Composition dependent thermoelectric properties of sintered Mg2Si1−xGex (x = 0 to 1) initiated from a melt-grown polycrystalline source

Fabrication of Mg2Si1−xGex (x = 0–1.0) was carried out using a spark plasma sintering technique initiated from melt-grown polycrystalline Mg2Si1−xGex powder. The thermoelectric properties were evaluated from RT to 873 K. The power factor of Mg2Si1−xGex with higher Ge content (x = 0.6–1.0) tends to decrease at higher temperatures, and the maximum value of about 2.2 × 10− 5 Wcm− 1K− 2 was observed at 420 K for Mg2Si and Mg2Si0.6Ge0.4. The coexistence of Si and Ge gave rise to a decrease in the thermal conductivity in the Mg2Si1−xGex. The values close to 0.02 Wcm− 1K− 1 were obtained for Mg2Si1−xGex (x = 0.4–0.6) over the temperature range from 573 to 773 K, with the minimum value being about 0.018 Wcm− 1K− 1 at 773 K for Mg2Si0.4Ge0.6. The maximum dimensionless figure of merit was estimated to be 0.67 at 750 K for samples of Mg2Si0.6Ge0.4.