| Project/Area Number |
18340126
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Solid earth and planetary physics
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| Research Institution | University of Tsukuba |
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Principal Investigator |
HIRAI Hisako University of Tsukuba, 地球深部ダイナミクス研究センター, グローバルCOE教授 (60218758)
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| Co-Investigator(Kenkyū-buntansha) |
山本 佳孝 産業総合技術研究所, メタンハイドレート研究ラボ, 主任研究員 (80358283)
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| Co-Investigator(Renkei-kenkyūsha) |
YAMAMOTO Yoshitaka 産業技術総合研究所, メタンハイドレートセンター, チームリーダー (80358283)
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| Project Period (FY) |
2006 – 2009
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| Project Status |
Completed (Fiscal Year 2009)
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| Budget Amount *help |
¥14,730,000 (Direct Cost: ¥14,100,000、Indirect Cost: ¥630,000)
Fiscal Year 2009: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2008: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥12,000,000 (Direct Cost: ¥12,000,000)
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| Keywords | 内部構造 / メタンハイドレート / 高温・高圧 / 海王星 / 氷惑星 / ダイヤモンドアンビルセル / レーザー加熱 / メタン |
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| Research Abstract |
This study intended firstly to clarify phase changes and properties of methane hydrate and solid methane under high-pressures and high-temperatures comparable to those of interiors of icy planets and satellites, and then to infer the states and internal structures of the icy bodies based on the experimental results. High-pressures and high-temperatures were generated by using laser heated diamond anvil cells (LHDAC), and characterization of the samples were made by X-ray diffractometry and Raman spectroscopy. For methane hydrate, the high-pressure phase of filled ice Ih structure survived at least up to 90 GPa. The reasons for the remarkable high-pressure stability were examined. The orentaional ordering of guest methane molecules and symmetrization of hydrogen bond of host molecules might substantiate the outstanding stability of the filled ice Ih structure under extremely high pressure. For solid methane, X-ray diffractometry and Raman spectroscopy revealed the melting conditions to be above approximately 1100 K in a wide pressure range of 10 to 80 GPa. Above 1100 K, polymerizations occurred to produce ethane molecules and further polymerized hydrocarbons. Above 3000 K, diamond was produced. These changes proceeded depending on temperature rather than on pressure. The present study provides some experimental supports to theoretical predictions that the middle ice layer of giant planets such as Neptune and Uranus melts into a hot methane-rich ocean, and will help to improve our understanding of the chemical process of the giant planets' interiors.
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