Effect of ball-milling on the phase formation and enhanced thermoelectric properties in zinc antimonides

We report the phase formation mechanism and the enhanced thermoelectric properties of zinc antimonide (ZnSb) thermoelectric material. The phase pure ZnSb thermoelectric material is achieved using high-energy ball milling of Zn and Sb in a shorter span of time. The ZnSb phase formation is explained by the kinetic energy transferred to the powders during milling for the solid-state reaction between Zn and Sb to form the desired ZnSb phase. The repeatability in transport properties up to three thermal cycles corroborates the thermal stability of the processed samples. The thermoelectric figure of merit obtained at 600 K is ~ 0.76 for the processed phase pure ZnSb sample, the highest value in binary ZnSb reported so far. Our results address the ZnSb phase evolution in a shorter milling time and the enhanced thermoelectric properties of the ZnSb materials. The observations will help to scale up the processing of high-performance ZnSb thermoelectric materials.