Patent ID: 7879395

Claim:
A method for coating a substrate, comprising the steps of: providing a substrate, and a coating solution prepared by the following steps: providing a first solution comprising: a lower alcohol having a chain length of four carbon atoms or less (C 1 -C 4 ); a polyethylene glycol; a complexing agent; and water; providing a second solution comprising: a higher alcohol having a chain length from eight to twenty carbon atoms (C 8 -C 20 ); and at least one metal alkoxide, wherein the metal in said at least one metal alkoxide is selected from the group consisting of zirconium, aluminium, titanium, tantalum and yttrium; forming a sol-gel solution by mixing said first and second solutions and thereby hydrolyzing said at least one metal alkoxide to a metal oxide and an alcohol; forming a concentrated solution by removing said lower alcohol and the alcohol resulting from the hydrolysis of said at least one metal alkoxide; and forming a coating solution by adding a medium alcohol having a chain length from 5 to 10 carbon atoms (C 5 -C 10 ) to said concentrated solution; spin-coating said coating solution onto said substrate to form a coated substrate; forming a dry coating on said substrate by subjecting said coated substrate to a drying step.