JPS61236888A - Fluorescent material and production thereof - Google Patents

Abstract

PURPOSE:To obtain a novel halogenated Cs.Rb fluorescent material doped with bivalent Eu and exhibiting intense accelerated phosphorescence by the excitation with specific electromagnetic wave. CONSTITUTION:The objective halogenated cesium rubidium fluorescent material doped with bivalent europium and represented by the formula (X and X' are Cl, Br or I; 0<a<=10.0; 0<x<=0.2) is produced e.g. by calcining a mixture of a cesium halide, rubidium halide and a europium compound such as halide, oxide, nitrate, sulfate, etc., in a weakly reducing atmosphere at 400-1,300 deg.C. USE:A fluorescent material for radiation image conversion panel or radiation intensifying screen for medical radiography such as X-ray photography or industrial radiography for non-destructive inspection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a phosphor and a method for manufacturing the same. More specifically, the present invention relates to a halide phosphor activated by divalent europium and a method for producing the same.

[Background of the Invention] As a type of halide-based phosphor activated with divalent europium, a divalent europium-activated alkaline earth metal fluoride halide phosphor (M” FX: E
u2°, where Ml is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca, and X is a halogen other than fluorine) is well known. For example, as disclosed in Japanese Patent Publication No. 51-28591, this phosphor exhibits near-ultraviolet light emission (instantaneous light emission) with an emission maximum around 390 nm when excited by radiation such as X-rays, electron beams, and ultraviolet rays. It is known that it is particularly useful as a phosphor for radiation-sensitizing screens used in X-ray photography.

Furthermore, in recent years, the divalent europium-activated alkaline earth metal fluorohalide phosphor has been irradiated with radiation such as X-rays, electron beams, and ultraviolet rays, and then excited with electromagnetic waves in the visible to infrared region. It has been found that the phosphor exhibits luminescence, that is, the phosphor exhibits stimulated luminescence. For this reason, for example, Japanese Patent Application Laid-Open No. 55-121
It is disclosed in Publication No. 43. As such, this phosphor is
It has attracted much attention as a phosphor for radiation image conversion panels used in radiation image conversion methods that utilize the photostimulability of phosphors.

[Summary of the Invention] An object of the present invention is to provide a novel divalent europium-activated halide phosphor and a method for producing the same.

That is, the phosphor of the present invention has a compositional formula (1): % formula % (
) (However, each of X and Xo is at least one type selected from the group consisting of C1, Br, and Engineering (7) halo)
)-n; and a is 0<a≦io.

(X is a numerical value in the range O<x≦0.2) This is a divalent europium activated cesium rubidium halide phosphor.

Furthermore, the method for producing the divalent europium-activated cesium e-rubidium halide phosphor of the present invention has a stoichiometric compositional formula (■): C5Xa aRbX' : xEu (II)
(However, X and Xo are each at least one kind of halogen selected from the group consisting of C1, Br, and OH; and a is 0<a≦io.

After preparing a phosphor raw material mixture so as to have a relative ratio corresponding to It is characterized by firing at a temperature in the range of 400 to 1300"O.

The divalent europium-activated cesium-rubidium halide phosphor of the present invention represented by the composition formula (I) has xll,
After irradiating with radiation such as ultraviolet rays and electron beams, 450 ~
The divalent europium-activated cesium-rubidium halide phosphor of the present invention, which exhibits stimulated luminescence in the near-ultraviolet to blue region when excited by electromagnetic waves in the wavelength region of 900 nm, and is represented by the composition formula (I), is subjected to X-rays, When irradiated with radiation such as ultraviolet rays or electron beams, it emits light (instantaneous light emission) in the near-ultraviolet to blue region.

[Structure of the Invention] The divalent europium-activated cesium-rubidium halide phosphor of the present invention can be manufactured, for example, by the manufacturing method described below.

First, as a raw material for the phosphor: 1) at least one type of halogenated cecilum selected from the group consisting of CsCJl, CsBr, and CsI.

2) at least one type of rubidium halide selected from the group consisting of RbCl, RbBr, and RbI, and 3) at least one compound selected from the group consisting of europium compounds such as halides, oxides, nitrates, and sulfates. prepare.

In some cases, ammonium halide (N
H,

When producing a phosphor, the above 1) /% cesium halide, 2) rubidium halide, and 3) europium compound are used to stoichiometrically form the composition formula (■): CsX* aRbX': xEu (II)
(wherein,
(X is a numerical value in the range of O<x≦0.2) A mixture of phosphor raw materials is prepared by weighing and mixing so as to have a relative ratio corresponding to the following.

In the method for producing a phosphor of the present invention, X and Xo in cesium halide (CsX) and rubidium halide (RbX') may be the same or different from each other. From the viewpoint of instantaneous luminance, the a value representing the ratio of CsX and RbX' in composition formula (n) is preferably in the range of 0.15≦a≦2.0; From the viewpoint of brightness, the X value representing the activation amount of europium in compositional formula (n) is preferably in the range of 10-5≦x≦10-2.

The phosphor raw material mixture may be prepared by: i) simply mixing the phosphor raw materials of 1), 2) and 3) above; or;

ii) First, the phosphor raw materials of 1) and 2) above are mixed in a solution state, and this solution is heated (preferably 50 to 2
00° C.) by vacuum drying, vacuum drying, spray drying, etc., and then mixing the phosphor raw material of 3) above into the obtained dried product.

゛ In addition, as a modification of method 1) above, 1) and 2
A method may also be used in which the phosphor raw materials in ) and 3) are mixed in a solution state and the solution is dried.

In both methods i) and ii), conventional mixers such as various mixers, V-type blenders, ball mills, and rod mills are used for mixing.

Next, the phosphor raw material mixture obtained as described above is filled into a heat-resistant container such as a quartz port, an alumina crucible, or a quartz crucible, and fired in an electric furnace.The firing temperature is 40°C.
A range of 0 to 1300°C is appropriate, preferably 700°C.
~1000°C. Although the firing time varies depending on the filling amount of the phosphor raw material mixture and the firing temperature, 0.5 to 6 hours is generally appropriate. As the firing atmosphere, a weakly reducing atmosphere such as a nitrogen gas atmosphere containing a small amount of hydrogen gas or a carbon dioxide atmosphere containing -carbon oxide is used. Generally, a trivalent europium compound is used as the phosphor raw material in 3) above, but in this case, during the firing process, the trivalent europium is reduced to divalent europium by the weakly reducing atmosphere mentioned above. be done.

The phosphor of the present invention in powder form is obtained by the above baking.

Note that the obtained powdered phosphor may be further subjected to various general operations in the production of phosphors, such as washing, drying, and sieving, as necessary.

The divalent europium-activated cesium-rubidium halide phosphor manufactured by the manufacturing method described above has one composition formula (1): % formula % () (where X and Xo are each a group consisting of Ci, Br, and and a is a numerical value in the range of Ova≦10.0;
X is a numerical value in the range of O<x≦0°2).

Divalent europium activation ° cesium halide of the present invention
When rubidium phosphor is irradiated with radiation such as X-rays, ultraviolet rays, and electron beams, and then excited with electromagnetic waves in the visible to infrared region of 450 to 900 nm, it emits stimulated light in the near ultraviolet to blue region (peak wavelength of emission: around 37 Onm). ) is shown.

Figures 1 and 2 respectively show the stimulated excitation spectrum and stimulated emission spectrum of a CsC1-RbBr:0.001E u'' phosphor, which is an example of the divalent europium-activated cesium rubidium halide phosphor of the present invention. It shows.

From Figure 1, C5CJL*RbBr: 0.001Eu”
Phosphors exhibit stimulated luminescence when excited with electromagnetic waves in the wavelength range of 450 to 9QQBm after irradiation with radiation, and in particular in the range of 600 to 7QBm.
It is clear that when excited with electromagnetic waves in the wavelength region of 50 nm, high-intensity stimulated luminescence is exhibited. Also, from Figure 2, C
5C! LLIRbBr: 0.001 E u "" It can be seen that the phosphor exhibits stimulated luminescence in the near ultraviolet to blue region, and the peak of its stimulated luminescence spectrum is around 370 nm. Therefore.

When this phosphor is excited with electromagnetic waves in the wavelength range of 600 to 750 nm, it is easy to separate the stimulated emission and excitation light, and the stimulated emission has high brightness.

Above, C5CfL@RbBr: 0.001 Eu2°
Taking the case of a phosphor as an example, 1. The photostimulated excitation spectrum and the stimulated emission spectrum of the divalent europium-activated cesium rubidium halide phosphor of the present invention have been explained; The spectrum and stimulated emission spectrum are the above CgCJl-RbB
r: 0.001 Eu”° Almost the same as the phosphor.

Furthermore, the divalent europium-activated cesium-rubidium halide phosphor of the present invention emits light (instantaneous light emission) in the near-ultraviolet to blue region when irradiated with radiation such as X-rays, ultraviolet rays, and electron beams.

FIG. 3 illustrates the instantaneous emission spectrum and its excitation spectrum in the case of ultraviolet excitation of the divalent europium-activated cesium rubidium halide phosphor of the present invention, and in FIG. 3, curves 1 and 2 are, respectively, 1:C5CfL-RbBr:0.001Eu" phosphor emission spectrum 2:C5CJl-RbBr:0.001Eu" phosphor emission spectrum From Figure 3, which is the excitation spectrum of the C5CJl-RbBr:0.001Eu" It can be seen that the cesium-rubidium phosphor emits instantaneous light in the near-ultraviolet to blue region under ultraviolet excitation, and the peak wavelength of its emission spectrum is around 370 nm, similar to the peak wavelength in the above-mentioned stimulated luminescence.

Above, the instantaneous emission spectrum and its excitation spectrum in the case of ultraviolet excitation of the divalent europium-activated cesium rubidium halide phosphor of the present invention have been explained using the case of the C5CfL*RbBr:0.001 Eu'' phosphor as an example. 1 The instantaneous emission spectrum and excitation spectrum of the other phosphors of the present invention are as follows:
It has been confirmed that the instantaneous emission spectrum and excitation spectrum of the phosphor of the present invention are almost the same as the instantaneous emission spectrum and excitation spectrum of the phosphor of the present invention when excited by X-rays and electron beams. It has also been confirmed that the spectrum is almost the same as the instantaneous emission spectrum in the case of ultraviolet excitation shown in Figure 3.Furthermore, as is clear from the comparison of curve 1 in Figures 2 and 3, The stimulated emission spectrum and the instantaneous emission spectrum of the divalent europium-activated cesium-rubidium halide phosphor of the present invention are almost the same.

Figure 4 shows C5CfL fist aRbBr: 0.001Eu”
The a value of the phosphor and the stimulated luminescence intensity [X of 80KVp
After irradiating the beam, a He-Ne laser beam (632,8n
FIG. As is clear from Fig. 4, the a value is O<a≦
C3C1L@aRbB of the present invention in the range of 1000
Among r:0.001Eu” phosphors, the a value is 0.1
A phosphor in the range of 5≦a≦2.0 exhibits stimulated luminescence with higher brightness.

Furthermore, it has been confirmed that for the phosphors of the present invention other than the C5CJL aRbBr:0.001Eu2° phosphor, the relationship between the a value and the stimulated luminescence intensity has the same tendency as shown in FIG. 4.

Due to the luminescent properties described above, the phosphor of the present invention can be used particularly in medical radiography such as X-ray photography for the purpose of medical diagnosis, and industrial radiography for the purpose of non-destructive testing of materials. As a phosphor for radiation image conversion panels used in radiation image conversion methods using stimulable phosphors, and for radiation intensifying screens used in radiography for medical diagnosis and non-destructive testing of materials. Very useful as a phosphor.

Next, examples of the present invention will be described. However, these examples do not limit the present invention.

[Example 1] 168.36 g of cesium chloride (CsCjL), 165.47 g of rubidium bromide A (RbBr), and 0.392 g of europium bromide (EuBr) were added to distilled water (H20
) and mixed to form an aqueous solution. After drying this aqueous solution under reduced pressure at 60°C for 3 hours,
0℃! Vacuum drying was performed for 3 hours.

Next, the obtained phosphor raw material mixture was filled into an alumina crucible, which was then placed in a high-temperature electric furnace and fired. Firing is carried out at 900°C in a carbon dioxide atmosphere containing carbon oxide.
The test was carried out at a temperature of 2 hours. After firing is completed,
The fired product was taken out of the furnace and cooled. In this way,
Powdered C5CfL ・RbB r: 0. ooIE u
A 2° phosphor was obtained.

[Example 2] In Example 1, powdered (
1) CsB r fist RbB r: 0.001E u”
A phosphor was obtained.

[Example 3] Powdered Cs ( I IIRb I :0.001Eu"+phosphor was obtained.

Next, the emission spectrum and the excitation spectrum when the phosphor obtained in Example 1 was excited with ultraviolet rays were measured. The results obtained are shown in FIG.

In FIG. 3, curves l and 2 are respectively 1 :C
Emission spectrum of 5CJl@RbBr: 0.001 Eu"" phosphor 2: Excitation spectrum of C5CfL*RbBr: 0.001 Eu" phosphor is shown.

Furthermore, the luminance of instantaneous light emission when each of the phosphors obtained in Examples 1 to 3 was excited with X-rays was measured. The results are shown in Table 1.

Below is a margin Table 1 Relative luminance Example 1 100 Example 2 80 Example 3 65 Furthermore, a tube voltage of 80 KVp was applied to the phosphor obtained in Example 1.
17) Stimulated emission spectrum when excited with He-Ne laser light (wavelength 632.8 nm) after irradiation with X-rays, and the peak wavelength of the stimulated emission (approximately 370 nm)
The photostimulation excitation spectrum was measured. The results obtained are shown in FIGS. 1 and 2.

Figure 1 shows C5CJl*RbBr:0.001 Eu”
The photostimulation excitation spectrum of the phosphor is shown.

FIG. 2 shows CsC1・RbBr: 0.001 Eu”.

The stimulated emission spectrum of the phosphor is shown.

In addition, each of the phosphors obtained in Examples 1 to 3 was given a subpressure of 80K.
VpcF) After irradiation with X-rays, the brightness of stimulated luminescence when excited with 632.8 nm light was measured. The result is the second
Shown in the table.

Table 2 Relative stimulated luminance Example 1 100 Example 2 70 Example 3 30

[Brief explanation of drawings]

Figure 1 shows C5CJl*R, which is an example of the divalent europium-activated cesium rubidium halide phosphor of the present invention.
bBr:0.001 Eu" phosphor. Figure 2 shows the C5CjL@R which is an example of the divalent europium-activated cesium halide rubidium phosphor of the present invention.
bBr: 0.001 Ear” is a stimulated emission spectrum of the phosphor. Figure 3 shows a C5CjLe which is a specific example of the divalent europium activated cesium rubidium halide phosphor of the present invention.
Figure 4 shows the instantaneous emission spectrum (curve 1) and its excitation spectrum (curve 2) of the RbBr:0,001 Eu'' phosphor under ultraviolet excitation. C5CJL* which is a specific example of the body
2 is a graph showing the relationship between the a value and the stimulated luminescence intensity in aRbBr:0.001Eu'' phosphor.

Claims (7)

[Claims] 1. Compositional formula (I): CsX・a_RbX':x_Eu^2^+(I) (wherein X and X' are each at least one type of halogen selected from the group consisting of Cl, Br and I;
and a is a numerical value in the range of 0<a≦10.0, and x is a numerical value in the range of 0<x≦0.2). 2. a in the composition formula (I) is 0.15≦a≦2.
The phosphor according to claim 1, wherein the phosphor has a numerical value in the range of 0. 3. x in compositional formula (I) is 10^-^5≦x≦
The phosphor according to claim 1, wherein the phosphor has a numerical value in the range of 10^-^2. 4. Stoichiometrically, the compositional formula (II): CsX・aRbX':x_Eu(II) (However, X and X' are Cl, Br and I, respectively.
at least one kind of halogen selected from the group consisting of: and a is a numerical value in the range of 0<a≦10.0;
x is a numerical value in the range of 0<x≦0.2) After preparing a phosphor raw material mixture so as to have a relative ratio corresponding to Compositional formula (I) characterized by firing at a temperature expressed by: CsX・a_RbX':x_Eu^2^+(I) (However, the definitions of X, X', a and x are the same as above) A method for producing divalent europium-activated cesium/rubidium halide phosphors. 5. a in compositional formula (II) is 0.15≦a≦2.
5. The method for producing a phosphor according to claim 4, wherein the numerical value is in the range of 0. 6. x in compositional formula (II) is 10^-^6≦x≦
5. The method for producing a phosphor according to claim 4, wherein the numerical value is in the range of 10^-^2. 7. Firing the phosphor raw material mixture at 700 to 1000℃
5. A method for producing a phosphor according to claim 4, wherein the method is carried out at a temperature in the range of .