Double-Doping Approach to Enhancing the Thermoelectric Figure-of-Merit of n-Type Mg2Si Synthesized by Use of Spark Plasma Sintering

We report significant enhancement of the thermoelectric figure-of-merit of Mg 2 Si by double-doping with a combination of Bi, Pb, and Sb as doping elements. Addition of any two of these three elements to Mg 2 Si increases the electrical conductivity by more than three orders of magnitude at 323 K, irrespective of the doping elements used. However, a corresponding decrease in the Seebeck coefficient is observed in comparison with undoped Mg 2 Si. Irrespective of the combination of the three elements used for double doping, a figure-of-merit of approximately 0.7 at 873 K is obtained for Mg 2 Si; this is primarily because of enhancement of the electrical conductivity.