Luminescent alkaline earth metal orthosilicate, luminescent screen provided with such a silicate and low-pressure mercury vapor discharge lamp provided with such a screen

摘要

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≦x≦0.10 and 0≦y≦0.10.