| 研究課題/領域番号 |
20K14580
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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 – 2024-03-31
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| キーワード | Ferropericlase / Grain boundaries / Ab initio simulations / Critical shear strength / Ferrous Iron / Spin transition / Plastic deformation / Earth's lower mantle |
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| 研究実績の概要 |
This year, we have studied the influence of ferrous Fe on the mechanical behavior of tilt grain boundaries in (Mg,Fe)O as a function of pressure. Atomistic simulations were conducted at the supercomputer systems of Nagoya University. Our results show that ferrous iron has a non-unique effect on the critical shear strength of grain boundaries. At pressures lower than 100 GPa, iron has the tendency to increase the critical grain boundary strength, whereas at higher pressures Fe induces a reduction of the critical strength. We also took the influence of the Fe spin state on grain boundary migration into account. We found that a spin transition of Fe in the grain boundary due to shear deformation only occurs in the direct vicinity of the spin transition pressure.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
The progress of research related to this grant develops as initially planned. All ab-initio simulations of this year were succesfully conducted at the supercomputer systems of the Information Technology Center at Nagoya University. The resulting data were analyzed at the Geodynamics Research Center of Ehime University. In summary, we were able to conduct our proposed research as planned and are preparing a manuscript on the results obtained in FY2020-2021.
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| 今後の研究の推進方策 |
We will start new computational research to constrain the extent of the Fe spin transition in ferropericlase across the pressure and temperature range of the lower mantle by including crystal imperfections, in particular iron disorder as a function of iron concentration in conjunction with the presence of grain boundaries. It is known that the presence of crystal imperfections influence the thermodynamic properties of minerals, but previous studies ignored these effects which might explain the discrepancy between current mineral physics models and seismic observations on the electronic spin transition of Fe in ferropericlase acrosse the lower mantle.
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| 次年度使用額が生じた理由 |
All initial planned business travels had to be cancelled in FY2021 due to the COVID-19 pandemic. Most conferences were converted into virtual meetings with significantly reduced registration fees. We plan to use the incurring amount in FY2022 on additional computational resources at the Information Technology Center, Nagoya University and on supplementary SSD to support our atomistic simulations and data processing. In addition, we may use the incurring budget for publication fees.
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