JPS61120885A - Phosphor and production thereof - Google Patents

Abstract

PURPOSE:To obtain a phosphor exhibiting improved stimulated emission brightness when excited with electromagnetic waves after radiation irradiation, by mixing starting materials in such a proportion as to give a pre-determined composition and firing the mixture under specified conditions. CONSTITUTION:A starting material mixture is prepd. in such a quantity as to give a relative ratio stoichimetrically satisfying formula I. The mixture is fired at 400-1,300 deg.C in a neutral or weakly reducing atmosphere to obtain a bivalent europium-activated composite halide phosphor of formula I (wherein MII is Ba, Sr, Ca; X, X' are each Cl, Br, I; 0.1<=a<=10.0; 0<b<=10<-3>; 0<x<=0.2). The phosphor is very useful as a phosphor for radiation image converting panels which are used in medical radiography such as X-ray photographing in medical examination and industrial radiography for non-destructive inspection of materials.

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] Bivalent europium-activated alkaline earth metal fluoride halide phosphor CM has been used as a type of alkaline earth gold IA halide phosphor activated with divalent europium.
” FX: E u2+, however, Mll is Ba, S
At least one alkaline earth metal selected from the group consisting of r and Ca, or a halogen other than fluorine) is well known. This phosphor exhibits near-ultraviolet light emission (instantaneous light emission) when excited with radiation such as (exhaustive luminescence).

In addition, as a phosphor different from the divalent europium-activated alkaline earth metal fluorohalide phosphor described in "-", the present applicant has proposed a novel divalent europium-activated alkaline earth metal halogen phosphor represented by the following compositional formula. We have already filed a patent application for a compound phosphor (Japanese Patent Application No. 193161/1982).

Compositional formula: M"X2 e aM"X'2: xE
u2+ (However, MM is at least one kind of 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 O, Br and I. And 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) This divalent europium-activated alkaline earth metal As described in the above application specification, the halide phosphor was found to be a different type of phosphor with a different crystal structure from the M"FX:Eu & phosphor from its X-ray diffraction pattern. When irradiated with radiation such as X-rays, ultraviolet rays, and electron beams, it emits near-ultraviolet to blue light (instantaneous light emission) with an emission maximum near 405 nm (·I).
When this phosphor is irradiated with radiation such as X-rays, ultraviolet rays, and electron beams and then excited with electromagnetic waves in the wavelength range of 450 to 11,000 nm, it emits light (stimulated luminescence) in the near-ultraviolet to blue region. Therefore, it is useful as a phosphor 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.

Even in such a useful phosphor, it is desired that its stimulated luminance is as high as possible.

[Summary of A Ming] The present invention provides a method for applying radiation such as 450 to 1
The object of the present invention is to provide the above-mentioned novel divalent europium-activated alkaline earth metal halide phosphor that exhibits a different stimulated luminescence brightness when excited by electromagnetic waves in the wavelength region of 1000 nm, and a method for producing the same. be.

The present inventor conducted various studies on the novel divalent europium-activated alkaline earth metal halide phosphor described in -1- in order to achieve the objective described in "-1". As a result, the inventors discovered that a phosphor obtained by adding a specific tin halide to the phosphor exhibits high-intensity stimulated luminescence, leading to the present invention.

That is, the phosphor of the present invention has the 81′l formula (I): M”
X2eaM]! X' 2 * bS nX" 2
:xEu2+...(I) (However, MM is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca;
and
X' is at least one kind of halogen selected from the group consisting of F, Omon, Br and I; and a is a numerical value in the range of 0.1≦a≦10.0, b is a numerical value in the range o<b≦10-3, and X is O< x≦
It is a divalent europium-activated composite halide phosphor represented by (with a numerical value in the range of 0.2).

Furthermore, the method for producing the phosphor of the present invention has a stoichiometric compositional formula (
■): M"X2 ・aM"X' 2 ・bSnX" 2:
xEu...(I[) (However, the definitions of M'', X, X', X'', a, b, and X are the same as above) The phosphor raw material mixture is After the adjustment, this mixture is characterized by being fired at a temperature in the range of 400 to 1300° C. in a neutral atmosphere or a weakly reducing atmosphere.

The present invention enables the phosphor to be irradiated with radiation such as X-rays by adding a specific amount of tin halide (tin halide) to the novel divalent europium-activated alkaline earth metal halide phosphor. After that 450-11000
This realizes an improvement in stimulated luminescence brightness when excited by electromagnetic waves in the wavelength range of n.

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

First, as phosphor raw materials: 1) 13aCJJ2, SrC, Q2, CaCJ12, B
aBr2.5rBr2, CaBr2, BaI2, SrI
2) at least two alkaline earth metal halides selected from the group consisting of SnF2, CaI2, SnBr2, and SnBr2;
At least one tin halide selected from the group consisting of I2, and 3) at least one compound selected from the group consisting of europium compounds such as halides, oxides, nitrates, and sulfates.

Here, as the phosphor raw material in 1) above, two or more alkaline earth metal halides containing at least different halogens are used. In some cases, ammonium halide (NH4X″°;
"° is C1, Br or ■)" may be used as a franc.

When manufacturing a phosphor, 1) an alkaline earth metal halide, 2) a tin halide, and 3) a europium compound are used to form a stoichiometric composition formula (■).
: MIIX2 * aM"X' 2 'bSnX" 2
:xEu...(n) (However, Mll is 4T consisting of Ba, Sr and Ca.
X and X' are both at least one halogen selected from the group consisting of CM, Br and I, and X#X';X'' is is at least one kind of halogen selected from the group consisting of F, C1, Br and A numerical value in the range, where X is O
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 b value of tin halide (SnX"2), which is an additive component in compositional formula (II), is 10-5≦b≦
It is preferably in the range of 5 x 10-', where x' is F
It is preferable that Similarly, from the point of view of stimulated luminescence brightness, M■X 2 in the compositional formula (It),! l: M M
The a value representing the ratio of X + 2 is 0.25≦a≦6.0
It is preferably in the range of 0.5≦, more preferably 0.5≦
The range is a≦2.0, and the X value representing the activation amount of europium is preferably in the range of 10-5≦X≦10-1.

The phosphor raw material mixture may be prepared by l) simply mixing the phosphor raw materials from 1) to 3) above, or by first mixing the phosphor raw materials from l) above.
) and 2) phosphor raw materials were mixed, and this mixture was mixed with 10
This may be carried out by heating at a temperature of 0'O or below for several hours and then mixing the phosphor raw material of 3) above into the obtained heat-treated product, or 1ii) First, the above 1) and 2) ) are mixed in solution form m1, and this solution is dried by vacuum drying, vacuum drying, spray drying, etc. under heating (preferably 50 to 200'0), and then the resulting dry This may be carried out by mixing the two phosphor raw materials in 3).

In addition, as a modification of the method of ``Nippon 11'', the above l) to 3
A method of mixing the phosphor raw materials of 1) and 3) and subjecting the resulting mixture to a double heat treatment, or a method of mixing the phosphor raw materials of 1) and 3) above and subjecting this mixture to the above heat treatment, and the resulting heat-treated product. The method of mixing phosphor thickness 1 in 2) above may also be used. In addition, as a modification of method 1ii), the phosphor raw materials of 1) to 3) above are mixed in a solution state and this solution is dried, or - the phosphor of 1) and 3) above is mixed. It is also possible to use the method of mixing the raw materials in the form of a solution, drying this solution, and then mixing the phosphor raw material in the above 2) with the obtained dried product.

In any of the methods i), ii), and 1ii), conventional mixers such as various mixers, V-type blenders, ball mills, and rod mills are used for mixing.

Next, the obtained phosphor raw material mixture is filled into a heat-resistant container such as a stone pod port, an alumina crucible, or a stone pod crucible, and fired in an electric furnace. The firing temperature is 4
A range of 00 to 1300°C is appropriate, preferably 50°C.
The range is from 0 to t o o'c. From the viewpoint of luminance, etc., it is particularly preferable to perform the firing at a temperature lower than the melting point of the phosphor (approximately 875° 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 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 a carbon 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 3) above, but in this case, the trivalent eurobilam is reduced to divalent europium in the firing process.

Note that a method may be used in which the phosphor raw material mixture is once fired under the above firing conditions, and then the fired product is left to cool, then pulverized, and then re-fired (secondary firing). Re-firing is carried out under a neutral atmosphere or a weakly reducing atmosphere at a temperature of 400 to 80%.
The firing is carried out at a firing temperature of 0.000C 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 powdered 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.

Composition formula (I); M”X2*aM”X’2*bSnX”2:xEu2+
...(I) (Tatashi, M", X, X', X", a, b and X
The definition of is the same as above) The phosphor of the present invention manufactured according to the above-mentioned manufacturing method, after being irradiated with radiation such as
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).
9 nm), and emits fluorescence (stimulated luminescence) at
"X2.aM"X"2: Shows a stimulated emission spectrum and a stimulated excitation spectrum that are almost the same as those of the Eu2+ phosphor.

The phosphor of the present invention can be used particularly as a phosphor for a radiation image conversion panel 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 is extremely useful.

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

However, each of these aspects does not limit the invention.

[Example 1] Aqueous solution of barium bromide (BaBr2) (+, 55X10
-'mol/g) 192, 7 g, aqueous solution of barium chloride (BaCuz) (I, 18X10''mol/
g) 253.

5g, and an aqueous solution of europium bromide (EuBr3) (2,841X 10-'mol/ml) 2,11
ml was mixed. 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, 10 g of the obtained phosphor raw material mixture and tin fluoride (S
After thoroughly mixing 0.6 mg of nF2), it was filled into an alumina crucible, and the mixture was placed in a high-temperature electric furnace for firing.

Firing was carried out at 85% in a carbon dioxide atmosphere containing -carbon oxide.
The test was carried out at a temperature of 0° C. for 1.5 hours. After the firing was completed, the fired product was taken out of the furnace and cooled. In this way, the divalent europium-activated composite halide phosphor (
B acu2 * B aBr2 *Q, 0O01S
nF2:0.001Eu'') was obtained.

[Example 2] Divalent europium-activated composite halide phosphor (BaClz・BaBr2 ・0.00005
S n F 2 :0.001E u2+) was obtained.

[Example 3] Divalent europium-activated composite halide phosphor (Ba0 Sentence 2・BaB r 2・0.001 S
n F 2 :0.0OIE u”) was obtained.

[Comparative Example 1] In Example 1, divalent europium-activated barium chloride bromide phosphor (BaCu・BaBr2: 0.001E
u2+) 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.

FIG. 1 shows BaCl2*BaBr2-bSnF2:
It is a graph showing the relationship between the content of tin fluoride (b value) and stimulated luminance in a 0.0OIE u 2+ phosphor.

As is clear from FIG. 1, the BaCu2*B of the present invention
a B r 2 fist b S n F 2 :O,0OI
The E u 2+ phosphor exhibits enhanced stimulated luminance when the b value is in the range of o<b≦10−3. In particular, a phosphor with a b value in the range of 10-5≦b≦5×10-' exhibits high-intensity stimulated luminescence.

[Example 4] In Example 1, tin chloride (Sn0
A divalent europium-activated composite halide phosphor (BaCu2/B
aBr2eO,QOOISnCl2:0.001E
u2+) was obtained.

[Example 5] In Example 1, tin bromide (SnB) was used instead of tin fluoride.
A divalent europium-activated composite halide phosphor (BaCu2'BaB
r 2 ”O,0OO1S nB r 2 :0.0
OIEu”) was obtained.

Next, each phosphor obtained in Examples 4 and 5 was applied with a tube voltage of 8
After irradiating with 0KVp X-rays, semiconductor laser light (7
The stimulated luminescence brightness was measured when excited at 80 nm).

The results are shown in Table 1.

Note that Table 1 also lists the results of Example 1 and Comparative Example 1.

Table 1 Relative stimulated luminance Example 1 121 Example 4 103 Example 5 103 Comparative example 1 100

[Brief explanation of drawings]

FIG. 1 shows BaCJlj2・EaBr, which is a specific example of the divalent europium-activated composite halide phosphor of the present invention.
2 ・bSnF2:0. (This is a graph showing the relationship between the b value and the stimulated luminance in a loIEu"fi light body. Patent applicant Fuji Photo Film Co., Ltd. Agent Patent attorney Yasuo Yanagawa b 1 December 14, 1981 [I

Claims (1)

[Claims] 1. Composition formula (I): M^IIX_2・a_M^IIX'2・b_SnX"_2:
x_Eu^2^+...(I) (However, M^II is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr and Ca; X and x' are both CL, Br and At least one halogen selected from the group consisting of I,
and X≠X';X'' is F, CL, Br and I
at least one halogen selected from the group consisting of; 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^-^3, X
is a numerical value in the range of 0<X≦0.2) A divalent europium-activated composite halide phosphor represented by: 2. b in compositional formula (I) is 10^-^5≦b≦5
The phosphor according to claim 1, wherein the phosphor has a numerical value in the range of x10^-^4. 3. The phosphor according to claim 1, wherein x'' in the compositional formula (I) is F. 4. a in the compositional formula (I) is 0.25≦a≦6.0
The phosphor according to claim 1, wherein the phosphor has a numerical value in the range of . 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 respectively,
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^-^1. 8. Stoichiometric composition formula (II): M^IIX_2・a_M^IIX'_2・b_SnX”_
2:x_Eu...(II) (However, M^II is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; X and x' are both Cl, Br, and I. at least one type of halogen selected from the group consisting of, and X≠X': X'' is at least one type of halogen selected from the group consisting of F, CL, Br and I;
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^-^3, and x is 0
<X≦0.2) After adjusting the phosphor raw material mixture to have a relative ratio corresponding to Compositional formula (I) characterized by firing at a temperature of: M^IIX_2・aM^IIX'_2・bSnX”_2
:xEu^2^+...(I) (However, M^II, X, x', x", a, b and X
(the definition is the same as above) A method for producing a divalent europium activated composite halide phosphor represented by 9. b in compositional formula (II) is 10^-^5≦b≦5
9. The method for producing a phosphor according to claim 8, wherein the numerical value is in the range of x10^-^4. 10. A method for producing a phosphor according to claim 8, characterized in that x'' in compositional formula (II) is F. 11. a in compositional formula (II) is 0.25≦a≦6.
9. The method for producing a phosphor according to claim 8, wherein the numerical value is in the range of 0. 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^-^1. 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 .