Pressure enhanced thermoelectric properties in Mg2Sn

Abstract

The pressure dependence of the electronic structure and thermoelectric properties of Mg₂Sn are investigated by using a modified Becke and Johnson exchange potential, including spin–orbit coupling. The corresponding value of spin–orbit splitting at the Γ point is 0.47 eV, which is in good agreement with the experimental value of 0.48 eV. With increasing pressure, the energy band gap first increases, and then decreases. In certain doping range, the power factor for n-type has the same trend with energy band gap, when the pressure increases. Calculated results show that the pressure can lead to a significantly enhanced power factor in n-type doping at the critical pressure, which can be understood by the pressure inducing accidental degeneracy of the conduction band minimum (CBM) at the critical pressure. It is also found that the corresponding lattice thermal conductivity near the critical pressure shows a relatively small value. These results make us believe that thermoelectric properties of Mg₂Sn can be improved in n-type doping by pressure.