Significant suppression of thermal conductivity in FeSb2 by Te doping

TL;DR

This study demonstrates that 5% Te doping in FeSb2 drastically reduces thermal conductivity and enhances thermoelectric performance at cryogenic temperatures, revealing a promising route for thermoelectric material optimization.

Contribution

It is the first to show that minimal Te doping can suppress thermal conductivity by two orders of magnitude in FeSb2, significantly improving its thermoelectric efficiency.

Findings

Thermal conductivity decreased by two orders of magnitude with 5% Te doping.

Thermoelectric figure of merit (ZT) increased by about ten times at 100K.

Te doping induces a transition from semiconductor to metal in FeSb2.

Abstract

Kondo insulator like material FeSb2 was found to exhibit colossal Seebeck coefficient. It would have had huge potential in thermoelectric applications in cryogenic temperature range if it had not been for the large thermal conductivity. Here we studied the influence of Te doping at Sb site on thermal conductivity and thermoelectric effect in high quality single crystals. Surprisingly, only 5% Te doping suppresses thermal conductivity by two orders of magnitude, which may be attributed to the substitution disorder. Te doping also results in transition from an semiconductor to a metal. Consequently thermoelectric figure of merit (ZT ? 0:05) in Fe(Sb0:9Te0:1)2 at ? 100K was enhanced by about one order of magnitude when compared to ZT < 0:005 in undoped FeSb2.