High-performance ZrNiSn-based half-Heusler thermoelectrics with hierarchical architectures enabled by reactive sintering.
basic_science · Level V
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- Record sourced from PubMed, PMID 40659688.
- Also identified by DOI 10.1038/s41467-025-61868-x and PMC identifier 12259942.
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Abstract
Half-Heusler compounds are promising thermoelectric materials for high-temperature applications, yet their performance is limited by high lattice thermal conductivity. Here, we present an alternative approach to synthesize ZrNiSn-based half-Heusler compounds with hierarchical architectures across multiple length scales. By utilizing short-duration mechanical alloying to produce nonequilibrium precursors, followed by reactive sintering, we enable precise control over phase composition and microstructural features. This approach results in multi-scale architectures comprising interstitial defects, grain boundaries, nanoprecipitates, and pores, enabling strong phonon scattering. The optimized Zr<sub>0.75</sub>Hf<sub>0.25</sub>NiSn<sub>0.99</sub>Sb<sub>0.01</sub> alloy exhibits a lattice thermal conductivity as low as 1.9 W m<sup>-1</sup> K<sup>-1</sup> and a high power factor of 50 µW cm<sup>-1</sup> K<sup>-2</sup>, yielding an impressive dimensionless figure of merit (zT) of 1.33 at 873 K. This performance surpasses that of ZrNiSn-based compounds synthesized via conventional methods such as arc melting and solid-state reaction. Our method, distinguished from conventional melting synthesis approaches through its simplicity, cost-effectiveness, and scalability, provides a versatile framework for achieving efficient hierarchical phonon scattering while preserving high carrier mobility in half-Heusler compounds and highlights the potential of reactive sintering for advancing thermoelectric materials.