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Updated: Oct 13, 2025
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Methane Hydrate Crystallization on Sessile Water Droplets
Published on: May 26, 2021
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Ethane and methane at high pressures: Structure and stability.
Elissaios Stavrou1, Alexander A Maryewski2, Sergey S Lobanov1
1Earth and Planets Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA.
The Journal of Chemical Physics
|November 14, 2021
Summary
Researchers studied ethane and methane under high pressure using experiments and theory. Ethane shows new crystal structures and phase transitions, while methane
Area of Science:
- Materials Science
- High-Pressure Physics
- Solid-State Chemistry
Background:
- Understanding the behavior of simple hydrocarbons like ethane and methane under extreme conditions is crucial for planetary science and materials development.
- Previous studies have characterized methane's high-pressure phases, but ethane's behavior at room temperature and high pressures remains less understood.
Purpose of the Study:
- To experimentally and theoretically investigate the high-pressure behavior of ethane and methane at 300 K up to 120 GPa.
- To determine the crystal structures and phase transitions of ethane under high pressure.
- To establish the equation of state (EOS) for both ethane and methane for comparative stability analysis.
Main Methods:
- Combined experimental techniques: X-ray diffraction and Raman spectroscopy.
- Theoretical calculations: USPEX ab initio evolutionary structural search algorithm.
- High-pressure generation: Diamond anvil cells (implied).
Main Results:
- Ethane crystallization point determined at 2.7 GPa at room temperature.
- A novel orientationally disordered (plastic) low-pressure crystal structure (phase A) for ethane was identified.
- A new pressure-induced phase transition in ethane at 13.6 GPa to a monoclinic phase B was discovered and its structure solved.
- Experimental X-ray diffraction data for methane confirmed previously reported high-pressure structures and equation of state (EOS).
- Equations of state (EOS) for both ethane and methane were determined.
Conclusions:
- Ethane exhibits unique high-pressure behavior with previously unknown crystal structures and phase transitions at room temperature.
- The determined EOS for ethane and methane provide a foundation for understanding their relative stability under extreme pressures.
- This study advances the understanding of hydrocarbon behavior in high-pressure environments relevant to planetary interiors.
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