Thermoelectric properties of tungsten-substituted Heusler Fe2VAl alloy

Mikami, Masashi; Kinemuchi, Yoshiaki; Ozaki, Kimihiro; Terazawa, Y.; Takeuchi, Tsunehiro

doi:10.1063/1.4710990

Cited by 103 publications

(94 citation statements)

References 20 publications

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“…We start our search from Fe2VAl, which, in spite of relatively modest TE properties (ZT ~ 0.13 -0.2 [24,58], PF = 4-6 mW/mK2 [24,28] at 300^400 K), is considered for low-cost TE applications [59], As clarified recently [21], it is an intrinsic semiconductor, with a low band gap between the highest valence bands of dominant Fe t2g character and a highly dispersive lowest conduction band of dominant V eg character (see the dotted line in Fig. 1).…”

Section: Low-dimensional Transport and Large Thermoelectric Power Facmentioning

confidence: 99%

Low-Dimensional Transport and Large Thermoelectric Power Factors in Bulk Semiconductors by Band Engineering of Highly Directional Electronic States

et al. 2015

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Thermoelectrics are promising for addressing energy issues but their exploitation is still hampered by low efficiencies. So far, much improvement has been achieved by reducing the thermal conductivity but less by maximizing the power factor. The latter imposes apparently conflicting requirements on the band structure: a narrow energy distribution and a low effective mass. Quantum confinement in nanostructures and the introduction of resonant states were suggested as possible solutions to this paradox, but with limited success. Here, we propose an original approach to fulfill both requirements in bulk semiconductors. It exploits the highly directional character of some orbitals to engineer the band structure and produce a type of low-dimensional transport similar to that targeted in nanostructures, while retaining isotropic properties. Using first-principle calculations, the theoretical concept is demonstrated in Fe2YZ Heusler compounds, yielding power factors 4 to 5 times larger than in classical thermoelectrics at room temperature. Our findings are totally generic and rationalize the search of alternative compounds with similar behavior. Beyond thermoelectricity, these might be relevant also in the context of electronic, superconducting, or photovoltaic applications.

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Section: Low-dimensional Transport and Large Thermoelectric Power Facmentioning

confidence: 99%

Low-Dimensional Transport and Large Thermoelectric Power Factors in Bulk Semiconductors by Band Engineering of Highly Directional Electronic States

et al. 2015

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“…The common strategy for reducing κ L of solids can be attained by enhancing the phonon scattering through introducing crystallographic disorder [35,36]. For example, the large κ L in Fe 2 VAl has been effectively reduced to 5 W/m K by substituting tungsten to the vanadium sites [37]. With this respect, the promising low κ L in Ru 2 NbGa has an advantage of improving the ZT = S 2 T /ρκ for thermoelectric applications.…”

Section: A Transport Measurementsmentioning

confidence: 99%

Ru2NbGa : A Heusler-type compound with semimetallic characteristics

et al. 2016

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The Heusler-type compound of Ru 2 NbGa has been successfully synthesized. X-ray analysis confirms that Ru 2 NbGa crystallizes in a cubic L2 1 structure. The electronic properties of Ru 2 NbGa have been characterized by means of the transport and nuclear magnetic resonance (NMR) measurements. The temperature dependence of the electrical resistivity exhibits a typical semimetallic behavior. The NMR spin-lattice relaxation rate shows activated behavior at higher temperatures, attributing to the thermally excited carriers across a pseudogap. We have also deduced a low Fermi-level density of states (DOS), being consistent with the semimetallic characteristic for Ru 2 NbGa. In addition, we have performed first-principles total-energy calculations including G 0 W 0 and GW 0 corrections for band gaps to investigate the electronic band structure of Ru 2 NbGa. The calculated result reveals an indirect overlap between electron and hole pockets that leads to a residual DOS at the Fermi level, providing a consistent explanation for the experimental observations.

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“…without greatly altering the electron transport properties [7][8][9] . The consequently obtained ZT, however, was still smaller than 0.3.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric Properties of Fe<sub>2</sub>VAl-Based Thin-Films Deposited at High Temperature

2016

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Fe 2 VAl-based thin-lms were prepared using radio frequency magnetron sputtering technique at various substrate temperatures up to 1073 K. At low substrate temperature below 773 K, we did not observe any evidences of L2 1 Heusler phase but the epitaxially grown B2-phase, which is considered as a chemically disordered structure of Heusler-phase. At high substrate temperatures above 773 K, L2 1 ordering became observable and its volume fraction was increased with increasing the substrate temperature. The sample deposited at 1073 K, that was considered as the highly ordered L2 1 -phase, possessed S ≈ −120 μV K −1 at around 340 K, and this value is almost the same with that previously reported for bulk samples. The power factor indicated large values exceeding 2.0 mWmat the room temperature. The thermal conductivity of Fe 2 VAl thin-lm was reduced to a half value of the bulk. As a result, the maximum gure of merit was almost doubled to 0.07 at 400 K from 0.04 of bulk samples.

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Thermoelectric properties of tungsten-substituted Heusler Fe2VAl alloy

Cited by 103 publications

References 20 publications

Low-Dimensional Transport and Large Thermoelectric Power Factors in Bulk Semiconductors by Band Engineering of Highly Directional Electronic States

Low-Dimensional Transport and Large Thermoelectric Power Factors in Bulk Semiconductors by Band Engineering of Highly Directional Electronic States

Ru2NbGa : A Heusler-type compound with semimetallic characteristics

Thermoelectric Properties of Fe<sub>2</sub>VAl-Based Thin-Films Deposited at High Temperature

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