| 摘要 |
PROBLEM TO BE SOLVED: To obtain a phosphorescent phosphor improved in both afterglow luminance and afterglow time by preparing an alkaline earth metal aluminate having a specified compsn. ratio and activated by divalent europium. SOLUTION: An alkaline earth metal aluminate represented by the formula: RO.a(Al1-xGax)2O3.bMmOn.cB2O3.dEu2+ (wherein 0.3<=a<=8; 0<=b<=0.2; 0.001<=c<=0.3; 0.001<=d<=0.3; and 0<=x<=1.0) and activated by divalent europium is prepd. In the formula, R is at least one element selected from among Zn and alkaline earth metals (Ba, Sr, Ca, Mg, or the like); and M is at least one element selected from among Y, Sc, and Si. Oxides of above elements or compds. easily convertible into R2+, Al3+, Y3+, Sc3+, Si4+, and Eu2+ are sufficiently mixed and then baked at 1,100-1,600 deg.C for 1-10 hr in a reducing atmosphere to give the objective phosphor.
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