Luminescent screen and low-pressure mercury vapor discharge lamp provided with such a screen
AssigneeU.S. Philips Corporation
InventorsEvert D. Schutten, Johannus G. Verlijsdonk
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Abstract
A luminescent screen provided with a terbium-activated silicate having a cuspidine crystal structure according to the formula Y.sub.4-x-z-p Ca.sub.x M.sub.z.sup.II Tb.sub.p Si.sub.2-y Al.sub.y O.sub.7+x+z+y N.sub.2-x-z-y. In this formula M.sup.II is at least one of the elements Mg, Sr and Ba. The yttrium can be replaced up to at most 50 mol. % by Gd and/or La. It further holds that: 0.ltoreq.x.ltoreq.1.9 0.ltoreq.z.ltoreq.1.0 o.ltoreq.y.ltoreq.1.9 x+z+y.ltoreq.1.9 0.05.ltoreq.p.ltoreq.1.5.
Claims4
A luminescent screen provided with a luminescent layer which is applied to a carrier and which comprises a luminescent terbium-activated silicate having a cuspidine crystal structure, characterized in that the silicate corresponds to the formula Y.sub.4-x-z-p Ca.sub.x M.sub.z.sup.II Tb.sub.p Si.sub.2-y Al.sub.y O.sub.7+x+z+y N.sub.2-x-z-y, where M.sup.II represents at least one of the elements Mg, Sr and Ba, where the yttrium is replaceable up to at most 50 mol.% by at least one of the elements Gd and La and
- 0.ltoreq.x.ltoreq.1.9
- 0.ltoreq.z.ltoreq.1.0
- 0.ltoreq.y.ltoreq.1.9
- x+z+y.ltoreq.1.9
- 0.05.ltoreq.p.ltoreq.1.5.
Dependencies are inferred from the claim text.