High performance n-type (Bi,Sb)2(Te,Se)3 for low temperature thermoelectric generator

Abstract

Starting with elemental chunks of bismuth, antimony, tellurium and selenium, densified bulk materials (Bi0.95Sb0.05)2(Te1−xSex)3 (x = 0.10, 0.13, 0.15 and 0.17) were prepared by melt spinning subsequently combined with a spark plasma sintering process. The prepared bulk materials display fine grain size and numerous layered structures with a size of 10–100 nm; moreover, details of the composition difference and phase difference cannot be observed. Measurements of electrical conductivity, Seebeck coefficient and thermal conductivity have been performed in the temperature range 300–500 K, and it is found that the thermoelectric properties are significantly affected by the content of selenium. All the prepared samples show higher ratios of electrical conductivity and total thermal conductivity compared with state-of-the-art commercial zone melted materials, mainly a large reduction in lattice thermal conductivity, which is more beneficial to the concept of ‘electron crystal phonon glass’. Subsequently, the resulting thermoelectric figure of merit ZT value reaches a maximum of 1.0 at 460 K for the n-type (Bi0.95Sb0.05)2(Te0.85Se0.15)3 bulk material. Compared with traditional zone melted materials, the peak ZTs move towards a higher temperature and this study demonstrates the possibility of preparing materials with high performance, which can be applied for low temperature power generation or multi-stage devices.