Influence of Sintering Temperature on Structure and Thermoelectric Properties of Cu2Se0.75Te0.25

The thermoelectric figure of merit (ZT) of Cu-2(Se, Te) liquid-like compounds is strongly dependent on the structural modification. Here, based on the modification of the sintering temperature from 673 K to 973 K, by using mechanical alloying and a solid-state reaction method, we observed a structural transformation and a modification of the morphology and grain size in Cu2Se0.75Te0.25 with increasing sintering temperature. The layered structure morphology was observed more clearly at the high sintering temperature. The decrease of electrical conductivity with higher measuring temperature indicates a degenerate semiconductor behavior of all samples. The Seebeck coefficients are not much different with increasing the sintering temperature, while the maximum electrical conductivity was obtained in the sample sintered at 823 K. According to that, the power factor and ZT values of this sample can be achieved up to 10.48 mu Wcm(-1) K-2 and 1.45 at the temperature of 773 K, respectively.