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标题：Structural stability of methane hydrate at high pressures
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作者：Jinfu Shu ; Xiaojia Chen ; I.-Ming Chou 等
期刊名称：Geoscience Frontiers
印刷版ISSN：1674-9871
出版年度：2011
卷号：2
期号：1
页码：93-100
DOI：10.1016/j.gsf.2010.12.001
语种：English
出版社：Elsevier
摘要：AbstractThe structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure types I, II, and H in diamond-anvil cells. The diffraction data for types II (sII) and H (sH) were refined to the known structures with space groupsFd3mandP63/mmc, respectively. Upon compression, sI methane hydrate transforms to the sII phase at 120 MPa, and then to the sH phase at 600 MPa. The sII methane hydrate was found to coexist locally with sI phase up to 500 MPa and with sH phase up to 600 MPa. The pure sH structure was found to be stable between 600 and 900 MPa. Methane hydrate decomposes at pressures above 3 GPa to form methane with the orientationally disorderedFm3mstructure and ice VII (Pn3m). The results highlight the role of guest (CH4)-host (H2O) interactions in the stabilization of the hydrate structures under pressure.
关键词：KeywordsenMethane hydrateStructural stabilityHigh pressure