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US4162232A
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Rare earth activated rare earth fluorogermanate
Assignee: GTE Sylvania Inc
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Filing: 1978-08-09
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Granted: 1979-07-24
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Expires: 1998-08-09
Abstract
Abstract Rare earth activated rare earth fluorogermanates, represented by the formula: [R 1 .sbsb.x R 2 .sbsb.(1-x) ] a F b GeO C wherein x is a value from about 0.9 to about 0.9998, a is a value of from about 2 to about 4, b is from about 0.85 to about 3.15, c is from about 4 to about 7.5 R 1 is selected from the group of Y, Gd and La and R 2 is selected from Eu, Gd, Tb and Pr and R 1 and R 2 are different, are excited by long or short wavelength ultraviolet light. A solid state process for using a blend of the metal oxides and a heat-decomposable fluorine compound is disclosed along with a preferred embodiment wherein the dual rare earth oxide is formed prior to forming the aforementioned blend of metal oxides.
Inventors
- 👤 Ramon L. Yale
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:27
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7766; C09K11/7775
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
93 words
A luminescent composition consisting essentially of a rare earth activated rare earth fluorogermanate represented by the formula: [R 1 .sbsb.x R 2 .sbsb.(1-x) ] a F b Ge O c wherein R 1 is selected from Y, La and Gd, R 2 is selected from Eu, Gd, Tb and Pr and R 1 and R 2 are different rare earth elements, x is from about 0.9 to about 0.9998, a is from about 2 to 4, b is from about 0.85 to about 3.15 and c is from about 4 to about 7.5.
Claim 2
Dependent Claim
93 words
A luminescent composition consisting essentially of a rare earth activated rare earth fluorogermanate represented by the formula: [R 1 .sbsb.x R 2 .sbsb.(1-x) ] a F b Ge O c wherein R 1 is selected from Y, La and Gd, R 2 is selected from Eu, Gd, Tb and Pr and R 1 and R 2 are different rare earth elements, x is from about 0.9 to about 0.9998, a is from about 2 to 4, b is from about 0.85 to about 3.15 and c is from about 4 to about 7.5.
Claim 3
Dependent Claim
20 words
A composition according to claim 1 wherein a is about 2, b is about 3 and c is about 5.
Claim 4
Dependent Claim
11 words
A composition according to claim 2 wherein R 2 is europium.
Claim 5
Dependent Claim
11 words
A composition according to claim 3 wherein R 1 is Y.
Claim 6
Dependent Claim
15 words
A compostion according to claim 4 wherein x is from about 0.94 to about 0.96.
Claim 7
Dependent Claim
132 words
A process for producing a luminescent composition according to claim 1. (a) forming a relatively uniform admixture of a first rare earth oxide selected from the group consisting of yttrium oxide, gadolinium oxide and lanthanium oxide, a second rare earth oxide selected from the oxides of europium, gadolinum, terbium and praseodymium, wherein said first and second rare earth oxides are different, germanium oxide and a heat decomposable fluorine source, said mixture having a first to second rare earth oxide molar ratio of from about 9:1 to about 9998:2, and a total rare earth: F:Ge atomic ratio of from about 2:0.85:1 to about 4:3.15:1 respectively, and (b) firing said admixture at a temperature of from about 1200° C. to about 1600° C. hours in a non-reducing atmosphere for at least about 8 hours.
Claim 8
Dependent Claim
76 words
A process according to claim 6 wherein a source of the first and second oxides are prepared by precipitating a mixed rare earth oxalate of a first rare earth and a second rare earth from an aqueous solution containing ions of said rare earths, heating said oxalate in an oxidizing atmosphere to a temperature of about 800° C. to about 1100° C. for a time sufficient to convert the oxalate to the mixed rare earth oxide.
Claim 9
Dependent Claim
23 words
A process according to claim 6 wherein said admixture is fired at a temperature of from about 1220° C. to about 1350° C.
Claim 10
Dependent Claim
21 words
A process according to claim 6 wherein the rare earth to the fluorine to germanium atomic ratio is about 3:3:1, respectively.
Claim 11
Dependent Claim
22 words
A process according to claim 6 wherein the ratio or rare earth to fluorine to germanium atomic ratio is about 2:0.85:1 respectively.
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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) | 1982-07-23 | 1983-01-22 | 1983-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-07-23 | 1987-01-22 | 1987-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-07-23 | 1991-01-22 | 1991-07-24 | $7700.00 | Window Closed / Lapsed |