| Project/Area Number |
20K14580
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 17040:Solid earth sciences-related
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| Research Institution | Ehime University |
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Principal Investigator |
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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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Project Status |
Discontinued (Fiscal Year 2022)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2023: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2022: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2021: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2020: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
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| Keywords | 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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| Outline of Research at the Start |
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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| Outline of Annual Research Achievements |
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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