부산대학교 도서관

Cu-based quaternary chalcogenide compounds have been thermoelectric topic of interest among researchers, especially in recent years, due to their intrinsically low thermal conductivity. Recently plenty of work is done on thermoelectric properties of Cu2ZnSnSe4-based alloys emphasizing on importance of Cu2ZnSnSe4-based alloys in thermoelectric power generation. In this study, we report the effect of annealing temperature on microstructure and thermoelectric properties of Cu2.1Zn0.9SnSe4 alloys. Cu2.1Zn0.9SnSe4 compounds were synthesized by high-temperature melting followed by annealing at four different temperatures (600 °C, 650 °C, 700 °C and 725 °C). X-ray diffraction combined with Raman spectroscopy confirmed the presence of Cu2ZnSnSe4 phase along with ZnSe and CuSe secondary phases. The increased annealing temperature critically affected the microstructure of Cu2.1Zn0.9SnSe4 alloys. Successive increase in annealing temperature subsequently increases the average grain size from 7.3 for 600 sample to 12.1 μm for 725 °C sample by shifting grain size distribution toward higher range. Increased grain size results in reduced carrier scattering and decreases the electrical resistivity eventually improving power factor and maximum power factor of about 400 μWk−2 m−1 is obtained for 725 °C sample. Besides, the increased annealing temperature resulted in increased thermal conductivity attributing increased grain size resulting in low phonon scattering. 725 °C sample shows highest power factor and moderate thermal conductivity among all the samples which resulted in highest value of figure of merit for 725 °C sample of about 0.1 at 673 K. [ABSTRACT FROM AUTHOR]