Revealing the intrinsic p-to-n transition mechanism on Mg3Sb2 through extra Mg

The intrinsic p-to-n transition mechanism for Mg3Sb2-based thermoelectrics is revealed through pristine Mg3Sb2 by tunning extra Mg. By using TEM characterization combined with transport measurements, the Mg3Sb2 matrix is proposed to have three stages of evolution with the increase in extra Mg content: Mg vacancy-rich (Sb-rich phase) period, Mg vacancy-compensated (nearly no precipitates) period, and Mg vacancy-deficient (Mg-rich phase) period, revealing that the Mg vacancy concentration is a key factor in the intrinsic p-to-n transition. Our work will deepen the understanding of p-to-n transition in Mg3Sb2-based thermoelectrics and provide valuable references for developing other p/n-coexisted thermoelectrics.