Patent ID: 7790232

Claim:
A process for the preparation and the deposition of a vitreous film on a substrate comprising: preparing a solution in an aprotic solvent selected from the group consisting of acetone, tetrahydrofuran and dioxane of at least one metal alkoxide corresponding to the formula X m —Me—(OR) n−m where Me is a metal selected from the group consisting of Group 3°, 4° and 5° of the Periodic Table of Elements; n is the valence of Me; X is R 1 or OR 1 , R 1 is the same as or different from R, m is either zero or integer number equal to or lower than 3; R and R 1 are hydrocarbon radicals with a number of carbon atoms equal to or lower than 12; adding a catalyst to the solution; hydrolyzing the solution in the presence of the catalyst in a hydrolysis reaction by addition of water to maintain a molar ratio of H 2 O/Me between 0.5 and 5 to obtain a clear hydrolysis reaction product; removing alcohol formed during the hydrolysis reaction under reduced pressure and forming a sol in the presence of the aprotic solvent wherein an equal volume of the aprotic solvent replaces the alcohol removed; depositing the hydrolysis reaction product in the form of a sol on the substrate; optionally drying and stabilizing of the vitreous film.