US4112194A
Expired / Lapsed
US
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Hexagonal hafnium, zirconium phosphate luminescent material, method of preparation, and x-ray intensifying screen containing the same
Assignee: GTE Sylvania Inc
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Filing: 1976-11-08
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Granted: 1978-09-05
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Expires: 1996-11-08
Abstract
Abstract A mixture of starting materials, corresponding to an oxide composition within an area of the ternary diagram for (Hf,Zr)O 2 , A 2 O, P 2 O 5 formed by connecting end member points defined by the molar compositions: 45 (Hf,Zr)O 2 - 10 A 2 O - 45 P 2 O 5 ; 45 (Hf,Zr)O 2 - 45 A 2 O - 10 P 2 O 5 ; and 10 (Hf,Zr)O 2 - 45 A 2 O - 45 P 2 O 5 , reacts to form large single crystalline essentially hexagonal particles of a new compound (Hf 1-x Zr x ) 3-y A 4y (PO 4 ) 4 , and an aqueous-soluble second phase removable by washing. The large single crystalline hexagonal particles are useful as the luminescent material in x-ray intensifying screens, with band emission which overlaps at least partially the absorption edge of an x-ray film base to give good image resolution without crossover distortion.
Inventors
- 👤 Charles Frederic Chenot
- 👤 James Evan Mathers
- 👤 Francis Nathan Shaffer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:22
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/70
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
66 words
A luminescent material with hexagonal crystal structure consisting essentially of large single crystalline particles of (Hf 1-x Zr x ) 3-y A 4y (PO 4 ) 4 ; where x is within the range of about 0.005 to 0.5, A is at least one alkali metal selected from the group consisting of lithium, sodium and potassium and y is within the range of 0.4 to 2.0.
Claim 2
Dependent Claim
66 words
A luminescent material with hexagonal crystal structure consisting essentially of large single crystalline particles of (Hf 1-x Zr x ) 3-y A 4y (PO 4 ) 4 ; where x is within the range of about 0.005 to 0.5, A is at least one alkali metal selected from the group consisting of lithium, sodium and potassium and y is within the range of 0.4 to 2.0.
Claim 3
Dependent Claim
16 words
The luminescent material of claim 1 wherein x is within the range of 0.05 to 0.3.
Claim 4
Dependent Claim
250 words
A process for producing a luminescent material consisting essentially of large single-crystalline hexagonal particles of M 3-y A 4y (PO 4 ) 4 wherein M is selected from the group consisting of Hf and Zr, expressed as (Hf 1-x Zr x ) where x is within the range of 0 to 1, and A is at least one alkali metal selected from the group consisting of Li, Na and K, the process comprising: (a) first forming a mixture of compounds selected from the group consisting of MO 2 , A 2 O, P 2 O 5 and precursors thereof, which mixture upon an oxide basis falls within the area A of the ternary diagram for MO 2 - A 2 O - P 2 O 5 of FIG. 3 of the drawing, the area A defined by points in the diagram corresponding to mole proportions of the oxides of: 45 MO 2 - 10 A 2 O - 45 P 2 O 5 ; 45 MO 2 - 45 A 2 O - 10 P 2 O 5 ; and 10 MO 2 45 A 2 O - 45 P 2 O 5 , respectively; (b) firing the mixture to a temperature within the range of about 800° C to 1300° C for about 1 to 16 hours, to form a fused reaction mass; (c) washing the mass with water to substantially remove aqueous-soluble contaminant material, thereby leaving a powder of substantially single crystalline particles; and (d) drying the powder.
Claim 5
Dependent Claim
250 words
A process for producing a luminescent material consisting essentially of large single-crystalline hexagonal particles of M 3-y A 4y (PO 4 ) 4 wherein M is selected from the group consisting of Hf and Zr, expressed as (Hf 1-x Zr x ) where x is within the range of 0 to 1, and A is at least one alkali metal selected from the group consisting of Li, Na and K, the process comprising: (a) first forming a mixture of compounds selected from the group consisting of MO 2 , A 2 O, P 2 O 5 and precursors thereof, which mixture upon an oxide basis falls within the area A of the ternary diagram for MO 2 - A 2 O - P 2 O 5 of FIG. 3 of the drawing, the area A defined by points in the diagram corresponding to mole proportions of the oxides of: 45 MO 2 - 10 A 2 O - 45 P 2 O 5 ; 45 MO 2 - 45 A 2 O - 10 P 2 O 5 ; and 10 MO 2 45 A 2 O - 45 P 2 O 5 , respectively; (b) firing the mixture to a temperature within the range of about 800° C to 1300° C for about 1 to 16 hours, to form a fused reaction mass; (c) washing the mass with water to substantially remove aqueous-soluble contaminant material, thereby leaving a powder of substantially single crystalline particles; and (d) drying the powder.
Claim 6
Dependent Claim
64 words
The process of claim 3 wherein prior to firing the mixture is: (a) heated at least once to a temperature within the range of from about 200° C to 500° C for about 1 to 16 hours, in order to insure removal of at least a portion of contained volatile material, followed by (b) comminuting the heated mixture to a relatively uniform powder mixture.
Claim 7
Dependent Claim
47 words
The process of claim 3 wherein washing comprises: (a) forming an aqueous slurry of the fused reaction mass; (b) agitating the slurry at a temperature within the range of from about 80° C to 105° C until a crystalline powder appears; and (c) water washing the powder.
Claim 8
Dependent Claim
15 words
The process of claim 3 wherein x is within the range of 0.005 to 0.5.
Claim 9
Dependent Claim
132 words
An x-ray intensifying screen for use with conventional silver halide emulsion x-ray film to intensify an exposed image on the film, the screen comprising: (a) a base layer of a material substantially transparent to x-rays, but substantially opaque to visible and ultraviolet radiation; and (b) a layer of an x-ray excitable luminescent material secured to base layer, characterized in that the luminescent material consists essentially of large single-crystalline hexagonal particles of (Hf 1=x Zr x ) 3-y A 4y (PO 4 ) 4 , wherein A is at least one alkali metal selected from the group consisting of Li, Na and K, x is within the range of 0.005 to 0.5, and y is within the range of 0.4 to 2.0, whereby good resolution of the image is achieved without substantial cross-over.
Claim 10
Dependent Claim
132 words
An x-ray intensifying screen for use with conventional silver halide emulsion x-ray film to intensify an exposed image on the film, the screen comprising: (a) a base layer of a material substantially transparent to x-rays, but substantially opaque to visible and ultraviolet radiation; and (b) a layer of an x-ray excitable luminescent material secured to base layer, characterized in that the luminescent material consists essentially of large single-crystalline hexagonal particles of (Hf 1=x Zr x ) 3-y A 4y (PO 4 ) 4 , wherein A is at least one alkali metal selected from the group consisting of Li, Na and K, x is within the range of 0.005 to 0.5, and y is within the range of 0.4 to 2.0, whereby good resolution of the image is achieved without substantial cross-over.
Claim 11
Dependent Claim
19 words
The x-ray intensifying screen of claim 7 wherein the x is within the range of about 0.05 to 0.3.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-09-04 | 1982-03-06 | 1982-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-09-04 | 1986-03-06 | 1986-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-09-04 | 1990-03-06 | 1990-09-05 | $7700.00 | Window Closed / Lapsed |