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Relaxation time of water's high-density amorphous ice phase
1Department of Physics, Umeå University, S-901 87 Umeå, Sweden.
Physical Review Letters
|December 31, 2005
Summary
High-density amorphous ice behaves as an ultraviscous liquid above 140 K. Its relaxation time is independent of pressure, suggesting a pressure-invariant glass transition temperature.
Area of Science:
- Physical Chemistry
- Materials Science
- Condensed Matter Physics
Background:
- Amorphous solid water exists in various forms, including high-density amorphous ice (HDA).
- Understanding the properties and phase transitions of amorphous water is crucial for planetary science and materials research.
Purpose of the Study:
- To investigate the dielectric relaxation and phase behavior of pressure-amorphized hexagonal ice.
- To determine the influence of pressure on the relaxation dynamics and glass transition of HDA.
Main Methods:
- Dielectric relaxation spectroscopy was employed to study hexagonal ice subjected to pressure amorphization.
- Measurements were conducted at varying temperatures and pressures, specifically around 140 K and 1 GPa.
Main Results:
- HDA exhibits relaxation in approximately 1 second at 140 K and 1 GPa.
- The relaxation process was found to be largely unaffected by pressure variations.
- The glass transition temperature of HDA was observed to be independent of pressure.
Conclusions:
- HDA behaves as an ultraviscous liquid above 140 K at 1 GPa.
- The glass transition temperature of HDA is close to that of amorphous solid water formed at atmospheric pressure.
- Pressure has a negligible effect on the relaxation dynamics of HDA within the studied conditions.
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