Phase Transition of a Structure II Cubic Clathrate Hydrate to a Tetragonal Form |
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| Authors: | Dr Satoshi Takeya Dr Hiroshi Fujihisa Dr Hiroshi Yamawaki Dr Yoshito Gotoh Prof Ryo Ohmura Dr Saman Alavi Dr John A Ripmeester |
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| Institution: | 1. National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan;2. Keio University, Kohoku-Ku, Yokohama, Japan;3. National Research Council of Canada, Ottawa, ON, Canada |
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| Abstract: | The crystal structure and phase transition of cubic structure II (sII) binary clathrate hydrates of methane (CH4) and propanol are reported from powder X‐ray diffraction measurements. The deformation of host water cages at the cubic–tetragonal phase transition of 2‐propanol+CH4 hydrate, but not 1‐propanol+CH4 hydrate, was observed below about 110 K. It is shown that the deformation of the host water cages of 2‐propanol+CH4 hydrate can be explained by the restriction of the motion of 2‐propanol within the 51264 host water cages. This result provides a low‐temperature structure due to a temperature‐induced symmetry‐lowering transition of clathrate hydrate. This is the first example of a cubic structure of the common clathrate hydrate families at a fixed composition. |
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| Keywords: | clathrates gas hydrates inclusion compounds phase transitions powder X-ray diffraction |
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