TECHNOLOGY FOCUS - CERAMICS AND GLASS - Preferred Components: The glass substrate comprises a soda-lime-silica glass including (wt.%) silica (SiO2) (67-75); sodium oxide (Na2O) (10-20); calcium oxide (CaO) (5-15); magnesium oxide (MgO) (0-7); alumina (Al2O3) (0-5); potassium oxide (K2O) (0-5); lithium oxide (Li2O) (0-1.5); and barium oxide (BaO) (0-1).    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The metal oxide sol further comprises a complex agent. The combined sol gel comprises at least two metal oxide sols. The metal oxide sol comprises the combined sol gel in an amount of at least 0.1 (preferably 1-5, especially 2) wt.%; and at least one metal oxide having a refractive index (n) of not greater than 2. The metal oxide comprises at least one metal oxide selected from aluminum tert-butoxide or zirconium butoxide. The metal oxide sol is at least one of mullite (3Al2O3:2SiO2), sillimanite (Al2O3:SiO2), spinel (MgAl2O4), zirconia (ZrO2), alumina (Al2O3) or anorthrite (CaAl2Si2O8).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The curing occurs at 100-150 degrees C for not greater than 2 minutes. The heat treating occurs at 600-750 degrees C for not greater than 5 minutes. The casting involves spin coating. Preferred Components: The silane is glycycloxypropyltrimethoxysilane. At least one of the first, second and third solvent is n-propanol. The catalyst is an acid (preferably hydrochloric acid). The colloidal silica comprises methyl ethyl ketone. The complex agent is acetylacetate. EXAMPLE - A silica sol was prepared as follows. A polymeric solution of silica was prepared by mixing n-propanol (64 wt.%), glycycloxypropyltrimethoxysilane (24 wt.%), water (7 wt.%) and hydrochloric acid (5 wt.%) for 24 hours. The coating solution was prepared by using (wt.%) the polymeric solution (21), colloidal silica (7) in methyl ethyl ketone and n-propanol (72). This was stirred for 2 hours to give silica sol. Anorthrite (CaAl2Si2O8) sol containing (parts) alumina (1), silica (2) and calcium oxide (1), was prepared by taking aluminum tert-butoxide (2.5 g), glycycloxypropyltrimethoxysilane (2.3 g) and calcium acetate (0.8 g) in a solution containing acetylacetate (2 g), hydrochloric acid (6 g), and n-propanol (20 g). This solution was stirred for 15 minutes. Then water (0.5 g) was added. The solution was stirred for another 15 minutes to obtain anorthrite sol. An antireflective coating comprising the anorthrite sol and silica sol in 2:98 % weight ratio respectively, was prepared using spin coating method with 1000 revolution per minute (rpm) for 18 seconds. The coating was heat treated in furnace at 625 degrees C for three and a half minutes. The critical scratch load of this coating was found to be 100 mN.