STRUCTURAL-PROPERTIES OF ALKALI-BORATE GLASSES DERIVED FROM A THEORETICAL-MODEL

A model for studying the growth of amorphous solids with medium range order is applied to the binary borate glasses (1-c) B2O3-cLi(2)O. The dynamics of growth is represented by a set of nonlinear differential equations and the amorphous state is associated with the solution with maximum configurational entropy. The analysis of the structure of the amorphous state obtained allows predictions to be made concerning the relative concentration of various local configurations involving four-coordinated boron atoms, and these are compared with experimental data. When one fixes the concentration c, new solutions are found in a finite range of temperatures around the glass-transition temperature. This model predicts structural changes that occur when one anneals the glasses at different temperatures. Changes in other physical quantities when one varies c can also be predicted from this model.