Electronic Transport and Thermoelectric Properties of Te-Doped Tetrahedrites Cu12Sb4-yTeyS13

Tetrahedrite is a promising thermoelectric material mainly due to its low thermal conductivity, a consequence of its complicated crystal structure. However, tetrahedrite has a high hole concentration; therefore, optimizing carrier concentration through doping is required to maximize the power factor. In this study, Te-doped tetrahedrites Cu12Sb4-yTeyS13 (0.1 <= y <= 0.4) were prepared using mechanical alloying and hot pressing. The mechanical alloying successfully prepared the tetrahedrites doped with Te at the Sb sites without secondary phases, and the hot pressing produced densely sintered bodies with a relative density >99.7%. As the Te content increased, the lattice constant increased from 1.0334 to 1.0346 nm, confirming the successful substitution of Te at the Sb sites. Te-doped tetrahedrites exhibited p-type characteristics, which were confirmed by the positive signs of the Hall and Seebeck coefficients. The carrier concentration decreased but the mobility increased with Te content. The electrical conductivity was relatively constant at 323-723 K, and decreased with Te substitution from 2.6 x 10(4) to 1.6 x 10(4) Sm-1 at 723 K. The Seebeck coefficient increased with temperature and Te content, achieving values of 184-204 mu VK-(1) at 723 K. The thermal conductivity was <1.0 Wm(-1)K(-1), and decreased with increasing Te content. Cu12Sb3.9Te0.1S13 exhibited the highest dimensionless figure of merit (ZT = 0.80) at 723 K, achieving a high power factor (0.91 mWm(-1)K(-2)) and a low thermal conductivity (0.80 Wm(-1)K(-1)).

Automated summary

Tetrahedrite is a promising thermoelectric material with low thermal conductivity due to its complex crystal structure, requiring carrier concentration optimization through doping to maximize the power factor. Te-doped tetrahedrites exhibit p-type characteristics with changing electrical properties at different Te content levels. A high figure of merit and power factor were achieved in Cu12Sb3.9Te0.1S13, showing potential for thermoelectric applications.