Preparation and thermoelectric properties of ternary superionic conductor CuCrS2

Transition metal chalcogenide CuCrS2 powder was synthesized by mechanical alloying (MA) and then consolidated by spark plasma sintering (SPS) technique at 673–1073 K. The phase structure, microstructure and thermoelectric properties of samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Seebeck coefficient/electrical conductivity measuring system, respectively. All the bulks indicated a single phase CuCrS2, while the high relative density over 90% were attained for the samples sintered at 873–1073 K. The electrical conductivity of bulk samples displayed a typical characteristic of semiconductor. With increasing measuring temperature, the conductive behaviour of bulk samples sintered over 973 K showed a semiconductor transformation from n-type to p-type due to the changes of main carrier type. The sample obtained by applying SPS at 873 K got the highest power factor 83.2 μW m−1 K−2, and the largest ZT value 0.11 at 673 K. - Graphical abstract: The samples sintered above 873 K, both of the Seebeck coefficient and electrical conductivity exhibit an increase tendency with increasing temperature, which is due to the mechanism of mix-conduction for CuCrS2. Highlights: ► Single phase CuCrS2 powder was synthesized by ball-milling at 425 rpm for 40 h. ► Dense CuCrS2 bulks were fabricated using SPS techniques at sintering temperature 873–1073 K. ► Seebeck coefficient of CuCrS2 samples sintered over 973 K change the signs. ► Highest power factor reached 83.2 μW m−1 K−2 at 673 K for the sample sintered at 873 K. ► ZT value was 0.11 at 673 K for the sample sintered at 873 K.