Low thermal conductivity of thermoelectric Fe₂VAl films

Abstract

Using molecular beam epitaxy techniques, we demonstrate the growth of thin-film Fe2VAl with a stoichiometric chemical composition. Even for a low-temperature-grown Fe2VAl film, the electrical properties are similar to those of bulk Fe2VAl reported previously. We note that the Seebeck coefficient (S) is slightly larger (∼40 µV/K) and the thermal conductivity (κ) is smaller [∼7.5 W/(m·K)] than those of bulk Fe2VAl [S = 30 µV/K, κ = 25 W/(m·K)]. This study shows that thermoelectric Fe2VAl films with relatively high performance compared to bulk Fe2VAl can be developed for potential applications.

Effect of Fe–V nonstoichiometry on electrical and thermoelectric properties of Fe2VAl films

“…Recently, by using molecular beam epitaxy (MBE) techniques, we demonstrated the growth of Fe 2 VAl epitaxial films with a perfectly stoichiometric chemical composition and a low thermal conductivity (κ) of ∼7.5 W=(m•K). 29) Even for a low-temperature-grown Fe 2 VAl film, the electrical properties exhibited almost the same features as bulk samples reported previously 6,30) and the value of S (∼40 µV=K) was almost equivalent to those of bulk samples. 7) We speculated that these results are attributed to the presence of a sharp pseudo-gap near the Fermi level even in the low-temperaturegrown Fe 2 VAl film.…”

Improved Power Factor in Self-Substituted Fe2VAl Thermoelectric Thin Films Prepared by Co-sputtering

“…The sputtering method has been mainly used for the development of full-Heusler Fe–V–Al thin films − and epitaxied Fe 2 VAl/W and Fe 2 VAl/Mo superlattices . Molecular beam epitaxy (MBE) techniques were also implemented, leading to Fe 2 VAl epitaxial films with a high crystallinity and a stoichiometric chemical composition. , Such studies mainly aimed at taking benefits of the thin film or superlattice forms to reach low thermal conductivity values such as λ = 4 W m –1 K –1 in ref , , , . However, a high power factor value could not be reached, except in ref , where P F was improved to 3.0 mW/K 2 m in Fe 1.93 V 1.05 Al 0.77 Si 0.24 .…”

Enhanced Thermoelectric Properties of SrSi2 Composite Films with Cubic and Layered Polymorphs

“…In this study, we assume small anisotropy of thermal conductivity. A similar assumption was used for estimating the TE performance of the film-based materials. ,, In particular, small anisotropy might be relevant for the films with I C /( I C + I L ) = 0.89 and 0.91, which show significantly reduced thermal conductivity, because they consist of matrix cubic phase and dispersed nanoprecipitates (layered phase). Due to the reduction of thermal conductivity shown in Figure c, the highest ZT over 0.4 was obtained for the film with I C /( I C + I L ) = 0.91, which is different from the films showing the highest power factor.…”