Red emitting phosphor with slow exponential decay
AssigneeGTE Laboratories Incorporated
InventorsRomano G. Pappalardo, John Walsh
Life of this patent
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Abstract
A luminescent phosphor composition having enhanced luminescent decay lifetime consists essentially of a non-stoichiometric cerium and manganese coactivated alkaline earth orthophosphate represented by the formula Sr.sub.(3-v-w-x-y-z) .quadrature..sub.v Mg.sub.w CA.sub.x (PO.sub.4).sub.2 :Ce.sub.y Mn.sub.z where 0.001.ltoreq.v.ltoreq.0.05 0.180.ltoreq.w.ltoreq.0.35 0.ltoreq.x.ltoreq.0.08 0.015.ltoreq.y.ltoreq.0.05 0.01.ltoreq.z.ltoreq.0.10. An improved fluorescent lamp employing the disclosed phosphor is also described.
Claims11
A luminescent phosphor composition consisting essentially of a non-stoichiometric cerium and manganese coactivated modified alkaline earth orthophosphate represented by the formula:
- Sr.sub.(3-v-w-x-y-z) .quadrature..sub.v Mg.sub.w Ca.sub.x (PO.sub.4).sub.2 :Ce.sub.y Mn.sub.z
- wherein .quadrature. represents the non-stoichiometry factor, and:
- 0.001.ltoreq.v.ltoreq.0.05
- 0.18.ltoreq.w.ltoreq.0.35
- 0.ltoreq.x.ltoreq.0.08
- 0.015.ltoreq.y.ltoreq.0.05
- 0.01.ltoreq.z.ltoreq.0.10
- said luminescent phosphor composition emitting red emission when excited, and characterized by extended fluorescence decay lifetime.
A fluorescent lamp comprising:
- a sealed light transmitting tubular envelope;
- a discharge sustaining filling contained within said envelope;
- electrodes disposed within said envelope and operable when energized to sustain a discharge therebetween to generate ultraviolet radiations including a substantial proportion of 254 nm radiations;
- and
- a phosphor coating disposed on the interior surface of said envelope, said phosphor coating including a composition consisting essentially of a non-stoichiometric cerium and manganese coactivated modified alkaline earth orthophosphate represented by the formula:
- Sr.sub.(3-v-w-x-y-z) .quadrature..sub.v Mg.sub.w Ca.sub.x (PO.sub.4).sub.2 :
- Ce.sub.y Mn.sub.z
- wherein .quadrature. represents the non-stoichiometric factor, and:
- 0.001.ltoreq.v.ltoreq.0.05
- 0.18.ltoreq.w.ltoreq.0.35
- 0.ltoreq.x.ltoreq.0.08
- 0.015.ltoreq.y.ltoreq.0.05
- 0.01.ltoreq.z.ltoreq.0.10.
Dependencies are inferred from the claim text.