It is known that silica sol-gel coatings microstructure depend on the components of the sol. In order to develop different microstructures of the silica coatings and comparing their optical properties, a variety of silica sols were prepared which were consist of TEOS, water, catalyst and changing the solvent content, at room temperature. Prepared glass surfaces were coated with silica sol using a dipping technique, with constant withdrawing rate. Prepared coatings were investigated by

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... sion scanning electron microscopy (FE-SEM) and UV-Vis. spectroscopy. Transmittance spectra showed that silica coatings featured a distinct increase of substrate transmittance at all wavelengths (400-1100 nm). The result indicated that by increasing the solvent content, the porosity of coating increased and the coating was more densified therefore the silica coating transmittance increased by 3-4% points. FE-SEM showed that the nanostructure silica coating grain size were estimated ~20-40 nm.