X in these compounds is at least one halide atom.Other phosphorescent materials suitable for this invention are alkaline earth aluminates of the formula MO.Al.sub.2O.sub.3.B.sub.2O.sub.3:R wherein M is a combination of more than one alkaline earth metal (strontium, calcium or barium orcombinations thereof) and R is a combination of Eu.sup.2+ activator, and at least one trivalent rare earth materia