Quick Fabrication and Thermoelectric Properties of Cu₁₂Sb₄S₁₃ Tetrahedrite

Abstract

Tetrahedrites, comprised mainly of earth-abundant and environment-friendly elements, copper and sulfur, may pave the way to many new and low-cost thermoelectric energy generation opportunities. However, the preparation of tetrahedrites is time- and energy-consuming. In this paper, we study the melting process and the effect of the annealing time on the microstructure and thermoelectric properties of the Cu₁₂Sb₄S₁₃ tetrahedrite, in an effort to shorten the synthesis (melting and annealing) time. Our results show that the Cu₁₂Sb₄S₁₃ tetrahedrite phase forms in the melt during cooling. Shortening the melting time does not affect the formation of Cu₁₂Sb₄S₁₃. The cooled ingot consists of the principal phase of Cu₁₂Sb₄S₁₃ and two secondary phases, Cu₃SbS₄ and CuSbS₂. It is found that prolonged annealing cannot eliminate the impurity phases in Cu₁₂Sb₄S₁₃ tetrahedrite, has a small effect on the electrical resistivity, and a negligible effect on the Seebeck coefficient and the thermal conductivity of the tetrahedrite. All our samples have a ZT above 0.47 at 600 K and the maximum ZT obtained was 0.52 when the sample was annealed for 1 day. Based on our experimental results, the time for preparing the Cu₁₂Sb₄S₁₃ tetrahedrite can be considerably shortened.