The glass transition in terms of Landau’s phenomenological approach

An attempt is made to apply to the glass transition the formalism, developed by Landau to describe thermodynamic phase transitions. The results obtained show that this classical approach opens a new way of understanding and describing vitrification. The glass transition is compared with the thermodynamics and kinetics of ‘normal’, i.e. thermodynamic phase transitions. A survey is given of existing phenomenological approaches in interpreting first and second-order thermodynamic phase transitions: Ehrenfest’s classification, the Justi–von Laue approach, Landau’s order parameter theory. The principal differences between thermodynamic phase transitions and the glass transition (as a thermodynamic/non-thermodynamic or as an ergodic/non-ergodic change) are pointed out, using Landau’s phenomenological approach. In this way a new, generalized possibility is found in analyzing glass transitions using appropriately chosen Taylor expansions of the thermodynamic potentials. A previously employed generic thermodynamic formalism to describe the kinetics of glass transitions, derived in the framework of the Bragg–Williams equation, is also applied, using Landau’s approach.