Silicon sensitized rare earth oxysulfide phosphors
First Claim
1. An X-ray intensifying screen comprising a substrate having coated on a surface thereof a plurality of particles of a rare earth oxysulfide phosphor consisting essentially of a rare earth oxysulfide matrix of the formula M2-x O2 S:
- xA wherein M is at least one rare earth element selected from the group consisting of lanthanum, gadolinium and yttrium, A is at least one rare earth activator selected from the group consisting of praseodymium, neodymium, samarium, europium, terbium, dysprosium, holmium, erbium, ytterbium, and thulium, and x is 0.001 to 0.1, silicon incorporated in said matrix in an amount from about 10 to 1,000 p.p.m. based on phosphor weight and, when M is gadolinium or yttrium, fluorine incorporated in said matrix in an amount from about 20 to 500 p.p.m.
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Abstract
Rare earth oxysulfide phosphors with excellent optical properties and optimum particle size control for use as photoluminescent, cathodoluminescent and X-ray luminescent phosphors are prepared by treating a solution of at least one salt of a rare earth metal and a salt of a rare earth activator to form solid salts and thereafter heating the oxidic compound with a sulfidizing agent and a silicon sensitizer, preferably in the presence of a fluoride. The rare earth oxysulfide phosphors thus obtained contain from 10 to 1,000 p.p.m. silicon sensitizer and, if used, 20 to 500 p.p.m. fluoride, incorporated in the crystal lattice structure.
28 Citations
3 Claims
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1. An X-ray intensifying screen comprising a substrate having coated on a surface thereof a plurality of particles of a rare earth oxysulfide phosphor consisting essentially of a rare earth oxysulfide matrix of the formula M2-x O2 S:
- xA wherein M is at least one rare earth element selected from the group consisting of lanthanum, gadolinium and yttrium, A is at least one rare earth activator selected from the group consisting of praseodymium, neodymium, samarium, europium, terbium, dysprosium, holmium, erbium, ytterbium, and thulium, and x is 0.001 to 0.1, silicon incorporated in said matrix in an amount from about 10 to 1,000 p.p.m. based on phosphor weight and, when M is gadolinium or yttrium, fluorine incorporated in said matrix in an amount from about 20 to 500 p.p.m.
- View Dependent Claims (2, 3)
- 3. An X-ray intensifying screen according to claim 1 wherein the phosphor particles are crystalline compounds having the formula
- space="preserve" listing-type="equation">Gd.sub.(2.sub.-x) Tb.sub.x O.sub.2 S
wherein x is 0.001 to 0.1, modified by incorporation into the crystal lattice of 10 to 1,000 p.p.m. of silicon and 20 to 500 p.p.m. of fluorine.
Specification
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- Resources
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Current AssigneeUS Radium Corporation
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Original AssigneeUS Radium Corporation
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InventorsTecotzky, Melvin, Mattis, James J.
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Primary Examiner(s)Borchelt, Archie R.
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Application NumberUS05/567,200Time in Patent Office522 DaysField of Search250/483, 250/486, 252/301.4 SUS Class Current250/483.1CPC Class CodesC09K 11/7771 Oxysulfides
