Synthesis and characterisation of the compound CoSbS

In the search for new intermetallic materials with high thermoelectric performances, the Co-Sb-S ternary system has been explored and polycrystalline CoSbS samples have been prepared by a vapour phase technique starting from the pure elements. The crystal cell of CoSbS belongs to the Pbca space group and shows an orthorhombic structural arrangement with the following lattice parameters: a = 5.8341(2) angstrom; b = 5.9477(2) angstrom, and c = 11.6540(4) angstrom. The structure belongs to the pyrite-marcasite family, as Co forms tilted corner- and edge-sharing octahedra with three Sb and three S atoms. Scanning electronic microscopy (SEM), electron-probe microanalysis (EPMA) and X-ray powder diffraction were used to investigate the microstructure and to carry out the structural analysis; the crystal structure was refined by the Rietveld method using the DBWS-9807 program. The thermal stability of CoSbS was investigated referring to the ternary Co-S-Sb phase diagram and by differential thermal analysis (DTA) measurements. Thermoelectric power measurements at room temperature were also performed by a home-made instrument.