Properties of thermoelectric Zn-Sb type material directly synthesized by spark plasma sintering

The aim of the work was to investigate a possibility of a direct synthesis of Zn4Sb3 compound by spark plasma sintering and evaluate the influence of the synthesis parameters on the materials properties. Materials with various initial compositions are sintered to multiphase samples composed of a Zn4Sb3 matrix in which ZnSb, Zn and Sb inclusions are found. For each initial stoichiometry, the temperature and sintering duration are limited in a different manner by decomposition of desired β-Zn4Sb3 phase. High concentration of inclusions is evidenced to degrade thermoelectric properties of Zn-Sb type materials. A high Power Factor of 1200 μW/(m K2) was found in the material of stoichiometric starting composition at 580 K. An interesting correlation between improvement of thermoelectric properties and zinc depletion of the β-Zn4Sb3 phase was discovered.