Crystallization kinetics in a lithium alumosilicate glass using SnO2 and ZrO2 additives

• Crystallization kinetics in a LAS glass with additions of SnO2 and ZrO2 were studied.
• ZrO2 and SnO2 promote heterogeneous nucleation and crystal growth of high quartz-ss.
• Strong increase in the nucleation rate (factor 10) with increasing fraction of SnO2
• Less pronounced increase in the growth rate with increasing fraction of SnO2.

The crystallization sequence, volume fractions and crystal sizes of nucleating agents, high-quartz (HQ-ss) and keatite (K-ss) solid solutions in a lithium alumosilicate glass with additions of SnO2 and ZrO2 were studied using high-temperature X-ray diffraction, differential thermal analysis and optical dilatometry. At low tin oxide fractions primary crystals were tetragonal zirconia solid solution, while at higher tin oxide fractions orthorhombic stannic srilankite solid solutions were detected. For continuously heated glasses we found that the substitution of zirconium by tin shifts in agreement with DTA and shrinkage curves the crystallization of HQ-ss and K-ss towards lower temperatures while only a minor effect on the glass transition temperature was evident. Isothermal annealing showed that the increase in the tin oxide fraction of the parent glass increases mainly the nucleation rate of HQ-ss (up to one order of magnitude) while the increase in the crystal growth rate is less pronounced. Dwelling of mixed ZrO2/SnO2-bearing glasses at the temperature of maximum nucleation results in fine-grained glass-ceramics (crystal size = 50 nm) of crystal number densities up to 1013 mm− 3.