LUMINESCENT SCREEN

摘要

A luminescent screen provided with a luminescent material having the hexagonal crystal structure, which material is an aluminate, a gallate or an aluminate gallate. The crystal structure of the luminescent material corresponds to that of at least one of the compounds beta -aluminium, beta ''-alumina and the hexagonal ferrites. The luminescent material is activated by at least one of the elements manganese, europium, lead, thallium, cerium, indium, terbium, dysprosium and bismuth and is a ternary compound whose composition can be represented in the ternary phase diagram ABC in which A represents at least one of the oxides 1/4Na2O, 1/2K2O, 1/2Rb2O, 1/2Cs2O, CaO, SrO, BaO, 1/2La2O3, 1/2Ce2O3, 1/2Tb2O3, 1/2Dy2O3, 1/2Bi2O3, EuO, PbO, 1/2Tl2O and 1/2In2O, in which B represents at least one of the oxides Al2O3 and Ga2O3 in which up to 25 mol. % of the oxides denoted by B may be replaced by Sc2O 3 and in which C represents at least one of the oxides MgO, ZnO, BeO, 1/2LiAlO2 and 1/2LiGaO2. The content of A is more than zero and less than that of B and the content of C is more than zero and less than 0.6.