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

Abstract

The efficient thermoelectric materials (GeTe)_0.85−x (Mn_0.6Sn_0.4Te)_0.15(Bi₂Te₃) _x (0 ≤ x ≤ 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.