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US4518546A
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Preparation of yttria-gadolinia ceramic scintillators by sintering and gas hot isostatic pressing
Assignee: General Electric Co
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Filing: 1984-05-08
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Granted: 1985-05-21
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Expires: 2004-05-08
Abstract
Abstract Sintering and gas hot isostatic pressing are used to prepare polycrystalline yttria-gadolinia ceramic scintillator bodies. Multi-component powder compacts, formed by cold pressing cold isostatic pressing, are sintered to the closed porosity stage. The density of the sintered compacts is then increased by gas hot isostatic pressing. The finished scintillator includes Y 2 O 3 , Gd 2 O 3 , and one or more of Eu 2 O 3 , Nd 2 O 3 , Yb 2 O 3 , Dy 2 O 3 , Pr 2 O 3 , and Tb 2 O 3 rare earth activator oxides. The finished scintillator may also include at least one of SrO and CaO as afterglow reducers.
Inventors
- 👤 Charles D. Greskovich
- 👤 Dominic A. Cusano
- 👤 Frank A. DiBianca
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 15:29
CPC Classifications
G; G01; G01T; G01T1/00; G01T1/16; G01T1/20; G01T1/202; G01T1/2023; C; C04; C04B; C04B35/00; C04B35/50; C04B35/505; C04B35/622; C04B35/64; C04B35/645; C04B35/6455; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7766; C09K11/7767; C09K11/7769; C09K11/7783; C09K11/7784; C09K11/7787; Y; Y10; Y10S; Y10S264/00; Y10S264/91
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
117 words
A method for preparing a transparent-to-translucent polycrystalline ceramic X-ray or gamma-ray scintillator body comprising the steps of: preparing a multicomponent powder consisting essentially of Y 2 O 3 , Gd 2 O 3 , and at least one rare earth activator oxide selected from the group consisting of Eu 2 O 3 , Nd 2 O 3 , Yb 2 O 3 , Dy 2 O 3 , Tb 2 O 3 , and Pr 2 O 3 ; pressing said multicomponent powder to form a powder compact; sintering said powder compact to the closed porosity stage; and gas hot isostatically pressing the sintered compact with an inert gas to yield a transparent-to-translucent polycrystalline ceramic scintillator body.
Claim 2
Independent Claim
117 words
A method for preparing a transparent-to-translucent polycrystalline ceramic X-ray or gamma-ray scintillator body comprising the steps of: preparing a multicomponent powder consisting essentially of Y 2 O 3 , Gd 2 O 3 , and at least one rare earth activator oxide selected from the group consisting of Eu 2 O 3 , Nd 2 O 3 , Yb 2 O 3 , Dy 2 O 3 , Tb 2 O 3 , and Pr 2 O 3 ; pressing said multicomponent powder to form a powder compact; sintering said powder compact to the closed porosity stage; and gas hot isostatically pressing the sintered compact with an inert gas to yield a transparent-to-translucent polycrystalline ceramic scintillator body.
Claim 3
Dependent Claim
47 words
The method of claim 1 wherein said multicomponent powder comprises between about 5 and 50 mole percent Gd 2 O 3 and between about 0.02 and 12 mole percent of at least one of said rare earth activator oxides, the remainder being Y 2 O 3 .
Claim 4
Dependent Claim
22 words
The method of claim 2 wherein said multicomponent powder comprises between about 20 and 40 mole percent Gd 2 O 3 .
Claim 5
Dependent Claim
55 words
The method of claim 1 wherein said multicomponent powder comprises between about 20 and 40 mole percent Gd 2 O 3 , between about 1 and 6 mole percent Eu 2 O 3 , and between about 0.1 and 2 mole percent Yb 2 O 3 , the remainder being Y 2 O 3 .
Claim 6
Dependent Claim
22 words
The method of claim 1 wherein said multicomponent powder comprises between about 1 and 6 mole percent Eu 2 O 3 .
Claim 7
Dependent Claim
22 words
The method of claim 1 wherein said multicomponent powder comprises between about 0.05 and 1.5 mole percent Nd 2 O 3 .
Claim 8
Dependent Claim
22 words
The method of claim 1 wherein said multicomponent powder comprises between about 0.05 and 3 mole percent Tb 2 O 3 .
Claim 9
Dependent Claim
22 words
The method of claim 1 wherein said multicomponent powder comprises between about 0.1 and 2 mole percent Yb 2 O 3 .
Claim 10
Dependent Claim
22 words
The method of claim 1 wherein said multicomponent powder comprises between about 0.03 and 1 mole percent Dy 2 O 3 .
Claim 11
Dependent Claim
22 words
The method of claim 1 wherein said multicomponent powder comprises between about 0.02 and 0.05 mole percent Pr 2 O 3 .
Claim 12
Dependent Claim
19 words
The method of claim 1 wherein said multicomponent powder further comprises between about 0.1 and 2 mole percent SrO.
Claim 13
Dependent Claim
19 words
The method of claim 1 wherein said multicomponent powder further comprises between about 0.1 and 2 mole percent CaO.
Claim 14
Dependent Claim
40 words
The method of claim 1 wherein said step of preparing said multicomponent powder comprises mixing high purity, micron-to-submicron powders of Gd 2 O 3 , Y 2 O 3 , and at least one of said rare earth activator oxides.
Claim 15
Dependent Claim
46 words
The method of claim 1 wherein said step of preparing said multicomponent powder comprises: coprecipitating by the wet chemical oxalate process the oxalates of Y, Gd, and at least one of said rare earth activators; and calcining said oxalates so as to obtain the corresponding oxides.
Claim 16
Dependent Claim
35 words
The method of claim 14 wherein said step of calcining comprises heating said oxalates in air at a temperature of between about 700° C. and 900° C. for between about 1 hour and 4 hours.
Claim 17
Dependent Claim
19 words
The method of claim 14 wherein said step of calcining is preceded by the step of milling said oxalates.
Claim 18
Dependent Claim
18 words
The method of claim 14 further comprising the step of milling said oxides obtained in said calcining step.
Claim 19
Dependent Claim
63 words
The method of claim 1 wherein said step of pressing to form said powder compact comprises: cold pressing said multicomponent powder at a pressure of between about 3,000 psi and 10,000 psi to form a preliminary powder compact; and then isostatically pressing said preliminary powder compact at a pressure of between about 15,000 psi and 60,000 psi to increase the green density thereof.
Claim 20
Dependent Claim
33 words
The method of claim 18 wherein said step of sintering comprises heating said powder compact at a temperature of between about 1500° C. and 1700° C. for between about 1 and 10 hours.
Claim 21
Dependent Claim
49 words
The method of claim 19 wherein said step of gas hot isostatically pressing the sintered compact comprises heating at a temperature of between about 1500° C. and 1800° C. for between about one-half and 2 hours at an argon gas pressure of between about 1,000 psi and 30,000 psi.
Claim 22
Dependent Claim
35 words
The method of claim 20 wherein said step of gas hot isostatically pressing the sintered compact comprises heating at a temperature of 1750° C. for one-half hour at an argon gas pressure of 15,000 psi.
Claim 23
Dependent Claim
88 words
The method of claim 20 wherein said step of gas hot isostatically pressing the sintered compact comprises: heating said compact for one hour to raise the temperature thereof to 1400° C., continue heating said compact for an additional one hour to raise the temperature thereof to 1750° C.; and then maintaining the temperature of said compact at 1750° C. for 1 hour prior to furnace-cooling said compact to room temperature, said steps of heating and maintaining the temperature being performed at an argon gas pressure of 25,000 psi.
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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) | 1988-05-20 | 1988-11-19 | 1989-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-05-20 | 1992-11-19 | 1993-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-05-20 | 1996-11-19 | 1997-05-21 | $7700.00 | Window Closed / Lapsed |