Luminescent lead-activated alkaline earth metal rare earth metal borates and mercury vapor discharge lamp containing the same
AssigneeU.S. Philips Corporation
InventorsWillebrordus H. M. M. van de Spijker, Willem L. Konijnendijk
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Abstract
Luminescent lead-activated alkaline earth metal rare earth metal borates having compositions defined by the formula Me.sub.1-p Pb.sub.p La.sub.1-x-y Y.sub.x Gd.sub.y BO.sub.4, where Me represents strontium and/or calcium, where 0.005 .ltoreq.p.ltoreq.0.30 and 0.ltoreq.x.ltoreq.0.1, and where O.ltoreq.y.ltoreq.0.5 when at least 75 mole% of Me is Ca and O.ltoreq.y.ltoreq.0.1 when less than 75 mole% of Me is Ca. The borate may be used in the luminescent screen of low-pressure mercury vapor discharge lamps.
Claims10
A luminescent lead-activated alkaline earth metal rare earth metal borate having a hexagonal crystal structure and a composition defined by the formula
- Me.sub.1-p Pb.sub.p La.sub.1-x-y Y.sub.x Gd.sub.y BO.sub.4,
- wherein Me represents strontium and/or calcium, where 0.005.ltoreq.p.ltoreq.0.30 and 0.ltoreq.x.ltoreq.0.1, and wherein 0.ltoreq.y.ltoreq.0.5 when at least 75 mole% of Me is Ca and 0.ltoreq.y.ltoreq.0.1 when less than 75 mole% of Me is Ca and exhibiting an emission maximum of 465-470 nm.
Dependencies are inferred from the claim text.