Abstract
Silica gel films were prepared by spin-coating from Si (OC2H5)4-H20-HNO3-ROH solutions where ROH = CH30H, C2H50H, CH3OC2H40H or CH3CH (OH) CH20H, and were heated at 200°C. Surface roughness parameters, Ra and Rz, were measured on lines crossing vertically to the radiative striations on the film surface. Ra and Rz were found to be decreased with increasing boiling point of ROH. Just after the spin-coating, optical microscopic observation was made on a film prepared from the solution containing CH3CH(OH)CH2OH. Striations were detected initially, which diminished with time when the film was kept in the ambient atmosphere. This indicates that striations are formed even when ROH of high boiling points is used, which, however, diminish during drying when ROH is less volatile.
