Stability and Thermoelectric Property of Cu9Fe9S16: Sulfide Mineral as a Promising Thermoelectric Material

Abstract

ABSTRACTThermoelectric materials based on non-toxic and earth-abundant elements are important from the viewpoint of energy harvesting from the widely-spread waste heat. We have investigated the thermoelectric properties of Cu9Fe9S16, known as the natural mineral mooihoekite or talnakhite. Seebeck coefficient shows a large negative value of about -140 μV/K around room temperature. Thermal conductivity is found to be as small as 2.0 W/Km above 100 K, which is attributed to the large unit cell and the complicated crystal structure. Our results indicate that Cu9Fe9S16 can make a high-performance and environmentally-friendly thermoelectric material if the concentration of carriers, especially holes, is reduced.