Lattice dynamics and thermal conductivity of FeO2 under high pressure and high temperature

Abstract

FeO2 is proposed to be a kind of substance in the Earth's lower mantle in recent years. In this paper, the equation of state, elastic properties and sound velocities are obtained based on the first principle calculations. By solving the Boltzmann transport equations, we investigated the lattice thermal conductivity of FeO2 under high pressure and high temperature. The calculated compressional and shear sound velocities of FeO2 agree with the data of preliminary reference Earth model. The lattice thermal conductivity of FeO2 at core-mantleboundary (∼135 GPa, ∼3500 K) is 1.77 W/mK, and the total thermal conductivity is 135.10 W/mK. The influence of lattice thermal conductivity can be ignored above 3000 K.