Phonon Drag Effect in Nanocomposite FeSb2

TL;DR

This study investigates how phonon drag influences thermoelectric properties in FeSb2 nanocomposites, revealing that grain size reduction suppresses phonon drag and limits ZT improvements despite lower thermal conductivity.

Contribution

It provides experimental evidence of phonon drag effects in FeSb2 nanocomposites and shows how grain size impacts thermoelectric performance.

Findings

Phonon drag significantly enhances Seebeck coefficient at low temperatures.

Reducing grain size suppresses phonon drag due to increased boundary scattering.

ZT values are not substantially improved despite reduced thermal conductivity.

Abstract

We study the temperature dependence of thermoelectric transport properties of four FeSb2 nanocomposite samples with different grain sizes. The comparison of the single crystals and nanocomposites of varying grain size indicates the presence of substantial phonon drag effects in this system contributing to a large Seebeck coefficient at low temperature. As the grain size decreases, the increased phonon scattering at the grain boundaries leads to a suppression of the phonon-drag effect, resulting in a much smaller peak value of the Seebeck coefficient in the nanostructured bulk materials. As a consequence, the ZT values are not improved significantly even though the thermal conductivity is drastically reduced.