Efficient Sc-Doped Mg3.05–xScxSbBi 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.