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US4100101A
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Europium-activated alkaline earth fluorohalide x-ray phosphors and method for preparing the same
Assignee: GTE Sylvania Inc
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Filing: 1976-06-21
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Granted: 1978-07-11
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Expires: 1996-06-21
Abstract
Abstract In europium-activated alkaline earth fluorohalide x-ray phosphors, the brightness is improved by having a detectable amount of the europium activator in the trivalent state. This beneficial effect is achieved by using a non-reducing firing atmosphere during synthesis for a sufficient time to produce an amount of trivalent europium that is detectable by exciting a sample of the phosphor after firing with 254 nanometer excitation.
Inventors
- 👤 Russell F. Messier
- 👤 Robert W. Wolfe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:22
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7728; C09K11/7732; C09K11/7733
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
66 words
A europium-activated x-ray phosphor composition of the formula: Ba.sub.1-x Sr.sub.x FH:yEu wherein x is from about 0 to about 0.5, y is from about 0.001 to about 0.100 and H is a halogen selected from the chlorine and bromine, characterized in that europium is present in the trivalent state in an amount of at least 1 percent of the amount of europium in the divalent state.
Claim 2
Dependent Claim
66 words
A europium-activated x-ray phosphor composition of the formula: Ba.sub.1-x Sr.sub.x FH:yEu wherein x is from about 0 to about 0.5, y is from about 0.001 to about 0.100 and H is a halogen selected from the chlorine and bromine, characterized in that europium is present in the trivalent state in an amount of at least 1 percent of the amount of europium in the divalent state.
Claim 3
Dependent Claim
22 words
A composition according to claim 1 wherein the ratio of Eu +2 to Eu +3 is from about 20:80 to about 80:20.
Claim 4
Dependent Claim
10 words
A composition according to claim 2 wherein H is chlorine.
Claim 5
Independent Claim
119 words
A method for producing a europium-activated x-ray phosphor composition of the formula: Ba.sub.1-x Sr.sub.x FH:yEu wherein x is from 0 to about 0.5, and y is from about 0.001 to about 0.100, and H is a halogen selected from chlorine and bromine, the method comprising mixing alkaline earth metal halides and europium halides, and heating the mixture at a temperature within the range of from about 550° C to about 850° C to form the phosphor composition, characterized in that heating is carried out in a non-reducing atmosphere for a time sufficient to result in europium being present in the trivalent state in an amount of at least 1 percent of the amount of europium in the divalent state.
Claim 6
Independent Claim
119 words
A method for producing a europium-activated x-ray phosphor composition of the formula: Ba.sub.1-x Sr.sub.x FH:yEu wherein x is from 0 to about 0.5, and y is from about 0.001 to about 0.100, and H is a halogen selected from chlorine and bromine, the method comprising mixing alkaline earth metal halides and europium halides, and heating the mixture at a temperature within the range of from about 550° C to about 850° C to form the phosphor composition, characterized in that heating is carried out in a non-reducing atmosphere for a time sufficient to result in europium being present in the trivalent state in an amount of at least 1 percent of the amount of europium in the divalent state.
Claim 7
Dependent Claim
13 words
A process according to claim 4 wherein said atmosphere is a neutral atmosphere.
Claim 8
Dependent Claim
11 words
The method according to claim 4 wherein said atmosphere is nitrogen.
References Cited (Backward Citations)
US3988252A
Cited
US3951848A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-07-10 | 1982-01-09 | 1982-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-10 | 1986-01-09 | 1986-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-10 | 1990-01-09 | 1990-07-11 | $7700.00 | Window Closed / Lapsed |