Enhancing the Figure of Merit in Te-doped FeSb2 through nanostructuring

TL;DR

This study demonstrates that Te-doping and nanostructuring of FeSb2 significantly improve its thermoelectric figure of merit by inducing a semiconductor-metal transition and reducing thermal conductivity, achieving a 62% increase in ZT at 100 K.

Contribution

It introduces a method of enhancing thermoelectric performance in FeSb2 through Te-doping combined with nanostructuring, leading to a notable increase in ZT.

Findings

ZT increased by 62% at 100 K in Te-doped nanostructured FeSb2

Thermal conductivity further reduced by point defect scattering

Carrier concentration increased, mobility decreased

Abstract

We study the thermoelectric properties of Te-doped FeSb2 nanostructured samples. Four samples of stoichiometry FeSb1.84Te0.16 were prepared by a hot press method at temperatures of 200, 400, 500, and 600 oC. Te-doping enhances the dimensionless figure of merit (ZT) on FeSb2 via two mechanisms. First, a semiconductor to metal transition is induced, which enhances the value of the power factor at low-temperatures. Second, the thermal conductivity, which was already reduced in nanostructured FeSb2 samples, is further reduced by increased point defect scattering through the n type substitution of Sb site by Te atom. The combined effect results in a ZT = 0.022 at 100 K, an increase of 62% over the ZT value for the optimized Te-doped single crystal sample. Hall coefficient and electrical resistivity measurements reveal a decreased mobility and increased concentration of the carriers in the doped sample.