2001 Fiscal Year Final Research Report Summary
Study on local structure of silicate perovskites by NMR spectroscopy
| Project/Area Number |
11304036
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 | OKAYAMA UNIVERSITY |
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Principal Investigator |
KANZAKI Masami Institute for Study of the Earth's Interior, Associate Professor, 固体地球研究センター, 助教授 (90234153)
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| Co-Investigator(Kenkyū-buntansha) |
薛 献宇 岡山大学, 固体地球研究センター, COE研究員
KATSURA Tomoo Institute for Study of the Earth's Interior, Associate Professor, 固体地球研究センター, 助教授 (40260666)
ITO Eiji Institute for Study of the Earth's Interior, Professor, 固体地球研究センター, 教授 (00033259)
XUE Xianyu Institute for Study of the Earth's Interior, COE Postdoc. Fellow
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| Project Period (FY) |
1999 – 2001
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| Keywords | NMR spectroscopy / high pressure mineral / silicate perovskite / local structure / mantle |
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| Research Abstract |
The results are summarized below.
1. Setup of NMR spectrometer: We have introduced a 400MHz solid MAS NMR spectrometer to our institute. Now routine measurements of MAS NMR for ^<29>Si, ^<27>Al, ^<23>Na, ^1H etc are possible. New probe introduced in 2001 allows us to study low frequency nuclei such as ^<25>Mg, and to conduct multi-quantum NMR experiments. The instrument is now open to external researchers for cooperative research projects.
2. Ab initio calculation of chemical shifts: Using molecular orbital technique, we have calculated wide varieties of silicate clusters relevant to melt or glass structures. Calculated shifts well reproduced observed chemical shifts. In order to better assignments of NMR spectra, we also calculated experimentally not-well characterized local structures, such as Al triclusters.
3. First-principles calculation of electric field gradient (EFG): In order to predict EFG at quadrupolar nuclei such as Al in minerals, first-principles calculations have been conducted. Large EFG in Ca_2Al_2O_5 oxygen-defected perovskite was predicted. For example.
4. Structure of hydrous glasses: In order to investigate water and silicate melt interaction, we have studied hydrous melts using ^<29>Si and ^1H MAS NMR and ^1H-^<29>Si CP MAS NMR. The result shows that water causes melt structure polymerize. This is contrary to common observation, and is very important discovery.
5. Structure of sulfur-bearing glasses: In order to see how sulfur dissolves in silicate melts, S-bearing glasses were studied by ^<29>Si MAS NMR. When sulfur is added as native S, melt structure was polymerized.
6. Hydration of minerals: Hydration processes of forsterite, enstatite and diopside have studied using ^<29>Si and ^1H MAS NMR. We observed polymerization in hydration layer in all systems studied.
7. Crystal chemistry of water-silicate interaction: From these studies, we have gained better crystal chemical insights of the interaction between water and silicate.
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