The Effect of Adding Nano-Bi2Te3 on Properties of GeTe-Based Thermoelectric Material

The efficient thermoelectric materials (GeTe)(0.85-x) (Mn0.6Sn0.4Te)(0.15)(Bi2Te3) (x) (0 a parts per thousand currency sign x a parts per thousand currency sign 0.05), in which Bi2Te3 is nanopowder, were prepared by hot pressing. The effect of adding neutral nano-Bi2Te3 content on the thermoelectric properties of germanium telluride was investigated. With increasing x, the thermal conductivity of the prepared samples decreased significantly and the Seebeck coefficient declined slightly, while there was no obvious change in electrical conductivity. In both electrical conductivity and Seebeck coefficient curves at different x values, there are inflection points around 600 K. The maximum dimensionless figure of merit ZT of the prepared materials is 1.54, attained in the temperature range from 700 K to 750 K for x = 0.03. The x-ray diffraction (XRD) pattern shows that Bi2Te3 has been alloyed into the GeTe-MnTe-SnTe alloy, which is consistent with the high-resolution scanning electron microscopy (HRSEM) images. Adding nano-Bi2Te3 to GeTe-based materials could also increase their performance stability at high temperature as a result of decreasing the phase-transition temperature T (c).