STRUCTURAL DIFFERENCES AND PHASE-SEPARATION IN ALKALI SILICATE-GLASSES

Reasonable and significant structural differences between potassium silicate glass and sodium silicate glass can be revealed by molecular dynamics computer simulations. The differences in their immiscibility behavior reflect these structural differences. The simulation results are consistent with the experimental observations of many researchers that the variation in the number of nonbridging oxygens per silicon decreases in the order Li > Na > K. The distribution of the silicon species with various numbers of nonbridging oxygens is a reflection of the degree of homogeneity in the distribution of the modifier cation and nonbridging oxygen clusters. Nanoscale inhomogeneity seems to be an inherent nature of alkali silicate glasses.