Viscosity and liquidus‐based predictor of glass‐forming ability of oxide glasses

Glass‐forming ability (GFA) is a measure of the easiness to vitrify a given substance. Theoretically, it is possible to make a glass from any liquid provided it is quenched from its liquidus temperature with a cooling rate above a critical value Rc to avoid crystallization. However, measuring GFA is a laborious and time‐consuming task. Moreover, predicting the GFA of substances that have never been vitrified is of greater interest. Here, we propose and evaluate a new parameter that can predict the glass forming ability of oxide mixtures. We derived a mother parameter, GFA = 1/Rc ∝ [U(Tmax) × TL]−1, where U(Tmax) is the maximum crystal growth rate, and TL is the liquidus temperature, which strongly correlates with the experimental critical cooling rates of oxide glass‐formers. A simplified version derived from the mother parameter—which does not need (scarce) crystal growth rate data and only relies on viscosity η and TL, GFA ∝ [η(TL)/TL2]—also correlates well with the Rc of several oxide compositions. This new GFA parameter, dubbed Jezica, works when heterogeneous nucleation prevails. It corroborates the widespread concept that substances having high viscosity at TL, and a low TL can be easily vitrified, and provides a powerful tool for the quest and design of novel glasses. Proposed predictor Jezica (y‐axis) vs Rc in Log scale to cover 8 o.m. (■) Stoichiometric glasses and (●) Nonstoichiometric glasses, both with calculated Rc; (▲) Experimental Rc data; (○) Al2O3 = calculated Jezica. The continuous line represents the expected slope (−1) for the linear regression between log[η(TL)/T2L] and log(Rc)