JPS61235486A - Phosphor and production of the same - Google Patents

Abstract

NEW MATERIAL:A phosphor of the formula I (wherein MII is Ba, Sr or Ca; X and X' are each independently Cl, Br or I, provided that X=X'; X'' and X'''''' are each independently X or F; 0.1<=a<=10.0; 0<b<=10.0; 10<-6=c<=2X10<-2>; and 0<x<=0.2). EXAMPLE:A phosphor of the formula II. USE:An Eu<2+>-activated composite halide phosphor which exhibits an excellent stimulated luminescence brightness (near ultraviolet - blue) when excited with an electromagnetic wave of 450-1,000nm after exposure to a radiation and useful for a radiation-activated screen and a radiation image converting panel. PREPARATION:Raw materials of phosphor such as at least two alkaline earth metal halides selected from among BaCl2, SrBr2, CaI2, etc., at least one cesium halide selected from among CsF, CsBr, etc. and a tin halide selected from among SnF2, SnCl2, etc. and a halide, oxide, etc. of Eu are mixed in an amount ratio corresponding to the formula III. The mixture is calcined in a neutral or weakly reducing atmosphere at 400-1,300 deg.C for 0.5-6hr.

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 composite halide phosphor activated by divalent europium and a method for producing the same.

[Background of the Invention] As a type of alkaline earth metal halide phosphor activated with divalent europium, a divalent europium activated alkaline earth metal fluoride halide phosphor (M”
FX: Eu2°, however, MII is Ba, Sr and Ca
(X is a halogen other than fluorine) is well known. This phosphor emits near-ultraviolet light (instantaneous light emission) when excited by radiation such as X-rays, and emits near-ultraviolet light (photostimulated light) when excited by electromagnetic waves in the visible to infrared region after being irradiated with radiation such as X-rays. luminescence).

In addition, as a phosphor different from the above-mentioned divalent europium-activated alkaline earth metal fluorohalide phosphor, the applicant has developed a novel divalent europium-activated alkaline earth metal halide phosphor represented by the following compositional formula. A patent application has already been filed for the body (Japanese Patent Application No. 193161/1982).

Compositional formula = M Rin X 2 Reference a M Rin X' 2 :)
*(However, M' is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca;
X and Xo are at least one kind of halogen selected from the group consisting of 0, Br, and I, and X≠X°
(and a is a numerical value in the range of 0.1≦a≦10.0, and X is a numerical value in the range of 0<x≦0.2) Furthermore, Ganjin Motoyama proposed A patent application has already been filed for a divalent europium-activated composite halide phosphor represented by the following compositional formula, which is obtained by adding a specific alkali metal halide to a valent europium-activated alkaline earth metal halide phosphor (Japanese Patent Application No. 1983). -22169).

Composition formula: % formula % (where M' is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; M
I is at least one alkali metal selected from the group consisting of Rh and Cs; X and X″ are both C
at least one halogen selected from the group consisting of fL, Br and engineering, and X≠X°; X'' is at least one halogen selected from the group consisting of F, Cl, Br and engineering: and a is 0.1≦a≦1
b is a numerical value in the range of 0.0, b is a numerical value in the range of o<b≦10.0, and X is a numerical value in the range of 0<X≦0.2) These novel phosphors are From its X-ray diffraction pattern as described in the above application specification, the M'FX
: It has been found that Eu2° phosphor is a different type of phosphor with a different crystal structure, and x! ! When irradiated with radiation such as ultraviolet rays or electron beams, it emits near-ultraviolet to blue light (instantaneous light emission) with an emission maximum around 405 nm. In addition, when these phosphors are irradiated with radiation such as X-rays, ultraviolet rays, and electron beams and then excited with electromagnetic waves in the wavelength range of 450-1000 nm, they emit light in the near-ultraviolet to blue region (stimulated luminescence). These phosphors are useful as phosphors for radiation intensifying screens used in X-ray photography and for radiation image conversion panels used in radiation image conversion methods that utilize the photostimulability of phosphors.

[Summary of the Invention] The divalent europium-activated composite halide phosphor of the above Japanese Patent Application No. 59-22169 is based on the above-mentioned Japanese Patent Application No. 58-1931.
The stimulated luminance of the divalent europium-activated alkaline earth metal halide phosphor No. 61 is improved by containing a specific amount of rubidium halide and/or cesium halide. The object of this patent application No. 59-22169 is to improve the stimulated luminance of a divalent europium-activated composite halide phosphor.

That is, the present invention provides the above-mentioned Japanese Patent Application No. 59-2216, which has improved stimulated luminescence brightness when excited by electromagnetic waves in the wavelength range of 450 to 11,000 nm after irradiation with radiation such as X-rays.
No. 9 divalent europium activated composite halide phosphor,
The object of the present invention is to provide a method for producing the same.

In order to achieve the above object, the inventor has made the above patent application filed in 1973.
Among the bivalent europium-activated composite halide phosphors of No. 9-22169, various studies were conducted on phosphors to which cesium halide was added (i.e., phosphors where M'=Cs in the above compositional formula). As a result, it was discovered that the 6 phosphor obtained by adding a specific amount of tin halide to the phosphor exhibits high-intensity stimulated luminescence, and the present invention was achieved.

That is, the phosphor of the present invention has one compositional formula: MIIX
2 Book aMIIX' 2* bCsX” @cSnX”
, : xEu” ・ (I) (However, Ma is B
a, Sr, and Ca; X and X' are both at least one halogen selected from the group consisting of Cl, Br, and Ca, and X≠ X′;
and X"° are each at least one kind of halogen selected from the group consisting of F, CM, Br and I, and
is a numerical value in the range of 10-5≦c≦2X10-2, and
is a numerical value in the range of 0<X≦0.2) This is a divalent europium-activated composite halide phosphor.

Furthermore, the method for producing the phosphor of the present invention has a stoichiometric compositional formula (
II): MIIX2 e aMIIX' 2 e bcsX"・
c S nX12: xE u...e(■
) (However, M', X, X', X", X"゛, a, b,
After adjusting the phosphor raw material mixture to have a relative ratio corresponding to
It is characterized by firing at a temperature in the range of 1300°C to 1300°C.

The present invention relates to a novel divalent europium-activated composite halide phosphor described in the above-mentioned Japanese Patent Application No. 59-22169, in which a specific amount of tin halide is added to a phosphor doped with cesium halide. By adding 450-10 after irradiating the phosphor with radiation such as X-rays,
This is to realize an improvement in stimulated luminescence brightness when excited by electromagnetic waves in a wavelength range of 0.00 nm.

[Structure of the Invention] The divalent europium-activated composite halide phosphor of the present invention can be produced, for example, by the production method described below.

First, as a raw material for phosphor.

1) EaCu2, S rcJ12, CaCJL2, Ba
Br2.5rBrz, CaBr2, BaI 2°SrI
, and at least two alkaline earth metal halides selected from the group consisting of CaI2, 2) at least one cesium halide selected from the group consisting of CsF, CsCl, CsBr and C3X, 3) SnF2.5nClz, S nB r 2 and 5
At least one type of tin halide selected from the group consisting of n12, and at least one compound selected from the group consisting of compounds of europium such as halides, oxides, nitrates, and sulfates are prepared.

Here, as the phosphor raw material (1) above, two or more alkaline earth metal halides containing at least different halogens are used. In some cases, further ammonium halide, Mu (N Ha
, Xl*CJ1, Brt (which is tI), etc. may be used as the flux.

In the production of the phosphor, the above alkaline earth metal halide (1), cesium halide (2), tin halide (3) and europium compound (4) are used.
Stoichiometrically, compositional formula (II): M dish
nX”'2: xEu2° ・(II) (However,
M'' is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca;
are at least one kind of halogen selected from the group consisting of Cl, Br and I, and X≠X';

and X'' are each at least one kind of halogen selected from the group consisting of F, CfL, Br, and It is a numerical value in the range of ≦10.0, and C is 1
It is a numerical value in the range of 0-'≦c≦2X10-', where X is 0
<A numerical value in the range of <X≦0.2) A mixture of phosphor raw materials is prepared by weighing and mixing so as to have a relative ratio corresponding to <X≦0.2.

In the method for producing the phosphor of the present invention, from the viewpoint of stimulated luminance, the C value representing the amount of tin halide (S n
It is preferable that c≦5×10−3, and the b value representing the amount of cesium halide (C3X″) is preferably in the range of o<b≦2.0. From the viewpoint of brightness, the a value representing the ratio of Mtakax2 and MIIX'2 in compositional formula (II) is 0.3≦a≦3.3.
It is preferably in the range of 0.5≦, more preferably 0.5≦
a≦2.0, and X゛ and X'' are each,
Preferably, it is either Cl or Br, and
The X value representing the activation amount of europium is to4≦X≦10
-2 is preferred.

The phosphor raw material mixture may be prepared by i) simply mixing the phosphor raw materials in 1) to 4) above, or ii) first, the phosphors in 1), 2), and 3) above. This may be carried out by mixing the raw materials, heating this mixture at a temperature of 100° C. or higher for several hours, and then mixing the phosphor raw material of 4) above into the obtained heat-treated product, or 1ii) First, The above phosphor raw materials 1), 2) and 3) are mixed in the form of a solution, and this solution is dried under reduced pressure drying, vacuum drying, spray drying, etc. under heating (preferably 50 to 200°C), This may be carried out by subsequently mixing the phosphor raw material of 4) above into the obtained dried product.

In addition, as a modification of the method ii) above, the above l) to 4)
A method of mixing the phosphor raw materials of 1) and subjecting the obtained mixture to the above heat treatment, or a method of mixing the phosphor raw materials of 1) and 4) above, subjecting this mixture to the above heat treatment, and applying the above heat treatment to the obtained heat-treated product. ) and 3) may be used. Alternatively, as a modified method of method 1ii), the phosphor raw materials of l) to 4) above may be mixed in a solution state, and this method may be used. A method of drying a solution, or mixing the phosphor raw materials of 1) and 4) above in a solution state, drying this solution, and then mixing the phosphor raw materials of 2) and 3) above into the obtained dried product. You may use the method.

In any of the above methods i), ii), and 1ii), a conventional mixer such as various mixers, a type blender, a ball mill, and a 7-mouth dome mill is used for mixing.

Next, the phosphor raw material mixture obtained as described above is filled into a heat-resistant container such as a quartz boat, an alumina crucible, or a quartz crucible, and fired in an electric furnace at a firing temperature of 40°C.
0 N A range of 1300°C is appropriate, preferably 50°C.
From the point of view of 0 luminance, which is in the range of 0 to 1000°C,
It is particularly preferable to perform the firing at a temperature lower than the melting point of the phosphor (approximately 875°C).The firing time varies depending on the filling amount of the phosphor raw material mixture and the firing temperature, but in general, 0.5 to 6 hours is appropriate. It is. As the firing atmosphere, a neutral atmosphere such as a nitrogen gas atmosphere or an argon gas atmosphere, or a weakly reducing atmosphere such as a nitrogen gas atmosphere containing a small amount of hydrogen gas or an industrial dioxide atmosphere containing -carbon oxide is used. Generally, a europium compound in which the valence of europium is trivalent is used as the phosphor raw material in 4) above, but in this case, the trivalent europium is reduced to divalent europium in the firing process.

Note that a method may also be used in which the phosphor raw material mixture is once fired under the above firing conditions, the fired product is left to cool, pulverized, and then re-fired (secondary firing). 400-80 under neutral or weakly reducing atmosphere
The firing is carried out at a firing temperature of 0° C. for 0.5 to 12 hours.

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

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

By the manufacturing method described above, the divalent europium-activated composite halide phosphor of the present invention represented by the following compositional formula (I) is manufactured.

Nagishiki (craft): M rin X, fist aMIIX' 2 e
bCsX ″ΦcsnX″+,, xEu”
...(I) (However, M ward, x, x', x'', x
"', a, b, c and X definitions are the same as above)
Note that the phosphor of the present invention manufactured according to the above-mentioned manufacturing method is irradiated with radiation such as X-rays, ultraviolet rays, and electron beams, and then
When excited with electromagnetic waves in the visible to infrared region of 450 to 11,000 nm, it emits light in the near ultraviolet to blue region (peak wavelength of emission: 40 nm).
yIMX2*ILMx', *bCsX', which emits stimulated luminescence at a wavelength of around 5 nm) and does not contain SnX"2.
:Shows almost the same stimulated emission spectrum and stimulated excitation spectrum as the Eu"° phosphor.

Furthermore, when the phosphor of the present invention is irradiated with radiation such as X-rays, ultraviolet rays, and electron beams, it emits light (instantaneous light emission) in the near-ultraviolet to blue region, and the peak wavelength of its emission spectrum is almost the same as the stimulated luminescence described above. It is in this area.

The phosphor of the present invention is a stimulable phosphor used 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. It has great utility as a phosphor for radiation image conversion panels used in image conversion methods, and also as a phosphor for radiation intensifying screens used in radiography for medical diagnosis and non-destructive testing of materials. It has a high value.

Next, Examples and Comparative Examples of the present invention will be described.

However, these six examples do not limit the present invention.

[Example 1] 333.2 g of barium bromide (BaBr2-2H20),
Barium chloride (BILCJlz"2HzO) 244.3
g, and europium bromide (EuBr3) 0.783
g was added to 800 ml of distilled water (H2O) and mixed to form an aqueous solution. This aqueous solution was dried under reduced pressure at 60°C for 3 hours, and then further vacuum dried at 150°C for 3 hours.

Next, tin chloride (SnC!) is added to the obtained phosphor raw material mixture.
L2-2H,o) 45.1 mg, cesium bromide (CsB
After sufficiently mixing 21.3 g of r), it was filled into an alumina crucible, and the mixture was placed in a high-temperature electric furnace for firing. Firing at 850°C in an industrial atmosphere containing -carbon dioxide.
The test was carried out at a temperature of 1° for 5 hours. After the firing was completed, the fired product was taken out of the furnace and cooled. In this way, a divalent europium-activated composite halide phosphor (Ba
CJL2 *BaBr2 *0. I C3Br*0.0
0025 n Cl 2 :0.002E u ”°)
I got it.

[Example 2] Divalent europium-activated composite halide phosphor (Ba CfL t・BaBr , −0,I
CsBr-0,002SnCl2:0
．． 002Eu'') was obtained.

[Example 3] Divalent europium-activated composite halide phosphor (BaC 2 eBaB r 2 *O, l
CsB r eO,02s nc fL
2:0.002 Eumu) was obtained.

[Comparative Example 1] In Example 1, a divalent europium-activated composite halide phosphor (BaClz/HaB r 2a O,I Cs
B r :0.002E u'') was obtained.

Next, each of the phosphors obtained in Examples 1 to 3 and Comparative Example 1 was irradiated with X-rays at a tube voltage of 80 KVp, and then the stimulated luminescence brightness when excited with semiconductor laser light (780 nm) was measured. The results are summarized in Figure 1.

Figure 1 shows BaClz fist BaBr2*Q, I CsB
r a c S n Cl 2 :0.002E u
It is a graph showing the relationship between the content of tin chloride (C value) and the stimulated luminance in a 2° phosphor.

As is clear from FIG. 1, the BaCjL2eBa of the present invention
Br2*0. lC5BrecSnCl2:0.002
E u ”° phosphor has a C value of 10-5≦c≦2×1
In the range of 0-2, the stimulated luminance was improved. In particular, phosphors with a C value in the range of 10-8≦c≦5×10 exhibited high-intensity stimulated luminescence.

[Brief explanation of drawings]

Figure 1 shows BaCJ12eBaBr2, which is a specific example of the divalent europium-activated composite halide phosphor of the present invention.
eO,I C5Bre csncJL2:0.002E
FIG. 2 is a graph showing the relationship between the C value and the stimulated luminance of the u" phosphor.

Claims (15)

[Claims] 1. Composition formula (I): M^IIX_2・aM^IIX'_2・bCsX”・cSn
X”'_2: xEu^2^+...(I) (However,
M^II is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca: X and X
' are at least one kind of halogen selected from the group consisting of Cl, Br and I, and X≠X';X'' and X'' are each selected from the group consisting of F, Cl, Br and I at least one selected halogen: and a is a numerical value in the range of 0.1≦a≦10.0, b is a numerical value in the range of 0<b≦10.0, and c
is a numerical value in the range of 10^-^6≦c≦2×10^-^2, and x is a numerical value in the range of 0<x≦0.2). body. 2. c in compositional formula (I) is 10^-^5≦c≦5
The phosphor according to claim 1, wherein the phosphor has a numerical value in the range of x10^-^3. 3. The phosphor according to claim 1, wherein b in the compositional formula (I) is a numerical value in the range of 0<b≦2.0. 4. Claim 1, wherein a in the compositional formula (I) is a numerical value in the range of 0.3≦a≦3.3.
Phosphor described in section. 5. The phosphor according to claim 1, wherein M^II in the compositional formula (I) is Ba. 6. X and X' in the composition formula (I) are each
The phosphor according to claim 1, characterized in that it is either Cl or Br. 7. x in compositional formula (I) is 10^-^5≦x≦1
The phosphor according to claim 1, wherein the phosphor has a numerical value in the range of 0^-^2. 8. Stoichiometric composition formula (II): M^IIX_2・aM^IIX'_2・bCsX”・cSn
X”'_2: xEu... (II) (However, M^I
I is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; X and X' are both at least one halogen selected from the group consisting of Cl, Br, and I, and X≠X';X" and X"' are respectively F, Cl, Br and I
at least one kind of halogen selected from the group consisting of 1
0^-^6≦c≦2×10^-^2, and x is a numerical value in the range of 0<x≦0.2). After preparing the mixture, this mixture is fired at a temperature in the range of 400 to 1300°C in a neutral atmosphere or a weakly reducing atmosphere. Compositional formula (I): M^IIX_2・aM^IIX'_2・bCsX"・cSn
X"'_2: xEu^2^+ ... (I) (However, the definitions of M^II, X, X', X", X"', a, b, c, and x are the same as above. ) A method for producing a divalent europium-activated composite halide phosphor. 9. c in compositional formula (II) is 10^-^5≦c≦5
9. The method for producing a phosphor according to claim 8, wherein the numerical value is in the range of x10^-^3. 10. 9. The method for producing a phosphor according to claim 8, wherein b in compositional formula (II) is a numerical value in the range of 0<b≦2.0. 11. a in compositional formula (II) is 0.3≦a≦3.3
9. The method for producing a phosphor according to claim 8, wherein the numerical value is in the range of . 12. 9. The method for producing a phosphor according to claim 8, wherein M^II in compositional formula (II) is Ba. 13. 9. The method for producing a phosphor according to claim 8, wherein X and X' in compositional formula (II) are each Cl or Br. 14. x in compositional formula (II) is 10^-^5≦x≦
9. The method for producing a phosphor according to claim 8, wherein the numerical value is in the range of 10^-^2. 15. Firing the phosphor raw material mixture at 500 to 1000°C
9. A method for producing a phosphor according to claim 8, characterized in that the method is carried out at a temperature in the range of .