Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Kim, Seong-Gon

Committee Member

Monts, David L.

Committee Member

Horstemeyer, Mark F.

Committee Member

Novotny, Mark

Committee Member

Clay, R. Torsten

Date of Degree

5-1-2010

Document Type

Dissertation - Open Access

Major

Applied Physics

Degree Name

Doctor of Philosophy

College

James Worth Bagley College of Engineering

Department

Department of Physics and Astronomy

Department

Applied Physics Program

Abstract

We performed atomistic modeling to study magnetic, mechanical, and thermal properties of materials. We executed molecular statics and dynamics simulations for this study, using density functional theory (DFT) and semi-empirical methods, such as embedded atom method (EAM) and modified embedded atom method (MEAM) potentials. In our first study, we showed that when Al atoms are substituted in barium hexaferrite, the total magnetization monotonically decreases due to the fact that Al atoms preferentially occupy the majorly contributing magnetic sites. The second study was to explore the diffusion mechanism of Ba atoms in hematite in order to study new techniques to build spherical nano-magnetic-particles. In the third study, we showed tungsten carbide growth is inhibited in the presence of vanadium carbide. In the fourth study, we showed how the mechanical and thermal properties of iron changes with vanadium doping with a newly developed MEAM interatomic potential. The physical properties of calcium were calculated in the next study, by the development of a MEAM potential which can be used for multiscale modeling. In the sixth study, the melting temperature of nanoparticles was analyzed and shown to decrease with a decrease of its size, confirming that the bulk properties of the material significantly change in its nano counterpart. Finally a portion of this research was dedicated for the simulation of sintering mechanisms of tungsten nanoparticles at different temperatures and pressures. While the first three studies were based on DFT, the last four studies focused on understanding physical phenomena using EAM/MEAMpotentials.

URI

https://hdl.handle.net/11668/14915

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