Luminescent material with alkaline earth metal silicate aluminate host lattice and low-pressure mercury vapor discharge lamp containing the same
AssigneeU.S. Philips Corporation
InventorsWillem L. Konijnendijk, Gert M. Boogerd, Henricus L. M. Tonnaer
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Abstract
Luminescent alkaline earth metal silicate aluminate defined by the formula Sr.sub.3-a-b Ba.sub.a Ca.sub.b Si.sub.1-y Ge.sub.y Al.sub.10-z Ga.sub.z O.sub.20 ; Ce.sub.p.sup.3+, Eu.sub.q.sup.2+, Tb.sub.r.sup.3+, wherein, if r=0, it holds that 0.ltoreq.a+b.ltoreq.1.5 0.ltoreq.p.ltoreq.0.75 0.ltoreq.q.ltoreq.0.25 0.001.ltoreq.p+q and wherein, if p+q=0, it holds that 0.ltoreq.a.ltoreq.3.0 0.ltoreq.b.ltoreq.1.5 a+b.ltoreq.3.0 0.01.ltoreq.r.ltoreq.1.0. The material is used in a luminescent screen, preferably in the luminescent screen of a low-pressure mercury vapor discharge lamp.
Claims4
A terbium or cerium activated alkaline earth metal silicate aluminate luminescent material having a composition selected from the formulae:
- Sr.sub.3-a Ba.sub.a SiAl.sub.10 O.sub.20 :Tb.sub.r.sup.3+
- wherein 0.ltoreq.a.ltoreq.3.0 and 0.10.ltoreq.r.ltoreq.0.50 and wherein charge compensation for the terbium is achieved by substitution of Na and/or K in a Sr site and/or by Al in a Si site and;
- Sr.sub.3-a-b Ba.sub.a Ca.sub.b SiAl.sub.10 O.sub.20 :Ce.sub.p.sup.3+
- wherein 0.ltoreq.a+b.ltoreq.1.0 and 0.10.ltoreq.p.ltoreq.0.50 and wherein charge compensation for the cerium is achieved by substitution of Na and/or K in a Sr site and/or Al in a Si site.
Dependencies are inferred from the claim text.