Enhanced thermoelectric properties of Cu1.8Se1-xSx alloys prepared by mechanical alloying and spark plasma sintering

Cu1.8Se1-xSx (0 <= x <= 1) thermoelectric alloys were prepared by mechanical alloying (MA) combined with spark plasma sintering (SPS) technology. The phase structure and morphologies of all the samples were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The electrical conductivity, Seebeck coefficient, thermal conductivity were investigated for all the Cu1.8Se1-xSx alloys with a special emphasis on the influence of the S doping. With the increasing of S contents, a phase transition of Cu1.8Se1-xSx was occurred from cubic to hexagonal. The electrical and thermal transport properties of the samples changed accordingly. The Cu1.8Se0.7SO3 alloy achieves the highest ZT of 0.78 at 773 K due to both optimized electrical transport properties and thermal transport properties, which is 44% higher than that of pristine Cu1.8S (0.54 at 773 K) and 95% higher than that of pristine Cu1.8Se (0.4 at 773 K). (C) 2016 Elsevier B.V. All rights reserved.