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EP0097296A1
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Rare earth doped yttria-gadolinia ceramic scintillators and methods for making
Assignee: General Electric Co
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Filing: 1983-06-11
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Granted: —
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Expires: 2003-06-11
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 ceramic scintillator may also include CaO and SrO as afterglow reducers. Sintering, sintering combined with gas hot isostatic pressing, and hot pressing methods for preparing the ceramic scintillators are also described.
Inventors
- 👤 Dominic Anthony Cusano
- 👤 Charles David Greskovich
- 👤 Frank Anthony Dibianca
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 13:56
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
Claims Analysis
Total Claims: 48
Claim 1
Independent Claim
71 words
A polycristalline ceramic scintillator consisting essentially of between 5 mole percent and 50 mole percent Gd203, and between 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 Pr203, the remainder being Y 2 O 3 .
Claim 2
Dependent Claim
71 words
A polycristalline ceramic scintillator consisting essentially of between 5 mole percent and 50 mole percent Gd203, and between 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 Pr203, the remainder being Y 2 O 3 .
Claim 3
Dependent Claim
89 words
A polycristalline ceramic scintillator comprising between 5 and 50 mole percent of Gd203, between 0.02 and 12 mole percent of at least one rare-earth activator selected from the group consistingt of Eu 2 0 3 , Nd 2 O 3 , Yb 2 O 3 , Dy 2 O 3 , Tb203' and Pr 2 O 3 , and between 0.1 a 2 mole percent each of at least one afterglow reducer selected from the group consisting of CaO and SrO, the remainder being Y 2 0 3 .
Claim 4
Dependent Claim
89 words
A polycristalline ceramic scintillator comprising between 5 and 50 mole percent of Gd203, between 0.02 and 12 mole percent of at least one rare-earth activator selected from the group consistingt of Eu 2 0 3 , Nd 2 O 3 , Yb 2 O 3 , Dy 2 O 3 , Tb203' and Pr 2 O 3 , and between 0.1 a 2 mole percent each of at least one afterglow reducer selected from the group consisting of CaO and SrO, the remainder being Y 2 0 3 .
Claim 5
Dependent Claim
43 words
A polycristalline ceramic scintillator consisting essentially of between 5 and 50 mole percent Gd 2 O 3 , 0,5 to 12 mole percent Eu 2 0 3 , and 0.1 and 2 mole percent Yb203, the remainder being Y 2 0 3 .
Claim 6
Dependent Claim
43 words
A polycristalline ceramic scintillator consisting essentially of between 5 and 50 mole percent Gd 2 O 3 , 0,5 to 12 mole percent Eu 2 0 3 , and 0.1 and 2 mole percent Yb203, the remainder being Y 2 0 3 .
Claim 7
Dependent Claim
29 words
The polycristalline ceramic scintillator of any of claims 1-3 wherein said rare-earth activator oxide consists essentially of between 1 and 6 mole percent of Eu 2 O 3 .
Claim 8
Dependent Claim
30 words
The polycristalline ceramic scintillator of any of claims 1-3 wherein said rare-earth activator oxide consists essentially of between 20 and 40 mole percent of G d 2 0 3 .
Claim 9
Dependent Claim
30 words
The polycristalline ceramic scintillator of claims 1 or 2 wherein said rare-earth activator oxide consists essentially of between 0.05 and 1.5 mole percent of N d 2 0 3 .
Claim 10
Dependent Claim
27 words
The polycristalline ceramic scintillator of claim 6 wherein said rare-earth activator oxide consists essentially of between 0.1 and 0.5 mole percent of Nd 2 0 3 .
Claim 11
Dependent Claim
29 words
The polycristalline ceramic scintillator of claim 1 or 2 wherein said rare-earth activator oxide consists essentially of between 0.5 and 3 mole percent of Tb 2 O 3 .
Claim 12
Dependent Claim
30 words
The polycristalline ceramic scintillator of claim 1 or 2 wherein said rare-earth activator oxide consists essentially of between 0.1 and 2 mole percent of Y b 2 0 3 .
Claim 13
Dependent Claim
27 words
The polycristalline ceramic scintillator of claim 9 wherein said rare-earth activator oxide consists essentially of between 0.15 and 0.7 mole percent of Yb 2 O 3 .
Claim 14
Dependent Claim
29 words
ll.The polycristalline ceramic scintillator of claim 1 or 2 wherein said rare-earth activator oxide consists essentially of between 0.03 and 1 mole percent of DY 2 0 3 .
Claim 15
Dependent Claim
29 words
The polycristalline ceramic scintillator of claim 1 or 2 wherein said rare-earth activator oxide consists essentially of between 0.02 and 0.05 mole percent of Pr 2 O 3 .
Claim 16
Independent Claim
107 words
A method for preparing a polycrystalline ceramic scintillator body comprising the steps of: preparing a multicomponent powder including between 5 and 50 mole percent Gd 2 O 3 , and between 0.02 and 12 mole percent of at least one rare earth activator oxide selected from the group consisting of Eu 2 O 3 , Nd203, Yb 2 O 3 , Dy 2 O 3 , Tb 2 O 3 , and Pr203, the remainder of said multicomponent powder being Y 2 0 3 ; cold pressing said multicomponent powder to form a powder compact; and sintering said powder compact to form said polycrystalline ceramic scintillator body.
Claim 17
Independent Claim
107 words
A method for preparing a polycrystalline ceramic scintillator body comprising the steps of: preparing a multicomponent powder including between 5 and 50 mole percent Gd 2 O 3 , and between 0.02 and 12 mole percent of at least one rare earth activator oxide selected from the group consisting of Eu 2 O 3 , Nd203, Yb 2 O 3 , Dy 2 O 3 , Tb 2 O 3 , and Pr203, the remainder of said multicomponent powder being Y 2 0 3 ; cold pressing said multicomponent powder to form a powder compact; and sintering said powder compact to form said polycrystalline ceramic scintillator body.
Claim 18
Independent Claim
125 words
A method for preparing a polycrystalline ceramic scintillator body comprising the steps of: preparing a multicomponent powder including between 5 and 50 mole percent Gd203, and between 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 0 31 Yb 2 O 3 , Dy 2 O 3 , Tb 2 O 3 , and Pr 2 O 3 , the remainder of said multicomponent powder being Y 2 0 3 ; pressing said multicomponent powder to form a powder compact; sintering said powder compact to closed porosity stage ; and pressing the sintered powder compact by the gas hot isostatic process to form said polycrystalline ceramic scintillator body.
Claim 19
Independent Claim
125 words
A method for preparing a polycrystalline ceramic scintillator body comprising the steps of: preparing a multicomponent powder including between 5 and 50 mole percent Gd203, and between 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 0 31 Yb 2 O 3 , Dy 2 O 3 , Tb 2 O 3 , and Pr 2 O 3 , the remainder of said multicomponent powder being Y 2 0 3 ; pressing said multicomponent powder to form a powder compact; sintering said powder compact to closed porosity stage ; and pressing the sintered powder compact by the gas hot isostatic process to form said polycrystalline ceramic scintillator body.
Claim 20
Independent Claim
146 words
A method for preparing a polycrystalline ceramic scintillator body comprising the steps of: preparing a multicomponent powder including between 5 and 50 mole percent Gd 2 O 3 , and between 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 , the remainder of said multicomponent powder being Y 2 0 3 ; pressing said multicomponent powder under vacuum at a first temperature and pressure for a first peredeter- mined period of time; and increasing said first temperature and pressure to a second temperature and pressure and maintaining said second temperature and pressure for a second period of time to form said polycrystalline ceramic scintillator body.
Claim 21
Independent Claim
146 words
A method for preparing a polycrystalline ceramic scintillator body comprising the steps of: preparing a multicomponent powder including between 5 and 50 mole percent Gd 2 O 3 , and between 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 , the remainder of said multicomponent powder being Y 2 0 3 ; pressing said multicomponent powder under vacuum at a first temperature and pressure for a first peredeter- mined period of time; and increasing said first temperature and pressure to a second temperature and pressure and maintaining said second temperature and pressure for a second period of time to form said polycrystalline ceramic scintillator body.
Claim 22
Independent Claim
19 words
The method of any of claims 13-15 wherein said multicomponent powder comprises between 20 and 40 mole percent Gd203.
Claim 23
Independent Claim
24 words
The method of any of claims 13-15 wherein said multicomponent powder comprises between 1 and 6 mole percent E u 2 0 3 .
Claim 24
Independent Claim
23 words
The method of any of claims 13-15 wherein said multicomponent powder comprises between 0.1 and 2 mole percent Yb 2 0 3 .
Claim 25
Independent Claim
49 words
The method of any of claims 13-15 wherein said multicomponent powder comprises between 20 and 40 mole percent Gd203, between 1 and 6 mole percent Eu 2 O 3 , between 0.1 and 2 mole percent Yb 2 0 3 , the remainder being Y 2 O 3 .
Claim 26
Independent Claim
23 words
The method of any of claims 13-15 wherein said multicomponent powder comprises between 0.05 and 1.5 mole percent N d 2 0 3
Claim 27
Independent Claim
22 words
The method of any of claims 13-15 wherein said multicomponent powder comprises between 0.05 and 3 mole percent Tb 2 0 3
Claim 28
Independent Claim
23 words
The method of any of claims 13-15 wherein said multicomponent powder comprises between 0.03 and 1 mole percent D Y 2 0 3
Claim 29
Independent Claim
22 words
The method of any of claims 13-15 wherein said multicomponent powder comprises between 0.02 and 0.05 mole percent Pr 2 O 3
Claim 30
Dependent Claim
22 words
24 The method of any of claims 13-15 wherein said multicomponent powder comprises between 0.1 and 2 mole percent SrO or CaO
Claim 31
Independent Claim
43 words
The method of any of claims 13-15 wherein said step of preparing said multicomponent powder comprises mixing high purity, micrometer-to-submicrometer powders of G d 2 0 3 , Y 2 0 3 , and at least one of said rare earth activator oxides.
Claim 32
Independent Claim
52 words
The method of any of claims 13-15 wherein said step of preparing said multicomponent powder comprises the steps of: coprecipitating by the wet chemical oxalate process the oxalates of Y, Gd, and at least one of said rare earth activator oxides; and calcining said oxalates so as to obtain the corresponding oxides.
Claim 33
Independent Claim
36 words
The method of any of claims 13-15 wherein said step of calcining comprises the step of heating said oxalates in air at a temperature of between 700°C and 900°C for between 1 hour and 4 hours.
Claim 34
Dependent Claim
19 words
The method of claim 26 wherein said step of calcining is preceded by the step of milling said oxalates.
Claim 35
Independent Claim
22 words
The method of any of claims 26 or 28 further comprising the step of milling said oxides obtained in said calcining step.
Claim 36
Independent Claim
41 words
The method of any of claims 13, 25 or 26 wherein said step of cold pressing comprises the step of die pressing said multicomponent powder at a pressure of between 2.068 daN/mm 2 (3.000 psi) and 10.34 daN/mm 2 (15,000 psi).
Claim 37
Dependent Claim
51 words
3l.The method of claim 30 wherein said step of cold pressing further comprises the step of isostatically pressing the die pressed multicomponent powder at a pressure of between 6.89 daN/mm 2 (10,000 psi) and 41.36 daN/mm 2 (60,000 psi) to further increase the green density and uniformity of said powder compact.
Claim 38
Dependent Claim
50 words
The method of claim 31 wherein said step of sintering comprises the steps of: heating said powder compact at a rate of between 100°C per hour and 700°C per hour to a sintering temperature of between 1800°C and 2100°C; and holding said sintering temperature for between 1 and 30 hours.
Claim 39
Dependent Claim
80 words
The method of claim 31 wherein said step of sintering comprises the steps of: heating said powder compact at a rate of between 300°C/hr and 400°C/hr to a holding temperature of between 1600°C and 1700°C; maintaining said holding temperature for between 1 and 20 hours and then increasing the temperature at a rate of between 25°C/hr and 75°C/hr to a final sintering temperature of between 1800°C and 2100°C; and maintaining the final sintering temperature for between 1 and 10 hours.
Claim 40
Dependent Claim
22 words
The method of claim 31 wherein said step of heating comprises heating said powder compact in vacuum or in a reducing atmosphere.
Claim 41
Dependent Claim
29 words
The method of claim 31 further comprising the step of cooling the resulting polycrystalline ceramic scintillator body to room temperature over a period of between 2 and 10 hours.
Claim 42
Independent Claim
81 words
The method of any of claims 14, 25 or 26 wherein said step of pressing to form said powder compact comprises the steps of: cold pressing said multi-component powder at a pressure of between 2.068 daN/mm 2 (3,000 psi) and 6.89 daN/mm 2 (10,000 psi) to form a preliminary powder compact; and then isostatically pressing said preliminary powder compact at a pressure of between 10.34 daN/mm 2 (15,000 psi) and 41.36 daN/mm 2 (60,000 psi) to increase the green density thereof.
Claim 43
Dependent Claim
29 words
The method of claim 36 wherein said step of sintering comprises heating said powder compact at a temperature of between 1500°C and 1700°C for between 1 and 10 hours.
Claim 44
Dependent Claim
57 words
The method of claim 37 wherein said step of pressing the sintered powder compact by the gas hot isostatic process comprises the step of heating at a temperature of between 1500°C and 1800°C for between 1 and 2 hours at an argon gas pressure of between 0.689 daN/mm 2 (1,000 psi) and 20.68 daN/mm 2 (30,000 psi).
Claim 45
Dependent Claim
90 words
The method of claim 38 wherein said step of pressing the sintered powder compact by the gas hot isostatic process more specifically comprises the steps of: heating said powder compact for one hour to raise the temperature thereof to 1400°C, continue heating said powder compact for an additional one jour to raise the temperature thereof to 1750°C; and then maintaining the temperature of said powder compact to room temperature, sais steps of heating and maintaining the temperature being performed at an argon gas pressure of 17.23 daN/mm 2 (25,000 psi)
Claim 46
Independent Claim
57 words
The method of any of claims 15, 25 or 26 wherein said step of pressing comprises the step of pressing said multicomponent powder at a pressure of between 0.689 daN/mm 2 (1,000 psi) and 0.827daNmm 2 (1,200 psi) at a temperature of between 600°C and 700°C under a vacuum of up to 200 micrometers for 1 hours.
Claim 47
Dependent Claim
54 words
The method of claim 40 wherein said step of increasing said first temperature and pressure comprises increasing the temperature to between 1300°C and 1600°C, increasing the pressure to between 2.75 daN/mm 2 (4,000 psi) and 6.89 daN/mm 2 (10,000 psi), and maintaining said increased temperature and pressure for between one-half hour to 4 hours.
Claim 48
Dependent Claim
49 words
The method of claim 41 further comprising the step of o idizing the resulting hot pressed ceramic, said step of oxidizing including heating said ceramic in an oxygen-containing atmosphere for between 1 and 20 hours at a temperature of between 800°C and 1200°C so as to remove any discoloration.
References Cited (Backward Citations)
US3640887A
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US4040845A
Cited
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