Unexpected thermal transport properties of MgSiO 3 monolayer at extreme conditions.

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 MgSiO 3 monolayer by CALYPSO method and first-principles calculations. A stable MgSiO 3 monolayer with Pmm 2 symmetry is uncovered, which possesses a wide indirect band gap of 4.39 eV. The calculations indicate the lattice thermal conductivities of MgSiO 3 monolayer are 49.86 W (mK) -1 and 9.09 W (mK) -1 in x and y directions at room temperature. Our findings suggest that MgSiO 3 monolayer is an excellent low-dimensional thermoelectric material with high ZT value of 4.58 from n-type doping in the y direction at 2000 K. The unexpected anisotropic thermal transport of MgSiO 3 monolayer 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 MgSiO 3 monolayer at extreme conditions.