Revealing the True Thermoelectric Properties of SnTe through Removing SnO2 Contamination

Abstract

Previous studies on SnTe have indicated that its low ZT value is associated with a high carrier concentration of up to 10²⁰–10²¹ cm⁻³ and an excessively high lattice thermal conductivity. However, the high carrier concentration and lattice thermal conductivity observed in SnTe are not solely attributable to the presence of numerous intrinsic tin vacancies and a simple crystal structure. Additionally, the oxides formed through the oxidation of Sn and SnTe exert a partial influence on these properties. In this study, by pretreating the raw Sn material and isolating it from oxygen during preparation, we achieve a significant improvement in the thermoelectric performance of binary SnTe at high temperatures, with a peak ZT of approximately 0.83 at 800 K. This approach effectively reduces the content of SnO₂ in the matrix, enhancing the electrical and thermal transport properties of the samples. Specifically, the high-thermal conductivity of SnO₂ facilitates the formation of channels at grain boundaries that are more conducive to heat transfer, while its poor electrical conductivity and Seebeck coefficient diminish the intrinsic electrical transport behavior of SnTe. The removal of SnO₂ reflects the true thermoelectric performance of SnTe, making the samples prepared by this method stand out compared to other reported binary SnTe materials.