Structural study and evaluation of thermoelectric properties of single-phase isocubanite (CuFe2S3) synthesized via an ultra-fast efficient microwave radiation technique

Current state-of-the-art materials for thermoelectrics are generally composed of expensive, scarce, and toxic elements. In this aspect, copper-based sulfide compounds have emerged as viable alternatives. Herein, we report for the first time the successful synthesis of single-phase cubic isocubanite CuFe2S3 using mechanical-alloying combined with microwave-assisted synthesis. The isocubanite phase synthesized via this ultra-fast out-of-equilibrium process exhibits a maximum thermoelectric figure of merit, zT(max) similar to 0.14 at 673 K. Besides the thermoelectric properties, insights about the structure of isocubanite, based on the refinement of X-ray diffraction data and first-principles calculations, are also elucidated in detail. They confirm that the Cu-Fe cations in synthetic isocubanite overwhelmingly occupy the 4d sites of the cubic structure in an inherently disordered fashion.