Novel aspects in the chemistry of the non-aqueous fluorolytic sol-gel synthesis of nanoscaled homodisperse MgF sub(2) sols for antireflective coatings

Water-clear transparent sols of nano-MgF sub(2) and nano-MgF sub(2)-CaF sub(2) composites in ethanol were synthesized through the fluorolytic sol-gel synthesis by the reaction of the insoluble precursor magnesium ethoxide with anhydrous hydrogen fluoride. CO sub(2), MgCl sub(2) or CaCl sub(2) are used as auxiliary reagents. The sols contain monodisperse nanoparticles with a size between 5 and 10 nm, depending on the particular synthesis method used. In contrast to all previous synthesis methods, the sols possess a low viscosity and offer a remarkably high long-time stability for more than one year. It has been demonstrated that they are very suitable for manufacturing antireflective porous coatings on glass substrates with remaining reflectivity below 1%, and high mechanical stability.