The Criterion for the Crystallization Ability Assessment as Applied to Borate Glass Powders and Monoliths

The glasses of three borate systems, Na2O-B2O3, K2O-B2O3 and BaO-B2O3, were studied over a wide range of the compositions by differential thermal analysis (DTA) and X-ray powder diffractometry (XRPD). The thermal parameters obtained by DTA method (the glass transition temperature, Tg, the crystallization onset temperature, Tx, and the melting temperature, Tm) were used to calculate the criteria (coefficients) characterizing glass stability against crystallization. The Lu–Liu, Weinberg and Hrubý coefficients were tested for verification of their consistency with several simple requirements. Since each of the criteria has its drawbacks, the coefficient of glass crystallization ability, Kcr, which meets all of the requirements, was also used. The advantage of this coefficient is demonstrated on the example of the glass powders and the monolithic glasses of the mentioned above borate systems.