Author(s)

Galina A. Sycheva

Grebenshchikov Institute of Silicate Chemistry, Russian Academy of Sciences, St. Petersburg, Russia.

The crystal growth and nucleation in glasses in the lithium silicate system have been investigated. Phase separation in ultimately homogenized glasses of the lithium silicate system xLi₂O·(100 ﹣ x)SiO₂ (where x = 23.4, 26.0, 29.1, and 33.5 mol% Li₂O) has been studied. The glasses of these compositions have been homogenized using the previously established special temperature-time conditions, which make it possible to provide a maximum dehydration and removal of bubbles from the glass melt. The parameters of nucleation and growth of phase separated in homogeneities and homogeneous crystal nucleation have been determined. The absolute values of the stationary nucleation rates I_st of lithium disilicate crystals in the 23.4Li₂O·76.6SiO₂, 26Li₂O·74SiO₂ and 29.1Li₂O·70.9SiO₂ glasses with the compositions lying in the metastable phase separation region have been compared with the corresponding rates I_st for the glass of the stoichiometric lithium disilicate composition 33.51Li₂O·66.5SiO₂. It has been found that the crystal growth rate has a tendency toward a monotonic increase with an increase in the temperature, whereas the dependences of the crystal growth rate on the time of low temperature heat treatment exhibit an oscillatory behavior with a monotonic decrease in the absolute value of oscillations. The character of crystallization in glasses with the compositions lying in the phase separation region of the Li₂O-SiO₂ system is compared with that in the glass of the stoichiometric lithium disilicate composition. The conclusion has been made that the phase separation weakly affects the nucleation parameters of the lithium disilicate and has a strong effect on the crystal growth.

Phase Separation, Crystal Nucleation, Stationary Nucleation, Crystal Growth in Phase Separated and Non-Phase Separated Glasses

Sycheva, G. (2016) Crystal Growth and Nucleation in Glasses in the Lithium Silicate System. Journal of Crystallization Process and Technology, 6, 29-55. doi: 10.4236/jcpt.2016.64004.