A defect theory of the viscosity in glass-forming liquids

Abstract

The viscosity of glass-forming liquids is calculated at constant volume, according to the assumption that intrinsic defects are exponentially distributed in energy. Under suitable conditions, it is shown that the viscosity displays a Vogel-Fulcher behaviour and a cross-over to an Arrhenius regime at lower temperatures. For a different choice of the parameters, a new cooperative expression of the viscosity is found, which is not of Vogel-Fulcher type but fits again an Arrhenius behaviour at lower temperatures.