First principles study of the lattice thermal conductivity of alkaline earth oxides

Abstract

Lattice thermal conductivity (κlatt) is an important physical parameter for understanding the thermal transport and dynamics evolution. Here, we calculate κlatt of alkaline earth metal oxides (MOs, M = Be, Mg, Ca, Sr, Ba) by first principles calculations combined with lattice dynamics theory. Our results indicate that the magnitudes of κlatt of MOs at ambient conditions are closely related to the atomic masses of metal atoms, that is, the lighter atomic masses of metals in MOs possess the larger κlatt, which is consistent with the order of alkaline earth metals in Periodic Table. Under high pressure, κlatt of MOs show linearly increase as a function of pressure; meanwhile, the pressure dependence of κlatt is relatively larger for MOs with lighter atomic masses. The calculations show that the structural phase transitions of MOs lead to obvious reductions in κlatt due to the giant variations in scattering rates. By contrast, the effect of phase transition on elastic property and wave velocities are weak, which implies the variation of group velocities are faintly effect on κlatt.