Thermoelectric Properties of Mechanically-Alloyed and Hot-Pressed Cu$_{12-x}$Co$_x$Sb$_4$S$_{13}$ Tetrahedrites

Department of Materials Science and Engineering, Korea National University of Transportation, Chungju 27469, Korea
Correspondence to: Il-Ho Kim
Abstract
Co-doped Cu$_{12-x}$Co$_x$Sb$_4$S$_{13}$ ($x$ = 0–1.0) tetrahedrites were prepared by mechanical alloying and hot pressing. X-ray diffraction analyses revealed that all specimens consisted of single-phase tetrahedrite without secondary phases and that the lattice constant increased with increasing Co content. The electrical conductivity decreased and the Seebeck coefficient increased with increasing Co content because of the reduction in the carrier (hole) concentration resulting from the substitution of Co at Cu sites. In addition, the thermal conductivity decreased as the Co content increased owing to a decrease in the electronic thermal conductivity. A dimensionless figure of merit ($ZT$) of 0.94 was obtained at 723 K for Cu$_{11.8}$Co$_{0.2}$Sb$_4$S$_{13}$.
PACS numbers: 72.15.Jf, 72.20.Pa
Keywords: Thermoelectric, Tetrahedrite, Mechanical alloying, Hot pressing

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