Discovery of homogeneous-nucleation-based crystallization in simple glass-forming liquid of toluene below its glass-transition temperature

摘要

Crystallization process of toluene was investigated at low temperatures in the glass-transition region to examine the universality of the existence of homogeneous-nucleation-based (HNB) crystallization in fragile liquids, and to check the dependence of the crystallization process on the entropy of fusion, Delta(fus)S. The HNB crystallization was actually observed in the supercooled liquid of toluene as in the cases of o-terphenyl, salol, triphenylethylene and benzophenone, while toluene has much smaller Delta(fus)S than the latter substances. The magnitude of the crystallization rate was essentially reproduced by the numerical calculation with taking the nucleation-enhancement effect in the vicinity of the liquid-crystal interface and the high molecular-rearrangement rate due to a beta-process. These results suggest that the HNB crystallization and thus homogeneous-nucleation process are not affected so much by the magnitude of Delta(fus)S, and that the HNB crystallization is a universal phenomenon, independent of the magnitude of Delta(fus)S, in fragile liquids. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 27]