Optimizing the thermoelectric performance of p-type Mg3Sb2 by Sn doping

The effects of Sn doping on thermoelectric performance of Mg3Sb2-based materials were investigated. First principle calculation results show an increased density of state near the Fermi level and flattened band structure after Sn doping, predicting that the introduction of Sn will enhance the electric transport properties as an effective acceptor dopant. The maximum ZT of Mg3Sb2-xSnx (0 <= x <= 0.04) samples is 0.42 at 773 K with x = 0.02. Experiments demonstrate that Sn doping can promote the thermoelectric performance of p-type Mg3Sb2 alloys, however the doping effect is limited by the appearance of n-type Mg2Sn during the preparation processes. Consequently, for further enhancing the thermoelectric performance of p-type Mg3Sb2-based materials, co-doping or composite method can be introduced while select a reasonable Sn doping amount.