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US5547807A
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Photostimulable phosphors
Assignee: Agfa Gevaert NV
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Filing: 1995-03-15
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Granted: 1996-08-20
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Expires: 2015-03-15
Abstract
Abstract A photostimulable phosphor of which the emission intensity at the stimulation wavelength of 550 nm is higher than the emission intensity at the stimulation wavelength of 600 nm, characterized in that said phosphor is a divalent europium activated barium fluorobromide containing as codopant samarium, and wherein the terminology barium fluorobromide stands for an empirical formula wherein (1) a minor part of the barium (less than 50 atom %) is replaced optionally by at least one metal selected from the group consisting of a monovalent alkali metal, a divalent alkaline earth metal other than barium, and a trivalent metal selected from the group consisting of Al, Ga, In, Tl, Sb, Bi, Y, and a rare earth metal selected from the group consisting of Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, (2) a minor part (less than 50 atom %) of the bromine is replaced by chlorine, and/or iodine, and (3) wherein fluorine is present stoichiometrically in a larger atom % than bromine taken alone or bromine combined with chlorine and/or iodine.
Inventors
- 👤 Paul Leblans
- 👤 Albert D. Adriaensens
- 👤 Melvin Tecotzky
- 👤 Jan A. Van den Bogaert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:49
CPC Classifications
G; G21; G21K; G21K4/00; C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7783; C09K11/779; C09K11/7791; G21K2004/06; Y; Y10; Y10S; Y10S430/00; Y10S430/146; Y10S430/167; Y10S430/168
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
237 words
A radiation image recording and reproducing method comprising the steps of: (I) causing a visible radiation stimulable phosphor to absorb penetrating radiation having passed through an object or emitted by an object and to store energy of said penetrating radiation in said phosphor, (ii) stimulating said phosphor with visible radiation in the wavelength range from 440 nm to 550 nm to release energy stored in said phosphor as fluorescent light differing in wavelength range from the stimulating light, and (iii) detecting said fluorescent light, wherein said photostimulable phosphor has an emission intensity at the stimulation wavelength of 550 nm that is higher than the emission intensity at the stimulation wavelength of 600 nm, and wherein said phosphor is a divalent europium activated barium fluorobromide containing as codopant samarium, and wherein the terminology barium fluorobromide stands for an empirical formula wherein (1) a minor part of the barium (less than 50 atom %) is replaced by an alkali metal, (2) a minor part (less than 50 atom %) of the bromine is replaced by chlorine, and/or iodine, and (3) fluorine is present stoichiometrically in a larger atom % than bromine alone or bromine combined with chlorine and/or iodine, and (iv) the alkali metal is selected from the group consisting of Li, Na, K, Rb and Cs and is present with respect to barium in an atom percent in the range of 10 -4 to 10 -2 at %.
Claim 2
Dependent Claim
237 words
A radiation image recording and reproducing method comprising the steps of: (I) causing a visible radiation stimulable phosphor to absorb penetrating radiation having passed through an object or emitted by an object and to store energy of said penetrating radiation in said phosphor, (ii) stimulating said phosphor with visible radiation in the wavelength range from 440 nm to 550 nm to release energy stored in said phosphor as fluorescent light differing in wavelength range from the stimulating light, and (iii) detecting said fluorescent light, wherein said photostimulable phosphor has an emission intensity at the stimulation wavelength of 550 nm that is higher than the emission intensity at the stimulation wavelength of 600 nm, and wherein said phosphor is a divalent europium activated barium fluorobromide containing as codopant samarium, and wherein the terminology barium fluorobromide stands for an empirical formula wherein (1) a minor part of the barium (less than 50 atom %) is replaced by an alkali metal, (2) a minor part (less than 50 atom %) of the bromine is replaced by chlorine, and/or iodine, and (3) fluorine is present stoichiometrically in a larger atom % than bromine alone or bromine combined with chlorine and/or iodine, and (iv) the alkali metal is selected from the group consisting of Li, Na, K, Rb and Cs and is present with respect to barium in an atom percent in the range of 10 -4 to 10 -2 at %.
Claim 3
Dependent Claim
19 words
Method according to claim 1, wherein the stimulation proceeds with 532 nm light of a frequency doubled Nd-YAG laser.
Claim 4
Dependent Claim
17 words
Method according to claim 1, wherein the stimulation proceeds with 514.5 nm light of argon ion laser.
Claim 5
Dependent Claim
17 words
Method according to claim 1, wherein the stimulation proceeds with 488 nm light of argon ion laser.
Claim 6
Dependent Claim
16 words
Method according to claim 1, wherein the stimulation proceeds with 442 nm light of He-Cd laser.
Claim 7
Dependent Claim
15 words
Method according to claim 1, wherein detection of the light emitted by photostimulation proceeds photo-electronically.
Claim 8
Dependent Claim
24 words
Method according to claim 1, wherein before detection of the light emitted by photostimulation the stimulating light is blocked substantially by a filter means.
Claim 9
Dependent Claim
78 words
The Method according to claim 1 wherein a part of the barium of said phosphor is further replaced with a member of the group consisting of a divalent alkali earth metal other than barium and a trivalent metal selected from the group consisting of Al, Ga, In, Tl, Sb and Bi, the total amount of the replaced barium by said alkali earth metal and said divalent alkali earth metal and trivalent metal being less than 50 atom percent.
Claim 10
Dependent Claim
28 words
Method according to claim 1, wherein samarium is present with respect to barium in an atom percent in the range of 10 -5 to 10 -1 at %.
Claim 11
Dependent Claim
41 words
Method according to claim 8, wherein an alkaline earth metal is present selected from the group consisting of Sr, Mg and Ca with respect to barium in an atom percent in the range of 10 -3 to 2×10 -1 at %.
Claim 12
Dependent Claim
30 words
Method according to claim 8, wherein a trivalent metal is present with respect to barium in an atom percent in the range of 10 -3 to 10 -1 at %.
Claim 13
Dependent Claim
13 words
Method according to claim 8, wherein strontium is present in combination with barium.
Claim 14
Dependent Claim
24 words
Method according to claim 1, wherein fluorine is 3 to 12 atom % in excess over bromine or bromine combined with chlorine and/or iodine.
Claim 15
Dependent Claim
178 words
Method according to claim 1, wherein said phosphor is within the scope of the following empirical formula (I) Ba.sub.1-x-y-p-3q-z-3m Sr.sub.x M.sub.y.sup.II M.sub.2q.sup.I M.sub.s1.sup.III F.sub.2-a-b Br.sub.a X.sub.b :zA:2mSm wherein: X is at least one halogen selected from the group consisting of C1 and I, M I is at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs; M II is at least one alkaline earth metal selected from the group consisting of Ca and Mg; M III is at least one metal selected from the group consisting of Al, Ga, In, Tl, Sb and Bi; a is a number satisfying the conditions of 0.85≦a≦0.96 when x is 0.17≦x ≦0.55 and 0.90≦a≦0.96 when x is 0.12 ≦x≦0.17; y is in the range 0≦y≦10 -1 ; b is in the range 0≦b<0.04; p is in the range 10 -4 ≦p≦10 -1 ; q is in the range 0≦q≦0.1; z is in the range 10 -6 ≦z≦10 -2 ; m is in the range 10 -5 ≦m≦10 -1 , and A is Eu 2+ .
Claim 16
Dependent Claim
16 words
Method according to claim 14, wherein in said empirical formula M I is Na or Rb.
Claim 17
Dependent Claim
20 words
Method according to claim 14, wherein in said empirical formula z is in the range 10 -6 <z≦10 -1 .
Claim 18
Dependent Claim
120 words
Method according to claim 14, wherein said phosphor is prepared by firing a mixture of the following starting materials: (1) barium fluoride; (2) ammonium bromide; (3) optionally barium halide (except barium fluoride); (4) at least one alkali metal compound selected from the group consisting of lithium fluoride, lithium chloride, lithium bromide, lithium iodide, sodium fluoride, sodium chloride, sodium bromide, potassium fluoride, rubidium fluoride and cesium fluoride, lithium hydroxide or oxide or lithium carbonate; (5) a strontium halide, optionally in admixture with a calcium and/or magnesium halide; (6) optionally a said M III compound; (7) at least one A containing compound selected from the group consisting of europium halide, europium oxide, europium nitrate and europium sulphate, and (8) a samarium compound.
References Cited (Backward Citations)
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