Connecting the liquid fragility to the average weakest metal–oxygen bond of its crystal in oxides.

This article focuses on establishing a novel quantitative correlation between the liquid fragility parameter (m) of oxide glasses and the ratio of average longest metal–oxygen to phosphorus, silicon, or boron–oxygen bond lengths in their corresponding crystals with identical chemical compositions. The study demonstrates that fragility, which characterizes the relaxation dynamics of glass-forming liquids at the glass transition temperature (Tg), is intrinsically linked to the network rigidity governed by the weakest bonds in the crystal structure—a concept described as the "bucket effect." By analyzing various phosphates, silicates, and borates, the authors reveal an exponential relationship between fragility and this bond length ratio, thereby providing a direct connection bridging the distinct microstructures and properties of glasses and crystals. This finding offers a new computational approach to predict glass fragility from crystal structural parameters and suggests broader implications for understanding other glass properties through crystalline characteristics.