Decoupled charge and heat transport in Fe2VAl composite thermoelectrics with topological-insulating grain boundary networks

Fabian Garmroudi; Illia Serhiienko; Michael Parzer; Sanyukta Ghosh; Pawel Ziolkowski; Gregor Oppitz; Hieu Duy Nguyen; Cédric Bourgès; Yuya Hattori; Alexander Riss; Sebastian Steyrer; Gerda Rogl; Peter Rogl; Erhard Schafler; Naoyuki Kawamoto; Eckhard Müller; Ernst Bauer; Johannes de Boor; Takao Mori

doi:10.1038/s41467-025-57250-6

Decoupled charge and heat transport in Fe₂VAl composite thermoelectrics with topological-insulating grain boundary networks

Fabian Garmroudi (Korresp. Autor*in), Illia Serhiienko, Michael Parzer, Sanyukta Ghosh, Pawel Ziolkowski, Gregor Oppitz, Hieu Duy Nguyen, Cédric Bourgès, Yuya Hattori, Alexander Riss, Sebastian Steyrer, Gerda Rogl, Peter Rogl, Erhard Schafler, Naoyuki Kawamoto, Eckhard Müller, Ernst Bauer, Johannes de Boor (Korresp. Autor*in), Takao Mori (Korresp. Autor*in)

Veröffentlichungen: Beitrag in Fachzeitschrift › Artikel › Peer Reviewed

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 Fe₂VAl Heusler compounds. Here, we demonstrate an innovative approach, which bypasses this tradeoff: via liquid-phase sintering, we incorporate the archetypal topological insulator Bi_1−xSb_x between Fe₂V_0.95Ta_0.1Al_0.95 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 × 10⁻³ K⁻¹ (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.

Originalsprache	Englisch
Aufsatznummer	2976
Fachzeitschrift	Nature Communications
Jahrgang	16
Ausgabenummer	1
DOIs	https://doi.org/10.1038/s41467-025-57250-6
Publikationsstatus	Veröffentlicht - Dez. 2025

Fördermittel

Research in this paper was financially supported by the Japan Science and Technology Agency (JST) program MIRAI, JPMJMI19A1. Furthermore, F.G. acknowledges financial support by the Lions Club Wien St. Stephan and J.d.B. acknowledges funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), project number 520487260\u00A0The authors also acknowledge\u00A0the TU Wien Bibliothek for financial support through its Open Access Funding Programme.

ÖFOS 2012

104017 Physikalische Chemie
103006 Chemische Physik
205019 Materialwissenschaften

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10.1038/s41467-025-57250-6

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Zitationsweisen

Garmroudi, F., Serhiienko, I., Parzer, M., Ghosh, S., Ziolkowski, P., Oppitz, G., Nguyen, H. D., Bourgès, C., Hattori, Y., Riss, A., Steyrer, S., Rogl, G., Rogl, P., Schafler, E., Kawamoto, N., Müller, E., Bauer, E., de Boor, J., & Mori, T. (2025). Decoupled charge and heat transport in Fe₂VAl composite thermoelectrics with topological-insulating grain boundary networks. Nature Communications, 16(1), Artikel 2976. https://doi.org/10.1038/s41467-025-57250-6

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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 Fe2VAl Heusler compounds. Here, we demonstrate an innovative approach, which bypasses this tradeoff: via liquid-phase sintering, we incorporate the archetypal topological insulator Bi1−xSbx between Fe2V0.95Ta0.1Al0.95 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 × 10−3 K−1 (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.",

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Garmroudi, F, Serhiienko, I, Parzer, M, Ghosh, S, Ziolkowski, P, Oppitz, G, Nguyen, HD, Bourgès, C, Hattori, Y, Riss, A, Steyrer, S, Rogl, G, Rogl, P, Schafler, E, Kawamoto, N, Müller, E, Bauer, E, de Boor, J & Mori, T 2025, 'Decoupled charge and heat transport in Fe₂VAl composite thermoelectrics with topological-insulating grain boundary networks', Nature Communications, Jg. 16, Nr. 1, 2976. https://doi.org/10.1038/s41467-025-57250-6

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AU - Garmroudi, Fabian

AU - Serhiienko, Illia

AU - Parzer, Michael

AU - Ghosh, Sanyukta

AU - Ziolkowski, Pawel

AU - Oppitz, Gregor

AU - Nguyen, Hieu Duy

AU - Bourgès, Cédric

AU - Hattori, Yuya

AU - Riss, Alexander

AU - Steyrer, Sebastian

AU - Rogl, Gerda

AU - Rogl, Peter

AU - Schafler, Erhard

AU - Kawamoto, Naoyuki

AU - Müller, Eckhard

AU - Bauer, Ernst

AU - de Boor, Johannes

AU - Mori, Takao

PY - 2025/12

Y1 - 2025/12

N2 - 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 Fe2VAl Heusler compounds. Here, we demonstrate an innovative approach, which bypasses this tradeoff: via liquid-phase sintering, we incorporate the archetypal topological insulator Bi1−xSbx between Fe2V0.95Ta0.1Al0.95 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 × 10−3 K−1 (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.

AB - 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 Fe2VAl Heusler compounds. Here, we demonstrate an innovative approach, which bypasses this tradeoff: via liquid-phase sintering, we incorporate the archetypal topological insulator Bi1−xSbx between Fe2V0.95Ta0.1Al0.95 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 × 10−3 K−1 (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.

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