Long afterglow silicate luminescent material and its manufacturing method

A long afterglow luminescent material, comprising silicates with activators, wherein said luminescent material has a chemical composition of:

• aMO.multidot.bM'O.multidot.bM'O.multidot.cSiO.sub.2 .multidot.dR:Eu.sub.x,Ln.sub.y, wherein
• M represents one or more elements selected from the group consisting of Sr, Ca, Ba and Zn;
• M' represents one or more elements selected from the group consisting of Mg, Cd and Be;
• R represents one or two components selected from B.sub.2 O.sub.3 and P.sub.2 O.sub.5 ;
• Ln represents one or more elements selected from the group consisting of Nd, Dy, Ho, Tm, La, Pr, Tb, Ce, Mn, Bi, Sn and Sb;
• and wherein
• a, b, c, d, x, and y represent mole coefficients, wherein 0.6.ltoreq.a.ltoreq.6, 0.ltoreq.b.ltoreq.5, 1.ltoreq.c.ltoreq.9, 0.ltoreq.d.ltoreq.0.7, 0.00001.ltoreq.x.ltoreq.0.2, and 0<y.ltoreq.0.3;
• with the proviso that when Ln includes Bi, Mn or Sn, d.noteq.0;
• and
• said luminescent material is capable of emitting an emission spectrum ranging from 420 nm to 650 nm when excited by short wavelength light ranging from 250 nm to 500 nm, with a peak position of the emission spectrum ranging from 450 nm to 580 nm, and wherein the long afterglow luminescent color of said luminescent material is blue, bluish-green, green, greenish-yellow or yellow.