The relationship between properties and glass structure is, perhaps, more clearly evident in borate and in borosilicates than it is in any other family of glasses. Nuclear magnetic resonance measurements have shown that, at room temperature, the manner in which oxygen bonds to boron depends on the ratio of alkali to boron. A statistical mechanical model indicated that the bonding is influenced by temperature and was used to calculate the relative numbers of various structural units for the glass as a function of composition and temperature. The results exhibit a reasonably good correlation with the measured strain point and softening point. A model for the halogen solubility as a function of temperature and of matrix compostion was also developed.
