Synergistic tuning of microstructure and thermoelectric performance of bismuth telluride based materials by ball milling

Abstract:

Bismuth telluride compounds are thermoelectric materials with the best performance near room temperature, which have important application value in waste heat recovery and solid state refrigeration. The main preparation method is ball grind milling, and slight changes of various parameters may affect the microstructure and thermoelectric properties of materials. Ball milling time, as an important ball grinding parameter, can not only affect the refinement of powder particle size, but also regulate the thermoelectric properties of materials. Therefore, it is urgent to analyze the influence of ball milling time on the crystal structure, particle size and the thermoelectric performance of products. In this paper, bismuth telluride compounds were prepared by adjusting different ball milling time with constant ball grinding speed. The response of grains to ball milling time is found through the analysis of crystal structure and powder particle size. The result of subsequent thermoelectric performance tests shows that, with the increase of ball milling time, the change of particle size leads to the synergistic tuning of electron and phonon transport. Finally, the maximum ZT merit of n-type and p-type bismuth telluride were increased to 0.91 and 1.11, respectively. This study systematically summarizes the influence of ball milling time on the microstructure and the thermoelectric capability of bismuth telluride. Our work shows the significance in the mergence of powder metallurgy and thermoelectrics, which may play some roles in the commercial application of thermoelectric conversion technology.