Glass preparation of the ZrO 2SiO 2 system by the sol-gel process from metal alkoxides

Abstract

Glasses in the ZrO 2SiO 2 system containing up to 50 mol.% ZrO 2 were prepared by heating the gels made from the mixed solutions of Zr(OC 3H 7) 4 and partially prehydrolyzed Si(OC 2H 5) 4. The anionic network structure similar to that of glass was already formed in the gels. And it was observed that the properties of the gels were determined by the porosity in the gel rather than the gel constituting structure. Porous gels converted into the non-porous impervious glasses through three major reactions with increasing temperature: the removal of the adsorbed water, dehydration-condensation and sintering. Density, refractive index and hardness of the non-porous glasses increased with the increase of ZrO 2 content. Infrared spectra and molar refractivity showed that the Zr 4+ ion was incorporated in the interstices of the silica network structure.