Abstract: A process for producing a columbite-type niobate and a process for producing a niobium-containing lead-type perovskite compound using the columbite-type niobate. A precursor slurry of a columbite compound composed of a fresh niobium hydroxide, a metal acetate and ammonium aqueous solution is spray-dried, and is calcined at 500.degree. C. or higher to obtain a crystalline columbite-type compound having grain sizes of 1 .mu.m or smaller to which was then mixed a lead component. The mixture is calcined, pulverized and is sintered at a temperature of 800.degree. to 1100.degree. C. to synthesize a highly dielectric material of a niobium-containing lead-type composite perovskite. The precursor of columbite is calcined at 500.degree. to 1100.degree. C. to obtain fine columbite-type niobate crystals of grain sizes of 1 .mu.m or smaller. A lead-type perovskite compound using the above crystals can be sintered at a temperature of as low as 950.degree. C.

Abstract: The present invention relates to new phosphors for use in panels, apparatus and methods for recording and reproducing a high energy radiation image, including the steps of stimulating a phosphor image-wise exposed to radiation and detecting the fluorescent light emitted by said phosphor upon stimulation, said phosphor being a green emitting terbium activated alkali metal tantalate, doped with at least one element selected in the group consisting of Mg, Ca, Sr, Ba, Al, Ga, Ge, Pb, Bi, transition elements and lanthanides.

Abstract: A photostimulable storage phosphor within the scope of following formula (I):M.sub.3 (PO.sub.4).sub.2 :xEu.sup.2+, yT.sup.3+, zZr.sup.4+wherein: M is at least one of the alkaline earth metals selected from the group consisting of Ca, Sr and Ba, x corresponds with an atom fraction value 5.times.10.sup.-5 .ltoreq..times..ltoreq.10.sup.-1, y corresponds with an atom fraction value 0.ltoreq.y.ltoreq.10.sup.-1, T.sup.3+ is at least one member selected from the group consisting of La.sup.3+, Lu.sup.3+, y.sup.3+ and Gd.sup.3+, z corresponds with an atom fraction value 0.ltoreq.z.ltoreq.10.sup.-1, and 5.times.10.sup.-5 .ltoreq.z+y.ltoreq.10.sup.-1.

Abstract: Disclosed are terbium-activated oxide phosphors having incorporated, at least one of ytterbium, thulium, samarium and europium. Incorporation of the element (s) has made it possible to produce phosphors exhibiting high brightness and suffering little brightness deterioration under high-density electron bombardment.

Abstract: A pigment-attached blue-emitting phosphor comprising a blue-emitting phosphor and a blue pigment attached to the surface of the blue-emitting phosphor, said blue pigment being a CoO.ZnO.SiO.sub.2 type pigment containing Mo.

Abstract: A method for preparing metal halide phosphor particles, e.g. barium- and/or strontium-containing halide phosphor particles, of a selected particle size range with improved powder flowability which method comprises the following steps:(1) firing the raw mixture materials of said phosphor to produce a sintered phosphor mass that is pulverized,(2) mixing said pulverized phosphor mass, optionally after one or more firings, in a liquid mainly containing a water-miscible organic solvent with an organic acid dissolved therein, said acid being capable of forming with metal contained in the phosphor a salt the solubility of which in water at 20.degree. C. is less than 0.5 g per 100 ml, and(3) subjecting the thus treated phosphor particles in wet and/or in dry state to a separation treatment to collect phosphor particles having a grain size smaller than 40 .mu.m but larger than 2 .mu.m.

Abstract: In a computed tomography machine employing a luminescent material in a scintillator in which a significant factor in afterglow is the release of holes from hole traps in the scintillator material, afterglow in the luminescent material is substantially reduced by adding a hole-trapping species to the scintillator composition which successfully competes with the hole traps in the basic scintillator composition. For a gadolinium gallium garnet scintillator activated with chromium, the addition of cerium reduces afterglow in this manner.

Abstract: Magnetic particles for perpendicular magnetic recording, which are hexagonal ferrite particles having a hexagonal platelet shape, and are represented by the formula MM'.sub.x M".sub.y Fe.sub.2x-y+2z O.sub.1+4x+3z (wherein M represents at least one element or a combination of elements selected from Ba, Sr, Ca and Pb; M' is at least one element or a combination of elements selected from Co, Zn and Mn; M" is at least one element or a combination of elements selected from Co, Ti, In, Zn, Mn, Ge, Nb, Zr, Ta, V and Sn, x is a number of z/4 to z, inclusive; y is a number of 0 to (x+z)/3, inclusive; and z is a number of 5.5 to 9.0, inclusive), and has an average particle size of from 0.01 to 0.3 .mu.m. The magnetic particles have a novel crystal structure different from both the magnetoplumbite structure and the spinel structure, even internally of the individual particles.

Abstract: This invention provides magnetite particles containing a silicon component inside and also a silicon component exposed on the surface of each particle, which are improved in the properties of electrical resistance, remanent magnetization, and fluidity in a well-balanced way and suited for use principally as powdery material for magnetic toner for electrostatic copying and as black pigment powder for coating materials; and also relates to a process for producing the particles.

Abstract: An improved method is proposed for the preparation of a composite carbonate powder of lanthanum, cerium and terbium as a base material of a green-emitting phosphor for which the carbonate powder is desired to have a uniform particle size distribution and a particle configuration as close to spherical as possible. The improved method is characterized by two-step heat treatment of the carbonate slurry formed by the addition of, for example, ammonium hydrogen carbonate to a mixed aqueous solution of lanthanum, cerium and terbium nitrates each under specified conditions while the pH of the aqueous slurry is adjusted to 5.0 to 7.5 after the first step heat treatment but before the second step heat treatment.

Abstract: A blue-emitting phosphor of europium-activated barium magnesium aluminate is used in a high color rendering three-band type fluorescent lamp, in which the particle size distribution is uniform to obtain excellent phosphor layer. A fluorescent lamp employing the blue-emitting phosphor mixed with red and green-emitting phosphors has a uniform emission luminance distribution and increased luminous flux intensity. The employed blue phosphor is expressed:Ba.sub.a Mg.sub.b Al.sub.c La.sub.x O.sub.a+b+3(c+x)/2 :Eu.sub.dwhere 0.1.ltoreq.a.ltoreq.2.4, 0.1.ltoreq.b.ltoreq.5, 8.ltoreq.c.ltoreq.64, 0.001.ltoreq.x.ltoreq.0.2, and 0.1.ltoreq.d.ltoreq.4.

Abstract: Metal phosphide used as a raw material in the synthesis of alkaline earth metal halophosphate phosphor activated by antimony and manganese acts as a reducing agent to prevent oxidation of the antimony and manganese. The result is maximum availability of trivalent antimony and divalent manganese for incorporation into the phosphor lattice.

Abstract: An oxide magnetic material comprises a basic composition consisting essentially of 45.0 to 49.0 mol % of Fe.sub.2 O.sub.3, 3.0 to 9.0 mol % of MgO, 1.0 to 4.0 mol % of CuO, 0.1 to 1.5 mol % of Bi.sub.2 O.sub.3, and the balance of NiO and additives, and contains, as additives, SiO.sub.2 and Co.sub.3 O.sub.4 incorporated in the basic composition in an amount of 0.1 to 0.5 wt % of SiO.sub.2 and 0.05 to 0.35 wt % of Co.sub.3 O.sub.4.

Abstract: A red-emitting phosphor represented by a general formula (Y.sub.1-x-y Cr.sub.x Gd.sub.y).sub.3 (Al.sub.1-z Ga.sub.z).sub.5 O.sub.12 with the provide that 0.0005.ltoreq.x.ltoreq.0.05, O.ltoreq.y.ltoreq.1, O.ltoreq.z.ltoreq.1, providing red- and infrared emitting luminescence, using alone or in a mixture with other phosphors in a cathode ray tube, having a constant main emission peak even if excited by a high current density, having a satisfactory luminescence efficiency, and causing less brightness saturation in proportion as a current density increases.

Abstract: In a method of preparing an alkaline earth halophospor having an antimony content greater than about 0.70 weight percent, a uniform mixture of starting raw materials is fired with already fired phosphor of the desired alkaline earth halophosphate so that the already fired phosphor is refired in an inert atmosphere containing volitile species from the uniform mixture of starting raw materials.

Abstract: Disclosed herein are spinel-type spherical black iron oxide particles containing 1.5 to 17.0 wt % of Zn, and having a specific surface area of 5 to 15 m.sup.2 /g, a magnetization of not less than 70 emu/g in an external magnetic field of 1 kOe and a coercive force (Hc) of not more than the value obtained from the following expression:Hc(Oe)=15+3.times.(specific surface area of the particles).and a process for producing the same.

Abstract: A method of reclaiming a phosphor from a recovered phosphor slurry containing carbon, a bichromate, and polyvinyl alcohol, comprises, (a) a decomposition treatment step of adding an alkali to the recovered phosphor slurry after the slurry is heated to prepare a phosphor suspension having an alkali concentration of 0.5N or less in the slurry, and adding an oxidizing agent in an amount of 1.0 to 20.0 wt % with respect to a dry solid component of the suspension, (b) a weak acid treatment step of separating a phosphor from the suspension, and adding a weak acid to a suspension obtained by adding water to the separated phosphor, thereby adjusting a pH to be 3.0 to 5.0, and (c) a surface treatment step of treating the surface of the phosphor separated from the suspension.

Abstract: The present invention discloses a phosphor slurry composition for color Braun tubes comprising deionized water, phosphor powder, polyvinyl alcohol, sodium dichromate, ethyl silicate and zinc sulfate. A color Braun tube manufactured using a phosphor slurry composition of the present invention shows an excellent mirror reflection effect and high luminescent brightness.

Abstract: Afterglow in a luminescent material in which a significant factor in afterglow is the release of holes from hole traps in the scintillator material is substantially reduced by adding a hole-trapping species to the scintillator composition which successfully competes with the hole traps in the basic scintillator composition. In gadolinium gallium garnet activated with chromium, the addition of cerium, terbium or praseodymium reduces afterglow in this manner.

Abstract: Needle-shaped solid crystallites of specific LaCeTb phosphates, well suited for the production of green phosphors therefrom, are essentially pure white in color after calcination at 900.degree. C. and have the formula (I):La.sub.x Ce.sub.y Tb.sub.(1-x-y) PO.sub.4 (I)in which x and y are numbers, with x ranging from 0.4 to 0.6 and x+y being greater than 0.8.