Mechanochemically Synthesized Skinnerite Cu3SbS3 and Wittichenite Cu3BiS3 Nanocrystals and Their Promising Thermoelectric Properties

The thermoelectric properties of skinnerite Cu3SbS3 and wittichenite Cu3BiS3 prepared by mechanochemical synthesis in a planetary ball mill from elemental precursors were investigated for the first time. X-ray diffraction (XRD) analysis of skinnerite after heat treatment revealed not only the presence of monoclinic skinnerite phase but also the presence of tetrahedrite phases. XRD analysis of wittichenite after both heat treatment and spark plasma sintering (SPS) revealed the presence of only the prepared orthorhombic wittichenite, whereas, in the case of skinnerite, not only skinnerite but also tetrahedrite is present after SPS treatment. The thermal stability of mechanochemically synthesized Cu3SbS3 and Cu3BiS3 samples was investigated by thermal analysis, which confirmed that Cu3SbS3 is thermally stable up to 604 K and Cu3BiS3 up to 550 K, respectively. Thermoelectric (TE) potential was evaluated by measuring the Seebeck coefficient, electrical and thermal conductivity, and figure of merit ZT. The performed thermoelectric (TE) measurements revealed a figure of merit ZT of 0.69 and 0.09 at 575 K for pristine skinnerite and wittichenite, respectively, sintered by SPS. The combination of mechanosynthesis followed by SPS allows for the preparation of materials that display a promising thermoelectric response. This approach opens up new possibilities for enhancing the thermoelectric properties of materials, which could have significant implications for various applications, such as energy conversion and waste heat recovery. Further research in this area is necessary to fully explore and exploit the potential of these materials for thermoelectric applications.