GB965903A - Improvements relating to the manufacture of transparent luminescent screens - Google Patents

Abstract

Method of manufacturing a transparent luminescent screen comprises forming a transparent layer of at least the base material of a phosphor on a transparent supporting plate, immersing the plate and layer in water in a pressure-tight vessel together with a quantity of the phosphor sufficient to ensure a continuously saturated solution of the phosphor when the vessel is heated, and heating the vessel at such a temperature and for such a time that the temperature and pressure produced within the vessel are sufficient to maintain the constituents of the phosphor in solution and to cause diffusion of the activator ions into the appropriate lattice sites in the transparent layer. The water can contain phosphor base modifying constituents and/or one or more activator materials, or these may be deposited on the supporting plate during the initial coating step. In one example a plate of silica is vacuum coated with a transparent layer of magnesium potassium fluoride and, after cooling, is placed in a silica ampoule filled to about half its volume with an aqueous solution containing 0.1% of manganese fluoride, 0.3% of zinc fluoride and a 5% weight by volume suspension of magnesium potassium zinc fluoride activated with manganese. The silica ampoule is then sealed and placed in an autoclave filled to about half its volume with water and heated to a temperature of 400 DEG C., corresponding to an internal pressure of about 300 atmospheres, for 20 hours.