Gte Sylvania Incorporated

Gte Products Corporation

James E Mathers

Ramon L Yale

John L Ferri

Francis N Shaffer

Charles F Chenot

H David Layman

Paul V Kelsey, Jr

An improved (Gd.sub.1-x Tb.sub.x).sub.2 O.sub.2 S X-ray phosphor, wherein x is from 0.0003 to 0.0045, and persistence causing impurity ions are kept below 5 ppm, exhibits increased brightness in the blue region of the spectrum, while exhibiting acceptably low persistence for X-ray intensifying screen applications.

Terbium-activated gadolinium oxysulfide X-ray phosphor

Y.sub.2 O.sub.3 :Eu red-emitting phosphor exhibits up to about 8 percent brightness increase upon cathode ray excitation and about 3 percent brightness increase upon UV excitation by the addition of about 250 parts per million of Mg(as MgO).

Y.sub.2 O.sub.3 :Eu phosphor having increased brightness

Europium and ytterbium when added to terbium-activated rare earth phosphors having either a lanthanum oxysulfide, gadolinium oxysulfide, or yttrium oxysulfide host increase the decay period of the phosphors in a controlled manner.

Terbium-activated rare earth oxysulfide phosphors with controlled decay

A mixture of starting materials, corresponding to an oxide composition within an area of the ternary diagram for (Hf,Zr)O.sub.2, A.sub.2 O, P.sub.2 O.sub.5 formed by connecting end member points defined by the molar compositions: 45 (Hf,Zr)O.sub.2 - 10 A.sub.2 O - 45 P.sub.2 O.sub.5 ; 45 (Hf,Zr)O.sub.2 - 45 A.sub.2 O - 10 P.sub.2 O.sub.5 ; and 10 (Hf,Zr)O.sub.2 - 45 A.sub.2 O - 45 P.sub.2 O.sub.5, reacts to form large single crystalline essentially hexagonal particles of a new compound (Hf.sub.1-x Zr.sub.x).sub.3-y A.sub.4y (PO.sub.4).sub.4, and an aqueous-soluble second phase removable by washing. The large single crystalline hexagonal particles are useful as the luminescent material in x-ray intensifying screens, with band emission which overlaps at least partially the absorption edge of an x-ray film base to give good image resolution without crossover distortion.

Hexagonal hafnium, zirconium phosphate luminescent material, method of

An oxide composition of 3:1 (Hf.sub.1-x Zr.sub.x)O.sub.2 :P.sub.2 O.sub.5, and having the empirical formula (Hf.sub.1-x Zr.sub.x).sub.3 P.sub.2 O.sub.11, where x is in the range of about 0 to 0.5, is an effective luminescent material for use in x-ray intensifying screens, and also an effective luminescent material host for Eu.sup.+2 blue emmissions. The luminescent material is obtained in essentially single crystalline large particles when prepared in the presence of a magnesium fluoride flux.

(Hf.sub.1-x Zr.sub.x).sub.3 P.sub.2 O.sub.11 luminescent material,

An X-ray phosphor composition consisting essentially of a material having the formula

Yttrium indium phosphate X-ray phosphors, method of preparation and

Phosphors having the general formula (A.sub.1.sub.-x RE.sub.x).sub.2 Hf.sub.2 O.sub.7 are disclosed wherein A is selected from the group consisting of yttrium, gadolium, lanthanum, scandium and lutetium; RE is selected from the group consisting of praseodymium, samarium, europium, terbium, dysprosium, holmium, erbium and thulium; and x is from about 0.001 to 0.10. The phosphors are prepared by dissolving an oxide of A and an oxide of RE in a mineral acid and dissolving HfOCl.sub.2 in water and combining the two solutions. A precipitating agent such as oxalic acid is added and the precipitate is washed, dried and fired to produce the phosphors.

Method of preparing rare earth pyrohafnate phosphors

Terbium-activated rare-earth oxysulfide X-ray phosphors containing small amounts of cerium exhibit shorter decay times than the same materials without cerium. X-ray intensifying screens employing such phosphors enable improved resolution.

Terbium-activated rare earth oxysulfide X-ray phosphors

An orange broad-band emitting phosphor is a titanium-activated lanthanum oxysulfide containing up to about 0.05 moles of titanium per mole of lanthanum oxysulfide host. The phosphor is prepared by incorporating titanium oxide in the desired ratio to lanthanum into the mixture at the time the lanthanum is sulfurized in the presence of an alkali metal carbonate, to form lanthanum oxysulfide.

Titanium-activated lanthanum oxysulfide phosphor and method of preparing

A process suitable for reclaiming europium-activated yttrium oxysulfide contaminated with europium-activated yttrium oxide and other non-rare earth cathodoluminescent phosphors comprises forming a relatively uniform admixture of specific fluxing agents, the contaminated yttrium oxysulfide phosphor, a sufficient amount of reactive rare earth source selected from reactive yttrium and europium sources to achieve a predetermined yttrium to europium ratio in the admixture and an excess of the theoretical amount of sulfur required to convert the yttrium oxide and the yttrium source to yttrium oxysulfide, heating the admixture at a temperature of at least 850.degree.C in non-oxidizing atmosphere for a time sufficient to convert the yttrium oxide and the yttrium source to a europium-activated yttrium oxysulfide whereby the rare earth materials form a cathodoluminescent material and whereby the non-rare earth materials form water soluble reaction products, washing the resulting material with sufficient water to remove water soluble materials leaving a cathodoluminescent europium-activated yttrium oxysulfide phosphor.

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Ulster, PA, United States of America

James E Mathers