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Updated: Mar 18, 2026
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Methane Hydrate Crystallization on Sessile Water Droplets
Published on: May 26, 2021
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Structural and dynamic studies on vapor-deposited amorphous methane hydrate.
Menghan Zhang1, Hiroshi Akiba1, Iwao Matsuda1
1Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
The Journal of Chemical Physics
|March 16, 2026
Summary
Amorphous methane hydrate (a-MH) exhibits hindered methane molecule rotation. Annealing improves cage structure and allows more spherical methane rotation, approaching structure I hydrate properties.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Chemistry
Background:
- Methane hydrate is a potential energy resource.
- Understanding methane molecule rotations in hydrates is crucial.
- Amorphous methane hydrate (a-MH) presents unique structural and dynamic properties.
Purpose of the Study:
- Investigate the local amorphous structure of a-MH.
- Analyze the dynamics of guest methane molecules within the hydrate cages.
- Determine the effects of annealing on a-MH structure and methane dynamics.
Main Methods:
- Low-temperature vapor deposition at 7 K to form a-MH.
- X-ray and neutron diffraction for structural analysis.
- Quasi-elastic neutron scattering and adiabatic calorimetry for dynamic studies.
Main Results:
- As-deposited a-MH shows disordered, distorted cages with hindered methane rotation.
- Annealing at 120 K induces local hydrogen-bond ordering and more defined cages.
- Methane molecule rotation becomes more spherical after annealing, resembling structure I hydrate.
Conclusions:
- Annealing transforms the amorphous structure towards ordered cages, influencing guest molecule dynamics.
- The rotational potential barrier for methane molecules is higher in as-deposited a-MH.
- a-MH can be controllably modified to approach crystalline hydrate characteristics.
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