Electronic and thermoelectric properties of Fe2VAl: The role of defects and disorder

TL;DR

This study uses first-principles calculations to show that the semiconducting properties of Fe2VAl are significantly affected by defects and disorder, which introduce localized states that impair its thermoelectric performance.

Contribution

It demonstrates that antisite defects and disorder, not intrinsic properties, cause the semimetallic character and reduce thermoelectric efficiency in Fe2VAl.

Findings

Fe2VAl is an indirect band gap semiconductor.

Defects and disorder introduce localized in-gap states.

These states decrease thermopower and power factor.

Abstract

Using first-principles calculations, we show that Fe2VAl is an indirect band gap semiconductor. Our calculations reveal that its, sometimes assigned, semimetallic character is not an intrinsic property but originates from the antisite defects and site disorder, which introduce localized ingap and resonant states changing the electronic properties close to band gap. These states negatively affect the thermopower S and power factor PF=S^2\sigma, decreasing the good thermoelectric performance of intrinsic Fe2VAl.