Decoupled charge and heat transport in Fe<sub>2</sub>VAl composite thermoelectrics with topological-insulating grain boundary networks.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40140370.
- Also identified by DOI 10.1038/s41467-025-57250-6 and PMC identifier 11947127.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Decoupling charge and heat transport is essential for optimizing thermoelectric materials. Strategies to inhibit lattice-driven heat transport, however, also compromise carrier mobility, limiting the performance of most thermoelectrics, including Fe<sub>2</sub>VAl Heusler compounds. Here, we demonstrate an innovative approach, which bypasses this tradeoff: via liquid-phase sintering, we incorporate the archetypal topological insulator Bi<sub>1-x</sub>Sb<sub>x</sub> between Fe<sub>2</sub>V<sub>0.95</sub>Ta<sub>0.1</sub>Al<sub>0.95</sub> grains. Structural investigations alongside extensive thermoelectric and magneto-transport measurements reveal distinct modifications in the microstructure, a reduced lattice thermal conductivity and a simultaneously enhanced carrier mobility arising from topologically protected charge transport along the grain boundaries. This yields a huge performance boost, resulting in one of the highest figure of merits among both half- and full-Heusler compounds, z ≈ 1.6 × 10<sup>-3</sup> K<sup>-1</sup> (zT ≈ 0.5) at 295 K. Our findings highlight the potential of topological-insulating secondary phases to decouple charge and heat transport and call for more advanced theoretical studies of multiphase composites.