A hybrid method for the synthesis of small Bi0.5Sb1.5Te3 alloy particles

Abstract

A reduction in the grain size of p-type thermoelectric materials, which increases phonon scattering at grain boundaries, can increase the figure of merit (ZT) due to decreased lattice thermal conductivity. Small grains are often observed in samples sintered from small powders. In this study, we investigated the effect of a reduction in powder size in Bi0.5Sb1.5Te3 alloys synthesized using a new hybrid method. Tellurium (Te) nanowires were chemically synthesized without an organic surfactant and Bi0.25Sb0.75 powders were physically synthesized using a ball-milling method. The Bi0.5Sb1.5Te3 powders synthesized from the previously prepared Te nanowires and Bi0.25Sb0.75 powder were thermally alloyed by a solid state reaction. The morphology of the Te was found to be important in determining the powder size of the alloyed Bi0.5Sb1.5Te3. Reduced thermal conductivity was associated with smaller grain size, which enhanced thermoelectric properties. (C) 2016 Elsevier B. V. All rights reserved.