Nichia Kagaku Kogyo K.k.

Satoru Chikutei

Genichi Shinomiya

Shigeharu Nakajima

Mizuho Takeda

Minamidani Takatoshi

The phosphor and the X-rays intensifing screen according to the present inventin emit light by the excitation of X-ray, and they are used for medical and industrial radiography. In addition to the conventional contents of rare earth tantalate and/or rare earth niobate, the phosphor according to the present invention contains a determined quantity of divalent metal. This divalent metal content can make the improvement of the afterglow characteristic and the light emission characteristic of the phosphor. The phosphor according to the present invention is represented by the general formula (I) MyLn.sub.1 -x-(2/3)yDO.sub.4 : xR.sup.3+ (I). In the general formula above, M is at least one divalent metal selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn and Cd, Ln being at least one selected from the group consisting of Y, Gd, La, and Lu, D being either or both of Ta and Nb, R being at least one selected from the group consisting of Tm, Pr, Sm, Eu, Tb, Dy and Yb or the base substance is self-activating, and y is a value in the range 1.times.10.sup.-5 .ltoreq.y.ltoreq.1, and x is a value in the range 0.ltoreq.y.ltoreq.0.05.

Phosphor which emits light by the excitation of X-ray, and a X-ray

This invention relates to rare earth tantalate and/or niobate phosphors which emit light under X-ray excitation, and an X-ray intensifing screen which utilizes these phosphors. The phosphor is represented by the general formula (I);

X-ray phosphors and X-ray intensifying screen using the phosphor

A phosphor for an X-ray intensifying screen contains a phosphor mixture of a phosphor represented by BaFBr:mEu.sup.2+ (5.times.10.sup.-4 .ltoreq.m.ltoreq.5.times.10.sup.-2), and a phosphor represented by Y.sub.1-2/3.times. M.sup.x TaO.sub.4 :nNb (10.sup.-5 .ltoreq..times..ltoreq.1, 0.ltoreq.n.ltoreq.0.05, and M is at least one member selected from the group consisting of Ca, Sr, and Cd). An X-ray intensifying screen includes a support and a phosphor layer formed on the support and containing the above phosphor. When this X-ray intensifying screen is used, an X-ray image producing less crossover light and having high graininess and sharpness can be obtained. An exposure amount of an object to be examined can be reduced in medical radiophotography, and radiation diagnostic performance can be improved.

Phosphor for X-ray intensifying screen and X-ray intensifying screen

The phosphor and the X-ray intensifying screen according to the present invention emit light by the excitation of X-rays and they are used for medical and industrial radiography. In addition to the conventional contents of rare earth tantalate and/or rare earth niobate, the phosphor according to the present invention contains a determined quantity of divalent metal. This divalent metal content can make the improvement of the afterglow characteristic and the light emission characteristic of the phosphor. The phosphor according to the present invention is represented by the general formula (I)

Phosphor which emits light by the excitation of X-ray

A phosphor material for a radiation intensifying screen includes phosphor particles which emit light upon radiation excitation, and alkaline-earth metal fluoride. The alkaline-earth metal fluoride is formed in situ on the surface of the phosphor particles through a reaction of a first reactant containing the alkaline-earth metal with a second reactant containing the fluoride to improve the dispersibility of the phosphor particles. The phosphor material is dispersed in a binder and coated on a base support as a phosphor layer to provide a radiation intensifying screen.

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Anan, Japan

Satoru Chikutei