Improvement of thermoelectric performance by high-pressure torsion of off-stoichiometric Heusler compounds and elucidation of their mechanism
| Project/Area Number |
17K06771
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Physical properties of metals/Metal-base materials
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| Research Institution | Nagoya Institute of Technology |
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Principal Investigator |
NISHINO Yoichi 名古屋工業大学, 工学(系)研究科(研究院), 教授 (50198488)
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2018: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2017: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Keywords | ホイスラー合金 / 熱電変換 / 擬ギャップ / 高圧ねじり加工 / 非化学量論組成 / ゼーベック効果 / 超微細粒組織 / 熱伝導率 / 熱電変換材料 / ホイスラー化合物 / 熱電材料 |
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| Outline of Final Research Achievements |
The off-stoichiometric Fe2V0.90+xTa0.10Al1-x alloys show a large Seebeck coefficient and a low electrical resistivity, combined with a low thermal conductivity of 6 W/mK for the x=0.08 alloy, which leads to a large enhancement of the dimensionless figure of merit up to ZT=0.29 at 400K. High-pressure torsion (HPT) processing further reduces the thermal conductivity to about 4 W/mK, and even after annealing at 973 K, an ultra-fine grained structure with an average grain size of less than 100 nm can be retained due to the solute segregation of Ta along grain boundaries. Thus it is possible to retain the low thermal conductivity, in parallel with the restoration of a large power factor after recurrence of the Heusler-type structure, so that ZT reaches 0.37 at around 400 K.
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| Academic Significance and Societal Importance of the Research Achievements |
擬ギャップ系では，フェルミ準位における状態密度が小さいだけでなく状態密度の立ち上がりも急峻であるため，わずかな合金組成の変化でもゼーベック係数は敏感に増大する。これは擬ギャップ系の大きな特徴であり，従来のように構成元素の組成を大きく変化させてベストな熱電材料を探索する研究とは異なるものである。さらに、HPT加工のような強加工によって超微細粒組織を形成して熱伝導率を大幅に低減することで熱電性能を向上させる試みも独創的な方法である。高性能の熱電材料を自動車やオートバイなどの移動体における熱電発電に応用することにより，温室効果ガスの削減に貢献できる。
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Report
(5 results)
Research Products
(90 results)
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[Journal Article] Local structure and atomic dynamics in Fe2VAl Heusler-type thermoelectric material: The effect of heavy element doping2020
Author(s)
K. Kimura, K. Yamamoto, K. Hayashi, S. Tsutsui, N. Happo, S. Yamazoe, H. Miyazaki, S. Nakagami, J. R. Stellhorn, S. Hosokawa, T. Matsushita, H. Tajiri, A. K. R. Ang, Y. Nishino
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Journal Title
Physical Review B
Volume: 101
Issue: 2
Pages: 024302-024302
DOI
Related Report
Peer Reviewed / Int'l Joint Research
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