Enthalpy Relaxation Phenomenon in a Heavy Ice Crystal
Abstract The heat capacities of quenched and annealed heavy ice Ih were measured in the temperature range 14 to 300 K by an adiabatic calorimeter. A relaxational thermal anomaly was found at around 115 K and this phenomenon was ascribed to the onset of deuteron ordering in the crystal. The average a...
| Published in: | Journal of Glaciology |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Cambridge University Press (CUP)
1978
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1017/s0022143000033931 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000033931 |
| Summary: | Abstract The heat capacities of quenched and annealed heavy ice Ih were measured in the temperature range 14 to 300 K by an adiabatic calorimeter. A relaxational thermal anomaly was found at around 115 K and this phenomenon was ascribed to the onset of deuteron ordering in the crystal. The average activation enthalpy of the relaxational process was determined to be (26±5) kJ mol -1 . Residual entropies of the crystal were recalculated on the basis of the present heat-capacity data combined with the revised values for enthalpy of vaporization, saturated vapour pressure, and spectroscopic entropy. They are (3.47±0.41 J K -1 mol -1 for the quenched crystal and (3.44±0.41) J K -1 mol -1 for a crystal annealed at 102-106 K for 264 h. The characteristics and the origin of the anomaly are discussed in comparison with that of ordinary ice. This paper has been accepted for publication in full in a forthcoming issue of the Journal of Glaciology . |
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