EP0321805A1
Expired / Lapsed
EP
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Phosphors, process for the preparation of said phosphors and method for recording and reproducing radiographic images
Assignee: 3M Co
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Filing: 1988-12-09
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Granted: —
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Expires: 2008-12-09
Abstract
Abstract Phosphors constituted by terbium and/or cerium activated lutetium-gadolinium-yttrium silicates have shown a high visible-light emission efficiency upon exposure to high energy radiation. Said phosphors are useful in the methods for recording and reproducing high energy radiation images.
Inventors
- 👤 Sibylle Kemmler-Sack
- 👤 Romano Morlotti
- 👤 Jürgen Reichardt
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 12:49
CPC Classifications
G; G21; G21K; G21K4/00; C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7766; C09K11/77742
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
13 words
A phosphor characterized by being a terbium and/or cerium activated ternary lutetium-gadolinium-yttrium silicate.
Claim 2
Dependent Claim
13 words
A phosphor characterized by being a terbium and/or cerium activated ternary lutetium-gadolinium-yttrium silicate.
Claim 3
Dependent Claim
14 words
The phosphor according to claim 1, wherein said ternary silicate has an orthosilicatic structure.
Claim 4
Dependent Claim
38 words
The phosphor according to claim 1, characterized by being selected from the group represented by the following formula: (Lu x Gd y Y z )₂ SiO₅ : aTb, bCe, wherein x+y+z=1, 0<x<1, 0<y<1, 0<z<1, 0≦a≦0.3, 0<b<0.01 and a+b≠0.
Claim 5
Dependent Claim
14 words
The phosphor according to claim 3, characterized by being 0.15≦x≦0.45, 0.15≦y≦0.45, 0.15≦z≦0.45, 0.01≦a≦0.2, 0.0008≦b≦0.0012.
Claim 6
Dependent Claim
80 words
A process for preparing a phosphor according to any of the preceding claims, characterized by comprising the steps of: - preparing a solution, by dissolving lutetium, gadolinium and yttrium oxides and terbium and/or cerium oxides in diluted nitric acid, - adding tetraethylorthosilicate and alcohol, - forming a gel, by adding an excess of ammonia, - drying the gel, by keeping it at about 70°C for 3-4 days, - firing it for several periods at gradually increasing temperature, up to 1400-1600°C.
Claim 7
Dependent Claim
23 words
The process according to claim 5, characterized in that a flux is added after having divided the dried gel and before firing it.
Claim 8
Dependent Claim
16 words
The process according to claim 5, characterized in that the the gel is fired in air.
Claim 9
Dependent Claim
21 words
The process according to claim 5, characterized in that the gel is fired in argon, nitrogen, nitrogen-hydrogen or nitrogen-carbon oxides atmosphere.
Claim 10
Independent Claim
92 words
A method of direct radiography for getting a radiograph from an X-ray image of an object, comprising the steps of: a) causing an X-ray radiation to pass through the object, b) collecting the passed radiation image onto a phosphor screen capable of converting the radiation image into a light image, c) collecting the light image onto a photographic film capable of being impressed by the light image, said method being further characterized in that said phosphor is a terbium and/or cerium activated ternary lutetium-gadolinium-yttrium orthosilicate phosphor according to claims 1 to 4.
Claim 11
Dependent Claim
39 words
An X-ray radiation image converting screen having a fluorescent layer comprising a binder and, dispersed therein, a phosphor, characterized in that said phosphor is a terbium and/or cerium activated ternary lutetium-gadolinium-yttrium silicate phosphor according to claims 1 to 4.
References Cited (Backward Citations)
DE2816069A1
Cited
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