Rare earth oxysulfide phosphor and X-ray detector using the same

Abstract

When each of a rare earth oxysulfide phosphor represented by the composition formula (I) of Ln.sub.2 O.sub.2 S:xRe, yM wherein Ln represents at least one rare earth element selected from Y, La and Gd; Re represents at least one rare earth element selected from Pr and Tb; M represents at least one element selected from Nb, Ta and Mn; and x and y are numbers which satisfy the conditions of 1.times.10.sup.-4 .ltoreq.x.ltoreq.0.2 and 0.01 ppm .ltoreq.y.ltoreq.1000 ppm, respectively, and a rare earth oxysulfide phosphor represented by the composition formula (II) of (Gd .sub.1-x-y-z, Pr.sub.x, Sc.sub.y, Ce.sub.z).sub.2 O.sub.2 S wherein x, y and z are numbers which satisfy the conditions of 10.sup.-4 .ltoreq.x.ltoreq.2.times.10.sup.-1, 10.sup.-4 .ltoreq.y.ltoreq.10.sup.-1 and 0.ltoreq.z.ltoreq.10.sup.-6, respectively is excited by radiation, each of them emits a scintillation at high efficiency, and decreases the afterglow. Each of the phosphors is used for an X-ray detector as a scintillator, and is useful for an X-ray CT apparatus.

Dependencies are inferred from the claim text.