| 摘要 |
PURPOSE:To obtain a phosphor having a short afterglow duration in a high conversion efficiency, by mixing predetermined proportions of a compd. contg. an element selected from Y, La and Gd, a compd. contg. an element selected from Pr, Tb and Eu a compd. contg. a halogen element and an S-contg. compd., together and burning the mixture. CONSTITUTION:A compd. of at least one element (A) selected from Y, La and Gd, a compd. of at least one element (Ln) selected from Pr, Tb and Eu, a compd. of at east one element (X) selected from F, Cl and Br and an S-contg. compd. or a mixture capable of forming a sulfide of an alkali metal upon heating, as starting materials, are mixed together in predetermined proportions and burnt at 900-1,300 deg.C to prepare a phosphor of the formula (wherein A, Ln and X are elements defined above, the amt. of X being in the range of 0-1,000wt.ppm; and 0.000003<=x<=0.2, 0.000001<=y<=0.005) of which the average of fluorescence output values for 2-14msec after discontinuation of excitation by radiation is about 1/500 or below of the fluorescence output during the excitation.
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