Unexpected thermal transport properties of MgSiO3monolayer at extreme conditions

Abstract

The thermal transport properties of mantle minerals are of paramount importance to understand the thermal evolution processes of the Earth. Here, we perform extensively structural searches of two-dimensional (2D) MgSiO₃monolayer by CALYPSO method and first-principles calculations. A stable MgSiO₃monolayer withPmm2 symmetry is uncovered, which possesses a wide indirect band gap of 4.39 eV. The calculations indicate the lattice thermal conductivities of MgSiO₃monolayer are 49.86 W/mK and 9.09 W/mK inxandydirections at room temperature. Our findings suggest that MgSiO₃monolayer is an excellent low-dimensional thermoelectric material with highZTvalue of 4.58 from n-type doping in theydirection at 2000 K. The unexpected anisotropic thermal transport of MgSiO₃monolayer is due to the puckered crystal structure and the asymmetric phonon dispersion as well as the distinct electron states around the Fermi level. These results offer a detailed description of structural and thermal transport properties of MgSiO₃monolayer at extreme conditions.

Keywords: CALYPSO method; First-principles calculations; Thermal transport properties; Two-dimensional MgSiO₃.