Efficient Sc-Doped Mg_3.05–xSc_xSbBi Thermoelectrics Near Room Temperature

For decades, significant thermoelectric enhancements at high temperatures have been witnessed in many materials. However, efficient materials working well near room temperature are still restricted to Bi₂Te₃-based alloys in both conduction types, in which the scarcity of tellurium is a concern for large-scale applications. Recently, Mg₃Sb₂–Mg₃Bi₂ alloys, particularly in n-type conduction, have been revealed to show great potential for efficient thermoelectric applications. The corresponding challenges rely on the realization of sufficient charge carriers with a high mobility, which respectively depends on effective doping and the removal of scattering sources. In this work, both a high carrier concentration and an inherently high mobility are enabled in Sc-doped Mg₃Sb₂–Mg₃Bi₂ alloys with coarse grains, synthesized by a melting and hot-deforming technique. This eventually leads to an average figure of merit zT of 1.1 within 300–500 K in optimal compositions, which is superior to that of state-of-the-art n-type Bi₂Te₃ alloys. This work strongly demonstrates the potential of these alloys as eco-friendly and sustainable alternatives to conventional n-type Bi₂Te₃-based alloys for thermoelectric applications near room temperature.