Thermoelectric properties of the Mg$_{2}$Ge$_{0.3}$Sn$_{0.7}$ solid solution with $p$-type conductivity

The thermoelectric properties of the Mg$_{2}$Ge$_{0.3}$Sn$_{0.7}$ solid solution doped with Ga and Li are studied. The samples with a hole concentration as high as 5 $\times$ 10$^{20}$ cm$^{-3}$ are obtained. The temperature dependences of the thermopower, electrical conductivity, and thermal conductivity are measured in the range from room temperature to 800 K. A higher mobility of free charge carriers is observed in the samples doped with lithium than in the samples doped with gallium. The largest thermoelectric figure of merit in the samples under study amounts to 0.42 at 700 K.