Study of the principles of fluorine fixation in melts and glass with polar groups

The results of the study of a series of M 2 O-ZrO 2 -SiO 2 (M = Li, Na) and Li 2 O-Ga 2 O 3 -SiO 2 glass, where the fraction of alkali oxide is replaced by fluoride, are given. Based on the considerations on halogen binding in the melt by the bulky polar groups, a simple model, which allows the prediction of the amount of halogen remaining in glass, is suggested. Good agreement of the calculated and experimental results is obtained: the model correctly predicts the halogen content in glass without a crystal phase, as well as the concentration boundary of the onset of crystallization in glass with excess fluorine content.