LUMINESCENT SCREEN

摘要

A luminescent screen provided with a luminescent layer disposed on a support 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, whilst 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 lowpressure mercury vapour discharge lamps.