Lamp containing long decay phosphor

An aftergrow lamp comprising

• a light emitting section for converting electric energy to optical energy, and
• a fluorescent layer which is excited to emit light by the light emitting section, and contains a long decay phosphor represented by the general formula
• (M.sub.1-p-q Eu.sub.p Q.sub.q)O.multidot.n(Al.sub.1-m B.sub.m).sub.2 O.sub.3 .multidot.kP.sub.2 O.sub.5 .multidot..alpha.X
• wherein the values of p, q, n, m, k, .alpha. and .alpha./n are in the ranges
• 0.0001.ltoreq.p.ltoreq.0.5
• 0.0001.ltoreq.q.ltoreq.0.5
• 0.5.ltoreq.n.ltoreq.3.0
• 0.ltoreq.m.ltoreq.0.5
• 0.ltoreq.k.ltoreq.0.2
• 0.ltoreq..alpha..ltoreq.0.5
• 0.ltoreq..alpha./n.ltoreq.0.4;
• and
• M is at least one member selected from a group of divalent metals consisting of Mg, Ca, Sr and Ba;
• Q is a coactivator and at least one member selected from a group consisting of Zr, Nb, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu;
• and
• X is at least one member selected from a group of halogen elements consisting of F, Cl, Br and I.