First-principles study of UO\(_2\) lattice thermal-conductivity: A simple description

Modeling the high-\(T\) paramagnetic state of bulk UO\(_2\) by a non-spin-polarized calculation and neglecting the Hubbard-U correction for the \(f\) electrons in U atoms, the lattice thermal conductivity of bulk UO\(_2\) is investigated by the exact solution of the Boltzmann transport equation for...

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Bibliographic Details
Published in:arXiv.org 2020-04
Main Authors: Sheykhi, Samira, Payami, Mahmoud
Format: Article
Language:English
Subjects:
Boltzmann transport equation
Distribution functions
First principles
Heat conductivity
Heat transfer
Phonons
Thermal conductivity
Online Access:Get full text
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Summary:Modeling the high-\(T\) paramagnetic state of bulk UO\(_2\) by a non-spin-polarized calculation and neglecting the Hubbard-U correction for the \(f\) electrons in U atoms, the lattice thermal conductivity of bulk UO\(_2\) is investigated by the exact solution of the Boltzmann transport equation for the steady-state phonon distribution function. The results show that TA branches corresponding to U-atoms vibrations have the largest lifetimes and therefore have dominant role in thermal conductivity, while the optical branches corresponding mainly to O-atoms vibrations have the shortest lifetimes. Using this simple model, our results for the thermal conductivity show a very good agreement with the experiments. The calculations are repeated for bulk UO\(_2\) with different U-235 concentrations of 3\%, 5\%, 7\%, and 20\%, and the results show a small decrease of thermal conductivity which arise from scattering of phonons by impurities.
ISSN:2331-8422
DOI:10.48550/arxiv.1907.04174