Method for making small particle blue emitting lanthanum phosphate based phosphors

摘要

Small particle lanthanum, thulium phosphate phosphors are produced by thermal decomposition of gels or solutions or powders including lanthanum, thulium, lithium and alkaline earth salts and an organic precursor such as trimethyl phosphate and boric acid at a temperature well below the normal temperature of solid state reaction. The phosphor of the present invention has the empirical formula:P P(La.sub.1-x-y-z Tm. sub.x Li.sub.y Sr.sub.z)PO.sub.4P Pwherein: 0.001≦x. ltoreq. 0.05; 0.01≦y≦0.05; and 0.0≦ z≦0.05 PPand exhibits a narrow band emission in blue region, peaking at 453 nm when excited by 147 and 173 nm radiation from Xenon gas mixture. The phosphor exhibits uniform and spherical shape particles in the range 0.1 to 5 microns, and is appropriate for thin phosphor screens required for a variety of flat panel display and lamp applications. The particle size varies with method of preparation. The phosphors also exhibit high brightness, good color saturation, better stability and shorter persistence when excited with 147 and 173 nm radiation than the currently available commercial phosphor, Eu.sup.2+ actvated barium magnesium aluminate for plasma display panels.