PURPOSE: To obtain high sensitivity and high resolution by composing this screen of a mixture composed of yttrium tantalate and lanthanum oxyhalide phosphors. CONSTITUTION: This screen consists of a base and a layer of a phosphor mixture dispersed into a binder on this base. The phosphor mixture is composed of tantalate which is rare earth tantalate of YNBx Ta1-x O4 having a monoclinic M' structure and in which X is from 0 to 0.15. The mixture is constituted by adding rare earth activated lanthanum oxyhalide to this tantalate at 10 to 80wt.% based on the total weight of the phosphor mixture. More preferably, the rare earth activated lanthanum oxyhalide is the lanthanum oxybromide activated by yttrium. The screen made from this mixture affords the results more than the high conversion efficiency of the oxyhalide component and the excellent image quality of the tantalate component and exhibits the high resolution more than predicted from the knowledge when using the individual components alone.
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