US4057508A
Expired / Lapsed
US
⏱️ 0.0 years remaining
X-ray phosphors with low afterglow
Assignee: GTE Sylvania Inc
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Filing: 1976-12-01
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Granted: 1977-11-08
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Expires: 1996-12-01
Abstract
Abstract In europium-activated alkaline earth mixed halide x-ray phosphor compositions the addition of minor amounts of yttrium significantly reduces afterglow or persistance. A syngeristic effect upon the reduction of afterglow is observed when both yttrium and lithium additives are both included. Additions of other rare earths and alkali metals are not effective to reduce afterglow. The effective amount of Y is from about 0.001 to about 0.1 moles of yttrium per mole of host. When lithium is used in conjunction with yttrium, about 0.001 to about 0.1 moles of lithium per mole of host is used.
Inventors
- 👤 Robert Wade Wolfe
- 👤 Russell Francis Messier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:58
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7783; C09K11/779; C09K11/7791; G; G21; G21K; G21K4/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
63 words
An x-ray luminescent composition consisting essentially of an activated host represented by the formula: Ba.sub.1-x Sr.sub.x FCl:yEu.aY.bLi wherein x is from 0 to about 0.3 y is from about 0.002 to about 0.2 a is from about 0.001 to about 0.1 b is from 0 to about 0.1, having a smaller afterglow than an X-ray luminescent composition consisting essentially of Ba.sub.1-x Sr.sub.x FCl:yEu.
Claim 2
Dependent Claim
63 words
An x-ray luminescent composition consisting essentially of an activated host represented by the formula: Ba.sub.1-x Sr.sub.x FCl:yEu.aY.bLi wherein x is from 0 to about 0.3 y is from about 0.002 to about 0.2 a is from about 0.001 to about 0.1 b is from 0 to about 0.1, having a smaller afterglow than an X-ray luminescent composition consisting essentially of Ba.sub.1-x Sr.sub.x FCl:yEu.
Claim 3
Dependent Claim
15 words
A composition according to claim 1 wherein b is from about 0.001 to about 0.05.
Claim 4
Dependent Claim
15 words
A composition according to claim 1 wherein x is from about 0.005 to about 0.1.
Claim 5
Dependent Claim
40 words
A composition according to claim 1 wherein x is from about 0.01 to about 0.07, y is from about 0.05 to about 0.15, a is from about 0.003 to about 0.05 and b is from about 0.001 to about 0.05.
Claim 6
Dependent Claim
15 words
A composition according to claim 1 wherein a is from about 0.003 to about 0.05.
Claim 7
Dependent Claim
15 words
A composition according to claim 5 wherein b is from about 0.001 to about 0.05.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-11-07 | 1981-05-09 | 1981-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-11-07 | 1985-05-09 | 1985-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-11-07 | 1989-05-09 | 1989-11-08 | $7700.00 | Window Closed / Lapsed |