Abstract: An oxide phosphor includes an oxide consisting of at least Gd, Ce, Al, Ga, and O, and has the crystal structure of a garnet structure, the atomic ratio (Gd+Ce)/(Al+Ga+Gd+Ce) of which is more than 0.375 and 0.44 or less, and the atomic ratio Ce/(Ce+Gd) of which is 0.0005 or more and 0.02 or less. This oxide phosphor reduces composition misalignment occurring during sintering, being a drawback of a phosphor having (Gd1-xCex)3Al5-yGayO12 composition, and has a property of extremely small afterglow and high luminescence efficiency. By using this oxide phosphor as a scintillator of a radiation detector having a light detector, the radiation detector with low afterglow and high output can be obtained. Further, by applying this radiation detector to an X-ray CT apparatus, a tomogram with high resolution and high quality can be obtained.

Abstract: An oxide phosphor includes an oxide consisting of at least Gd, Ce, Al, Ga, and O, and has the crystal structure of a garnet structure, the atomic ratio (Gd+Ce)/(Al+Ga+Gd+Ce) of which is more than 0.375 and 0.44 or less, and the atomic ratio Ce/(Ce+Gd) of which is 0.0005 or more and 0.02 or less. This oxide phosphor reduces composition misalignment occurring during sintering, being a drawback of a phosphor having (Gd1-xCex)3Al5-yGayO12 composition, and has a property of extremely small afterglow and high luminescence efficiency. By using this oxide phosphor as a scintillator of a radiation detector having a light detector, the radiation detector with low afterglow and high output can be obtained. Further, by applying this radiation detector to an X-ray CT apparatus, a tomogram with high resolution and high quality can be obtained.

Abstract: A novel phosphor represented by the general formula (Gd1-y-zCeyScz)3Al5-dGadO12 (wherein y, z and d are values falling in the ranges of 0.0005≦y≦0.05, 0<z≦0.03 and 0<d<5) is provided by adding scandium (Sc) to a phosphor represented by the general formula of (Gd1-yCey)3Al5-dGadO12 (wherein y and d are values falling in the ranges of 0.0005≦y≦0.02 and 0<d<5). The phosphor has a high luminous efficiency and a very small afterglow. A radiation detector using this phosphor as ceramic scintillator is capable of obtaining a high luminous output and suitable for a radiation detector of X-ray CT because of its high luminous output and a very small afterglow.

Abstract: A novel phosphor represented by the general formula

Abstract: A method of producing a high-temperature oxide superconducting material, which comprises the steps of (a) preparing a material corresponding to an oxide superconductor of the perovskite type structure consisting essentially of a first member selected from the group consisting yttrium, lanthanoids, thallium and bismuth; at least one alkaline earth metal; copper; and oxygen and (b) heating the material in the presence of an alkali metal selected from the group consisting of potassium, sodium, rubidium and cesium to a temperature around the melting point of the alkali metal or to a higher temperature for a time sufficient to effect grain growth in the superconductor material, thereby to produce the superconductor containing the alkali metal in an amount not larger than 4 mole % based on the first member.

Abstract: There is obtained, by mixing oxide raw material powders, compacting the mixture and sintering the compact, a silicon nitride sintered body mainly composed of silicon nitride and having a grain boundary phase wherein crystals represented by Yb.sub.2 Si.sub.2 O.sub.7 and a Zr.sub.3 Yb.sub.4 O.sub.12 are present in the grain boundary phase and molar ratio ZrO.sub.2 /Yb.sub.2 O.sub.3 in terms of ZrO.sub.2 and Yb.sub.2 O.sub.3 is 2/98 to 75/25 and the total amount of ZrO.sub.2 and Yb.sub.2 O.sub.3 is 1-40% by weight of the sintered body.