In-situ measurement at high pressure and temperature for iron state in lower mantle minerals

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K23457
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0204:Astronomy, earth and planetary science, and related fields
• Research Institution: Hiroshima University (2020-2021); The University of Tokyo (2019)
• Principal Investigator: Kakizawa Sho 広島大学, 先進理工系科学研究科(理), 助教 (10846819)
• Project Period (FY): 2019-08-30 – 2022-03-31
• Keywords: ダイヤモンドアンビルセル / 高圧 / X線吸収微細構造 / 放射線X線回折 / 鉄 / スピン転移

Outline of Final Research Achievements

Minerals in the Earth's interior contain iron, which is known to occur spin transition at high temperatures and pressures. When iron in minerals occurs in the spin transition, it significantly changes the lattice volume, compressibility, elastic wave velocity, thermal conductivity, electrical conductivity, and other physical properties of the mineral. There is a simultaneous effect on the chemical composition and structure of the lower mantle and mantle convection, as predicted from the seismic wave velocity structure. However, there are experimental and technical difficulties in determining the spin state at high temperatures and pressures, and a unified view has not yet been reached. In this study, I have laid the foundation for a new method to determine the spin state under high pressure and high temperature by using X-ray absorption fine structure.

Free Research Field

高圧地球科学

Academic Significance and Societal Importance of the Research Achievements

本研究の成果は、高圧下におけるスピン状態を決定する新たな手法を提案するものであり、統一的な見解が得られていないマントルに存在している鉱物中のスピン転移に関する研究を促進する可能性がある。また、X線吸収微細構造において結合距離の変化からの間接的な方法であるがスピン転移を捉えられる可能性があることが実験的に示された。