High thermoelectric performance of Bi2-xSbxTe3 bulk alloys prepared from non-nanostructured starting powders

Highlights: • High ZT Bi_2-xSb_xTe₃ alloys are obtained using non-nanostructured starting materials. • Hot pressed and hot deformed samples have an average ZT of 1 and 1.15, respectively. • All thermoelectric properties have been measured in the same in-plane direction. • A low Lotgering factor is not a good criterion to treat Bi_2-xSb_xTe₃ samples as isotropic. -- Abstract: In this work, hot press and hot deformation were applied to p-type Bi_2-xSb_xTe₃ (x = 1.5–1.8) starting powders that have not undergone nanostructuring processing. The effects of hot pressing and hot deformation, as well as Sb-alloying, on the microstructure and the thermoelectric properties of the Bi_2-xSb_xTe₃ alloys were systematically investigated. The results of this study are compared to those of others, which have addressed similar issues in samples prepared with analogous compaction techniques. ZT value of 1.12 at 375 K for hot pressed Bi_0.4Sb_1.6Te₃ and ZT value of 1.24 at 375 K for hot deformed Bi_0.4Sb_1.6Te₃ were achieved. To our knowledge, the latter ZT value is only slightly lower than the highest ever reported (ZT~1.3) for p-type bismuth telluride-based alloys prepared using starting materials without nanostructuring, suggesting that simpler preparation techniques can be applicable in modules fabrication.