A synthesis process development for tetrahedrite p-type thermoelectric materials

A current challenge in the thermoelectric field is the discovery of new materials which are inexpensive, easy to synthesize, and comprised of earth-abundant elements. First works regarding Tetrahedrite mineral family (Cu12-xTrxSb4S13 where Tr= Mn, Fe, Co, Ni, Zn), the most widespread sulfosalts on Earth, showed as they could be attractive for thermoelectric application, possessing considerably high values of figure of merit ZT (nearly 1 at 445 °C) among p-Type Pb-free sulphides, mainly due to the intrinsic low lattice thermal conductivity [1-3]. For these reasons, the direct use of natural tetrahedrite mineral could be very appealing way for purchasing an inexpensive and earth-abundant TE material with high conversion efficiency. [1, 4] In this work a solvothermal synthesis was developed for tetrahedrite materials optimizing the synthesis procedures in order to obtain single phase tetrahedrites. Moreover, a preliminary sintering process was performed by means of Open Die Pressing. Structural, morphological, compositional, and functional properties of the material were carried out by X-Ray Diffraction, Field Emission Scanning Electron Microscopy (coupled with Energy Dispersion Spectroscopy), Laser Flash Analysis and electrical conductivity and Seebeck coefficient measurements, respectively. Further thermal analyses were carried out in order to understand the behaviour of the synthesized powders up to 500 °C. References: [1] X. Lu, D.T. Morelli, Physical Chemistry Chemical Physics, 15 (2013) 5762-5766. [2] X. Lu, D.T. Morelli, Y. Xia, F. Zhou, V. Ozolins, H. Chi, X. Zhou, C. Uher, Advanced Energy Materials, 3 (2013) 342-348. [3] K. Suekuni, K. Tsuruta, M. Kunii, H. Nishiate, E. Nishibori, S. Maki, M. Ohta, A. Yamamoto, M. Koyano, Journal of Applied Physics, 113 (2013). [4] X. Fan, E.D. Case, X. Lu, D.T. Morelli, Journal of Materials Science, (2013) 1-11.