.8 and Rb0.6 powdered samples are also shown. (Figure 4-10) The ac magnetic susceptibility versus temper ature in the dark st ate after zero-fieldcooling for all samples was also investigated. The 3.3 nm and 6.9 nm samples of particles displayed no frequency dependence. The real component of the ac ma gnetic susceptibility versus temperature is shown for the 9.7 nm and 13 nm particles. (Figure 4-11) This provides additional evidence that to 2 K the smaller na noparticles are non-interacting and follow Curielike behavior. Surface Effects in Nanoparticles In nanoparticles the amount of surface mate rial becomes a significant fraction of the material present. The surface may be chemically different than the core material. The percent core material was calculated by assuming comple te unit cells (cobalt a nd iron are equal) for cubic nanoparticles. The tota l number of cobalt atoms was 4n3, with n = number of unit cells on an edge The surface cobalt atoms were subtracted from the total: 4 corner, 12(n-1) edge, and 6(n-1)(2n-2) face. The remaining cobalt atoms were considered core atoms and divided by the total to give the percent of core atoms. The 3 nm particles contained 30% core atoms, and the percentage of core atoms increased quickly with particle size to 63, 73 an d 79% for the 7, 10 and 13 nm particles respectiv ely. (Table 4-3) The magnetization data per unit cell at 7 T was used to determine the amount of ferrimagnetic material in the samples. First the spin value of the unit cell was determined using

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88 the equation Msat = Ng Bs104 where Msat is the magnetization/mol (emuG/mol) at 7 T, N is Avogadros number, g is Land c onstant and approximated at 2, B is Bohr magneton (9.27 x 1021 erg/G), and s is the spin value of the molar formula unit which was set to the unit cell. It was then assumed that only two types of unit cells we re present in the samples, diamagnetic unit cells and ferrimagnetic unit cells. The average spin value of each samples unit cell was divided by the calculated spin value of a ferrimagnetic unit cell to determine the percent of ferrimagnetic unit cells in the sample. In the 3 nm particles only 1% of the unit cells are ferrimagnetic and the rest of the material is diamagnetic. The 13 nm particle had 62% of the unit cells in the ferrimagnetic spin state and 79% of the material in the core. For all samples the percentage of ferrimagnetic material is less than the percent core material indicating that the surfaces of the particles are diamagnetic. (Table 4-3) Discussion The data presented have led to some obs ervations about cobalt iron Prussian blue analogue nanoparticles. First nanop articles of the cobalt iron analogue have been synthesized with the ability to control particle size. Th e magnetic and photomagnetic behavior of the nanoparticles evolves with size from non-interacting Curie-like to powdered solid behavior with increasing particle size. Chemical differences between the surface of th e nanoparticles and core appear to be present. Critical Size of Nanoparticles Two main features are seen when considering the evolution of magnetic properties due to the increasing average size of the separate batc hes, namely the onset of long-range magnetic order and an increasing net magnetization. This scaling of magnetizati on may be linked to an increased diamagnetic surface to magnetically-activ e-volume ratio in smaller particle sizes.

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89 At low temperatures, the Fe and high-spin Co ions interact antiferromagnetically, giving rise to a ferrimagnetic transition at TC, which is about 24 K for photoinduced powdered solid samples. For the magnetic data shown in Figures 47 and 4-8, the onset of this transition can be estimated, and these temperatures are listed in Table 4-2. Particles larger th an a critical size will allow domains large enough to approach bulk-like magnetic prope rties. Conversely, smaller particles may put limits on allowed domain size, suppressing the ordering temperature. Microscopically, if the size of th e magnetic domains is less than or of the order of the magnetic coherence length, then a spectrum of TC values can be expected until the superparamagnetic limit is achieved. Consider the magnetic propert ies of the samples presented in conjunction with the TEM analysis. The 3.3 nm particles have no observe d coercivity and follow Curie-like behavior. Samples of 6.9 nm and 9.7 nm particles show a combination of Curie-ta il and partial ordering with a reduced TC (Figure 4-7), as well as finite coercive fields (Table 4-2). Finally, the active sites in the 13 nm sample are almost entirely fe rrimagnetically ordered with the largest coercive field of all batches presented. In addition, th e differences between the fc and zfc data for the dark state and the ac magnetic susceptibility in the 9.7 nm and 13 nm samples are consistent with spin glass or cluster glass behavior,23,75 in accord with the presence of large magnetic domains observed in the bulk samples. These interpre tations are consistent with the M versus H measurements performed at 2 K, where HC, and remnant magnetization values are observed for the largest sets of particles but not for the smallest sets of particles. (Figures 4-7 and 4-8, and Table 4-2) The size dependent beha vior is also confirmed by the ac magnetic susceptibility data. The smaller particles follow the field regardless of the field strength. The larger particles show frequency dependent temper ature shifts in the susceptibility indicating that the larger particles

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90 have sufficient size to order. By making the assumption that the 3 nm particles magnetic behavior is entirely Curie-like the Curie-like co ntribution in the other samples can then be subtracted from the data. Analysis of the data suggests that the supe rparamagnetic contribution for each of the four samples of nanopartic les (A-D) is 100%, 90%, 50%, and 10%. The percentage of superparamagnetic contributions in each sample was than applied to the particle size histograms. An observation th at 90% of sample B, 50% of sample C and 10% of sample D present in each histogram are particles 10 nm in diameter was made. Consequently, at least down to 2 K, nanoparticles with sizes below ~10 nm are in the superparamagnetic limit. Core Shell Nanoparticles Treatment of the data thus far has been made with the assumption that the entire particle is chemically one species and photoactive in the enti re particle. Investigation of the IR data and saturation magnetization indicate that within a part icle there are cobalt iron pairs that have been rendered diamagnetic and photoinactive. Using the Msat data in Table 4-3 the following two observations were made. Most of the material in the nanoparticles are diamagnetic (CoIII(ls)-FeII). The percentage of ferrimagnetic (CoII(hs)-FeIII) material present in the dark state, primordial spin, increases with particle size along with the percent of core material sugges ting that the surfaces of the nanoparticles are diamagnetic. IR data also supports the increase in diamagnetic material with a decrease in particle size. (Figure 4-5, 4-6) Cobalt ions with six strong fiel d ligands have been shown to be locked in the low spin state. At the surface the nitrogen atoms in the PVP are available to coordinate to the Co and fill the coordination sphe re. The PVP is stronger field ligand then the displaced water and results in a strong ligand field. The 13 nm particles have a larg e fraction of high spin material in the dark state due to the low concentration of Rb ion in the unit cell. By making the assumption that all the ferrimagnetic

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91 material is in the core of the particle 62% of the material is a cube with an edge length of 11 nm. The diamagnetic surface is 1 nm thick, which corresponds to the length of one unit cell of Prussian blue, suggesting that the PVP is only in teracting with the surfa ce. (Figure 4-12) A diamagnetic 1 nm surface on a 3 nm particle would result in only a single unit cell of the 27 total unit cells, 4%, able to be a ferrimagnetic pa ir accounting for the low amount of magnetic material observed in the 3 nm samples. Conclusion In conclusion, the synthesizes of four different sizes of RbjCok[Fe(CN)6]l nH2O nanoparticles protected by PVP was achieved. Ea ch sample of particles is photoinducible, but the strength of this effect, as well as other global properties, e.g. TC and HC, are correlated with the intrinsic particle size distri butions of each sample, and the surface area to volume ratio. The combination of photoinduced magnetism and nanosi zed Prussian blue analogue particles with finite coercive fields is unique and establishes a length scale limit of ~10 nm for these properties. As the size of the nanopartic les decrease, the surface area to volume ratio increases, and the surfaces of the nanoparticle are diamagnetic. Nanoparticle s yntheses without the addition of Rb ion more clearly showed cyanide stretching be havior that was differe nt than the powdered solids, which changes with particle size. Th is effect is confined to the surface of the nanoparticle.

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92 Table 4-1. Summary of the material properties of the four sample sets Sample Starting PVP (mg) Resulting chemical formula PVP:Co ratio Diameter (nm) A 1000 Rb1.9Co4[Fe(CN)6]3.2.8H2O 360 3.3 0.8 B 500 Rb1.8Co4[Fe(CN)6]3.2.8H2O 200 6.9 2.5 C 200 Rb1.7Co4[Fe(CN)6]3.2.8H2O 60 9.7 2.1 D 100 Rb0.9Co4[Fe(CN)6]2.9.6H2O 20 13.0 3.2 Table 4-2. Summary of magnetic data for different nanoparticle samples Diameter (nm) dark onset CT(K) light onset CT(K) dark CH (G) light CH (G) dark (emu/mol) 3.3 0.8 < 2 < 2 < 10 < 10 0.27 6.9 2.5 10 13 ~ 15 ~ 30 0.37 9.7 2.1 13 17 250 330 3.7 13.0 3.2 19 22 1000 1500 29 Rb1.8 powder < 2 24 < 10 300 1.1 Rb0.6 powder 18 22 540 950 4.8 Table 4-3. Calculation based on magnetic data for PVP nanoparticles Size (nm) Msat Dark (emuG/mol) Msat Light (emuG/mol) % ferrimagnetic Dark % core atoms 3.3 484 629 1.0 30. 6.9 3480 3620 7.1 63 9.7 14300 14600 29 73 13. 31700 35000 62 79

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93 Figure 4-1. The TEM images of cobalt iron Pr ussian blue analogue with nominal sizes of (a) 3.3 nm, (b) 6.9 nm, (c) 9.7 nm, (d) 13.0 nm, (e) powdered solid. A 5 nm (a-d) and 50 nm (e) scale bar is shown. Figure 4-2. The SAED pattern of (a) a large agglomerate cons isting of over 100 nanoparticles and (b) a powdered solid with the 200, 220 and 400 reflections identified.

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94 Figure 4-3. The particle distribut ions, normalized to the largest bin, versus diameter for the four samples of cobalt iron Prussian blue analogue particles, shown in Table 4-1. The total number of particles for each distribution, smallest to larg est, is 44, 27, 53, and 62, respectively. The solid lines are the resu lts of log-normal fits that provide the characteristic diameters shown for each distribution. Adapted from New J. Phys. 2007, 9, 222.101 0.0 0.2 0.4 0.6 0.8 1.0 3.3 ( + 0.8) nm 0.0 0.2 0.4 0.6 0.8 1.0 6.9 ( + 2.5) nm 0.0 0.2 0.4 0.6 0.8 1.0 Normalized Number of Particles9.7 ( + 2.1) nm051015200.0 0.2 0.4 0.6 0.8 1.0 13.0 ( + 3.2) nmDiameter (nm)

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95 Figure 4-4. The TEM images of cobalt iron Pru ssian blue analogue nanoparticles and powdered solid prepared immediately af ter synthesis using: (a) 1000 mg PVP: (b) 500 mg PVP: (c) 200 mg PVP: (d) 100 mg PVP: (e) 0 mg PV P. A 5 nm scale bar is shown. All sets of particles start out at 3-5 nm in size particle si ze evolve with the one week aging of the samples. Figure 4-5. Absorbance IR spectra of cobalt ir on Prussian blue analogue nanoparticles from batches (A-D) and powdered solid (P) sample s. Samples A-D are displayed with a powdered solid sample containing 1.8 rubidi um ions per unit cell. Sample D and a powdered solid (P) with a rubidium con centration of 0.6 ions per unit cell are displayed at right. 220021002000 Absorbance (arb. units)Wavenumbers (cm-1) B Rb1.8 A C P220021002000 Absorbance (arb. units)Wavenumbers (cm-1) P D Rb0.6220021002000 Absorbance (arb. units)Wavenumbers (cm-1) B Rb1.8 A C P220021002000 Absorbance (arb. units)Wavenumbers (cm-1) B Rb1.8 A C P220021002000 Absorbance (arb. units)Wavenumbers (cm-1) P D Rb0.6220021002000 Absorbance (arb. units)Wavenumbers (cm-1) P D Rb0.6 P D Rb0.6

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96 Figure 4-6. Absorbance IR spectra of powde red solid samples (left) with different concentrations of rubidium ion. IR of na noparticles prepared without rubidium (right) samples (A, D), with powdered solid (P). The powdered solid spectra shows the three cyanide stretches of interest at 2165 cm-1, 2130 cm-1, and 2085 cm-1 attributed to the ferrimagnetic, diamagnetic and paramagne tic cobalt iron pairs respectively. Nanoparticles with no alkali cation show a d ecrease in ferrimagnetic pairs and an increase in diamagnetic pairs with size reduction. 220021002000 Absorbance (arb. units)Wavenumbers (cm-1) 220021002000 Absorbance (arb. units)Wavenumbers (cm-1) P D A Rb 0 Rb 1.8220021002000 Absorbance (arb. units)Wavenumbers (cm-1) 220021002000 Absorbance (arb. units)Wavenumbers (cm-1) 220021002000 Absorbance (arb. units)Wavenumbers (cm-1) P D A Rb 0 Rb 1.8 220021002000 Absorbance (arb. units)Wavenumbers (cm-1) P D A Rb 0 Rb 1.8

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97 Figure 4-7. The temperature dependences of the lo w field, 100 G, suscepti bilities are shown for the zfc dark (), fc dark ( ), and fc light ( ) states of each rubidium containing sample produced. The insets display the di fferences between the fc light and dark states. Finite values for this differen ce can only arise from photoinduced magnetism. Adapted from New J. Phys. 2007, 9, 222.101 0.0 0.1 0.2 0.3 0.0 0.2 0.4 0 2 4 051015202530 0 10 20 30 (emu / mol)T (K) 0510152025 0 2 4 6 8 13 nm T (K) 0510152025 0.0 0.5 1.0 1.5 9.7 nm T (K) 0510152025 0.00 0.05 0.10 0.15 6.9 nm T (K) 0510152025 0.00 0.01 0.02 0.03 3.3 nm (emu / mol) (emu / mol) (emu / mol) T (K) (emu / mol)

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98 Figure 4-8. The temperature dependences of the lo w field, 100 G, suscepti bilities are shown for the zfc dark (), fc dark ( ), zfc light (o) and fc light ( ) states of a Rb1.8Co4[Fe(CN)6]3.2 .8H2O powdered solid and a Rb0.6Co4[Fe(CN)6]2.9 6.6H2O powdered solid. 0102030 0 5 10 (emu / mol)T (K)Rb0.60102030 0 2 4 (emu / mol)T (K)Rb1.8 0102030 0 5 10 (emu / mol)T (K)Rb0.60102030 0 2 4 (emu / mol)T (K)Rb1.8

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99 Figure 4-9. The T = 2 K magnetization versus ma gnetic field sweeps for the two largest sizes of nanoparticles, Samples C 9.7 nm and D 13 nm are shown on the left full sweep, and on the right hysteresis, for the light ( ) and dark ( ) states. The HC for the light and dark states for each batch are list ed in Table 4-2. Adapted from New J. Phys. 2007, 9, 222.101 -505 -40 -20 0 20 40 M (103 emu G/mol)H (Tesla)13 nm-0.04-0.020.000.020.04 -5 0 5 M (103 emu G/mol)H (Tesla) -505 -10 0 10 M (103emu G/mol)H (Tesla)9.7 nm-0.04-0.020.000.020.04 -2 -1 0 1 2 M (103emu G/mol)H (Tesla) -505 -40 -20 0 20 40 M (103 emu G/mol)H (Tesla)13 nm-0.04-0.020.000.020.04 -5 0 5 M (103 emu G/mol)H (Tesla) -505 -10 0 10 M (103emu G/mol)H (Tesla)9.7 nm-0.04-0.020.000.020.04 -2 -1 0 1 2 M (103emu G/mol)H (Tesla)

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100 Figure 4-10. The T = 2 K magnetization versus magne tic field sweeps for the two powdered solid rubidium concentrations, Rubidium 1. 8 and 0.6, are shown on the left for full sweep, and on the right for hysteresis, for the light ( ) and dark ( ) states. The HC for the light and dark states for each batch are listed in Table 4-2. -505 -10 0 10 M (103 emu G/mol)H (Tesla)Rb1.8-0.10-0.050.000.050.10 -2 -1 0 1 2 M (103 emu G/mol)H (Tesla) -505 -10 -5 0 5 10 M (103 emu G/mol)H (Tesla)Rb0.6-0.10-0.050.000.050.10 -2 0 2 M (103 emu G/mol)H (Tesla) -505 -10 0 10 M (103 emu G/mol)H (Tesla)Rb1.8-0.10-0.050.000.050.10 -2 -1 0 1 2 M (103 emu G/mol)H (Tesla) -505 -10 -5 0 5 10 M (103 emu G/mol)H (Tesla)Rb0.6-0.10-0.050.000.050.10 -2 0 2 M (103 emu G/mol)H (Tesla)

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101 Figure 4-11. The temperature dependences of th e ac-susceptibilities are shown for the four samples. All samples were measured with no applied static fiel d and an alternating field of 4 G (except for the 13 nm sample which was measured in 1 G ac). The frequency dependence wa s studied at 1 Hz (), 10 Hz ( ), 100 Hz ( ), and 1000 Hz () for all samples (except for the 13 nm sample, which has an additional data point at 333 Hz (+)). Adapted from New J. Phys. 2007, 9, 222.101-0.1 0.0 0.1 0.2 0.3 13 nm 9.7 nm 6.9 nm 3.3 nm0.0 0.5 1.0 Tf' (emu/molPBA) Tf0.0 0.2 0.4 05101520 0 5 10 15 T (K)

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102 Figure 4-12. Core shell behavi or model theorized in the 13 nm cobalt iron Prussian blue analogue particle. If the ferrimagnetic ma terial accounts for 62% of the volume of the nanoparticle, an 11 nm cube can be fo rmed. The remaining 38% of diamagnetic material surrounding the core is 1 nm thic k corresponding to one un it cell edge length of cobalt iron Prussian blue analogue. 11 nm 13 nm 1 nm 11 nm 13 nm 1 nm

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103 CHAPTER 5 ALTERNATE SYNTHESIS OF COBALT IRON PRUSSIAN BLUE ANALOGUE NANOPARTICLES Introduction In chapter four, the size-dependent ma gnetization of cobalt iron Prussian blue analogue nanoparticles was i nvestigated by adapting procedures from Uemura and Kitagawa.71,72 Yamada et al.73 had reported the synthesis of cobalt iron Prussian blue analogue nanoparticles that were 5 to 7 nm in length using a reverse micelle protocol. In chapter four it was determined that small na noparticles in the size range of 5 to 7 nm do not show magnetic ordering at 2 K. An attempt to modify the synthesi s to generate larger nanoparticles is presented here. Experimental Section Reagents and Materials All reagents were purchased from SigmaAldrich or Fisher Scientific and used without further purification. Holey carbon transmission electron microcopy (TEM) grids were purchased from Ted Pella. Deionized (DI) water (18 M ) was used for all experiments. Sample Preparation of AjCok[Fe(CN)6]l nH2O Nanoparticles Four sets of nanoparticles were synthesi zed by modifying the procedure described by Yamada et al.73 Three stock solutions were made: 1) 10. mL of 245 mg of Co(NO3)2 6H2O (84 mM) in DI water, 2) 10. mL of 269 mg K3Fe(CN)6 (82 mM) and 66 mg RbNO3 (45 mM) in DI water, and 3) 10. mL of 1.85 g of Igepal CO520 in cyclohexane. Emulsions were generated by addi ng the organic stock solution (3) to each separate aqueous solution (1,2). The amount of organic solution was varied to control particle size. Sample A was comprised of 1. 0 mL of aqueous and 2 mL of organic stock

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104 solution. Sample B was comprised of 1.0 mL of aqueous and 1.0 mL of organic stock solution. Sample C was comprised of 1.0 mL of aqueous and 0.50 mL of organic stock solution. Sample D was comprised of 1.0 mL of aqueous and 0.25 mL of organic stock solution. Once the emulsions were formed, the rubidium/ferricyanide emulsion was added to the cobalt emulsion and stirred for f our hours. Solid octadecylamine was added to the emulsions (40. mg to sample A, 20. mg to sample B, 10. mg to sample C, and 5 mg to sample D). The emulsions were stirre d overnight. The emulsions were separated using methanol and washed several times with water and methanol. The material in the organic phase was retained and isolated by centrifugation. Instrumentation FT-IR spectra were recorded using a Nicolet 6700 spectrometer. TEM, selected area electron diffraction (SAED) and Ener gy dispersive spectroscopy (EDS) were performed on a JOEL 2010F. Magnetic measurements were made by the University of Florida Department of Physics using a Quantum Design MPMS XL superconducting quantum interference device (SQUID) magneto meter. A bundle of 10 optical fibers, 270 m O.D. (Ocean Optics Model 200) was used to introduce light, from a roomtemperature, halogen-light source, of 1~2 mW power into the SQUID magnetometer for photoinduced experiments.85 Analysis preparations For TEM analysis, 5 mg of isolated solid was placed in 1 mL of cyclohexane and sonicated for 30 minutes. A sample of 10.0 L of the suspension was placed on a holey carbon TEM grid. The FT-IR spectra of the nanoparticles were obtained by transmission IR using NaCl salt plates. For magnetic measurements, the samples were mounted to commercial transparent tape and were irradiated with light from a room-temperature,

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105 halogen source from a homemade probe equipped with a bundle of optical fibers.74 Background contributions from the holder and tape were independently measured and were subtracted from the data. Results Nanoparticle Generation and Characterization The nanoparticles were generated by adding a water/cyclohexane emulsion containing potassium ferricyanide, rubidium nitrate and Igepal to water/cyclohexane emulsions with cobalt(II) nitrat e and Igepal. After four hours of stirring, octadecylamine was added and the resulting emulsion was stir red overnight. The nanoparticles were then isolated as a solid and used for experiment s. Nanoparticles were placed on TEM grids for TEM imaging, SAED and EDS. Repr esentative TEM images are shown in Figure 5-1. In addition, SAED of the na noparticles was compared to SAED of the powdered solid samples, PVP nanoparticles, and to published powder X-ray diffraction patterns to confirm the stru cture of the nanoparticles.22 (Figure 5-2) Using Image J imaging software,102 the TEM images were analyzed to obtain the particle size distribution for 50 particles of samples A-D and these data were fit to a log-normal103 distribution that yielded a char acteristic diameter of (A-D ) 8.2 ( 0.9), 10.6 ( 0.8), 13.5 ( 1.2), and 16.7 ( 1.1) nm respectivel y. (Figure 5-3) Chemical analysis was performed using EDS. The metal ratios of the nanoparticles were obtained and normalized to four cobalt ions to calculate the unit cell formula. All nanoparticles had rubidium ion concentrations between 1.5 a nd 1.8 ions per unit cell and were charged balanced with ferricyanide complexes. Th e water content was calculated in the same manner as the films by considering the amount of ferricyanide vacancies. Table 5-1 lists the nanoparticles synthesis condi tions, chemical formula, and size. Significant amounts

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106 of potassium were also detect ed by EDS. The amount of po tassium per unit cell is also listed in Table 5-1. The potassium ion is larg ely present as a contam inant, charge balance and ferricyanide vacancies indicate that most of the potassium ions are not in the network. Magnetic Behavior The temperature dependences of the dc magnetic susceptibilities, (T), of the four samples of particles are show n in Figure 5-4. The magnetic signals are expressed per gram of each sample. The dark state zero fi eld cooled (zfc) data were obtained after cooling in zero applied field fr om 300 K to 2 K, while the dark state field cooled (fc) data were taken after cooling in 100 G from 300 K to 2 K. The light state was established after field cooling the sample s from 300 K to 5 K in 100 G and subsequent irradiation with light for five hours that saturated the phot oinduced response. The light state fc data were obtained after cycling the sample to 30 K in 100 G. All particles followed Curielike behavior in the dark state. This behavi or is typical of powde red solids with higher alkali cation concentrations.25 A significant increase in TC from 10 to 14 K and 10 to 20 K with photoexcitation was observed for the 13.5 and 16.7 nm particles respectively. The 10.6 nm sample showed a small photoinduc ed increase in magnetic signal. The strength of the photoinduced change increase d in the larger partic les and was correlated with the size of the particles. The larger particle sizes displaye d a larger increase in magnetic susceptibilities when photoexcited. The fc/zfc temperature traces followed the same path for most of the samples i ndicating no long-range magnetic ordering was occurring. For the 16.7 nm particles the phot oinduced fc/zfc trac e diverges indicating that long range ordering is occurring.

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107 Time Dependent Behavior Changing magnetic and chemical behavi ors were observed in the nanoparticles over time. The temperature dependences of the dc magnetic susceptibilities, (T), of 16.7 nm particles are shown in Figure 5-5. The magnetic signals ar e expressed per gram of each sample. The dark state fc data were taken after cooling in 100 G from 300 K to 2 K. The sample was stored at ambient c onditions. The measurement was than repeated twice, once after one day a nd again after 12 days. Ther e was a decrease in magnetic susceptibility of the sample over time. The room temperature FT-IR spectrum of a 16.7 nm sample that had undergone magnetic measurements was compared to a sample of the same age that had not undergone magnetic measurements. (Figure 5-6) The two spectra were almost identical, with a peak consistent with the diamagnetic CoIII(ls)-FeII pair observed.23 The identical spectra of the two samples indicates that sample handling and magnetic measurements do not change the sample. The room temperat ure FT-IR spectrum of a 10.6 nm sample was obtained immediately after synt hesis (day 1) and compared to a spectrum of the sample that was 20 days old. (Figure 5-7) The day 1 spectrum displayed a small peak consistent with the CoII(hs)-FeIII ferrimagnetic pair at 2160 cm-1 and a major peak at 2095 cm-1 that was between the energies of the CoIII(ls)-FeII diamagnetic and CoII(hs)-FeII paramagnetic pairs.23 There were also shoulders on the major peak below 2050 cm-1 that are consistent with a terminal ferrocyanide st retch. After 20 days, the 2160 cm-1 peak diminished and the major peak broadened and shifted to 2080 cm-1, and the shoulder peaks were also more evident. The time dependent IR data indicates that the iron is being reduced is presumably at the surfac e of the nanoparticles.

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108 Discussion The emulsion based synthesis of cobalt ir on Prussian blue an alogue nanoparticles offers advantages and disadvantages when compared to the aqueous synthesis method used to produce nanoparticles in chapter four. The primary advantages of the emulsion synthesis are shorter reaction tim e, better images and a more mono-dispersed sample set. Disadvantages to the emulsion synthesis are the potassium contamination and the decrease in magnetism over time. Emulsion Synthesis Advantages For the emulsion synthesis, the nanoparti cles formed and were full size in less than a 24 hour period. When Igepal was us ed as the surface modifier, the nanoparticle coating would be less bulky there is a large difference in the formula weights (F.W.) of the two coatings, Igepal (F.W. 441 amu) and PV P (F.W. ~55 kamu). It can be reasoned that the smaller Igepal particles could achie ve a faster formation of nanoparticles for steric and mixing reasons. The Igepal was then exchanged with the octadecylamine to provide a surface on which to separate the na noparticles. This thin coating provided a small amount of amorphous material that can interfere with imagi ng of the nanoparticles resulting in images with bette r contrast and defined edges. The images of the emulsion nanoparticles indicated that cube s of material were formed. The nanoparticles also selfassembled on the TEM grid. Two contributo rs to the self-ass embly were the monodispersity of the nanoparticles and the octadecylamine coati ng. Particles with regular size and shape can more easily combine into larger arrangements as frequently seen in nanoparticles of metal oxides.105,106 The octadecylamine chains interacted with each other to form larger nanopart icle structures. Measuremen ts were conducted on the interparticle spacing, and spaces w ith averages of 2.1 nm were found when the particles were

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109 in a regular arrangement. This distance is less than the 2.5 nm length of the octadecylamine, indicating that the chains are likely interdigitated and not normal to the surface of the particle. Emulsion Synthesis Disadvantages The disadvantages of the emulsion synthesi s were the presence of potassium ions and the decay of magnetic properties of th e nanoparticles. The presence of this contamination makes an accurate determina tion of the chemical formula and surface coating impossible. The potassium ions are the ferricyanide counter-i ons in the synthesis and combine with the nitrate counter-ions from the cobalt and rubidium. In the aqueous synthesis of the PVP nanoparticles, the potassium was removed by centrifuging in a water acetone mixture. The emulsion synthesi s used methanol to separate the emulsion but potassium nitrate has a low solubility in methanol. Attempts were made to remove the potassium, and although the amount was reduced, all the potassium in the samples was not eliminated. It is cri tical to know the concentration of all the alkali ions present because they can be used for charge balance and thus affect the number of vacancies in the sample. If the potassium ions are added to the unit cell as part of the formula, the charge will not balance. Also, powdered soli d samples with high con centrations of alkali ions are known to form diamagnetic cobalt ir on pairs that are locked in the low spin state.25,35 Photomagnetism was observed in the larger nanoparticles. The number of vacancies was also consistent with photomagne tic material. The lack of charge balance with potassium, photomagnetism and ferricyanid e vacancies all indica te that potassium was incorporated into the unit cell. The loss of magnetic susceptibility over ti me indicates that the nanoparticles were unstable. Thermal cycling was thought to be a cause of a chemical change in the system.

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110 Room temperature FT-IR showed no differenc es between a sample that had undergone three magnetic measurements and a sample that had remained at room temperature. (Figure 5-6) The nanoparticles did change spin states or oxi dation states with time, as observed by room temperature IR. (Figure 5-7) Over 20 days, the ferrimagnetic pair that accounts for the primordial spin and photoswitchi ng diminished in the 10.6 nm particle. Comparison with PVP Nanoparticles The evolution of magnetic behavior with particle size was partially confirmed with the emulsion synthesis. A greater pho toeffect was observed as the nanoparticles increase in size. There was an increase in magnetic susceptibility in the 13.5 and 16.7 nm particles with photoexcitation. The 16.7 nm particles also showed the beginning of longrange ordering when photoexc ited. (Figure 5-4) The size of the nanoparticle and photeff ects do not match when the aqueous PVP and emulsion methods are compared. For th e aqueous PVP nanoparticle synthesis, the 13 nm particles displayed long ra nge magnetic ordering with a TC of 19 K in the light state. In the emulsion synthesis, the 13. 5 nm particles displayed long range magnetic ordering with a TC of 14 K in the light state. The suppressed TC of the emulsion nanoparticles indicates that the particles are smaller from a magnetic perspective. The PVP nanoparticle established a 10 nm size limit where smaller nanoparticles followed Curie-like behavior and larger particles begin to interact. In the PVP nanoparticles data was presented suggesting that the shell of the nanoparticle is trapped in a low spin state. Following the same l ogic the emulsion nanopa rticles could have a trapped shell that is thicker than the PVP nanoparticles accounting for the apparent magnetically small size of the emulsion nanopart icles. The emulsion nanoparticles were

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111 larger, yet the magnetic behavior suggested that a smaller amount of material was not participating in the particle. One probable cause for the disparate core shell behavior between the two synthesis methods is the surface coating us ed, PVP vs. octadecylamine. The emulsion nanoparticles were more exposed to the environment, coated by ~2 nm of octadecylamine. The octadecylamine coul d not provide a full surface coating. The surface of a nanoparticle can be thought of as monolayer of a metal cyanide grid that our group has worked with previously.62,64,66 Each face-centered squa re grid would provide two surface cobalt ions for the octadecylamine to coordinate. The area of the grid unit cell is ~100 2 the mean molecular area of octadecylamine is 21 2 per molecule. Even with the nanoparticles assembled to allow the oc tadecylamine to interdigitate there is still 16 2 of free space per surface un it cell. In addition to the chemical effects the octadecylamine would have at the surface by coordinating to the cobalt the outer shells would be exposed to the environment. Fo r comparison the average coating of PVP was between 20-25 nm for the aqueous nanoparticle s. The PVP encapsula ted the nanoparticle and only affected the surface, but protected th e core from the environment allowing for a larger photoactive nanoparticle core. Conclusions The emulsion-based synthesis of cobalt ir on Prussian blue an alogue nanoparticles offers advantages and disadvantages when co mpared to the aqueous synthesis used to produce nanoparticles discussed in chapter four. The shorter reaction time, better images and a more mono-dispersed sample sets are an improvement over the aqueous PVP nanoparticle synthesis. The disadvantages are the impurities that still need to be removed from the nanoparticles. The loss of magnetis m over time in the pa rticles is of much

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112 greater concern. The suspected cause for the loss of magnetism is the low amount of protection provided by the octa decylamine for the nanoparticle. The emulsion synthesis displayed evolving magnetic behavior with pa rticle size. The apparent small magnetic contribution of the emulsion nanoparticles gi ves more evidence for nanoparticle surface behavior that is different from the core of the particle.

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113 Table 5-1. Emulsion nanoparticle s synthesis and physical data Sample Water: cyclohexane Resulting chemical formula K ion Present (per formula unit) Diameter (nm) A 1 : 2 Rb1.9Co4[Fe(CN)6]3.2.8H2O 2.2 8.2 0.9 B 1 : 1 Rb1.6Co4[Fe(CN)6]3.1.4H2O 1.7 10.6 0.8 C 2 : 1 Rb1.5Co4[Fe(CN)6]3.3.2H2O 0.8 13.5 1.2 D 4 : 1 Rb1.9Co4[Fe(CN)6]3.3.2H2O 1.1 16.7 1.1

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114 Figure 5-1. The TEM images of cobalt iron Prussian blue (a) 8.2 nm, (b) 10.6 nm, (c) 13.5 nm, (d) 16.7 nm. A 50 nm (a,c,d) and 10 nm (b) scale bar is shown. Figure 5-2. The SAED pattern of an orga nized region of nanopart icles with the 200, 220 and 400 reflections identified.

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115 Figure 5-3. The particle lengt h distributions of the four samples are shown. The total number of particles for e ach distribution was 50. The solid lines are the results of log-normal fits that provide the ch aracteristic diameters shown for each distribution. 14151617181920 0 5 10 15 Counts 78910 0 5 10 8.2 + 0.9 nm 910111213 0 5 10 10.6 + 0.8 nm 111213141516 0 10 20 13.5 + 1.2 nm16.7 + 1.1 nmLength (nm) 14151617181920 0 5 10 15 Counts 78910 0 5 10 8.2 + 0.9 nm 910111213 0 5 10 10.6 + 0.8 nm 78910 0 5 10 8.2 + 0.9 nm 910111213 0 5 10 78910 0 5 10 8.2 + 0.9 nm 910111213 0 5 10 10.6 + 0.8 nm 111213141516 0 10 20 13.5 + 1.2 nm16.7 + 1.1 nmLength (nm)

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116 Figure 5-4. The temperature dependences of the low field, 100 G, susceptibilities are shown for the fc dark ( ), zfc light ( ) and fc light ( ) states of each sample produced. The zfc dark temperature trace follows the fc dark and for the two smaller samples the zfc light trace follows the fc light and has been omitted for clarity. The magnetic prope rties of the nanoparticles evolve with size toward bulk like behavior.0 1 2 3 4 8.6 + 0.9 nm 0 1 2 3 4 (10-3 emu/g)T (K) 10.6 + 0.8 nm 0 1 2 3 4 13.5 + 1.2 nm 0102030 0 2 4 6 16.7 + 1.1 nm 0 1 2 3 4 8.6 + 0.9 nm 0 1 2 3 4 (10-3 emu/g)T (K) 10.6 + 0.8 nm 0 1 2 3 4 13.5 + 1.2 nm 0102030 0 2 4 6 16.7 + 1.1 nm

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117 0102030 0 2 (10 -3 emu/gram)T (K) Figure 5-5. The temperature dependences of the low field, 100 G, susceptibilities are shown for the FC dark of a 16.7 nm particle initial (), one day ( ), 12 days ( ). There is a reduction in susceptibilities over time. Figure 5-6. The IR room temperature abso rbance spectra of a 16.7 nm nanoparticle sample the same age stored at room temperature (line) and undergone magnetic measurements (). There is no change in the room temperature spectra of the sample attributed to magnetic measurements.220021002000 Absorbance (arb. units)Wavenumber (cm-1) 220021002000 Absorbance (arb. units)Wavenumber (cm-1)

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118 Figure 5-7. The IR room temperature abso rbance spectra of a 10.6 nm nanoparticle sample obtained on day one (line) and on day 20 (). As the sample aged the ferrimagnetic peak at 2160 cm-1 diminishes and the 2095 cm-1 broadens and shifts to 2080 cm-1. In addition the increase of the terminal ferrocyanide peak below 2050 cm-1 increases with time. 220021002000 Absorbance (arb. units)Wavenumbers (cm-1) 220021002000 Absorbance (arb. units)Wavenumbers (cm-1)

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119 CHAPTER 6 CONCLUSIONS AND FUTURE WORK Conclusions In the preceding chapters, a detailed report of the different uses of Prussian blue analogues was given. First, the formation and unique anisotropic magne tic behavior of the cobalt iron Prussian blue analogue in thin films wa s discussed. The anisotropic behavior showed that the magnetic properties of the cobalt iron analogue are diffe rent from the powdered solid when the material is confined to a quasi-twodimensional network. The incorporation of a higher TC nickel chromium Prussian blue analogue into the film was accomplished. Anisotropic behavior was observed in the film that was not reported in the powdered so lid. In addition, the two different analogues in the film interacted causing different magne tic behavior than was observed in the lone cobalt iron f ilms. Two different methods of generating nanoparticles of the cobalt iron Prussian blue analogue were investigated. Both sets of nanoparticles displayed sizedependent magnetic behavior. The final chapte rs demonstrate that pho tomagnetic nanoparticles can be synthesized, but the powdered solid beha vior observed can be su ppressed by restricting the size of the nanoparticle, indicating that desi rable behavior may not translate into nanoscale objects from larger systems. Future Work No research project is ever finished and more experime nts can be done to provide a deeper understanding of any project. The thin fi lms and nanoparticle projects presented here are no different. Theories about the behavior of a system continue to be tested and revised.

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120 Thin Films Most of the understanding of th e behavior of the thin films of the Prussian blue analogues discussed here is based upon the application of a qualitative dipol ar field model. This model provides a basic mechanism for understanding the photoinduced increases or decreases in magnetism observed in the thin f ilms through the orientation of th e film and the dipolar field relative to the applied magnetic field. The obs ervation of a magnetic easy axis in the nickel chromium films raises the question of the uni queness of the axis to the nickel chromium analogue. Both analogues are cubic and were de posited using a sequential assembly method. If the easy axis resulted from the solid support eff ect or early deposition of the cubic networks, the same axis should be observed in both analogues. There were also other differences in the two analogues. The nickel chromium analogue is a ferromagnetic system for which changing oxidation states are not expected when all the material interacts. The cobalt iron analogue is a ferrimagnetic system for which changing oxidation st ates are expected. The change in oxidation states of the cobalt iron analogue gives rise to the photomagne tic behavior observed. The presence of another photoinduced directing forc e would cause a re-evalu ation of the current model. Another study necessary to completely unders tand the heterogeneous portion of the thin film project is simultaneous chemical characteriz ation of the two different layers. The current method employed for elemental characterization is th e total digestion of the film and analysis of the mixed sample. Complete digestion of the samp le gives the relative total amount of metals in the heterogeneous films but give s no location data. Informati on about the chemical purity and the mixing region between the layers would bring a greater understanding to the behavior of the heterogeneous films. Techniques that could probe th e surface or sections of the film need to be investigated. A surface measuring technique su ch as X-ray photoelectron spectroscopy (XPS)

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121 that can then remove layers of material could be used to profile the metals in the film. Also, taking cross-sections of the films and using ar ea specific energy dispersive spectroscopy (EDS) is another alternative for obtaining chemical info rmation on the films related to depth. Another advantage of depth specific characterization of th e chemical environment would give indications of surface chemical anisotropy that may be present in the films at the inte rfaces with the air or solid support that as yet have not been detected. To date another probe that may be able to detect metal ions in different chemical environments is electron paramagnetic resonance spectroscopy (EPR). A recurring challenge in the characteriza tion of the films is the low amount of sample relative to the solid support present. High field EP R would require a sample that contains at least 1019 spins in the sample cavity. A prelimin ary calculation using one of the 10.6 mm2 sample chips with a 75 nm thick film of nickel chromium containing 10 spins/ unit cell on both sides indicates that ~1.6 1016 spins would be present. The samp le thickness could be increased an order of magnitude but 100 sample ch ips would still be required to f it into the instruments cavity. Nanoparticles The immediate concern for the nanoparticle project is in the area of the surface core behavior displayed by the nanoparticles. Both synthesis procedures disp layed evidence that the surface of the nanoparticle was different from th e photoactive core. The aqueous PVP synthesis appeared to have a surface effect Understanding the na ture of the interaction of the PVP with the Prussian blue analogue is necessary to unde rstand the surface effect. In small particles, a large portion of the cobalt will be at the surface. Determining the average coordination spheres of the cobalt ions is necessary to determine the molecules interacting with the cobalt. Keeping in mind that the only diamagnetic cobalt analogue present in the particle is the octahedral cobalt(III) low spin ion, another future direction

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122 for the nanoparticle project is investigation into the emulsion synthesis. Addressing the disadvantages of the emulsion may lead to bette r nanoparticles. The use of counter-ions other than potassium, such as quaternar y ammonium ions, that are not in corporated into the lattice is one possible method to reduce the potassium c ontamination of the analogues. The other modification to the synthesis would be to vary the coating used. The PVP nanoparticles have a 20 nm coating of polymer. The coating a ppears to provide enough protection for the nanoparticles to isolate it from the environmen t but makes imaging and magnetic measurements more difficult because a only 2-5 % of the material is the Prussian blue analogue. By adding a bulkier alkyl group after the formation of the nanoparticle, a better su rface coating may be achieved. A more complete surface coating may pr otect the particles better and lead to a larger magnetically active core or show damage done to th e analogue before the al kyl group is added to the surface. Again the mechanism of formation of the nanoparticles is not we ll understood. In the literature, some studies used a large excess of organic phase leading to a reverse micelle.73 The understanding is that two reverse micelles combin e, and the particle size is limited by the amount of material contained in the re verse micelle. In the synthesis presented here there is more aqueous phase present and the mate rials are not in reverse micelles. There is too much water present to form reverse micelles and thus to li mit the particle size. A thorough investigation using other surface modifiers or solvents could be conducted. The cobalt iron Prussian analogue continues to be the subject of a great deal of research. The analogue is still being studi ed in the powdered solid form as well as in thin films and nanoparticles by us and a great many other researchers.

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123 LIST OF REFERENCES 1. Davidson, D.; Welo, L.A.; J. Phys. Chem. 1928, 32, 1191. 2. BuserH. J.; Schwarzenbach D.; Petter, W.; Ludi. A. Inorg.Chem. 1977, 16, 2704. 3. Day, P,; Herren, F,; Ludi, A,; Gudel, H. U.; Hulliger, F.; Givord, D. Helv. Chim. Acta 1980, 63, 148. 4. Rosseinsky, .D. R.; Glidle, A. J. Electrochem. Soc. 2003, 150, 9. 5. Roger, M.J.; Reynolds, J. R. J. Mat. Chem. 2005, 15, 22. 6. Nigrovic V. Phys. Med. and bio. 1965, 10, 81. 7. Stather J. W. Health Phys. 1972, 20, 1. 8. Kaye, S. S.; Long, J. R. J. Am. Chem. Soc 2005, 127, 6506. 9. Karyakin, A. A.; Karyakina, E. E.; Gorton, L. Anal. Chem. 2000, 72, 1720. 10. Dawei, P.; Jinhua, C.; Lihua, N. ; Wenyan, T.; Shouzhuo, Y. Anal. Biochem. 2004, 324, 115. 11. Ito, A.; Suenaga, M.; Ono, K. J. Chem. Phys. 1968, 48, 3597. 12. Dunbar, K. R.; Heintz, R. A. Progress in Inorganic Chemistry. Wiley: New York, 1997. 13. Verdaguer, M.; Girolami, G. Magnetism: Molecule s to Materials V ed Wiley-VCH: Weinheim 2004. 14. Gadet, V.; Mallah, T.; Castro, I.; Verdaguer, M.; Veillet, P. J. Am. Chem. Soc. 1992, 114, 9213. 15. Greibler, W. D.; Babel, D. Naturforsch. 1982, 87b. 832. 16. Entley, W.; Girolami, G. Science 1995, 268, 397. 17. Mallah, T.; Thiebaut, S.; Verdaguer, M.; Veillet, P. Science 1993, 262, 1554. 18. Hatlevik, O.; Buschmann, W.; Zh ang, J.; Manson, J.; Miller. J. Adv. Mater. 1999, 11, 914. 19. Sato, O.; Iyoda, T.; Fujishima, A.; Hashimoto, K. Science 1996, 272, 704. 20. Sato, O.; Einaga, Y.; Iyoda, T.; Fujishima, A.; Hashimoto, K. J. Phys. Chem. B 1997, 101, 3903. 21. Sato, O.; Einaga, Y.; Iyoda, T.; Fujishima, A.; Hashimoto, K. J. Electrochem. Soc. 1997, 144, L11.

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124 22. Yoshizawa, K.; Mohri, F.; Nuspl G.; Yamabe, T. J. Phys. Chem. B 1998, 102, 5432. 23. Sato, O.; Einaga, Y.; Fujishima, A.; Hashimoto, K. Inorg. Chem. 1999, 38, 4405. 24. Yokoyama, T.; Kiguchi, M.;Ohta, T.; Sato, O.; Einaga, Y.; Hashimoto, K. Phys. Rev. B 1999, 60, 9340. 25. Bleuzen, A.; Lomenech, C.; Escax, V.; V illain, F.; Varret, F.; Cartier dit Moulin, C.; Verdaguer, M. J. Am. Chem. Soc. 2000, 122, 6648. 26. Pejakovi D.; Manson, J.; Miller, J.; Epstein, A. Phys. Rev. Lett. 2000, 85, 1994. 27. Goujon, A.; Roubeau, O.; Varret, F.; Dolbecq, A.; Bleuzen, A.; Verdaguer, M. Eur. Phys. J. B 2000, 14, 115. 28. Champion, G.; Escax, V.; Cartier dit Moulin C.; Bleuzen, A.; Villain, F.; Baudelet, F.; Dartyge, E.; Verdaguer, M. J. Am. Chem. Soc. 2001 123, 12544. 29. Escax, V.; Bleuzen, A.; Cartier dit Moulin C.; Villain, F.; Goujon, A.; Varret, F.; Verdaguer, M.; J. Am. Chem. Soc. 2001, 123, 12536. 30. Goujon, A.; Varret, F.; Escax, V.; Bleuzen, A.; Verdaguer, M.; Polyhedron 2001, 20, 1339. 31. Goujon, A.; Varret, F.; Escax, V.; Bleuzen, A.; Verdaguer, M.; Polyhedron 2001, 20, 1347. 32. Kawamoto, T.; Asai, Y.; Abe, S.; Phys. Rev. Lett. 2001, 86, 348. 33. Ng, C.; Ding, J.; Gan, L. J. Solid State Chem. 2001, 156, 400. 34. Ohkoshi, S.; Hashimoto, K. Photochem. Photobiol. C: Photochemistry Reviews 2001, 2, 71. 35. Shimamoto, N.; Ohkoshi, S.; Sato, O.; Hashimoto, K. Inorg. Chem. 2002, 41, 678. 36. Liu, H.; Matsuda, K.; Gu, Z.; Takahashi, K.; Cui, A.; Nakajima, R.; Fujishima, A.; Sato, O. Phys. Rev. Lett. 2003, 90, 167403 37. Bleuzen, A.; Excax, V.; Ferrier, A.; Villain, F.; Verdaguer, M.; Munsch, P.; Itie, J.-P. Angew. Chem. Int. Ed., 2004, 43, 3728. 38. Kamiya, M.; Hananwa, M.; Moritomo, Y.; Is obe, Y.;Tateishi, J.; Kato, K.; Nakamura, A. Phys. Rev. B 2004, 69, 052102. 39. Boukheddanden, K.; Nishino, M.; Miyashita, S.; Varret, F. Phys. Rev. B 2005, 72, 014467.

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125 40. Gawali-Salunke, S.; Varret, F.; Maurin, I.; Enachescu, C.; Malarova, M.; Boukheddanden, K.; Codjovi, E.; Tokoro, H.; Ohkoshi, S.; Hashimoto, K. J. Phys. Chem. B 2005, 109, 8251. 41. Park, J.-H.; Frye, F. A.; Anderson, N. E.; Pajerowski, D. M.; Huh, Y.-D.; Talham, D. R.; Meisel, M. W. J. Mag. Magn. Mater. 2007, 310, 1458. 42. Neff, V. J. Electrochem. Soc. 1978, 125, 886. 43. Itaya, K.; Ataka, T.; Toshima, S. J. Am. Chem. Soc, 1982, 104, 4767. 44. Buschmann, W.; Paulson, S. : Wynn, C.; Gi rtu, M.; Epstien, A.; White, A.; Miller, J. Chem. Mater. 1988, 10, 1386. 45. Lundgren, C.; Murray, R. Inorg. Chem. 1988, 27, 933. 46. Ohkoshi, S.; Einaga, Y.; Fujishima, A.; Hashimoto, K. J. Electroanal. Chem. 1999, 473, 245. 47. Ivanov, V.; Kaplun, M.; Kondratev, V. ; Tikhomirova, A.; Zigel, V.; Yakovleva, S.; Malev, V. Russ. J. Electrochem., 2002, 38, 200. 48. Tacconi, N.; Rajeshwar, K. Chem. Mater. 2003, 15, 3046. 49. Toshima, N.; Liu, K.; Kaneko, M. Chem. Lett. 1990, 485. 50. Honda, K.; Hayashi, H.; Chiba, K. Chem. Lett. 1988, 191. 51. Guo, Y.; Guadalupe, A.; Resto, O.; Fonseca, L.; Weisz, S. Chem. Mater. 1999, 11, 135. 52. Ravaine, S.; Lafuente, C.; Mingotaud, C. Langmuir 1998, 14, 6347. 53. Mingotaud, C.; Lafuente, C.; Amiell, J.; Delhaes, P. Langmuir 1999, 15, 289. 54. Torres, G. Agricole, Chem. Mater. 2002, 14 4012. 55. Romualdo-Torres, G.; Agricole, B.; Mi ngotaud, C.; Ravaine, S.; Delhaes, P. Langmuir 2003, 19, 4688 56. T. Yamamoto, Y. Umemura, Sato, O.; Einaga, Y. Chem. Lett. 2004, 33, 500. 57. T. Yamamoto, Y. Umemura, Sato, O.; Einaga, Y. Chem. Mater. 2004, 16, 1195. 58. T. Yamamoto, Y. Umemura, Sato, O.; Einaga, Y. J. Am. Chem. Soc. 2005, 127, 16065. 59. T. Yamamoto, Y. Umemura, Sato, O.; Einaga, Sci. Tec. Adv. Mat. 2006, 7, 134. 60. Millward, R.; Madden, C.; Sutherl, I. ; Mortimer, R.; Fletcher, S.; Marken, F. Chem. Commun. 2001, 1994.

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126 61. Pyrasch, M.; Tieke, B.; Langmuir 117 2001, 117, 7706. 62. Culp, J.; Park, J.-H.; I. Benitez, Huh, Y.-D.; Meisel, M.; Talham, D. Chem. Matter. 2003, 15, 3431. 63. Jin, W.; Toutianoush, A.; Pyrasch, M.; Schnepf, J.; Gottschalk, H.; Rammensee, W.; Tieke, B. J. Phys. Chem. B 2003, 107, 12062. 64. Park, J.-H.; Huh, Y.-D.; imr, E.; Gamble, S.; Talham, D.; Meisel, M.; J. Magn. Magn. Mater. 2004, 272-276, 1116. 65. Park, J.-H.; imr, E.; Meisel, M.; Huh, Y.-D.; F. Frye, S. Lane, Talham, D. Appl. Phys. Lett. 2004, 85, 3797. 66. Culp, J.; Park, J-H,; Frye, F.; Huh, Y-D. Meisel, M.; Talham, D. Coordination Chem. Rev. 2005, 249, 2642. 67. Park, J.-H.; Frye, F.; Lane, S.; imr, E.; Huh, Y.-D.; Talham, D.; Meisel, M. Polyhedron 2005, 24, 2355. 68. Vaucher, S,; Li, M.; Mann, S. Angew. Chem. Int. Ed. Engl. 2000, 39, 1793. 69. Ng, C. W.; Ding, J.; Chow, P. Y.; Gan, L. M.; Quek, C. H. J. Appl. Phys. 2000, 87, 6049. 70. Vaucher, S.; Fielden, J.; Li, M.; Dujardin, E.; Mann, S., Nano. Lett. 2002, 2, 225. 71. Uemura, T.; Kitagawa, S. J. Am.Chem. Soc. 2003, 125, 7814. 72. Uemura, T.; Ohba, M.; Kitagawa, S. Inorg. Chem. 2004, 43, 7339 73. Yamada, M.; Arai, M.; Kurihara, M.; Sakamoto, M.; Miyake, M., J. Am. Chem. Soc. 2004, 126, 9482. 74. Johansson, A.; Widenkvist, E.; Lu, J.; Boman, M.; Jansson, U. Nano Lett. 2005, 5, 1603. 75. Xian, Y.; Zhou, Y.; Xian, Y.; Zhou, L.; Wang, H.; Jin, L. Anal. Chim. Acta 2005, 546, 139. 76. Taguchi, M.; Yamada, K.; Suzuki, K.; Sato, O.; Einaga, Y.; Chem. Mater. 2005, 17, 4554. 77. Taguchi, M.; Yagi, I.; Nakagawa, M.; Iyoda, T.; Einaga, Y.; J. Am. Chem. Soc. 2006, 128, 10978 78. Catala, L.; Gloter, A.; Stephan, O.; Rogez, G.; Mallah, T. Chem. Commun. 2006, 1018. 79. Moore, J. G.; Lochner, E. J.; Ramsey, C.; Dalal, N. S.; Stiegman, A. E. Angew. Chem. 2003, 115, 2847.

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127 80. Catala, L.; Mathonire. C.; Gloter, A.; Stepha n, O.; Gacoin, T.; Boilot, J.-P.; Mallah, T. Chem. Commun. 2005, 746. 81. Culp, J. T.; Park, J.-H.; Meisel, M. W.; Talham, D. R. Inorg. Chem. 2003, 42, 2842. 82. Culp, J. T.; Park, J.-H.; Benitez, I. O.; Meisel, M. W.; Talham, D. R. Polyhedron 2003, 22, 2125. 83. Culp, J. T.; Park, J.-H.; Meisel, M. W.; Talham, D. R. Polyhedron 2003, 22, 3059. 84. Frye, F. A.; Pajerowski, D. M.; Lane, S. M. ; Anderson, N. E.; Park, J.-H.; Meisel, M. W.; Talham, D. R. Polyhedron 2007, 26, 2281. 85. Park, J.-H. Ph.D., University of Florida, 2006. 86. Mydosh, J. A. Spin Glasses: An Experimental Introduction. Taylor and Francis: London, 1993. 87. Pejakovic, D. A.; Manson, J. L.; Miller, J. S.; Epstein, A. J. Synth. Met. 2001, 122, 529. 88. Coronado, E.; Delhas P.; Gatteschi, D.; Miller, J. S. Molecular Mangnetism: From Molecular Assemblies to the Devices. Klumer Academic Publishers: Boston, 1996. 89. Verdaguer, M.; Bleuzen, A.; Marvaud, V.; Va issermann, J.; Seuleiman, M.; Desplanches, C.; Scuiller, A.; Train, C.; Garde, R.; Gelly G.; Lomenech, C.; Rosenman, I.; Veillet, P.; Cartier, C.; Villain, F. Coord. Chem. Rev. 1999, 192, 1023. 90. Gay, J. G.; Richter, R. Phys. Rev. Lett. 1986, 56, 2728. 91. Jonker, B.T.; Walker, K.-H.; Kisker, E.; Prinz, G. A.; Carbone C. Phys. Rev. Lett. 1986, 56, 142. 92. Gay, J. G.; Richter, R. J. Appl. Phys. 1987, 61, 3362. 93. Heinrich, B.; Urquhart, K. B.; Arrott, A. S.; Cochran, J. F.; Myrtle, K.; Purcell, S. T. Phys. Rev. Lett. 1987, 59, 1756. 94. Koon, N. C.; Jonker, B. T.; Volkening F. A.; Krebs, J. J.; Prinz, G. A. Phys. Rev. Lett. 1987, 59, 2463. 95. Chappert, C.; Bruno, P. J. Appl. Phys. 1988, 64, 5736. 96. Stamps, R. L.; Camley, R. E. ; Hillerbrands, B.; Gntherodt, G. Phys. Rev. B 1993, 47, 5072. 97. Chuang, D. S.; Ballentine, C. A.; OHandley R. C. Phys. Rev. B 1994, 49, 15084. 98. Rosenbusch, P.; Lee, J.; Lauhoff, G.; Bland J. A. C. J. Magn. Magn. Mater. 1997, 172, 19.

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128 99. Frey, N. A.; Srinath, S.; Srikanth, H.; Varele, M.; Pennycook, S. Phys. Rev. B 2006, 74, 024420. 100. Frye, F. A.; Pajerowski, D. M.; Anderson, N. E.; Long, J.; Park, J.-H.; Meisel, M. W.; Talham, D. R.; Polyhedron 2007, 26, 2273. 101. Pajerowski, D. M.; Frye, F. A.; Talham, D. R.; Meisel, M. W. New J. Phys. 2007, 9, 222. 102. Rasband, W.S. and Image J, US Nationa l Institutes of Health, Bethesda, MD, USA (accessed 1 October 2006) online at http://rsb.info.nih.gov/ij/ 103. Evans, M.; Hastings, N.; Peacock, B. Statistical Distributions. Wiley: New York, 2000. 104. Carlin, R. Magnetochemistry. Springer-Verlag: New York, 1986. 105. Chen,M.; Liu, J. P.; Sun, S. J. Am. Chem. Soc., 2004, 126, 8394 106. Shevchenko, E. V.; Talapin, D. V.; Murray, C. B.; O'Brien, S. J. Am. Chem. Soc. 2006, 128, 3620.

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129 BIOGRAPHICAL SKETCH Franz Frye was born in Austria while his father was in a t eaching exchange program. He then moved to and grew up in Franklin, New Yo rk while attending Franklin Central School for K-12 before graduating. My undergraduate educa tion was conducted at Hartwick College with a research project on soil chemistry overseen by Fr ank Dunnivant and Meredith Newman. After graduating from Hartwick he en tered industry and worked for se veral companies over a span of four years in the areas of environmental regula tion, hazardous waste dispos al, water testing, and solution manufacture. He then entered grad uate school in 2002 and has been conducting research on the cobalt iron Prussian blue analogue in the Talham research group at the University of Florida.