Influence of Small Additions of Al2O3 on the Properties of the Na2O·3SiO2 Glass

Changes in the structural properties of sodium alumino-silicate glasses of general formula Na2O·xAl2O3·(3−x)SiO2 were investigated as a function of Al2O3 concentration. The experimental evidences provided by density, elastic modulus, glass chemical resistance measures, 29Si and 27Al MAS NMR investigations were complemented by molecular dynamics simulations. While neither of the experimental techniques or computational investigation utilized in this study were able to furnish unequivocable responses for the rationalization of the measured properties of sodium alumino-silicate glasses, the synergistic application of experimental and computational techniques showed that the anomalies observed in bulk properties like density and elastic modulus find their origin in medium-range structural features.