Enhanced figure of merit in nanostructured (Bi, Sb) 2 Te 3 with optimized composition, prepared by a straightforward arc-melting procedure

TL;DR

This paper introduces a rapid, cost-effective arc-melting method to produce nanostructured Bi-Sb-Te thermoelectric pellets with enhanced figure of merit due to low thermal conductivity and high Seebeck coefficient, confirmed by structural analysis.

Contribution

The study demonstrates a straightforward arc-melting technique to synthesize nanostructured thermoelectric materials with improved performance, supported by detailed neutron diffraction analysis.

Findings

Nanostructured pellets show increased ZT due to low thermal conductivity.

Arc-melting produces layered nanosheets less than 50 nm thick.

Structural analysis highlights the role of atomic vibrations in thermoelectric properties.

Abstract

Sb-doped Bi2Te3 is known since the 1950s as the best thermoelectric material for near-room temperature operation. Improvements in material performance are expected from nanostructuring procedures. We present a straightforward and fast method to synthesize already nanostructured pellets that show an enhanced ZT due to a remarkably low thermal conductivity and unusually high Seebeck coefficient for a nominal composition optimized for arc-melting: Bi0.35Sb1.65Te3. We provide a detailed structural analysis of the Bi2-xSbxTe3 series based on neutron powder diffraction as a function of composition and temperature that reveals the important role played by atomic vibrations. Arc-melting produces layered platelets with less than 50 nm-thick sheets. The low thermal conductivity is attributed to the phonon scattering at the grain boundaries of the nanosheets. This is a fast and cost-effective production method of highly efficient thermoelectric materials.