Gte Products Corporation

Osram Sylvania Inc.

Chung N Chau

Anthony F Kasenga

Charles F Chenot

Leslie F Gray

Cheryl M Forster

Jeffrey A Smith

A surface modified phosphor powder exhibiting increased lumen maintenance. At the outer surface of each phosphor particle, the cations of the phosphor material have been replaced by other cations, e.g., a metal or metalloid cation such as aluminum, barium, calcium, lanthanum, magnesium, strontium, yttrium, zinc, titanium, tantalum, boron, or silicon. The phosphor powder is chemically modified by forming a suspension of phosphor particles in a liquid medium including the metal or metalloid ions in solution. The phosphor suspension is stirred for a time sufficient to permit an ion exchange reaction in which the metal or metalloid ions are substituted for cations of the phosphor to form a layer of the desired metal or metalloid compound at the phosphor outer surface.

Phosphor with modified surface composition and method for preparation

A process for producing a manganese activated zinc orthosilicate phosphor. An aqueous dispersion is prepared including fumed silica having an ultrafine average particle size of less than 50 nm, a zinc precursor, and a manganese precursor. The molar ratio of zinc:silicon in the dispersion is approximately 1.3:1 to 2.0:1, and the molar ratio of manganese in the dispersion is sufficient to activate the phosphor. The precipitate from the dispersion is calcined in an inert atmosphere at a temperature and for a time sufficient to form a manganese activated zinc silicate phosphor having a broad band emission peaking in the green region of the visible spectrum when stimulated by external radiation at approximately 254 nm. The calcined phosphor may be milled to achieve an average particle size of less than 5 .mu.m, the milling step being performed without significant loss of plaque brightness. Also disclosed is a green emitting manganese activated zinc silicate phosphor having an average particle size of less than 5 .mu.m and excellent brightness.

Method of preparing manganese activated zinc orthosilicate phosphor

Phosphor particles are coated with a continuous, non-particulate, conformal coating of a metal oxide by suspending the phosphor particles in a gel solution containing a metal alkoxide. The gel suspension is then gelled after which the gelled suspension is dried, during which process the metal alkoxide is converted to metal oxide which coats the particles. Such coated phosphor particles can improve maintenance of lamps in which they are employed.

Coated phosphor articles

A method of making a lanthanum cerium terbium phosphate phosphor involves the single-step reaction of single-phase, mixed valence state lanthanum cerium terbium oxide with boron phosphate in the presence of a flux-forming compound containing lithium. The resulting phosphor is up to 5% brighter than the same phosphor prepared without the lithium-containing compound.

Method of making lanthanum cerium terbium phosphate phosphor with

A method of making a lanthanum cerium terbium phosphate phosphor involves the single-step reaction of a single-phase, mixed valence state lanthanum cerium terbium oxide and boron phosphate. Alternatively, the single-step reaction may involve a mixture of lanthanum oxide, cerium oxide, terbium oxide and boron phosphate.

Method of making lanthanum cerium terbium phosphate phosphor

A method of making a lanthanum cerium terbium phosphate phosphor involves the single-step reaction of lanthanum cerium terbium oxalate and boron phosphate.

Luminescent grade, small particle size boron phosphate is prepared by reacting diammonium phosphate with an excess amount of boric acid and washing the product with ammonium hydroxide solution.

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Sayre, PA, United States of America

Chung N Chau