MISC

2002年1月10日

In situ observations of high-pressure phase transformations in a synthetic methane hydrate

Journal of Physical Chemistry B
  • Hiroyasu Shimizu
  • ,
  • Tatsuya Kumazaki
  • ,
  • Tetsuji Kume
  • ,
  • Shigeo Sasaki

106
1
開始ページ
30
終了ページ
33
記述言語
英語
掲載種別
DOI
10.1021/jp013010a

A methane hydrate (MH) single crystal was synthesized in a diamond anvil cell to investigate its intrinsic high-pressure properties. With increasing pressure, the cubic si phase of MH changed to the MH-II phase at P = 0.9 GPa and room temperature, and this phase remains stable up to P = 1.9 GPa, which was visually observed by optical microscopy. In situ Raman spectra for CH4 molecules encaged in different cages of MH-II show two vibrational bands
the higher frequency band shows a remarkable increase in its frequency versus pressure (17.0 cm-1/GPa), and the lower band shows a progressive increase in frequency with pressure (6.3 cm-1/GPa). These results are interpreted on the basis of two different structures recently reported for MH-II. Above P = 1.9 GPa, MH-II crystals visually decomposed and the O-H stretching Raman band of host cages became unobservable, indicating no more existence of the cage structure. Raman spectra of CH4 molecules in MH-III show almost the same behavior as those of pure solid methane up to at least 5.2 GPa, which may be consistent with the existence of a new type of MH.

リンク情報
DOI
https://doi.org/10.1021/jp013010a
ID情報
  • DOI : 10.1021/jp013010a
  • ISSN : 1089-5647
  • SCOPUS ID : 0037050586

エクスポート
BibTeX RIS