Thermoelectric performance enhancement of Mg2Si-based silicides synthesized in nitrogen atmosphere

Abstract

In this work, we compare the thermoelectric performance of Mg₂Si-based compounds by synthesizing them in N₂ compared to Ar atmosphere during ball milling. In addition, we achieved high thermoelectric performance by introducing Sn-alloying as well as Zn- and Bi-co doping. The high performance originated from simultaneous improvement in electrical conductivity and reduced thermal conductivity. This results in peak zT near 1.0 at 760 K for Mg_1.9925Zn_0.0075Si_0.48Sn_0.5Bi_0.02. Owing to the much lower cost (higher abundance) of N₂ compared to Ar owing to their much higher relative abundance, such processing strategy is expected to improve sustainability. Furthermore, the insights derived from this work can potentially be applied to other compounds containing Mg- and other reactive elements. Fundamentally, this result will also motivate further studies on the intrinsic defect formation in N₂ vs Ar atmosphere, which affects both electronic and thermal transports.