Entropy catastrophe and superheating of crystals

Lele, S. ; Ramachandra Rao, P. ; Dubey, K. S. (1988) Entropy catastrophe and superheating of crystals Nature, 336 (6199). pp. 567-568. ISSN 0028-0836

Full text not available from this repository.

Official URL: http://www.nature.com/nature/journal/v336/n6199/ab...

Related URL: http://dx.doi.org/10.1038/336567a0


Kauzmann has pointed out that at a temperature (Tk) far below the melting temperature (Tm) of a crystal, the entropies of an undercooled liquid and its corresponding equilibrium crystal tend to become equal. At temperatures below Tk, the crystal would have a greater entropy than its liquid. Such a catastrophe is avoided through a glass transition of the liquid above Tk. Fecht and Johnson have shown that such a transition should occur for aluminium at 0.23 Tm. A similar entropy catastrophe can also arise at a temperature, TiS, above Tm. Above TiS, the crystalline solid is once again expected to have an entropy greater than that of the liquid. Cahn has considered the implications of this idea with respect to the superheating of a solid. Here we present an alternative evaluation of the two temperatures of instability, Tk and TiS, from experimentally measurable parameters. Results for alkali metals show that the Kauzmann-type entropy catastrophe occurs at about half the absolute melting temperature, whereas we find that the entropy catastrophe as described by Fecht and Johnson occurs at twice the absolute melting temperature. For most solids, vaporization will probably intervene before the entropy catastrophe temperature above the melting temperature is reached.

Item Type:Article
Source:Copyright of this article belongs to Nature Publishing Group.
ID Code:34574
Deposited On:14 Apr 2011 14:29
Last Modified:06 Jul 2011 10:38

Repository Staff Only: item control page