Remembrances of things past; silicon and sodium local environments in sols, gels, glasses and aqueous solutions

• Published in: Journal of non-crystalline solids 1990-08, Vol.123 (1), p.170-175
• Main Authors: de Jong, B.H.W.S., Janssen, R., Veeman, W.S.
• Format: Article
• Language: English
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/0022-3093(90)90782-H

The distribution of silica species has been determined by 29Si high resolution and magic angle spinning NMR in a sol, gel, glass, and solution made from a commercially available soluble sodium silicate solution. The present results indicate that silicon remembers its past: the species distribution of a solution, prepared by dissolution of the glass, is comparable to that of the starting solution. The species distribution of the gel made, from the soluble sodium silicate solution by drying & 80°C is identical to that of the starting solution. Heating this gel to temperatures ⪰ 80°C causes polymerization of silica resulting in a distribution comparable to that of sodium silicate glass. 23Na nutation NMR shows the presence of primarily two different sodium environments: one with a small quadrupole interaction prevailing at room temperature, and another with a large quadrupole interaction occuring in gels dried at higher temperatures. The latter environment is the only one remaining in the glass made from the gel.