US5116559A
Expired / Lapsed
US
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Method of forming yttria-gadolinia ceramic scintillator using hydroxide coprecipitation step
Assignee: General Electric Co
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Filing: 1991-02-26
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Granted: 1992-05-26
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Expires: 2011-02-26
Abstract
Abstract A simplified method of forming polycrystalline translucent-to-transparent yttria-gadolinia composition scintillators comprises forming an aqueous suspension of hydroxide coprecipitates of the yttria-gadolinia composition, and converting the hydroxides to oxalates. The oxalates are neutralized by washing, dried, and granulated to form a finely dispersed oxalate powder. The oxalate powder is calcined, cold pressed to form a compact, and sintered in a reducing atmosphere or vacuum to form the polycrystalline translucent-to-transparent yttria-gadolinia composition scintillator.
Inventors
- 👤 Stephen L. Dole
- 👤 Subramaniam Venkataramani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 11:46
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/50; C04B35/505; C04B35/622; C04B35/626; C04B35/62605; C04B35/6261; C04B35/62645; C04B35/62655; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7783; C09K11/7784; C09K11/7787; G; G01; G01T; G01T1/00; G01T1/16; G01T1/20; G01T1/202; G01T1/2023; C04B2235/00; C04B2235/02; C04B2235/30; C04B2235/32; C04B2235/3224; C04B2235/3225; C04B2235/44; C04B2235/449; C04B2235/60; C04B2235/604; C04B2235/65; C04B2235/652; C04B2235/656; C04B2235/6562; C04B2235/658; C04B2235/6581; C04B2235/6582; C04B2235/66; C04B2235/661; C04B2235/70; C04B2235/74; C04B2235/76; C04B2235/762; C04B2235/96; C04B2235/9646; C04B2235/9653
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
95 words
A method of forming a polycrystalline translucent-to-transparent yttria-gadolinia composition scintillator that does not require milling, comprising: forming an aqueous suspension of hydroxide coprecipitates of the yttria-gadolinia composition by a wet ammonium hydroxide process; agitating the hydroxide suspension while admixing an effective amount of oxalic acid to convert the hydroxides to oxalates; calcining the oxalates to substantially fully oxidize the oxalates and form a powder of the yttriagadolinia scintillator 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 composition scintillator.
Claim 2
Independent Claim
95 words
A method of forming a polycrystalline translucent-to-transparent yttria-gadolinia composition scintillator that does not require milling, comprising: forming an aqueous suspension of hydroxide coprecipitates of the yttria-gadolinia composition by a wet ammonium hydroxide process; agitating the hydroxide suspension while admixing an effective amount of oxalic acid to convert the hydroxides to oxalates; calcining the oxalates to substantially fully oxidize the oxalates and form a powder of the yttriagadolinia scintillator 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 composition scintillator.
Claim 3
Dependent Claim
65 words
The method of claim 1 wherein the step of forming an aqueous suspension of hydroxide coprecipitates comprises dissolving a mixture of oxides of the yttria-gadolinia composition in an aqueous hydrochloric or nitric acid solution, and agitating the acid solution while admixing an ammonium hydroxide solution to form the aqueous suspension, the ammonium hydroxide solution raising the pH to at least 7 in the aqueous suspension.
Claim 4
Dependent Claim
17 words
The method of claim 1 wherein agitating is performed until the pH of the oxalate suspension stabilizes.
Claim 5
Dependent Claim
19 words
The method of claim 3 wherein the oxalate precipitates are washed with water prior to the step of calcining.
Claim 6
Dependent Claim
18 words
The method of claim 4 wherein the water does not increase to a pH above 7 during washing.
Claim 7
Dependent Claim
34 words
The method of claim 5 further including the step of drying the oxalates at about 75° to 125° C. to a friable mass, and granulating the friable mass prior to the step of calcining.
Claim 8
Dependent Claim
19 words
The method of claim 6 wherein the step of calcining is preceded by the step of milling the oxalates.
Claim 9
Dependent Claim
20 words
The method of claim 7 wherein the step of milling is vibration milling with a rigid organic polymer milling media.
References Cited (Backward Citations)
US4421671A
Cited
US4466930A
Cited
US4466929A
Cited
US4518545A
Cited
US4525628A
Cited
US4747973A
Cited
US4755492A
Cited
US5021376A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-05-26 | 1995-11-25 | 1996-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-05-26 | 1999-11-25 | 2000-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-05-26 | 2003-11-25 | 2004-05-26 | $7700.00 | Window Closed / Lapsed |