US4948527A
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US
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Method of making europium activated yttrium oxide phosphor
Assignee: Osram Sylvania Inc
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Filing: 1989-10-10
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Granted: 1990-08-14
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Expires: 2009-10-10
Abstract
Abstract A europium activated yttrium oxide phosphor is prepared as follows. Europium oxide is dissolved in nitric acid. Ammonium hydroxide is added to precipitate europium hydroxide, which is then dissolved in citric acid monohydrate to form europium citrate solution. Yttrium oxide powder is added to the solution to form a slurry, which is then spray dried. The spray dried powder is fired at a high temperature to form the phosphor.
Inventors
- 👤 Joseph E. Ritsko
- 👤 Anthony F. Kasenga
- 👤 Scott A. Renninger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 21:07
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7783; C09K11/7784; C09K11/7787
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
70 words
The method of making europium activated yttrium oxide phosphor comprising the steps of dissolving europium oxide in nitric acid, adding ammonium hydroxide thereto to precipitate europium hydroxide, dissolving the europium hydroxide in citric acid monohydrate to form europium citrate solution, dispersing yttrium oxide powder in the europium citrate solution to form a slurry, spray drying the slurry, and firing the resultant spray dried powder in air to form the phosphor.
Claim 2
Independent Claim
70 words
The method of making europium activated yttrium oxide phosphor comprising the steps of dissolving europium oxide in nitric acid, adding ammonium hydroxide thereto to precipitate europium hydroxide, dissolving the europium hydroxide in citric acid monohydrate to form europium citrate solution, dispersing yttrium oxide powder in the europium citrate solution to form a slurry, spray drying the slurry, and firing the resultant spray dried powder in air to form the phosphor.
Claim 3
Dependent Claim
27 words
The method of claim 1 wherein the europium citrate solution is adjusted to a pH of 6.0 prior to the addition thereto of the yttrium oxide powder.
Claim 4
Dependent Claim
26 words
The method of claim 1 wherein the spray dried powder is first fired in air at 1000° C. and then second-fired in air at 1600° C.
References Cited (Backward Citations)
US3870650A
Cited
US4191662A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-13 | 1994-02-12 | 1994-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-13 | 1998-02-12 | 1998-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-13 | 2002-02-12 | 2002-08-14 | $7700.00 | Window Closed / Lapsed |