Temperature Dependence of Thermoelectric Properties of Mg₂Si_0.6Ge_0.4

Abstract

The thermoelectric properties of Sb-doped n-type and Ag-doped p-type Mg₂Si_0.6Ge_0.4 samples were investigated in the temperature range 300 to 900 K. The scattering factor r was determined to be 0.0 by measuring the temperature dependence of the Hall mobility. Thermoelectric power and electrical conductivity were measured and discussed on the basis of the degenerated carriers. The thermal conductivity was evaluated from the values measured at 300 K. The maximum figure-of-merits Z’s were estimated to be 1.61×10⁻³ K⁻¹ at 663 K for the n-type and 2.67×10⁻³ K⁻¹ at 629 K for the p-type, respectively. From the fact that the dimensionless figure-of-merits ZT’s exceeded unity, the Mg₂Si_1−xGe_x solid solution semiconductors can be expected as a new promising material for high-efficiency thermoelectric energy conversion in the middle-temperature range of 500 to 800 K.