Osram Sylvania Inc.

Global Tungsten & Powders Corp.

Gte Products Corporation

Tuan A Dang

Dale E Benjamin

Chen-Wen Fan

Anthony F Kasenga

Robert G Mendenhall

Joel B Christian

David C Sheppeck

Joan M Coveleskie

Frank A Schwab

Richard G W Gingerich

Ricky D Morgan

Hans-Joachim Lunk

Henry J Stevens

Timothy A Frisk

An electroluminescent (EL) phosphor is described wherein each individual phosphor particle is encapsulated in an inorganic coating, preferably aluminum oxyhydroxide. The encapsulated phosphor shows an extreme insensitivity to atmospheric moisture and suffers only minor loss of initial brightness in lamps. The method of applying the coating is a hybrid process, which involves EL phosphor particles first being coated with a thin inorganic film using an atomic layer deposition (ALD) method in a fluidized bed wherein the precursors are introduced sequentially in repeated cycles, subsequently followed by an additional coating layer applied by a chemical vapor deposition (CVD) method in which the precursors are introduced simultaneously.

Moisture resistant electroluminescent phosphor with high initial brightness and method of making

The coating the tungsten powder particles with a ceramic barrier suppresses the leachability of tungsten in aqueous media. Preferably, the ceramic coating substantially encapsulates each particle of tungsten and has a thickness of at least about 30 nm and, more preferable, from about 200 nm to about 500 nm. Examples of ceramic coatings that may be used include, but are not limited to, aluminum oxide (alumina), aluminum oxyhydroxide (AlOOH), zirconium oxide (zirconia), cerium oxide (ceria), hafnium oxide (hafnia), and magnesium oxide (magnesia).

Ceramic-coated tungsten powder

The present invention is an electroluminescent phosphor wherein each individual phosphor particle is encapsulated in an inorganic coating applied by an atomic layer deposition (ALD) coating method. In a preferred embodiment, the coating is aluminum oxyhydroxide. The encapsulated phosphor shows an extreme insensitivity to atmospheric moisture and suffers only minor loss of initial brightness in lamps.

Moisture-resistant electroluminescent phosphor with high initial brightness and method of making

A supported tungsten carbide material is provided. The material has a unique structure as defined by its x-ray diffraction pattern and consists of extremely small crystallites on the order of about 15 to about 30 angstroms in size. The tungsten carbide material is supported on a high-surface-area support to allow for a greater number of active sites for catalysis. The support consists preferably of a high-surface-area carbon.

Supported tungsten carbide material

A method of coating phosphor particles that comprises the steps of introducing an inert gas into a reaction vessel; charging phosphor particles into the reaction vessel; heating the reaction vessel to a reaction temperature; introducing a coating precursor into the reaction vessel; introducing an oxygen/ozone mixture into the reaction vessel; and maintaining the agitation, inert gas flow, oxygen/ozone mixture flow and precursor supply for a time sufficient to coat the phosphor particles. This process yields phosphors having a half-life of upwards of 3,100 hours with efficacys of greater than 6 lumens per watt (lm/w).

Method of making long life electroluminescent phosphor

The initial power output and maintenance of a fluorescent lamp containing europium-activated barium magnesium silicate phosphor is significantly improved by combining the phosphor with a flux and subjecting the phosphor/flux mixture to a refiring and rewashing process before applying the phosphor to the interior of a fluorescent lamp envelope. Surface concentrations of europium and barium are significantly increased, while surface concentrations of magnesium and silicon are decreased.

Europium-activated barium magnesium silicate phosphor

Method of improving the maintenance of a fluorescent lamp containing

Growing community of inventors

Sayre, PA, United States of America

Tuan A Dang