US5100598A
Expired / Lapsed
US
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Method of forming yttria-gadolinia ceramic scintillator from ammonium dispersed oxalate precipitates
Assignee: General Electric Co
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Filing: 1991-02-19
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Granted: 1992-03-31
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Expires: 2011-02-19
Abstract
Abstract A simplified method of forming polycrystalline translucent-to-transparent yttria-gadolinia scintillators comprises coprecipitating oxalates of the yttria-gadolinia composition, drying the oxalates at about 75° C. to 125° C., forming an aqueous suspension of the dried oxalates, and agitating the suspension while admixing an effective amount of an ammonium hydroxide solution to disperse agglomerations of the oxalate coprecipitates. The dispersed oxalates are calcined to substantially fully oxidize the oxalates and form an oxide powder of the yttria-gadolinia composition. The oxide powder is cold pressed to form a compact, and the compact is sintered in a reducing atmosphere or vacuum to form the polycrystalline translucent-to-transparent yttria-gadolinia scintillator.
Inventors
- 👤 Stephen L. Dole
- 👤 Charles D. Greskovich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:21
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/50; C04B35/505; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7783; C09K11/7784; C09K11/7787
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
102 words
A method of forming a polycrystalline translucent-to-transparent yttria-gadolinia composition scintillator that does not require milling comprising: coprecipitating oxalates of the yttria-gadolinia composition; drying the oxalates at about 75° to 125° C.; dispersing the oxalates by agitating an admixture of an aqueous suspension of the oxalates, and an effective amount of an ammonium hydroxide solution to disperse agglomerations of the oxalates; calcining the oxalates to substantially fully oxidize the oxalates and form a powder of the yttria-gadolinia composition; cold pressing the powder to form a compact; and sintering the compact in a reducing atmosphere or vacuum to form the polycrystalline translucent-to-transparent yttria-gadolinia scintillator.
Claim 2
Independent Claim
102 words
A method of forming a polycrystalline translucent-to-transparent yttria-gadolinia composition scintillator that does not require milling comprising: coprecipitating oxalates of the yttria-gadolinia composition; drying the oxalates at about 75° to 125° C.; dispersing the oxalates by agitating an admixture of an aqueous suspension of the oxalates, and an effective amount of an ammonium hydroxide solution to disperse agglomerations of the oxalates; calcining the oxalates to substantially fully oxidize the oxalates and form a powder of the yttria-gadolinia composition; cold pressing the powder to form a compact; and sintering the compact in a reducing atmosphere or vacuum to form the polycrystalline translucent-to-transparent yttria-gadolinia scintillator.
Claim 3
Dependent Claim
37 words
The method of claim 1 wherein the step of coprecipitating oxalates comprises admixing an aqueous nitrate or chloride solution of the yttria-gadolinia composition, with an aqueous oxalic acid solution in an effective amount to coprecipitate the oxalates.
Claim 4
Dependent Claim
22 words
The method of claim 2 wherein an effective amount of ammonium hydroxide solution raises the mixture pH to about 8 to 10.
Claim 5
Dependent Claim
15 words
The method of claim 3 wherein the agitating is for about 15 to 45 minutes.
Claim 6
Dependent Claim
16 words
The method of claim 4 wherein the dispersed oxalates are washed to remove excess ammonium hydroxide.
Claim 7
Dependent Claim
22 words
The method of claim 5 further comprising the step of settling the dispersed oxalates by adding an effective amount of oxalic acid.
Claim 8
Dependent Claim
21 words
The method of claim 1 wherein the step of calcining is preceded by the step of milling or screening the oxalates.
Claim 9
Dependent Claim
21 words
The method of claim 6 wherein the step of calcining is preceded by the step of milling or screening the oxalates.
Claim 10
Dependent Claim
18 words
The method of claim 7 wherein the milling is vibration milling with a rigid organic polymer milling media.
Claim 11
Dependent Claim
18 words
The method of claim 8 wherein the milling is vibration milling with a rigid organic polymer milling media.
References Cited (Backward Citations)
US4755492A
Cited
US5021376A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1995-03-31 | 1995-09-30 | 1996-03-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-31 | 1999-09-30 | 2000-03-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-31 | 2003-09-30 | 2004-03-31 | $7700.00 | Window Closed / Lapsed |