Thermoelectric properties of Cu2S obtained by high temperature synthesis and sintered by IHP method

Abstract Copper(I) sulphide is one of the most intensely studied superionic thermoelectric materials. High mobility of copper ions have positive impact on thermoelectric figure of merit, however it brings some stability drawbacks. In this work we compare thermoelectric properties of Cu2S synthesized under various conditions. All of the obtained powders were densified by induction hot pressing (IHP) at the same conditions. Phase composition, microstructure and thermoelectric homogeneity were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and scanning thermoelectric microprobe (STM), respectively. The influence of synthesis conditions on transport properties, i.e. electrical conductivity, thermal conductivity and Seebeck coefficient were examined in the temperature range 300–923 K. Based on those results, ZT parameter was calculated and the optimal method of the Cu2S synthesis chosen. The highest obtained ZTmax parameter equal to 0.68 at 923 K is 20–40% higher than in other works, where Cu2S was densified by SPS method.