Stoichiometric and off-stoichiometric full Heusler $\mathbf {Fe_2V_{1-x}W_xAl} $ thermoelectric systems

TL;DR

This study investigates full-Heusler alloys with V/W substitution, revealing improved thermoelectric performance, including a 10% increase in figure of merit and a change in carrier type, supported by experimental and ab-initio analysis.

Contribution

It introduces off-stoichiometric Fe2V1-xWxAl alloys with enhanced thermoelectric properties and provides a microscopic understanding through ab-initio calculations.

Findings

10% improvement in thermoelectric figure of merit

Change from hole to electron carriers with V/W substitution

ZT values above 0.2 achieved

Abstract

A series of full-Heusler alloys, $\rm Fe_2V_{1-x}W_xAl$, $0 \leq x \leq 0.2$, was prepared, characterized and relevant physical properties to account for the thermoelectric performance were studied in a wide temperature range. Additionally, off-stoichiometric samples with similar compositions have been included, and a 10~\% improvement of the thermoelectric figure of merit was obtained. The V/W substitution causes i) a change of the main carrier type, from holes to electrons as evidenced from Seebeck and Hall measurements and ii) a substantial reduction of the lattice thermal conductivity due to a creation of lattice disorder by means of a distinct different mass and metallic radius upon the V/W substitution. Moreover $ZT$ values above 0.2 have been obtained. A microscopic understanding of the experimental data observed is revealed from ab-initio calculations of the electronic and phononic structure.