Numerical Study of The Mechanical Loss in Amorphous Oxides

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Material Information

Title:
Numerical Study of The Mechanical Loss in Amorphous Oxides
Physical Description:
1 online resource (86 p.)
Language:
english
Creator:
Hamdan, Rashid M
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
Publication Date:

Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Physics
Committee Chair:
CHENG,HAI PING
Committee Co-Chair:
SABIN,JOHN R
Committee Members:
MERZ,KENNETH MALCOLM,JR
OBUKHOV,SERGEI
GOWER,LAURIE B

Subjects

Subjects / Keywords:
amorphous -- dlpoly -- glasses -- ligo -- md -- moleculardynamics -- numerical -- oxides
Physics -- Dissertations, Academic -- UF
Genre:
Physics thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract:
Many high-precision optical measurement devices, including gravitational wave detectors, use layers of optical coatings to form highly reflective mirrors. These coating layers are usually dielectric amorphous oxides. However, the thermal noise associated with the mechanical dissipation in these coating materials is a major contributor to the total noise in the devices. This thermal noise is projected to be the limiting factor for the precision of the new generation of the Laser interferometer Gravitational Wave Observatory (LIGO). In this project, we investigate the sources of mechanical loss at the atomic level using numerical models for pure and doped amorphous oxides that are used for coating. We have implemented different numerical techniques including the trajectory bisection method and the non-local ridge method in the molecular dynamics simulation software DL-POLY. These techniques allow us to search the potential energy landscape for possible transitions between local consecutive energy minimums and to calculate the barrier height and other properties associated with each transition, including the energy asymmetry and the relaxation rate from saddle point to minimum. From distributions of these properties, we calculate the internal friction of pure and mixed amorphous oxides. We compare with experiment when possible and use the results of the numerical calculations to comment on the validity of the theoretical assumptions. In the future, we will use this method to propose new materials that should be better candidates to reduce thermal noise. In the last chapter, we present a first-principles study of the structure and functionality of stage two bromine doped of graphite, where an enhanced in-plane conductivity is reported experimentally. We study two forms of the bromine doping: molecular (Br$_2$) and atomic (Br). We compare their stability function of the interlayer separation. And in addition to the the charge transfer between the graphite layer and the bromine atoms, we calculate the density of state and the band structure for each form of doping to find their effect on the conductivity. Finally we investigate the effect of doping disorder on the out-of-plane band structure.
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 Rashid M Hamdan.
Thesis:
Thesis (Ph.D.)--University of Florida, 2014.
Local:
Adviser: CHENG,HAI PING.
Local:
Co-adviser: SABIN,JOHN R.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2016-05-31

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Classification:
lcc - LD1780 2014
System ID:
UFE0046555:00001