Metastability and instability of organic crystalline substances

The Journal of Physical Chemistry. B
Stanislaw L Randzio, Andrzej Kutner

Abstract

Discovery of an unexpected and thermodynamically paradoxical transition from a crystalline state to an amorphous dense glassy state induced in pure organic substances by a direct absorption of a quantity of heat under atmospheric pressure and its detailed analysis performed with the use of a sensitive scanning transitiometer are described. The obtained results present first experimental precise evidence for understanding the mechanism of such a structural instability of crystalline substances in the form of c-a transition. The observed c-a transition is a purely physical phenomenon, occurring between two nonequilibrium states, a metastable crystalline phase and a dense glass, occurring through a local transient phenomenon of virtual melting. The metastable state of a crystalline substance can be caused by existence of a number of crystalline imperfections created either during crystallization or by external actions. By measuring extremely sensitive energetic effects, we found the present method to be helpful for quantitative determination of the critical number of imperfections in a crystalline solid, which make it metastable and for an indication under which conditions such a metastable crystalline form becomes unstable. By pe...Continue Reading

References

Feb 9, 1995·Nature·K Duff, J Hardy
Dec 14, 1987·Physical Review Letters·H Hsieh, S Yip
Feb 15, 2003·Journal of Pharmaceutical Sciences·Manish K GuptaRobin H Bogner
Sep 23, 2003·Biophysical Chemistry·Frank H Stillinger, Pablo G Debenedetti
Oct 4, 2005·Physical Review Letters·Valery I Levitas
May 29, 2007·International Journal of Pharmaceutics·Bernard Legendre, Stanislaw L Randzio

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Citations

Apr 12, 2012·Cyberpsychology, Behavior and Social Networking·David R EwoldsenJamie DeCoster
Apr 22, 2010·Analytical Chemistry·Sergey Vyazovkin

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