Abstract: A phosphorescent phosphor represented by m(Sr.sub.1-a,M.sup.1.sub.a)O.n(Mg.sub.1-b, M.sup.2.sub.b)O.2(Si.sub.1-c,Ge.sub.c)O.sub.2 :Eu.sub.x Ln.sub.y, wherein M.sup.1 is Ca and/or Ba, M.sup.2 Be, Zn and/or Cd, Ln is Sc, Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, B, Al, Ga, In, Tl, Sb, Bi, As, P, Sn, Pb, Ti, Zr, Hf, V, Nb, Ta, Mo, W, Cr and/or Mn, and wherein a, b, c, m, n, x and y are within ranges of 0.ltoreq.a.ltoreq.0.8, 0.ltoreq.b.ltoreq.0.2, 0.ltoreq.c.ltoreq.0.2, 1.5.ltoreq.m.ltoreq.3.5, 0.5.ltoreq.n.ltoreq.1.5. 1.times.10.sup.-5 .ltoreq.x.ltoreq.1.times.10.sup.-1, and 1.times.10.sup.-5 .ltoreq.y.ltoreq.1.times.10.sup.-1, and which contains a halogen element such as F, Cl, Br or I in an amount within range of from 1.times.10.sup.-5 to 1.times.10.sup.-1 g.multidot.atm/mol of the host material.

Abstract: A monochrome display cathode ray tube which comprises a white emitting fluorescent screen formed on a face plate facing an electron gun to emit cathode rays, said white emitting fluorescent screen being composed essentially of a phosphor mixture comprising from 40 to 70% by weight of a long after-glow red emitting europium-activated indium borate phosphor, from 10 to 40% by weight of a long after-glow green emitting manganese-activated zinc silicate phosphor and from 10 to 50% by weight of a long after-glow blue emitting silver-activated zinc sulfide phosphor.