Coarse-grained model of the glass transition in network-forming oxides

Properties of network-forming oxide glasses, including both the glass transition point and fragility, are often associated with the density of covalent bonds that impose mechanical constraints on the structure. Yet, even in the simplest of alkali-modified oxides, inconsistencies exist that have remained unanswered for many decades. Here we highlight these inconsistencies and demonstrate how an alternative measure of the bond density, arrived at through coarse-graining of certain rigid structures present in the network, could resolve these puzzles and provide a single-parameter description of the glass transition in network-forming materials.