Doctoral Dissertations

Keywords and Phrases

DFT; Electron-phonon coupling; Heavy Ion; Silicon carbide; Thermal spike model; Vacancy

Abstract

“The electron-phonon interaction is an important interaction in many solids as it influences transport phenomena and related quantities such as the electrical and thermal conductivities, especially in nuclear and space applications. The importance of the electron-phonon interaction in primary damage production in 3C-SiC is the subject of this research.

The electron-phonon coupling factor was calculated using a hybrid Density Functional Perturbation Theory - Classical Electron Gas model. The coupling factor was calculated as a function of electron temperature in pristine and defective 3C-SiC, and relaxed defective cells. The electron-phonon coupling is found to depend strongly on the electronic temperature and on the presence of vacancies. Electron-phonon mean free paths were calculated to explore the possibility of extending those calculations to lower vacancy concentrations using a rule-of-mixtures approach.

The electron-temperature-dependent couplings were implemented in the Two-Temperature Model (TTM), which was used to model the evolution of electron and phonon temperatures following impact from a Swift Heavy Ion. Those results were compared to similar calculations using constant coupling values. The use of a constant coupling is justifiable at lower electronic stopping powers far from the track core (beyond several nm). At the center of the track, however, the coupling is strong (on the order of 1016 W cm-3 K) and decreases rapidly with radius. These results reveal some weaknesses of the TTM model and indicate that near the track core, the assumption of quasi-thermal equilibrium is not necessarily valid at high electronic excitation densities”--Abstract, page iv.

Advisor(s)

Graham, Joseph T.

Committee Member(s)

Al-Dahhan, Muthanna H.
Alajo, Ayodeji Babatunde
Castano Giraldo, Carlos Henry
Chernatynskiy, Aleksandr V.

Department(s)

Nuclear Engineering and Radiation Science

Degree Name

Ph. D. in Nuclear Engineering

Comments

This work was supported in part by U.S. Nuclear Regulatory Commission Faculty Development Grant NRC-HQ-84-15-G-0044.

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2022

Journal article titles appearing in thesis/dissertation

  • Vacancy-induced enhanced of electron-phonon coupling in cubic silicon carbide and its relationship to two temperature model
  • The temperature-variable electron-phonon coupling and its role in the inelastic thermal spike in 3C-SiC

Pagination

x, 96 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2022 Salah Abdul-Rahman Al-Smairat, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12104

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