Statistical mechanical model of bonding in mixed modifier glasses

Oxide glasses often consist of multiple network formers that create the backbone of the glass network and modifiers that serve as either charge compensators or creators of non-bridging oxygens. The variety of bonding preferences results in very rich composition-property relationships. In this work, we present a statistical description of the glass structure governed by the relative enthalpic and entropic contributions to the bonding preferences in a glassy system. Using the proposed model, we derive an analytical expression to represent the bonding in mixed modifier glasses and explain the role of composition and fictive temperature on glass structure. The model provides the criteria for nonlinearity in bonding preference and reveals regions where high fluctuations in local structure are predicted.