Low-cost preparation of highly-efficient thermoelectric BixSb2-xTe3 nanostructured powders via mechanical alloying

Abstract

In this paper, a low-cost and facile method for preparing highly-efficient Bi2Te3-based thermoelectric materials is demonstrated. P-type BixSb2-xTe3 (x ​= ​0.2, 0.3, 0.4, 0.5) nanostructured powders were fabricated via mechanical alloying, and consequently consolidated into pellets by hot-press sintering. The effect of Bi/Sb ratio on the thermoelectric properties was investigated. The higher hole density and mobility in samples with lower Bi concentration resulted in higher electrical conductivity and power factor values. The absence of preferred grain orientation and the high density of grain boundaries in these nanostructured materials led to significantly low lattice thermal conductivity. As a result, a peak ZT of 1.13 ​at 355 ​K and an average ZT of 1.01 over the investigated temperature range was achieved for Bi0.3Sb1.7Te3, suggesting that mechanical alloying can be considered as an advantageous technique for single-step synthesis of highly-efficient thermoelectric BixSb2-xTe3 alloys.