On the dependence of the properties of glasses on cooling and heating rates II: Prigogine–Defay ratio, fictive temperature and fictive pressure

Abstract

In a previous analysis (J. Chem. Phys. 125 (2006) 094505) it was shown by us that – in contrast to earlier believe – a satisfactory theoretical interpretation of the experimentally measured values of the so-called Prigogine–Defay ratio, Π, can be given employing only one structural order parameter. According to this analysis, the value of this ratio has to be, in accordance with experimental findings, larger than one (Π > 1). This analysis is extended here and, in particular, the dependence of the value of Π on cooling and heating rates is studied. Finally, employing the general model-independent definition of internal (fictive) pressure and fictive temperature, developed by us (J. Non-Crystalline Solids 355 (2009) 653), it is shown how these parameters behave in dependence on temperature for different sets of cooling and heating rates. Some further consequences and possible extensions are discussed briefly.