PERCOLATION PHENOMENON FOR DISSOLUTION OF SODIUM BOROSILICATE GLASSES IN AQUEOUS-SOLUTIONS

A percolation phenomenon has been discovered for the dissolution of sodium borosilicate glasses in aqueous solutions under low-pH conditions (pH approximately 2). The glasses fall into one of two categories which are markedly different in the dissolution behavior, in terms of whether the Si/B ratio in the glass network exceeds a threshold value or not. The transition from one of the categories to the other is very sharp when the Si/B ratio is changed as the key parameter. The qualitative aspects of the experimental observation can be explained very well by a simple model combined with the site percolation theory.