Gte Products Corporation

Gte Sylvania Incorporated

Henry B Minnier

Charles F Chenot

A Gary Sigai

Robert E Dodds

Fred R Taubner

Harry O Schulze

H David Layman

Carl E Landmesser

A method for preparing a specific zinc orthosilicate phosphor particle having a nonparticulate, conformal aluminum oxide coating wherein all of a manganese activator is present as manganese (II) and occupies zinc (II) sites includes the steps of blending a zinc source, a manganese (II) source, a silicon source, and a tungsten source in amounts in accordance with said formula with an amount of up to about 2 weight percent NH.sub.4 Cl and up to about 0.2 weight percent NH.sub.4 F to form a relatively uniform admixture, firing the mixture in a closed container under an inert non-oxidizing atmosphere to promote retention of manganese in the plus two valance state whereby oxidation of manganese to a higher valence state is avoided and conditions promote larger particle size formation; milling and washing the phosphor in an aqueous citric acid solution to remove unreacted manganese; rinsing, drying and sieving the dried phosphor; and depositing a continuous, nonparticulate, conformal aluminum oxide coating on the dried phosphor particle.

Method for preparing zinc orthosilicate phosphor particle

A manganese-activated zinc orthosilicate phosphor having the empirical formula:

Method for preparing zinc orthosilicate phosphor

The red and blue color cathode ray tube phosphors for color television are pigmented with a coating of an aqueous-insoluble silicate-based glass matrix containing pigment particles. When incorporated into a tridot color cathode ray tube, the contrast of the tube is improved. The coated particles are formed by dispersing the particles in a slurry with a silicate, the pigment particles and an optional wetting agent, and evaporating the slurry to dryness. The dried coated particles are then heated in order to insolubilize the glass matrix, and soluble ions are then removed by washing.

Coated phosphors, method for producing same and articles employing same

A green emitting ZnS : Cu, Al cathodoluminescent phosphor having x and y coordinate values of from 0.250 to 0.280 and 0.560 to 0.615 respectively, is produced by a critical firing schedule exemplified by slow heating to about 1000.degree. C, soaking at this temperature for about 1 hour, followed by slow cooling at about 3.degree. C per minute to 700.degree. C, followed by air quenching. The phosphor is useful for example, in tri-color television color television cathode ray tube.

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Dushore, PA, United States of America

Henry B Minnier