US4421671A
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US
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Rare-earth-doped yttria-gadolinia ceramic scintillators
Assignee: General Electric Co
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Filing: 1982-06-18
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Granted: 1983-12-20
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Expires: 2002-06-18
Abstract
Abstract Rare-earth-doped, polycrystalline yttria-gadolinia ceramic scintillators with high density, optical clarity, uniformity, cubic structure and which are useful in the detection of X-rays, include one or more of the oxides of rare-earth elements Eu, Nd, Yb, Dy, Tb, and Pr as activators. The oxides of elements Zr, Th, and Ta are included as transparency-promoting densifying agents. Any decrease in scintillator light output, due to the addition of transparency promoting additives, may be partially restored by the addition of either calcium oxide (CaO) or strontium oxide (SrO). Sintering, sintering combined with gas hot isostatic pressing, and hot pressing methods for preparing the ceramic scintillators are also described.
Inventors
- 👤 Dominic A. Cusano
- 👤 Charles D. Greskovich
- 👤 Frank A. DiBianca
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:57
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/622; C04B35/64; C04B35/645; C04B35/6455; C04B35/50; C04B35/505; 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
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
176 words
A polycrystalline ceramic scintillator comprising a composition consisting essentially of between about 5 and 50 mole percent Gd 2 O 3 , between about 0.02 and 12 mole percent of 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 , at least one transparency promoter selected from the group consisting of ThO 2 in an amount up to 0.7 mole percent, ZrO 2 , in an amount up to 0.7 mole percent and Ta 2 O 5 in an amount up to 0.5 mole percent, said transparency promoter being present in amount sufficient to improve the transparency of the ceramic scintillator, and at least one light output restorer selected from the group consisting of CaO and SrO, in an amount sufficient to effect a higher light output than said ceramic scintillator absent said restorer the remainder being Y 2 O 3 .
Claim 2
Dependent Claim
176 words
A polycrystalline ceramic scintillator comprising a composition consisting essentially of between about 5 and 50 mole percent Gd 2 O 3 , between about 0.02 and 12 mole percent of 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 , at least one transparency promoter selected from the group consisting of ThO 2 in an amount up to 0.7 mole percent, ZrO 2 , in an amount up to 0.7 mole percent and Ta 2 O 5 in an amount up to 0.5 mole percent, said transparency promoter being present in amount sufficient to improve the transparency of the ceramic scintillator, and at least one light output restorer selected from the group consisting of CaO and SrO, in an amount sufficient to effect a higher light output than said ceramic scintillator absent said restorer the remainder being Y 2 O 3 .
Claim 3
Dependent Claim
26 words
The polycrystalline ceramic scintillator of claim 1 wherein said transparency promoter is ThO 2 present in an amount of between about 0.2 and 0.7 mole percent.
Claim 4
Dependent Claim
26 words
The polycrystalline ceramic scintillator of claim 1 wherein said transparency promoter is ZrO 2 present in an amount of between about 0.2 and 0.7 mole percent.
Claim 5
Dependent Claim
26 words
The polycrystalline ceramic scintillator of claim 1 wherein said transparency promoter Ta 2 O 5 present in amount of between about 0.1 and 0.5 mole percent.
Claim 6
Dependent Claim
25 words
The polycrystalline ceramic scintillator of claim 1 wherein Gd 2 O 3 is present in an amount of between about 20 and 40 mole percent.
Claim 7
Dependent Claim
26 words
The polycrystalline ceramic scintillator of claim 1 wherein said light output restorer is CaO present in an amount of between about 0.2 and 4 mole percent.
Claim 8
Dependent Claim
35 words
The polycrystalline ceramic scintillator of claim 1, 2, 3, 4, 5, or 6 wherein the rare earth activator is Eu 2 O 3 present in an amount of between about 1 and 6 mole percent.
Claim 9
Dependent Claim
35 words
The polycrystalline ceramic scintillator of claim 1, 2, 3, 4, 5, or 6 wherein the rare earth activator is Nd 2 O 3 present in an amount of between about 0.05 and 1.5 mole percent.
Claim 10
Dependent Claim
35 words
The polycrystalline ceramic scintillator of claim 1, 2, 3, 4, 5, or 6 wherein the rare earth activator is Nd 2 O 3 present in an amount of between about 0.1 and 0.5 mole percent.
Claim 11
Dependent Claim
35 words
The polycrystalline ceramic scintillator of claim 1, 2, 3, 4, 5, or 6 wherein the rare earth activator is Tb 2 O 3 present in an amount of between about 0.05 and 3 mole percent.
Claim 12
Dependent Claim
35 words
The polycrystalline ceramic scintillator of claim 1, 2, 3, 4, 5, or 6 wherein the rare earth activator is Yb 2 O 3 present in an amount of between about 0.1 and 2 mole percent.
Claim 13
Dependent Claim
35 words
The polycrystalline ceramic scintillator of claim 1, 2, 3, 4, 5, or 6 wherein the rare earth activator is Dy 2 O 3 present in an amount of between about 0.03 and 1 mole percent.
Claim 14
Dependent Claim
35 words
The polycrystalline ceramic scintillator of claim 1, 2, 3, 4, 5, or 6 wherein the rare earth activator is Pr 2 O 3 present in an amount of between about 0.02 and 0.05 mole percent.
Claim 15
Dependent Claim
26 words
The polycrystalline ceramic scintillator of claim 1 wherein said light output restorer is SrO present in an amount of between about 0.1 and 3 mole percent.
Claim 16
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 14 wherein the rare earth activator is Eu 2 O 3 present in an amount of between about 1 and 6 mole percent.
Claim 17
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 14 wherein the rare earth activator is Nd 2 O 3 present in an amount of between about 0.05 and 1.5 mole percent.
Claim 18
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 14 wherein the rare earth activator is Nd 2 O 3 present in an amount of between about 0.1 and 0.5 mole percent.
Claim 19
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 14 wherein the rare earth activator is Tb 2 O 3 present in an amount of between about 0.05 and 3 mole percent.
Claim 20
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 14 wherein the rare earth activator is Yb 2 O 3 present in an amount of between about 0.1 and 2 mole percent.
Claim 21
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 14 wherein the rare earth activator is Dy 2 O 3 present in an amount of between about 0.03 and 1 mole percent.
Claim 22
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 14 wherein the rare earth activator is Pr 2 O 3 present in an amount of between about 0.02 and 0.05 mole percent.
Claim 23
Dependent Claim
142 words
A polycrystalline ceramic scintillator comprising a composition consisting essentially of between about 5 and 50 mole percent Gd 2 O 3 , between about 0.02 and 12 mole percent of 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 , and a transparency promoter selected from the group consisting of ThO 2 in an amount up to 0.35 mole percent, ZrO 2 in an amount up to 0.35 mole percent, and Ta 2 O 5 in an amount up to 0.3 mole percent, said transparency promoter being present in an amount sufficient to improve the transparency of the ceramic scintillator, the remainder being Y 2 O 3 .
Claim 24
Dependent Claim
142 words
A polycrystalline ceramic scintillator comprising a composition consisting essentially of between about 5 and 50 mole percent Gd 2 O 3 , between about 0.02 and 12 mole percent of 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 , and a transparency promoter selected from the group consisting of ThO 2 in an amount up to 0.35 mole percent, ZrO 2 in an amount up to 0.35 mole percent, and Ta 2 O 5 in an amount up to 0.3 mole percent, said transparency promoter being present in an amount sufficient to improve the transparency of the ceramic scintillator, the remainder being Y 2 O 3 .
Claim 25
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 22 wherein the rare earth activator is Eu 2 O 3 present in an amount of between about 1 and 6 mole percent.
Claim 26
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 22 wherein the rare earth activator is Nd 2 O 3 present in an amount of between about 0.05 and 1.5 mole percent.
Claim 27
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 22 wherein the rare earth activator is Nd 2 O 3 present in an amount of between about 0.1 and 0.5 mole percent.
Claim 28
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 22 wherein the rare earth activator is Tb 2 O 3 present in an amount of between about 0.05 and 3 mole percent.
Claim 29
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 22 wherein the rare earth activator is Yb 2 O 3 present in an amount of between about 0.1 and 2 mole percent.
Claim 30
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 22 wherein the rare earth activator is Pr 2 O 3 present in an amount of between about 0.02 and 0.05 mole percent.
Claim 31
Dependent Claim
29 words
The polycrystalline ceramic scintillator of claim 22 wherein the rare earth activator is Dy 2 O 3 present in an amount of between about 0.03 and 1 mole percent.
Claim 32
Dependent Claim
37 words
The polycrystalline ceramic scintillator of claim 22, 23, 24, 25, 26, 27, 28, or 29 wherein the rare earth activator is Dy 2 O 3 present in an amount of between about 20 and 40 mole percent.
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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) | 1986-12-19 | 1987-06-20 | 1987-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-19 | 1991-06-20 | 1991-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-19 | 1995-06-20 | 1995-12-20 | $7700.00 | Window Closed / Lapsed |