Thermoelectric properties of Spark plasma sintered PbTe synthesized without any surfactant and organic solvent

We report a systematic investigation on structural and thermoelectric properties of Spark plasma sintered Lead telluride synthesized by hydrothermal route and a low temperature aqueous chemical route without using any organic solvent and surfactant. The as-synthesized powder samples obtained from these two different synthesis routes were identically subjected to spark plasma sintering. The size of nanocubes formed by the hydrothermal method, as evident from TEM-HRTEM images, is 50 nm; however, the samples synthesized by aqueous chemical route shows mixed morphology with particle size < 50 nm. The thermoelectric properties of spark plasma sintered bulk nanostructured samples have been measured from RT to 700K. Notably, large Seebeck coefficient and small electrical resistivity values are observed in the sample synthesized by the hydrothermal route, which is ascribed to the charge carrier energy filtering effect. A maximum reduction of similar to 38% and similar to 58% has been observed in the sample synthesized by the hydrothermal route and aqueous chemical route, respectively, compared to the bulk ingot. The maximum figure of merit attained is 0.18 at 673 K in the lead telluride sample synthesized by the hydrothermal route.