The synthesis of CaZn2Sb2 and its thermoelectric properties

CaZn₂Sb₂ was prepared and examined for use as a high temperature thermoelectric material. It has a high Seebeck coefficient and high electrical conductivity-comparable to β-Zn₄Sb₃. These two properties are vital in determining the ability of the compound to change heat into electricity isentropically. The dimensionless figure of merit, ZT, a measure of the thermoelectric material´s efficiency is defined as ZT = S²σT/λ where S is the Seebeck coefficient, Z the figure of merit, T the temperature, σ the electrical conductivity, and λ the thermal conductivity. However, due to its simple structure, CaZn₂Sb₂ has high λ. Doping CaZn₂Sb₂ with Ga³⁺ or modifying the (Ca, Zn) to Sb ratio was also investigated. Samples were prepared from Zn, Sb, and the binary compound CaSb₂. They were tested for material composition, structure, and thermoelectric properties. Results of this experiment are presented and discussed as are the applicability of these materials to future thermoelectric use. Conservative estimates show a ZT of .5 at 500°C; CaZn₂Sb₂ could be a good thermoelectric to use at temperatures above 400°C.