| Summary: | In this study, we demonstrate the feasibility of Bi-doped tetrahedrite Cu<sub>12</sub>Sb<sub>4−x</sub>Bi<sub>x</sub>S<sub>13</sub> (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 Cu<sub>12</sub>Sb<sub>4</sub>S<sub>13</sub> (71–87%) and famatinite Cu<sub>3</sub>SbS<sub>4</sub> (13–21%), together with small amounts of skinnerite Cu<sub>3</sub>SbS<sub>3</sub>, have been detected. The occurrence of the individual Cu-Sb-S phases and oxidation states of bismuth identified as Bi<sup>0</sup> and Bi<sup>3+</sup> are correlated. The most prominent effect of the simultaneous milling and doping on the thermoelectric properties is a decrease in the total thermal conductivity (<i>κ</i>) with increasing Bi content, in relation with the increasing amount of famatinite and skinnerite contents. The lowest value of <i>κ</i> was achieved for x = 0.2 (1.1 W m<sup>−1</sup> K<sup>−1</sup> at 675 K). However, this sample also manifests the lowest electrical conductivity <i>σ</i>, combined with relatively unchanged values for the Seebeck coefficient (<i>S</i>) 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.
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