Experimental investigation of the predicted band structure modification of Mg2X (X: Si, Sn) thermoelectric materials due to scandium addition

Abstract

Modification of the electronic band structure via doping is an effective way to improve the thermoelectric properties of a material. Theoretical calculations from a previous study have predicted that Sc substitution on the Mg site in Mg2X materials drastically increase their Seebeck coefficient. Herein, we experimentally studied the influence of scandium substitution on the thermoelectric properties of Mg2Si0.4Sn0.6 and Mg2Sn. We found that the thermoelectric properties of these materials are unaffected by Sc addition, and we did not find hints for a modification of the electronic band structure. The SEM-energy dispersive X-ray analysis revealed that the scandium does not substitute Mg but forms a secondary phase (Sc-Si) in Mg2Si0.4Sn0.6 and remains inert in Mg2Sn, respectively. Thus, this study proves that scandium is an ineffective dopant for Mg2X materials.