Reduction in the thermal conductivity of Heusler-type thermoelectric material thin film by controlling structural defects

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K13789
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 21050:Electric and electronic materials-related
• Research Institution: Osaka University
• Principal Investigator: Yamada Shinya 大阪大学, 基礎工学研究科, 助教 (30725049)
• Project Period (FY): 2018-04-01 – 2020-03-31
• Keywords: ホイスラー合金 / 熱電変換材料 / 薄膜 / 熱伝導率

Outline of Final Research Achievements

Fe-based Heusler alloys such as Fe2VAl and Fe2TSi have been expected as a next-generation thermoelectric material to replace Bi-Te compounds from the viewpoint of not containing toxic elements. In this project, for applications as a potential thermoelectric material, we examined the possibility of improvement in thermoelectric performance of thin-film Fe-based Heusler alloys. First, we experimentally find that the presence of the V-Si antisite defect in the Si-substituted Fe2VAl films contributes to the significant reduction in the thermal conductivity. Second, we experimentally clarified the room-temperature Seebeck coefficient and thermal conductivity values of 101 uV/K and 5.6 W/(mK), respectively, for the Fe2TiSi films. These results will open a new way for Fe-based full-Heusler alloy thermoelectric materials.

Free Research Field

電気電子材料

Academic Significance and Societal Importance of the Research Achievements

Fe系フルホイスラー合金は，低環境負荷で高い熱電性能が期待されている一方，その作製の難しさから，信頼性の高い薄膜作製技術の開発や物性評価が十分に行われてこなかった．本研究は，Fe系フルホイスラー合金薄膜の作製技術の確立，電気・熱電特性の制御を実証した点に加えて，これまで議論されてこなかった熱電物性を制御する新たな手法を提言した．低環境負荷の新しい熱電変換材料の薄膜の高性能化の指針を提示した点に，産業，学術面の両方で大変意義のある研究であるといえる．