Riedel-de Haen Aktiengesellschaft

Karl Franz

Bernd Schonfeld

Wolfgang Jager

Filter phosphors consist of phosphor particles coated with a filter material. A phosphor which shows a red emission when excited by cathode rays may be coated with red iron oxide by producing a thin layer of pyrite on the phosphor particles and thereafter converting the said layer into hematite. Thus, the surface of the phosphor particles is evenly coated with a uniform, dense pigment layer of extreme adherence. The filter phosphors thus obtained are used in cathode ray tubes and especially in color picture tubes.

Process for the preparation of a red emitting phosphor coated with red

An inorganic fluorescent pigment for use in artificial teeth is provided and a method for producing the same, the pigment having the formula

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Barsinghausen, Germany

Karl Franz