Silicate melt structural relaxation: Rheology, kinetics, and Adam-Gibbs theory

Several applications of the Adam-Gibbs theory of relaxation processes in viscous liquids to the rheology of silicate melts are reviewed. This theory reproduces very well the isostructural viscosity observations, it explains the occurrence of shear thinning and offers a rationale for the pressure dependence of silicate melt viscosities. The key feature of the Adam-Gibbs theory is the calculation of the structural relaxation time. This aspect makes it also possible to use it for studying the kinetics of structural relaxation. Kinetic data obtained with static experiments are shown to be in good agreement with this model.