Thermal conductivities of ThO2, NpO2 and their related oxides: Molecular dynamics study

The thermal conductivities of ThO2, NpO2, (Th, U)O-2, (Th, Pu)O-2 and (U, Np)O-2 have been investigated by molecular dynamics (MD) simulation up to 2000 K using the Busing-Ida potential function with partial ionic charges. In the present study, the thermal conductivity was calculated mainly by the Green-Kubo formula in the equilibrium MD scheme. The thermal conductivities of above actinide dioxides decreased with the increase of temperature due to the phonon-phonon interaction (Umklapp process). Concerning the composition of solid solutions, the decrease in thermal conductivity of (Th, Pu)O-2 is great as compared to other ones. Various MD calculations elucidated that this result was caused by phonon scattering by lattice defects as additives rather than the phonon-phonon interaction, and that the lattice strain dominantly contributed to it. (C) 2013 Elsevier B.V. All rights reserved.