On the Heat Capacity, Entropy, and “Glass Transition” of Vitreous Ice
Abstract An analysis of the thermal properties of vitreous ice shows that both its heat capacity C p and its entropy above 100 K are partly configurational in origin. The configurational contribution increases with temperature, and the excess C p and entropy near the solid-liquid transformation temp...
| Published in: | Journal of Glaciology |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
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Cambridge University Press (CUP)
1978
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| Online Access: | http://dx.doi.org/10.1017/s0022143000033803 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000033803 |
| Summary: | Abstract An analysis of the thermal properties of vitreous ice shows that both its heat capacity C p and its entropy above 100 K are partly configurational in origin. The configurational contribution increases with temperature, and the excess C p and entropy near the solid-liquid transformation temperature are 36.7 and 2.1 J K -1 mo1 -1 , respectively. The increase is interpreted as indicating the onset of molecular mobility in vitreous ice. The configurational C p , of the melt of vitreous ice at 133.6 K, of ≈ 36.7 J K -1 mo1 -1 , is the same as the configurational C p , of water at 273 K. Thus, the short-range order in the melt differs little from that in water at 273 K. The maximum calorimetric residual entropy of vitreous ice is 13.4 J K -1 mol -1 , which is in fair agreement with the maximum value of 9.2 J K -1 mol -1 anticipated for a tetrahedral random-network model with fully disordered positions of H atoms. Thermodynamic consideration of a glass transition in supercooled liquid water indicates that there is no continuity of state between supercooled water and vitreous ice and, therefore, the structure and thermodynamic properties of a possible glassy state of water should be different from that of vapour-deposited vitreous ice. This paper is published in full in Philosophical Magazine , Eighth Ser., Vol. 35, No. 4, 1977, p. 1077-90. |
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