Electronic structure, elastic and thermal transport properties of thorium monocarbide based on first-principles study

Abstract

We investigate the electronic structure, mechanical properties and thermal transport properties of ThC based on density functional theory. We find that thorium monocarbide shows metallic and mechanically stable at ground state, and the 5f-orbital and 6d-orbital electrons of Th atoms do not exhibit strong correlation properties. The Debye temperature obtained from the elastic constant is also in good agreement with the results of others. The thermal transport properties of ThC were discussed with the Boltzmann transport equation. It is found that the thermal conductivity of the lattice comes from the contribution of the acoustic support, and the optical branch has a lower thermal conductivity because of the suppression of the anharmonicity. The Seebeck coefficient and the power factor of ThC have a maximum at the valence band and increase with the increasing temperature, while the conductivity is less affected by the temperature. The electronic thermal conductivity increases with the increasing temperature, and at high temperatures, Widman-Franz law is ineffective. At low temperatures, the total thermal conductivity mainly comes from the lattice thermal conductivity; electrons occupy a major role at high temperatures. The thermoelectric figure of ThC is close to 0 at room temperature and cannot be used as a good thermoelectric material.