The first order transition recently postulated by Cohen and Grest to lie somewhere between the normal glass transition temperature Tg and the so-called "ideal glass" transition temperature To. will be difficult to observe if it exists because of the long relaxation times needed for any structural changes in this temperature regime. We have recently identified a system in which the possibility for such a transition occurring would seem unsually high. The glass Ag7I4AsO4 has a structural relaxation function such that it equilibrates at room temperature, 40 K below Tg, in a matter of weeks. Samples of this glass which have lain in an equilibrium state 40 K below Tg for a year or more have been characterized thermally to examine the possibility that a first order transition has occurred. The conclusion is that despite the favorable circumtances of the case, and the large thermal spike observed on reheating the annealed glass, nothing unaccounted for by normal annealing processes has occurred.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry