Abstract: A luminescent screen provided with a luminescent layer (4) disposed on a support (1) and containing an alkaline earth metal aluminate activated by bivalent europium. The alkaline earth metal is barium which may be replaced up to 25 mol. % by strontium. The aluminate has a crystal structure, the X-ray powder diagram of which corresponds or substantially corresponds to the diagram given in Table I of the description, while the ratio of alkaline earth metal to aluminium in the aluminate has a value of 1:5 to 1:10. An advantageous use of such a luminescent screen is found in low-pressure mercury vapor discharge lamps.

Abstract: A luminescent screen provided with a luminescent layer formed on a carrier, which layer comprises an aluminate and/or a gallate of strontium and/or barium activated by bivalent europium or by trivalent chromium. The aluminate and/or gallate has an orthorhombic crystal structure with a space group P.sub.nnm and has a composition defined by the formula Me.sub.2-x Eu.sub.x A.sub.6-y Cr.sub.y O.sub.11 (Me=Sr, Ba and A-Al, Ga).An advantageous application of such a luminescent screen is found in low-pressure mercury vapor discharge lamps.