Development of metal/Mg2Si composite materials with high thermoelectric efficiency

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H03398
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Composite materials/Surface and interface engineering
• Research Institution: Tohoku University
• Principal Investigator: HAYASHI Kei 東北大学, 工学研究科, 准教授 (70360625)
• Co-Investigator(Kenkyū-buntansha): 宮崎 讓 東北大学, 工学研究科, 教授 (40261606)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 熱電変換 / コンポジット / 金属相 / マグネシウムシリサイド

Outline of Final Research Achievements

We prepared composite thermoelectric materials consisting of Mg2Si and metal to enhance power factor PF and dimensionless figure-of-merit zT of Mg2Si. As a metal, Mg, Al, and Ni were selected. According to the effective-medium theory, it was predicted that PF and zT are enhanced for all these metals; however, it is valid for the Mg/Mg2Si and Al/Mg2Si composite materials. In the case of Ni, PF and zT decreased by preparing the Ni/Mg2Si composite material. This is due to difference in microstructures and barrier heights at the interface between Mg2Si and metal. The maximum zT value of 0.6 (800 K) was obtained for the Al/Mg2Si composite material by the refinement of the microstructure of the dispersed Al metal phase in Mg2Si, which lead to increase in electrical conductivity and decrease thermal conductivity. This value was higher than an partially Al-substituted Mg2Si materials.

Free Research Field

応用物性・結晶工学

Academic Significance and Societal Importance of the Research Achievements

本研究により、金属粒界相を用いてMg2Siの出力因子PFと無次元性能指数zTを両方向上できることが明らかになった。微細組織の形態を制御することで、電気伝導率の増加だけなく、熱伝導率を低減することができる。本成果は、Mg2Siだけでなく、他の熱電材料にも適用できることから、高効率の熱電材料開発を加速するとともに、化石燃料を使用せず、有害ガスや騒音を出さないクリーンな熱電発電の普及に貢献するものと期待される。