Lower temperature of the structural transition, and thermoelectric properties in Sn-substituted GeTe

Abstract GeTe is a potential thermoelectric material for mid-temperature range applications. Here, we report on GeTe and Ge0.9Sn0.1Te prepared using a fast and simple arc-melting method. Their crystal structures have been analyzed by synchrotron X-ray diffraction. Calorimetry identified a shift in the rhombohedral to cubic structural transition temperature from 700 K to 557 K due to Sn alloying. Nevertheless, the temperature of the maximum Seebeck-coefficient is preserved, at 770 K. The thermoelectric properties are also reported, with a strong decrease of electric and thermal conductivities of the Sn-doped compound, as compared to the undoped one. The Hall-mobility also decreases strongly upon doping.