| Project/Area Number |
09640570
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | Osaka University |
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Principal Investigator |
YOSHIASA Akira Graguate School of Science, Osaka University Associate professor, 大学院・理学研究科, 助教授 (00191536)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1998: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1997: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Keywords | the Eath internal materials / diffraction method / EXAFS spectroscopy / thermal motion / ionic conduction / effective pair potential / phase transition / molecular dynamic simulation / 回析法 / 有効二体間ポランシャル / 非調和熱振動解析 / 下部マントルの導電機構 / ペロブスカイト型固溶体 / EXAFS / 固体イオニクス / 有効二体間ポテンシャル / 化学結合性 / イオン移動の活性化エネルギー |
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| Research Abstract |
The usefulness of Extended X-ray absorption fine structure (EXAFS) spectroscopy arid diffraction method in studying vibration dynamics has been discussed by this study. Our studies have explored the possibility that EXAFS and diffraction experiments provide an effective interatomic potential and an effective adiabatic one-particle potential with temperaturew-independent shape, respectively, from each Debye-Waller factor. EXAFS method has been utilized as a reliability test for the interatomic potentials in molecular dynamics simulation. Reliable representation of interatomic potential is important for better understanding the thermal properties of the Earth intrenal materials.
Precise crystal structure and thermal properties in many materials in the Earth's mantle such as majorite garnet, magnesia wustite, MgSiO3 perovskite, Mg2SiO4 spinel and stishovite heve been revealed by the EXAFS and diffraction method. In the potential parameter fitting, we have directly carried out the numerical integration of the EXAFS function and evaluated the anharmonic effective pair potential. The phonon energies have been estimated using the potential parameter by calculating the dynamical matrix. The Gruneisen parameter is also calculated from the obtained parameter values. The vibrational motion of pair of atoms depend on the lattice type and chemical bonding. Vibrational properties in materials is influenced not only by pressure but also by coordination number The effective pair potential is affected largely by the change in coordination number at a phase transition point.. High pressure phase with higher coordination number has broader effective pair potential than low pressure phase with lower coordination number. Ionic conduction mechanism in menerals has been discussed based on the effective pair potential and distribution of cation-anion distances. The strongly correlated displacement can be attributed to covalent bonds which interact locally.
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