FINITE-TIME THERMODYNAMICS OF A SCHOTTKY ANOMALY - THE MINIMAL GLASS-TRANSITION

It has been assumed that, for a glass transition to exist in a reorientationally disordered crystal, some symmetry departure must exist. This assumption has suggested a two-level model which depends on a symmetry departure parameter, DELTA-E, and whose behaviour can be described in terms of a population temperature analogous to a fictive temperature. This model reproduces characteristic properties of systems that vitrify, such as different behaviours at decreasing and increasing temperatures. It also allows the calculation of the heat capacity increment, DELTA-C(p,g), at the glass transition as a function of heat treatment. It is shown that DELTA-C(p,g) is not a monotonic function of DELTA-E and this could be a path towards the understanding of Angell's strong glasses.