X=ray intensification screen - has layer contg. europium doped luminescent fluoride halide(s) of alkaline earth metals and layer contg. calcium tungstate

Abstract

Abstract X-ray intensification screen comprises a support carrying (a) a first layer contg. europium doped luminescent fluoride halides of alkaline earth metals having the formula (Me1-f, Mgf)F2. aMe'X2.bKX'.cMe"SO4:dEu2+,eTb3+ (I) in which Me, Me' and Me" are each at least one alkaline earth metal chosen from Ba, Sr and Ca, X and X' are each at least one of Cl and Br, and a, b, c, d, e and f satisfy one of the following 5 combinations: 1. 0.80 a1=1.50, b1=0.10-1.50; c1=0, d1=0.001-0.20, e1=0 and f1=0; 2. a2=0.30-1.50, b2=0.10-2.00; c2=0.01-1.00, d2=0.001-0.20, e2=0 and f2=0; 3. a3 is up to 1, b3 is up to 0, c3=0, d3=0.01-0.10, e3=0-0.05 and f3=0; 4. a4=1. b4=0, c4=0, d4=0.001-0.20, e4=0 and f4=0-1; and 5. a5=1, b5=0-1.5, c5=0, d5=0.001-0.20, e5=0 and f5=0;1; and (b) a second luminescent lyer contg. Ca tungstate on the first luminescent layer. The Eu(2+) activated phosphors of the invention have shorter afterglow period after excitation by X-rays, cathode rays or UV than prior art Eu)2+) doped phosphors and are more suitable for the prodn. of X-ray intensification screens.

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