Thermoelectric properties of the Bi-doped Mg2Si system

Thermoelectric elements of Bi-added Mg2Si compounds were fabricated in a vacuum melting method followed by a Spark Plasma Sintering (SPS) process. The electrical conductivity, the Seebeck coefficient, and thermal conductivity between 300 and 900 K were measured to evaluate the thermoelectric properties of Mg2Si. All of the stoichiometric and Bi-added Mg2Si samples exhibited n-type behavior throughout the temperature range. Their thermoelectric properties were improved with up to 2 at% addition Bi. The maximum value of the dimensionless figure of merit, ZT, was 0.74 with a specimen with 2 at% of Bi added at 840 K.

► Ag-doping effects on Mg2Si thermoelectrics.
► Both the Bi-donor effect and the grain boundary phase enhance the power factor.
► The maximum ZT 0.74 at 840 K for the 2at%-added case.