Thermoelectric Transport of a Novel Zr-Based Half-Heusler High-Entropy Alloy

The high-entropy concept, extensively studied in alloys and ceramics, has produced intriguing results, but its use in thermoelectric materials is still in its infancy. This study introduces a pioneering high-entropy half-Heusler (hH) alloy, ZrTiNiFeSnSb, synthesized via arc melting and heat treatment. Phonon scattering from multiple elements significantly reduces the lattice thermal conductivity of the alloy, which decreases to a minimum of 3.5 Wm-1 K-1 (700 K) in this material. The experimental thermal data matches the density functional theory calculations for phonon dispersion, phonon group velocity, and Gruneisen parameters. This demonstrates that crystal distortion induced anharmonicity slows the alloy's phonon heat transport, which is suitable for thermoelectric applications. Notably possessing elevated electrical conductivity and a moderate Seebeck coefficient, this high-entropy hH alloy emerges as a promising thermoelectric material for energy harvesting. The high-entropy alloy ZrTiNiFeSnSb, a multielement half Heusler, exhibits a p-type thermoelectric material with an efficiency (ZT) of approximate to 0.006 at 773 K. First-principles calculations indicate the potential for low lattice thermal conductivity and exhibit a value of 3.5 W mK-1 obtained at 700 K. The graph includes an inset depicting a model unit cell of the alloy.image (c) 2023 WILEY-VCH GmbH

Automated summary

This study introduces a pioneering high-entropy half-Heusler alloy, ZrTiNiFeSnSb, which significantly reduces the lattice thermal conductivity through phonon scattering from multiple elements. It shows elevated electrical conductivity and a moderate Seebeck coefficient, making it a promising thermoelectric material.