Thermoelectric power properties of Ge doped PbTe alloys

Abstract

In this work, stoichiometric Pb1−xGexTe (x = 0.0, 0.03, 0.06, 0.09, 0.12) crystalline alloys were synthesized using the monotonical temperature melting technique. The synthesized alloys were examined using x-ray diffraction and scanning electron microscope. It was revealed that the crystal structure in all samples is a cubic phase of PbTe. In terms of Seebeck coefficient and electrical conductivity, thermoelectric measurements were carried out in the temperature range of 83–373 K. The Seebeck coefficient of the compounds showed a positive sign, which refers to p-type conduction. The thermoelectric power factor (PF) was studied as a function of temperature, with different amounts of Ge content (x). The highest PF was recorded for the highly Ge-doped samples at higher temperatures (373 K). The maximum PF was observed at 3.2 × 102 µW/m K2 for the sample with x = 0.09, which is quite high for the studied compounds. The electronic part of thermal conductivity was calculated using the Wiedemann-Franz law. A noticeable reduction of this thermal conductivity was detected due to stronger point defect scattering introduced by Ge doping. The reduction in the electronic thermal conductivity can led to a considerable enhancement in the thermoelectric figure of merit.