Synthesis and characterization of nanostructured tetrahedrite and its composite with dielectric inclusions

Abstract

The nanostructured Cu-Sb-S materials have been synthesized by a low-cost and versatile polyol technique in a triethylene glycol medium at different temperatures (Ts = 473-533 K). The content of tetrahedrite (Cu12Sb4S13), skinnerite (Cu3SbS3), famatinite (Cu3SbS4), and chalcostibite (CuSbS2) phases was quantitatively determined via the Rietveld refinement of X-ray diffraction (XRD) patterns which showed that Cu-Sb-S pellets densified from powders synthesized at 493 K possess the highest content of tetrahedrite (i.e., ∼96.6 vol.%) with small amount of skinnerite (i.e., ∼3.4 vol.%). The inclusion of dielectric polyvinylpyrrolidone (PVP) up to 2.5 wt.% to tetrahedrite phase induced the alteration of structural (unit cell parameter a and volume Vunit) and microstructural (sizes of coherent scattering domains L, levels of microdeformations lε, microstresses lσ, and density of dislocations dρ) parameters. The change in the microstructure of Cu12Sb4S13-PVP composites caused the decrease of electronic thermal conductivity κe by 3 times. The increase of Seebeck coefficient (S) resulted in a power factor (PF) of (100-180) μV/K at (300-473) K for Cu12Sb4S13-PVP composite. The presented approach proves the effectiveness of the tuning thermoelectric characteristics of tetrahedrite via admixing with dielectric inclusions.