Bismuth Doping in Nanostructured Tetrahedrite: Scalable Synthesis and Thermoelectric Performance.

In this study, we demonstrate the feasibility of Bi-doped tetrahedrite CuSbBiS (x = 0.02-0.20) synthesis in an industrial eccentric vibratory mill using Cu, Sb, Bi and S elemental precursors. High-energy milling was followed by spark plasma sintering. In all the samples, the prevailing content of tetrahedrite CuSbS (71-87%) and famatinite CuSbS (13-21%), together with small amounts of skinnerite CuSbS, have been detected. The occurrence of the individual Cu-Sb-S phases and oxidation states of bismuth identified as Bi and Bi are correlated. The most prominent effect of the simultaneous milling and doping on the thermoelectric properties is a decrease in the total thermal conductivity () with increasing Bi content, in relation with the increasing amount of famatinite and skinnerite contents. The lowest value of was achieved for x = 0.2 (1.1 W m K at 675 K). However, this sample also manifests the lowest electrical conductivity , combined with relatively unchanged values for the Seebeck coefficient () compared with the un-doped sample. Overall, the lowered electrical performances outweigh the benefits from the decrease in thermal conductivity and the resulting figure-of-merit values illustrate a degradation effect of Bi doping on the thermoelectric properties of tetrahedrite in these synthesis conditions.