Boris P. Petroff

The phenomenology of metastable liquids and the glass transition

A survey is given on classical and new phenomenological approaches for describing the thermodynamics of undercooled metastable liquids and for glass transition and on the nature of glasses. It begins with Simon’s (1926/1930) and Prigogine’s (1954) concepts on the thermodynamics of vitrification. A generalized approach in the phenomenology of glass-transition is developed based on a quasi-linear extension of the formalism of the thermodynamics of irreversible processes. This approach is a generalization of ideas for the description of the kinetics of glass transition as developed initially by Vol’kenstein and Ptizyn (1956), Moynihan (1974), and Gutzow et al. (2000). It allows us to determine, as a second particular application, the temperature course of the thermodynamic functions upon vitrification (Gutzow et al. (2000)). In performing this task, both entropy freezing-in and entropy production are accounted for (Möller, Schmelzer, Gutzow (2006)), thus, essentially correcting Simon’s classical approximation, which has been in use for many years. In addition, the approach developed allows a new interpretation of the value of the Prigogine-Defay ratio (Schmelzer, Gutzow (2006)) employing in the description of vitrification only one appropriately chosen internal structural order parameter: ξ. In this way, a new picture of the thermodynamics of undercooled liquids, the glass transition, and glass stabilization is formulated.Based on the theoretical approach developed, the applicability of the third law of thermodynamics to nonequilibrium systems, in general, and to glasses, in particular, is reconsidered. It is shown that a formulation of the third principle of thermodynamics can be given—as the principle of nonaccessibility of the absolute zero temperature—comprising both equilibrium and nonequilibrium systems. Experimental results are summarized confirming the predictions of the theoretical concepts outlined.