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US 6,783,700 B2Granted
Red photoluminescent phosphors
AssigneeSarnoff Corporation
InventorsYongchi Tian, Diane Zaremba, Ian Gregory Hill
Life of this patent
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Abstract
A red-emitting strontium-calcium sulfide phosphor doped with europium and a halide. These phosphors are made by combining their insoluble sulfates, adding europium as an activator, firing in hydrogen sulfide to form the corresponding sulfides, adding a halide co-activator and firing in nitrogen. The resulting phosphors can be used with various electroluminescent devices to produce colored or white light.
Claims14
A strontium calcium sulfide phosphor comprising
- SrxCa1−xS:Eu2+, Y
- wherein x is an integer of from about 0.3 to about 0.8, and Y is one or more halides in atomic or ionic form.
A method of making a red-emitting phosphor comprising
- a) forming a mixture of the sulfate salts of strontium and calcium;
- b) adding a solution of europium oxide to the sulfate salts;
- c) firing to a temperature of about 900° C. in a forming gas atmosphere;
- d) firing to a temperature of about 1000° C. in hydrogen sulfide;
- e) adding an appropriate amount of a halide;
- and
- f) firing to a temperature of about 1100° C. in nitrogen.
4 more elements
A light source comprising:
- a blue light emitting diode;
- a strontium calcium sulfide phosphor comprising
- SrxCa1−xS:Eu2+,Y
- wherein x is an integer of from about 0.3 to about 0.8, and Y is one or more halides in atomic or ionic form;
- and
- wherein the strontium calcium sulfide phosphor is positioned so as to alter the light spectrum of light emitted by the diode.
3 more elements
Dependencies are inferred from the claim text.