Facile synthesis and thermoelectric properties of Cu1.96S compounds

Abstract

Cu2-xS compounds with low-cost and low-toxicity elements have been reported as good candidates for thermoelectric (TE) application. In this work, the Cu1.96S powders were synthesized by both hydrothermal synthesis (HS) and mechanical alloying (MA) methods. The HS synthesis process and mechanism was discussed in detail. The polycrystalline Cu1.96S bulk materials were obtained by condensing the powders (prepared by HS and MA) or the mixed HS and MA powers with the different ratio (1:0, 9:1, 1:9 and 0:1) using spark plasma sintering (SPS) technique. The phase structure, microstructure of the powders and bulk samples were checked. The results show that the Cu1.96S powders synthesized by HS are more stable than the powder prepared by MA method during the SPS process. And the thermoelectric properties of all bulk samples were investigated in detail at the temperature ranges from 323 to 773 K. The Cu1.96S bulk sample sintered by using mixed powders of 90 wt% HSed powders and 10 wt% MAed powders obtained the maximum ZT value of 1.01 at 773 K, which is currently the highest reported value for the Cu1.96S system at this temperature.