Synthesis and transport properties of AgBi3S5 ternary sulfide compound
Abstract Ternary sulfide AgBi 3 S 5 compound is expected to be a promising thermoelectric material because of its merits such as low electrical resistivity and environmentally compatible composition. In this study, a combined process of mechanical alloying and spark plasma sintering was applied to the fabrication of AgBi 3 S 5 bulk materials, and nearly single phase was obtained by optimizing the sintering conditions, although the mill-derived powders consisted of AgBiS 2 and Bi 2 S 3 phases. The electrical conductivity of the AgBi 3 S 5 bulk material decreases from 178 to 79 Scm −1 with raising temperature from 323 to 573 K, while the Seebeck coefficient ranges from −83 to −167 μV K −1 , thereby a maximum power factor 221 μW m −1  K −2 achieved at 573 K. It is notable that AgBi 3 S 5 has a low thermal conductivity, ranging from 0.70 to 0.64 W m −1  K −1 from room temperature to 573 K, which is the lowest value reported so far for this material. A peak thermoelectric figure of merit value of 0.20 was obtained at 573 K in the present pristine AgBi 3 S 5 sample.