U.S. Philips Corporation

Bruno M Smets

Johannus G Verlijsdonk

Robert J Pet

Joseph Rutten

Luminescent alkaline earth metal orthosilicate activated by praseodymium, defined by the formula M.sub.2-3/2x-1/2y Pr.sub.x M'.sub.y SiO.sub.4 in which M is at least one of the elements Ca and Sr of which up to 50 mol % may be replaced by Ba and/or of which up to 20 mol % may be replaced by Mg, in which M' is at least one of the elements Li, Na and K and in which 0.004.ltoreq.x.ltoreq.0.10 and 0.ltoreq.y.ltoreq.0.10.

Luminescent alkaline earth metal orthosilicate, luminescent screen

Luminescent terbium-activated alkaline earth metal rare earth metal borate having a monoclinic crystal structure and being defined by the formula M.sub.3 Ln.sub.1-x Tb.sub.x (BO.sub.3).sub.3 in which M is at least one of the elements Ba, Sr and Ca of which up to 34 mol % may be replaced by Mg, in which Ln is at least one of the elements La, Gd, Y and Sc and in which 0.005.ltoreq.x.ltoreq.1.

Luminescent terbium-activated borate, luminescent screen provided with

Luminescent Eu.sup.3+ -activated alkaline earth metal-rare earth metal silicate, which is defined by the formula Ba.sub.2 Gd.sub.2-x-y Y.sub.x Eu.sub.y Si.sub.4-z Ge.sub.z O.sub.13, in which O.ltoreq.x.ltoreq.1.3, 0.01.ltoreq.y.ltoreq.1.0 and O.ltoreq.z.ltoreq.4, luminescent screen provided with such a silicate and low-pressure mercury vapor discharge lamp provided with such a screen.

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Eindhoven, Netherlands

Bruno M Smets