Microstructure analysis and thermoelectric properties of iron doped CuGaTe2

Chalcopyrite related compounds have attracted much attention in recent years due to their promising thermoelectric properties. In this research we report Fe doping in chalcopyrite-type CuGaTe2 and its influence on structural and thermal transport properties. We synthesized polycrystalline samples with composition CuGa1-x FexTe2 with x = 0.0 to 0.05 by spark plasma sintering method. For structural analysis powder X-ray diffraction and electron probe micro analysis were employed. Solubility of Fe in CuGaTe2 was found to be very small, and other phases like FeTe2 and CuTe were identified. Thermal conductivity showed a significant decrease with the addition of Fe up to x= 0.02, which started to increase for x >= 0.03. On the other hand, the addition of Fe caused slight increase in the power factor from 1.3 mW/K(2)m for x= 0.0 to 1.6 mW/K(2)m for x = 0.02 at T = 770 K. As a result, ZT peak value of 0.92 is recorded for x= 0.02 at 870 K, which corresponds to an enhancement of 60% from that of non-doped CuGaTe2. This work demonstrates that thermoelectric properties of composite materials can be greatly improved by controlling its microstructure. (C) 2018 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.