Kinetic model of softening of glasses

A liquid-glass transition (vitrification) has been analyzed in terms of the softening of a solid phase through diffusion jumps. It has been shown that the assumption of a Gibbs momentum distribution (in fact, local thermalization) in glass automatically results in the existence of diffusion in glasses at any temperatures. In view of this conclusion, the possibility of a virtual “thermodynamic” transition responsible for vitrification is questionable. A model of jumps of “hot” particles has been proposed that predicts the existence of two characteristic temperatures $T_A$ and $T_B$ and describes qualitative changes in the temperature dependence of the viscosity of a liquid upon cooling (“Arrhenius”–“super-Arrhenius”–“Arrhenius”). The temperatures $T_A$ and $T_B$ are related to the number of particles in the first coordination sphere and the number of particles in the region of structural correlations (intermediate order region) in disordered media. The concept of ergodicity is discussed in application to glasses.