Growth and thermoelectric characterization of chalcopyrite ZnSnSb2 with pseudocubic structure

Abstract We investigated the growth mechanism and the thermoelectric (TE) properties of the II-IV-V2 group chalcopyrite ZnSnSb2 with a pseudocubic structure, which is a key strategy for improving the TE performance by increasing the degeneracy at the valence band edge. The growth mechanism of ZnSnSb2 shows the peritectic reaction as: ZnSb + SnSb + liquid phase ↔ ZnSnSb2 for 320–360 °C. The ZnSnSb2 single phase was obtained from the starting composition of Zn:Sn:Sb = 1:5:2. The high-temperature TE properties were measured up to 573 K, and the thermal conductivity values were 1.5 times lower than the reported value, which was caused by enhanced phonon scattering by the off-stoichiometric composition. Consequently, the TE figure of merit for off-stoichiometric ZnSnSb2 reached 0.12 at 573 K, which is 1.4 times higher than that of the reported stoichiometric sample.