Composition–structure–property relationships in boroaluminosilicate glasses

The complicated structural speciation in boroaluminosilicate glasses leads to a mixed network former effect yielding nonlinear variation in many macroscopic properties as a function of chemical composition. Here we study the composition–structure–property relationships in a series of sodium boroaluminosilicate glasses from peralkaline to peraluminous compositions by substituting Al2O3 for SiO2. Our results reveal a pronounced change in all the measured physical properties (density, elastic moduli, hardness, glass transition temperature, and liquid fragility) around [Al2O3]–[Na2O] = 0. The structural origin of this change is elucidated through nuclear magnetic resonance analyses and topological considerations. Furthermore, we find that addition of 1 mol% Fe2O3 exerts a complicated impact on the measured properties.

► The composition–structure–property relationship in boroaluminosilicate glasses is explored by substituting Al2O3 for SiO2.
► Density, fragility, Young's and shear moduli, and hardness change non-linearly with composition.
► Pronounced minima for density, fragility, Young's and shear moduli, and hardness are observed around [Al2O3]–[Na2O] = 0.
► The non-linearity and minima of the property changes with composition are clarified in terms of network speciation.
► Impact of Fe2O3 on the properties of the studied glasses is detected and explained.