Recent progress in the study on phonon heat transport property of Earth’s lower mantle minerals

Abstract

The lattice thermal conductivities ( κ lat ) of Earth’s lower mantle (LM) minerals is a crucial parameter in the study of deep Earth dynamics and its determination is also one of the grand challenges in condensed matter physics. Here, we review recent progress on theoretical and experimental studies for the κ lat under high pressure (P) and high temperature (T) condition up to 150 GPa and 4000 K. After the critical parameters necessary to obtain converged values of the κ lat are summarized, the theoretical κ lat of the LM minerals, determined through various computational methodologies, is compiled along with experimental findings. Although significant scattering is found in the experimental results at LM P,T, the quantum anharmonic lattice dynamics theory combined with the phonon Boltzmann transport theory demonstrates a clear relationship in the κ lat of the end-member LM phases, MgO, MgSiO3 bridgmanite (Brg) and post-perovskite (PPv), κ lat MgO >> κ lat PPv > κ lat Brg , and a discontinuous change in the κ lat by ∼20%-50% expected across the Brg-PPv transition. Knowledge on the additional but geophysically important factors, such as the effects of iron solid solution, isotopic mass difference, and higher order crystal anharmonicity are also summarized in detail. Current problems and future perspectives are finally mentioned.