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 R c 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/ R c   ∝  [ U ( T max ) ×  T L ] −1 , where U ( T max ) is the maximum crystal growth rate, and T L 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 T L , GFA  ∝  [ η ( T L )/ T L 2 ]—also correlates well with the R c 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 T L , and a low T L can be easily vitrified, and provides a powerful tool for the quest and design of novel glasses.