Comparative Study of Thermal Conductivity of SiC and BeO from Ab Initio Calculations

Silicon Carbide (SiC) and Beryllium Oxide (BeO) are materials proposed to use in accident tolerant fuel. Therefore, we did a systematic study of the thermal conductivity of SiC and BeO and its dependence on temperatures and structure by solving the Boltzmann transport equation using the shengBTE a solver for phonon thermal conductivity (k_L) with ab initio techniques. We also predict the structural, elastic, and thermodynamic properties of alpha-SiC, wurtzite (w)-SiC and w-BeO by first principles calculation using Quantum ESPRESSO within quasi-harmonic approximation. k_L is also predicted using the Slack model. The thermo-mechanical properties of these materials show significant improvement over Urania with one order of magnitude higher thermal conductivity. Wurtzite structure shows the directional dependence of k_L. Hence, we provide the directional thermal conductivity of w-BeO, w-SiC and compare with the thermal conductivity of cubic SiC. The simulated results are compared with the available experimental data and showed excellent agreement.