Fe isotope fractionation by Seebeck effect at the core-mantle boundary

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18657
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 17:Earth and planetary science and related fields
• Research Institution: Okayama University
• Principal Investigator: Yoshino Takashi 岡山大学, 惑星物質研究所, 教授 (30423338)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: 鉄同位体 / ゼーベック係数 / 酸化還元反応 / 核マントル境界 / 高圧実験

Outline of Final Research Achievements

Through this research project, many advances have been made in the development of thermoelectric measurements of mantle and nuclear materials under ultra-high pressure using a large-capacity multi-anvil press. It was confirmed that the redox reaction occurs in the electric field at the nuclear-mantle boundary expected by the Seebeck effect. The Seebeck coefficients of mantle minerals under high pressure have not been reported so far, but in this study, the Seebeck coefficients of olivine and wadsleyite, which are the most abundant minerals in the upper mantle minerals and the mantle transition zone, were successfully measured. These advances will lead to the determination of iron isotope fractionation by the Seebeck effect at the Earth's core-mantle boundary in the near future.

Free Research Field

高圧地球惑星科学

Academic Significance and Societal Importance of the Research Achievements

地球の核マントル境界で安定であると期待されるブリッジマナイトの直流電場における酸化還元反応の実験、ゼーベック係数の測定に至らなかったため、鉄同位体分別に関する見識を得ることはできなかったが、高温高圧下の熱電測定に向けた技術は直実に進展した。このことは多くの電極を小さい高圧セルに組み込む非常に難しい実験の超高圧下での実現に期待を持たせる。一方で地球内部での温度差に起因したゼーベック効果の研究は皆無であるが、その効果に一石を投じることができた。高圧下における熱電特性の研究の進展は、熱変換デバイスの評価、電極反応の研究の促進にも応用することで社会実装可能なデバイス開発にもつながることが期待される。