Thermoelectric Properties of beta-Zn4Sb3 Synthesized by MA-SPS Method

Abstract

Thermoelectric power generation is a hopeful method harnessing waste thermal energy especially covering the middle temperature range between 500 and 800K. The compound βZn4Sb3 has become the focus of attention as a thermoelectric material available to thermoelectric power generation around 700K. In this research, the method combined the mechanical allying (MA) with the spark plasma sintering (SPS) was adopted in order to obtain the sintered device of compound β-Zn4Sb3. The pure zinc powder and pure antimony powder were used as the starting powders for mechanical alloying. The zinc and antimony powders were mixed in the stoichiometry ratio of 4 to 3 or more Zn-rich. The mechanical alloying was carried out by planetary ball milling under the conditions of fixed revolution speed and variable milling time. The influence of the milling time on the synthesis of compound β-Zn4Sb3 was investigated. The sintering was executed under two types of sintering temperature and under fixed conditions of sintering time, pressing pressure and atmosphere. The influence of the sintering temperature by SPS on the thermoelectric properties was also investigated. The following results were clarified. The phases of ZnSb and Zn are easily obtained by mechanical alloying of more than 50hr. These phases change to single phase of β-Zn4Sb3 by SPS under optimum condition of Zn-rich mixing. The sintered device of β-Zn4Sb3 with 1.17 of non-dimensional figure of merit at 673K can be obtained by MA-SPS method.