Deformation–activation model of viscous flow of glass-forming liquids

• Low activation stretching of a network is a necessary condition for activated transition (hopping) of bridge atoms.
• η(T) dependence is determined by low activation deformation of a valence bond network.
• The model successfully describes the dependence of the free activation energy of viscous flow in a wide temperature range.

We suggest a model, according to which the local low activation stretching of a valence bond network is a necessary condition for the realization of an elementary act of viscous flow of inorganic glasses and their melt-activated transition of the kinetic unit (bridge atom) into a deformed microregion. Exactly this kind of local configurational change of structure of a kinetic unit responsible for yield plays an important role in the temperature dependence of the viscosity of these systems, especially in the vicinity of vitrification of liquids. In the framework of this model the temperature dependence of free activation energy of viscous flow of glass melts in the wide temperature range is described and explained.