How Relevant is the Network Dynamics for the Alkali Diffusion in Alkali Silicate Glasses?

Abstract

Abstract The relevance of network dynamics in a disordered alkali silicate ion conductor is studied via computer simulations. It is shown that the network dynamics below the glass transition is very localized and does not give rise to major fluctuations of ionic sites. These local network fluctuations are, however, very important to understand the alkali dynamics. After immobilising the network the activation energy roughly doubles. Furthermore dynamic heterogeneities as well as backdragging forces are much stronger. Qualitatively, these observations can be rationalized by a scenario similar to the Anderson-Stuart model of ion dynamics.