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US5116560A
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Method of forming rare earth oxide ceramic scintillator with ammonium dispersion of oxalate precipitates
Assignee: General Electric Co
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Filing: 1991-03-22
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Granted: 1992-05-26
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Expires: 2011-03-22
Abstract
Abstract A method of forming polycrystalline rare earth oxide ceramic scintillators formed by dissolving a mixture of oxides of the scintillator in an aqueous hydrochloric or nitric acid solution to form a rare earth solution, precipitating oxalates from the rare earth solution, calcining the oxalates to form the respective oxides, cold pressing the oxides to form a compact, and sintering the compact in a reducing atmosphere or vacuum to form the scintillator, the method being improved by precipitating the oxalates by admixing the rare earth solution with an oxalic solution comprised of, oxalic acid and ammonium ions in an amount that disperses the oxalate precipitates.
Inventors
- 👤 Stephen Lee Dole
- 👤 Subramaniam Venkataramani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 00:31
CPC Classifications
G; G01; G01T; G01T1/00; G01T1/16; G01T1/20; G01T1/202; C; C01; C01F; C01F17/00; C01F17/20; C01F17/206; C01F17/241; C04; C04B; C04B35/00; C04B35/50; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7783; C09K11/7784; C09K11/7787; G01T1/2023
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
134 words
A method of forming a polycrystalline rare earth oxide ceramic scintillator containing an oxide of a rare earth activator selected from the group consisting of europium, neodymium, ytterbium, dysprosium, terbium and praseodymium, having improved transparency that does not require milling, said scintillator being formed by dissolving a mixture of oxides of the scintillator composition in an aqueous hydrochloric or nitric acid solution to form a rare earth solution, precipitating oxalates from the rare earth solution, calcining the oxalates to form oxides, cold pressing the oxides to form a compact, and sintering the compact in a reducing atmosphere or vacuum to form the scintillator, the improvement comprising: precipitating the oxalates by admixing the rare earth solution with an oxalic solution comprised of, oxalic acid and ammonium ions in an amount that disperses the oxalate precipitates.
Claim 2
Independent Claim
134 words
A method of forming a polycrystalline rare earth oxide ceramic scintillator containing an oxide of a rare earth activator selected from the group consisting of europium, neodymium, ytterbium, dysprosium, terbium and praseodymium, having improved transparency that does not require milling, said scintillator being formed by dissolving a mixture of oxides of the scintillator composition in an aqueous hydrochloric or nitric acid solution to form a rare earth solution, precipitating oxalates from the rare earth solution, calcining the oxalates to form oxides, cold pressing the oxides to form a compact, and sintering the compact in a reducing atmosphere or vacuum to form the scintillator, the improvement comprising: precipitating the oxalates by admixing the rare earth solution with an oxalic solution comprised of, oxalic acid and ammonium ions in an amount that disperses the oxalate precipitates.
Claim 3
Dependent Claim
28 words
The method of claim 1 wherein the ammonium ions are in a ratio of at least about 1 mole of ammonium ions per mole of rare earth ions.
Claim 4
Dependent Claim
28 words
The method of claim 2 wherein the ammonium ions are in a ratio of about 1 to 2 moles of ammonium ions per mole of rare earth ions.
Claim 5
Dependent Claim
23 words
The method of claim 2 further comprising the step of washing the oxalate precipitates with water to remove excess ammonium or oxalate salts.
Claim 6
Dependent Claim
16 words
The method of claim 4 wherein the water has a pH between about 2 and 10.
Claim 7
Dependent Claim
13 words
The method of claim 2 further comprising the step of milling the oxalates
Claim 8
Dependent Claim
20 words
The method of claim 6 wherein the step of milling is vibration milling with a rigid organic polymer milling media.
Claim 9
Independent Claim
110 words
A method of forming a polycrystalline yttria-dolinia scintillator having improved transparency that does not require milling said scintillator being formed by dissolving a mixture of oxides of the scintillator composition in an aqueous hydrochloric or nitric acid solution to form a rare earth solution, precipitating oxalates from the rare earth solution, calcining the oxalates to form oxides, cold pressing the oxides to form a compact, and sintering the compact in a reducing atmosphere or vacuum to form the scintillator, the improvement comprising: precipitating the oxalates by admixing the rare earth solution with an oxalic solution comprised of, oxalic acid and ammonium ions in an amount that disperses the oxalate precipitates.
Claim 10
Independent Claim
110 words
A method of forming a polycrystalline yttria-dolinia scintillator having improved transparency that does not require milling said scintillator being formed by dissolving a mixture of oxides of the scintillator composition in an aqueous hydrochloric or nitric acid solution to form a rare earth solution, precipitating oxalates from the rare earth solution, calcining the oxalates to form oxides, cold pressing the oxides to form a compact, and sintering the compact in a reducing atmosphere or vacuum to form the scintillator, the improvement comprising: precipitating the oxalates by admixing the rare earth solution with an oxalic solution comprised of, oxalic acid and ammonium ions in an amount that disperses the oxalate precipitates.
Claim 11
Dependent Claim
28 words
The method of claim 8 wherein the ammonium ions are in a ratio of at least about 1 mole of ammonium ions per mole of rare earth ions.
Claim 12
Dependent Claim
28 words
The method of claim 9 wherein the ammonium ions are in a ratio of about 1 to 2 moles of ammonium ions per mole of rare earth ions.
Claim 13
Dependent Claim
23 words
The method of claim 9 further comprising the step of washing the oxalate precipitates with water to remove excess ammonium or oxalate salts.
Claim 14
Dependent Claim
16 words
The method of claim 11 wherein the water has a pH between about 2 and 10.
Claim 15
Dependent Claim
13 words
The method of claim 9 further comprising the step of milling the oxalates.
Claim 16
Dependent Claim
20 words
The method of claim 13 wherein the step of milling is vibration milling with a rigid organic polymer milling media.
Claim 17
Independent Claim
110 words
A method of forming a polycrystalline lutetia-gadolinia scintillator having improved transparency that does not require milling said scintillator being formed by dissolving a mixture of oxides of the scintillator composition in an aqueous hydrochloric or nitric acid solution to form a rare earth solution, precipitating oxalates from the rare earth solution, calcining the oxalates to form oxides, cold pressing the oxides to form a compact, and sintering the compact in a reducing atmosphere or vacuum to form the scintillator, the improvement comprising: precipitating the oxalates by admixing the rare earth solution with an oxalic solution comprised of, oxalic acid and ammonium ions in an amount that disperses the oxalate precipitates.
Claim 18
Independent Claim
110 words
A method of forming a polycrystalline lutetia-gadolinia scintillator having improved transparency that does not require milling said scintillator being formed by dissolving a mixture of oxides of the scintillator composition in an aqueous hydrochloric or nitric acid solution to form a rare earth solution, precipitating oxalates from the rare earth solution, calcining the oxalates to form oxides, cold pressing the oxides to form a compact, and sintering the compact in a reducing atmosphere or vacuum to form the scintillator, the improvement comprising: precipitating the oxalates by admixing the rare earth solution with an oxalic solution comprised of, oxalic acid and ammonium ions in an amount that disperses the oxalate precipitates.
Claim 19
Dependent Claim
28 words
The method of claim 15 wherein the ammonium ions are in a ratio of at least about 1 mole of ammonium ions per mole of rare earth ions.
Claim 20
Dependent Claim
28 words
The method of claim 16 wherein the ammonium ions are in a ratio of about 1 to 2 moles of ammonium ions per mole of rare earth ions.
Claim 21
Dependent Claim
23 words
The method of claim 16 further comprising the step of washing the oxalate precipitates with water to remove excess ammonium or oxalate salts.
Claim 22
Dependent Claim
16 words
The method of claim 18 wherein the water has a pH between about 2 and 10.
Claim 23
Dependent Claim
13 words
The method of claim 16 further comprising the step of milling the oxalates.
Claim 24
Dependent Claim
20 words
The method of claim 20 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
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