| 研究課題/領域番号 |
20K14580
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| 研究種目 |
若手研究
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| 配分区分 | 基金 |
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| 審査区分 |
小区分17040:固体地球科学関連
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| 研究機関 | 愛媛大学 |
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研究代表者 |
RITTERBEX S 愛媛大学, 地球深部ダイナミクス研究センター, 特定研究員 (00791782)
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| 研究期間 (年度) |
2020-04-01 – 2023-03-31
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| 研究課題ステータス |
中途終了 (2022年度)
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| 配分額 *注記 |
4,160千円 (直接経費: 3,200千円、間接経費: 960千円)
2023年度: 910千円 (直接経費: 700千円、間接経費: 210千円)
2022年度: 1,040千円 (直接経費: 800千円、間接経費: 240千円)
2021年度: 1,040千円 (直接経費: 800千円、間接経費: 240千円)
2020年度: 1,170千円 (直接経費: 900千円、間接経費: 270千円)
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| キーワード | Grain boundaries / Ferropericlase / Mechanical behavior / Earth's mantle / Super-Earth exoplanets / Iron partitioning / Ab initio simulations / Critical shear strength / Ferrous Iron / Spin transition / Plastic deformation / Earth's lower mantle / Ideal shear strength / Grain boundary mobility / Super-Earth's mantle / Mantle rheology / Mantle defect chemistry |
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| 研究開始時の研究の概要 |
The dynamics of the Earth, including its plate tectonics, is controlled by the flow of rocks through the motion of crystal defects. Atomic diffusion is a key process controlling this flow behavior which relies on the poorly constrained redox state of the rocky part of the Earth's deep interior. Using a theoretical mineral physics approach based on the "ab initio" methods, this research, conducted by Dr. Sebastian Ritterbex from the Geodynamics Research Center, Ehime University, aims to constrain the relation between the point defect chemistry and flow behavior of the Earth's deep interior.
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| 研究実績の概要 |
This project aimed investigating the relation between crystal chemistry, lattice defects and the mechanical behavior of ferropericlase. We carried out atomistic simulations based on the density functional theory, conducted on Type I and II subsystems of the Information Technology Center at Nagoya University.
Results show iron to prefer specific grain boundary sites affecting the pressure-induced spin transition and grain boundary partitioning of iron. With those data, ideal shear strengths were determined. It has been shown that high-angle grain boundary motion is particularly accommodated by either shear-coupled migration or grain boundary sliding. The mechanical strengths were found to strongly vary with pressure resulting in grain boundary hardening and weakening across a broad pressure range. By considering the influence of iron spin state on grain boundary migration, we have shown that ferrous iron has a non-unique effect on the criticial shear strength of grain boundaries. In the mantle of super-Earth exoplanets, significant grain boundary weakening is observed to occur, providing a new mechanism of enhanced ductility with depth.
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