JP4349379B2 - Method for producing rare earth activated alkaline earth metal fluoroiodide stimulable phosphor - Google Patents

Description

  The present invention relates to a method for producing a rare earth activated alkaline earth metal fluoroiodide stimulable phosphor.

  As a method for replacing the conventional radiographic method, a radiation image recording / reproducing method using a stimulable phosphor as described in, for example, JP-A No. 55-12145 is known. This method uses a radiation image conversion panel (accumulative phosphor sheet) containing a stimulable phosphor, and the radiation transmitted through the subject or emitted from the subject is stimulated by the panel. The radiation energy stored in the stimulable phosphor is absorbed by the body, and then the stimulable phosphor is excited in time series with electromagnetic waves (excitation light) such as visible light and infrared rays. It emits as fluorescence (stimulated luminescence light), photoelectrically reads this fluorescence to obtain an electrical signal, and then reproduces a radiographic image of a subject or subject as a visible image based on the obtained electrical signal. . The panel which has been read is prepared for the next photographing after the remaining image is erased. That is, the radiation image conversion panel can be used repeatedly.

  According to the above radiographic image recording / reproducing method, a radiographic image with abundant information amount can be obtained with a much smaller exposure dose than in the case of the radiographic method using a combination of a conventional radiographic film and an intensifying screen. There is an advantage that you can. Furthermore, the conventional radiographic method consumes a radiographic film for each radiographing, whereas in this radiographic image conversion method, the radiographic image conversion panel is used repeatedly, so that also from the viewpoint of resource protection and economic efficiency. It is advantageous.

  Stimulable phosphors are phosphors that exhibit stimulating luminescence when irradiated with excitation light after being irradiated with radiation, but in practice, wavelengths of 300 to 500 nm are obtained by excitation light having a wavelength in the range of 400 to 900 nm. Phosphors that exhibit a range of stimulated luminescence are generally utilized.

  The radiation image conversion panel used in the radiation image recording / reproducing method includes, as a basic structure, a support and a phosphor layer (stimulable phosphor layer) provided on the surface thereof. However, a support is not necessarily required when the phosphor layer is self-supporting. The photostimulable phosphor layer is usually composed of a photostimulable phosphor and a binder containing and supporting the phosphor in a dispersed state. However, the photostimulable phosphor layer is known to be composed only of aggregates of photostimulable phosphors without containing a binder formed by vapor deposition or sintering.

  There is also known a radiation image conversion panel having a stimulable phosphor layer impregnated with a polymer substance in the gaps between aggregates of stimulable phosphors. In any of these phosphor layers, the photostimulable phosphor has the property of exhibiting photostimulated luminescence when irradiated with excitation light after absorbing radiation such as X-rays. Radiation emitted from the specimen is absorbed by the stimulable phosphor layer of the radiation image conversion panel in proportion to the radiation dose, and a radiation image of the subject or subject is formed on the panel as a stored image of radiation energy. . This accumulated image can be emitted as stimulated emission light by irradiating the excitation light, and the stored image of radiation energy is imaged by photoelectrically reading this stimulated emission light and converting it into an electrical signal. It becomes possible to do.

  In addition, the surface of the photostimulable phosphor layer (the surface on the side not facing the support) is usually provided with a protective film made of a polymer film or an inorganic vapor deposition film. Protects against natural alteration or physical impact.

Examples of stimulable phosphors conventionally used in radiation image conversion panels are (1) (Ba _1-X , M 2 ⁺ X) FX: yA described in JP-A No. 55-12145. (Where M ²⁺ is at least one of Mg, Ca, Sr, Zn and Cd, X is at least one of Cl, Br, and I, A is Eu, Tb, Ce, Tm, Dy, Pr, At least one of Ho, Nd, Yb, and Er, and x is 0 ≦ x ≦ 0.6 and y is 0 ≦ y ≦ 0.2. Alkaline earth metal fluoride halide phosphors;

The phosphor may contain the following additives:
As described in JP 56-74175 ^{discloses, X ', BeX'',} M 3 X''' 3 ( however, X ', X'', and X''' are each Cl, Br and I At least one of them, and M ³ is a trivalent metal);
_BeO as described in JP 55-160078 _{discloses, BgO, CaO, SrO, BaO} , ZnO, Al 2 O 3, Y 2 O 3, La 2 O 3, In 2 O 3, SiO 2, TiO 2 _{, ZrO 2, GeO 2, SnO} 2, Nb 2 O 5, metal oxide such as _Ta 2 _{O 5} and ThO _2;

Zr, Sc described in JP-A-56-116777;
B described in JP-A-57-23673;
As and Si described in JP-A-57-23675;
M · L described in JP-A-58-206678 (where M is at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs; L is Sc, Y At least one trivalent metal selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In, and Tl is there);

A calcined product of a tetrafluoroboric acid compound described in JP-A-59-27980;
A calcined product of a monovalent or divalent metal salt of hexafluorosilicic acid, hexafluorotitanic acid and hexafluorozirconic acid described in JP-A-59-27289; JP-A-59-56479 NaX ′ as described (where X ′ is at least one of Cl, Br and I);
Transition metals such as V, Cr, Mn, Fe, Co and Ni described in JP-A-59-56480;

JP 59-75200 JP ^M 1 ^X that are described in ^{', M' 2 X ''} , M 3 X ''', A ( however, ^{M 1} is Li, Na, K, Rb, and the Cs And M ′ ² is at least one divalent metal selected from the group consisting of Be and Mg; and M ³ is from the group consisting of Al, Ga, In, and Tl. At least one trivalent metal selected; A is a metal oxide; X ′, X ″ and X ″ ′ are at least one halogen selected from the group consisting of F, Cl, Br and I, respectively. is there);

M ¹ X ′ described in JP-A-60-101173 (where M ¹ is at least one alkali metal selected from the group consisting of Rb and Cs; X ′ is F, Cl, Br and I) At least one halogen selected from the group consisting of:
JP 61-23679 No. ^M 2 are described in JP ^{_{'X' 2 · M 2 '}} X''2 ( however, ^{M 2'} is at least one alkaline earth selected from the group consisting of Ba, Sr and Ca X ′ and X ′ are each at least one halogen selected from the group consisting of Cl, Br and I, and X ′ ≠ X ″); and

LnX ″ ₃ described in Japanese Patent Application No. 60-106752 (where Ln is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm And at least one rare earth element selected from the group consisting of Y, Yb and Lu; X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I);
(2) M ² X ₂ · aM ² ′ ₂ : xEu ²⁺ described in JP-A-60-84381 (where M ² is at least one alkaline earth selected from the group consisting of Ba, Sr and Ca) X and X ′ are at least one halogen selected from the group consisting of Cl, Br and I, and X ≠ X ′; and a is 0.1 ≦ a ≦ 0.0, x is 0 <x ≦ 0.2) divalent europium activated alkaline earth metal halide phosphor represented by the composition formula:

The phosphor may contain the following additives:
M ¹ X ″ described in JP-A-60-166379 (where M ¹ is at least one alkali metal selected from the group consisting of Rb and Cs; X ″ is F, Cl, Br) And at least one halogen selected from the group consisting of I and I);
JP 60-221483 Patent KX that publication is described in ^{_{'', MgX '''2}} , M 3 X''''3 ( however, ^{M 3} is Sc, Y, La, from the group consisting of Gd and Lu At least one trivalent metal selected; X ″, X ″ ′ and X ″ ′ ′ are all at least one halogen selected from the group consisting of F, Cl, Br and I);

B described in JP-A-60-228592;
Oxides such as SiO ₂ and P ₂ O ₅ described in JP-A-60-228593;
LiX ″, NaX ″ described in JP-A No. 61-120882 (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I);
SiO described in JP-A-61-120883;
SnX ″ ₂ described in JP-A-61-120885 (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I);

CsX ″, SnX ″ ″ ₂ described in JP-A-61-235486 (where X ″ and X ″ ′ are at least one selected from the group consisting of F, Cl, Br and I, respectively) And CsX ″, Ln ³⁺ described in JP-A No. 61-235487 (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br, and I) Ln is at least one rare earth element selected from the group consisting of Sc, Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu);

(3) LnOX: xA described in JP-A-55-12144 (where Ln is at least one of La, Y, Gd, and Lu; X is at least one of Cl, Br, and I) A is at least one of Ce and Tb; and x is a rare earth element-activated rare earth oxyhalide phosphor represented by a composition formula: 0 <x <0.1;

(4) M ³ OX: xCe described in JP-A-58-69281 (where M ³ is Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and At least one metal oxide selected from the group consisting of Bi; X is at least one of Cl, Br, and I; x is 0 <x <0.1) Activated trivalent metal oxyhalide phosphor;

(5) M ¹ X: xBi described in Japanese Patent Application No. 60-70484 (where M ¹ is at least one alkali metal selected from the group consisting of Rb and Cs; X is Cl, Br A bismuth-activated alkali metal halide phosphor represented by a composition formula: at least one halogen selected from the group consisting of and I; and x is a numerical value in the range of 0 <x ≦ 0.2.

(6) M ² ₅ (PO ₄ ) ₃ x: xEu ²⁺ described in JP-A-60-141784 (where M ² is at least one alkaline earth selected from the group consisting of Ca, Sr and Ba) X is at least one halogen selected from the group consisting of F, Cl, Br and I; and x is a numerical value in the range of 0 <x ≦ 0.2. Europium activated alkaline earth metal halophosphate phosphor;

(7) M ² ₂ BO ₃ X: xEu ²⁺ described in JP-A-60-157099 (wherein M ² is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba) Yes; X is at least one halogen selected from the group consisting of Cl, Br and I; x is a numerical value in the range of 0 <x ≦ 0.2) and a divalent europium-activated alkali Earth metal haloborate phosphors;

(8) M ² ₂ PO ₄ X: xEu ²⁺ described in JP-A-60-157100 (where M ² is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba) Yes; X is at least one halogen selected from the group consisting of Cl, Br and I; x is a numerical value in the range of 0 <x ≦ 0.2) and a divalent europium-activated alkali Earth metal halophosphate phosphors;

(9) M ² HX: xEu ²⁺ described in JP-A-60-217354 (wherein M ² is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba; X Is at least one halogen selected from the group consisting of Cl, Br and I; x is a numerical value in the range of 0 <x ≦ 0.2) and a divalent europium activated alkaline earth metal Hydride halide phosphors;

(10) LnX ₃ · aLn′X ′ ₃ : xCe ³⁺ described in JP-A No. 61-21173 (where Ln and Ln ′ are at least selected from the group consisting of Y, La, Gd and Lu, respectively) X and X ′ are each at least one halogen selected from the group consisting of F, Cl, Br and I, and X ≠ X ′; and a is 0.1 <a A numerical value in the range of ≦ 10.0, and x is a numerical value in the range of 0 <x ≦ 0.2).

(11) LnX ₃ · aM ¹ X ′: xCe ³⁺ described in JP-A-61-21182 (where Ln and Ln ′ are at least one selected from the group consisting of Y, La, Gd and Lu, respectively) M1 is at least one alkali metal selected from the group consisting of Li, Na, K, Cs and Rb; X and X ′ are at least one selected from the group consisting of Cl, Br and I, respectively 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). Fluoride phosphors;

(12) LnPO ₄ · aLnX ₃ : xCe ³⁺ described in JP-A No. 61-40390 (where Ln is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; X is at least one 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, and x is 0 <x ≦ 0.2. A cerium-activated rare earth halophosphate phosphor represented by a composition formula:

(13) CsX: aRbX ′: xEu ²⁺ described in Japanese Patent Application No. 60-78151 (where X and X ′ are at least one halogen selected from the group consisting of Cl, Br and I, respectively) 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). The divalent europium-activated cesium halide and rubidium A phosphor; and

(14) M ² X ₂ · aM ¹ X ′: xEu ²⁺ described in Japanese Patent Application No. 60-78153 (where M ² is at least one alkali selected from the group consisting of Ba, Sr and Ca) M ¹ is at least one alkali metal selected from the group consisting of Li, Rb and Cs; and X and X ′ are at least one halogen selected from the group consisting of Cl, Br and I, respectively. Yes, and a is a numerical value in the range of 0.1 ≦ a ≦ 20.0, and x is a numerical value in the range of 0 <x ≦ 0.2). Fluoride phosphor;
(15) In addition to the above, those described in Patent Document 1 and Patent Document 2 below are also known.

  Among the photostimulable phosphors described above, a divalent europium activated alkaline earth metal fluoride halide phosphor containing iodine, and a divalent europium activated alkaline earth metal halide phosphor containing iodine. The rare earth element activated rare earth oxyhalide phosphors containing iodine and the bismuth activated alkali metal halide phosphors containing iodine show stimulated luminescence with high brightness.

These conventionally known methods for producing photostimulable phosphors are called solid-phase methods or sintering methods, but pulverization after firing is essential, and particle shapes that affect sensitivity and image performance are essential. There is a problem that control is difficult.
JP-A-7-233369 JP 55-160078

  The present invention relates to a method for producing a rare earth activated alkaline earth metal fluoroiodide-based stimulable phosphor, and in particular, a rare earth activated alkali having excellent sensitivity, sharpness, and image characteristics represented by graininess. An object of the present invention is to provide a method for producing an earth metal fluoroiodide stimulable phosphor.

The present invention for solving the above problems has the following configuration.
1. Formula ^{_{(1) Ba 1-x M}} 2 xFI: yM 1, zLn
M ² : at least one alkaline earth metal selected from the group consisting of Sr and Ca M ¹ : at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs Ln: Ce, Pr, Sm, At least one rare earth element x, y and z selected from the group consisting of Eu, Gd, Tb, Tm and Yb is 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.05, and 0 <z ≦ 0. 2
A rare earth activated alkaline earth metal fluoroiodide photostimulable phosphor having the following steps for producing a rare earth activated alkaline earth metal fluoroiodide photostimulable phosphor represented by the formula: .

A step of preparing an aqueous solution containing a halide of M ² when x in the general formula (1) is not 0 and further containing a halide of M ¹ when y is not 0 and having a BaI ₂ concentration of 2N or more. ;
While maintaining the above aqueous solution at a temperature of 50 ° C. or higher, an aqueous solution of an inorganic fluoride having a concentration of 5 N or higher and an aqueous solution of a halide of Ln are added to the rare earth activated alkaline earth metal fluoride iodide. Obtaining a precipitate of crystalline phosphor precursor crystals;
Separating the precursor crystal precipitate from an aqueous solution;
And the process of baking the deposit of the separated precursor crystal | crystallization.

2. 2. The method for producing a rare earth activated alkaline earth metal fluoroiodide stimulable phosphor according to the above 1, wherein the inorganic fluoride is ammonium fluoride or an alkali metal fluoride.

3. 3. The rare earth activated alkaline earth metal fluoroiodide stimulable phosphor according to 1 or 2 above, wherein in the step of firing the precipitate, firing is performed while avoiding sintering of the precipitate. Production method.

The following can be mentioned as reference examples of the present invention.
(1) In formula ^{_{(1) Ba 1-x M}} 2 xFI: yM 1, zLn
M ² : at least one alkaline earth metal selected from the group consisting of Sr and Ca M ¹ : at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs Ln: Ce, Pr, Sm, At least one rare earth element x, y and z selected from the group consisting of Eu, Gd, Tb, Tm and Yb is 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.05, and 0 <z ≦ 0. 2
A rare earth activated alkaline earth metal fluoroiodide photostimulable phosphor having the following steps for producing a rare earth activated alkaline earth metal fluoroiodide photostimulable phosphor represented by the formula: .

BaI ₂ and a halide of Ln, and if x in the general formula (1) is not 0, further include a halide of M ² , and if y is not 0, further include a halide of M ¹ Preparing an aqueous solution having a BaI ₂ concentration of 2N or more;
While maintaining the above aqueous solution at a temperature of 50 ° C. or higher, an inorganic fluoride aqueous solution having a concentration of 5N or more is added to the rare earth activated alkaline earth metal fluoride iodide photostimulable phosphor precursor crystal. Obtaining a precipitate;
Separating the precursor crystal precipitate from an aqueous solution;
And the process of baking the deposit of the separated precursor crystal | crystallization.

(2) Rare earth activated alkaline earth metal fluoroiodide having the following steps for producing the rare earth activated alkaline earth metal fluoride iodide photostimulable phosphor represented by the general formula (1) A method for producing a photostimulable phosphor.

An ammonium halide and a halide of Ln, and if x in the general formula (1) is not 0, further a halide of M ² , and if y is not 0, further a halide of M ¹ A step of preparing an aqueous solution containing 3N or higher ammonium halide;
While maintaining the above aqueous solution at a temperature of 50 ° C. or higher, an aqueous solution of an inorganic fluoride having a concentration of 5N or higher and an aqueous solution of BaI 2 are added to the rare earth activated alkaline earth metal fluoroiodide-based stimulable fluorescence. Obtaining a precipitate of precursor precursor crystals;
Separating the precursor crystal precipitate from an aqueous solution;
And the process of baking the deposit of the separated precursor crystal | crystallization.

(3) obtaining the precipitate step, while the ratio of the Ba fluorine and an aqueous solution of the BaI ₂ of an aqueous solution of the inorganic fluoride constant, the addition of an aqueous solution of inorganic fluoride aqueous solution and BaI ₂ The method for producing a rare earth activated alkaline earth metal fluoroiodide stimulable phosphor according to (2) above,

(4) Rare earth activated alkaline earth metal fluoroiodide having the following steps for producing the rare earth activated alkaline earth metal fluoroiodide stimulable phosphor represented by the general formula (1) A method for producing a photostimulable phosphor.

When x in the general formula (1) is not 0, an aqueous solution containing an M ² halide, and when y is not 0, further containing an M ¹ halide and having an ammonium halide concentration of 3N or more is prepared. Process;
While maintaining the above aqueous solution at a temperature of 50 ° C. or higher, an aqueous solution of an inorganic fluoride having a concentration of 5N or higher, an aqueous solution of BaI ₂ , and an aqueous solution of a halide of Ln are added to the rare earth activated alkaline earth metal. Obtaining a precipitate of fluoroiodide-based stimulable phosphor precursor crystals;
Separating the precursor crystal precipitate from an aqueous solution;
And the process of baking the deposit of the separated precursor crystal | crystallization.

(5) In the step of obtaining the precipitate, the ratio of the inorganic fluoride aqueous solution, the BaI ₂ aqueous solution Ba, and the Ln halide aqueous solution Ln is kept constant while the inorganic fluoride aqueous solution The method for producing a rare earth activated alkaline earth metal fluoroiodide stimulable phosphor according to (4), wherein an aqueous solution and an aqueous solution of BaI ₂ are added.

(6) Rare earth activated alkaline earth metal fluoroiodide having the following steps for producing the rare earth activated alkaline earth metal fluoroiodide stimulable phosphor represented by the general formula (1) Method for producing a fluoride-based stimulable phosphor.

An ammonium halide, and when x in the general formula (1) is not 0, further contains a halide of M ² , and when y is not 0, further contains a halide of M ¹ , Preparing an aqueous solution of 3N or more;
Maintaining an aqueous solution at a temperature of 50 ° C. or higher while adding an inorganic fluoride aqueous solution having a concentration of 5N or higher and an aqueous solution of BaI ₂ to obtain a precipitate of an alkaline earth metal fluoroiodide;
Separating the precipitate from the aqueous solution;
And the process of baking after mixing the isolate | separated precipitate and the halide of Ln.

(7) Rare earth activated alkaline earth metal fluorination produced by the method for producing a rare earth activated alkaline earth metal fluoroiodide stimulable phosphor according to any one of (1) to (6) A radiation image conversion panel comprising a phosphor layer containing an iodide photostimulable phosphor.

  According to the present invention, the image characteristics represented by sensitivity, sharpness, and graininess are all excellent.

Details of the method for producing the photostimulable phosphor will be described below.
(Preparation of precursor crystal precipitates and stimulable phosphors)
The production methods 1 and 2 of the precursor crystal precipitate will be described.

Production method 1:
BaI ₂ and, if necessary, further M ² halide, and further M ¹ halide are placed in an aqueous medium and mixed well and dissolved to prepare an aqueous solution in which they are dissolved. However, the amount ratio between the BaI ₂ concentration and the aqueous solvent is adjusted so that the BaI ₂ concentration is 2N or higher, preferably 2.7N or higher. At this time, if desired, a small amount of acid, ammonia, alcohol, water-soluble polymer, water-insoluble metal oxide fine particle powder or the like may be added.

  This aqueous solution is maintained at 50 ° C. or higher, preferably 80 ° C. or higher. Next, an aqueous solution of an inorganic fluoride (ammonium fluoride or alkali metal fluoride) having a concentration of 5N or more, preferably 8N or more, is added to the aqueous solution stirred at the temperature to add a rare earth activated alkaline earth metal fluoride iodide. A precipitate of a fluoride-based stimulable phosphor precursor crystal is obtained. Addition of an aqueous solution of inorganic fluoride (ammonium fluoride, alkali metal fluoride, etc.) is performed using a pipe with a pump. It may be present at the same time or after the inorganic fluoride. Further, a precursor crystal precipitate before firing and a halide of Ln may be mixed.

Production method 2 (reference example):
If the mother liquor contains ammonium halide, x in the general formula (1) is not 0, it further contains a halide of M ² , and if y is not 0, it further contains a halide of M ¹ , which dissolves After that, an aqueous solution having an ammonium halide concentration of 3N or higher, preferably 4N or higher is prepared.

The aqueous solution is maintained at a temperature of 50 ° C or higher, preferably 80 ° C or higher. Next, an aqueous solution of inorganic fluoride (ammonium fluoride or alkali metal fluoride) and an aqueous solution of BaI ₂ having a concentration of 5N or more, preferably 8N or more, and an aqueous solution of BaI ₂ are added to the aqueous solution stirred at the temperature. The precipitate of the rare earth activated alkaline earth metal fluoroiodide stimulable phosphor precursor crystal is obtained by adding continuously or intermittently while maintaining a constant ratio. Crystals having a uniform elemental composition in the depth direction are obtained by making the ratio of the addition amounts of fluorine and Ba or fluorine, Ba and Ln constant. By firing the crystal, a phosphor with little variation in performance is obtained.

Note that timing of addition of the halide of Ln regardless, added at the start may be a previously into the mother liquor or the like, simultaneously with an aqueous solution of an inorganic fluoride and BaI ₂ or may be added later. Further, a precursor crystal precipitate before firing and a halide of Ln may be mixed.

  Next, the phosphor precursor crystals are separated from the solution by filtration, centrifugation, etc., sufficiently washed with methanol or the like, and dried.

  In order to achieve a uniform reduction reaction of the activator, it is preferable to carry out while avoiding sintering. In order to avoid sintering during firing, a sintering inhibitor such as alumina fine powder or silica fine powder is added to and mixed with the dried phosphor precursor crystal, and the fine powder of the sintering inhibitor is uniformly applied to the crystal surface. Adhere. It should be noted that the addition of the sintering inhibitor can be omitted by selecting the firing conditions.

  Next, the phosphor precursor crystal is filled in a heat-resistant container such as a quartz port, an alumina crucible, or a quartz crucible, and is fired in a core of an electric furnace. The range of 400-1300 degreeC is suitable for a calcination temperature, and the range of 500-1000 degreeC is preferable. The firing time varies depending on the filling amount of the phosphor raw material mixture, the firing temperature, the temperature of taking out from the furnace, and the like, but generally 0.5 to 12 hours is appropriate.

  As the firing atmosphere, a neutral atmosphere such as a nitrogen gas atmosphere or an argon gas atmosphere, a weakly reducing atmosphere such as a nitrogen gas atmosphere containing a small amount of hydrogen gas, a carbon dioxide atmosphere containing carbon monoxide, or a small amount of oxygen introduced The atmosphere is used.

The desired rare earth activated alkaline earth metal fluoride halide photostimulable phosphor is obtained by the above-mentioned firing. The obtained phosphor is, for example,
BaFI: 0.005 Eu,
BaFI: 0.001Eu,
Ba _0.97 Sr _0.03 FI: 0.0001K, 0.013Eu,
BaFI: 0.0002K, 0.005Eu,
Ba _0.998 Ca _0.002 FI: 0.005 Eu,
BaFI: 0.005 Ce,
Ba _0.99 Ca _0.01 FI: 0.0002K, 0.005Eu,
BaFI: 0.0001Ce, 0.0001Tb
It is.

  The particles (crystals) according to the present invention are preferably monodispersed, and the average particle size distribution (%) is preferably 20% or less, particularly preferably 15% or less.

(Panel creation, phosphor layer, coating process, support, protective layer)
As the support used in the radiation image conversion panel of the present invention, various polymer materials, glass, metal and the like are used. In particular, a material that can be processed into a flexible sheet or web for handling as an information recording material is suitable. From this point, a cellulose acetate film, a polyester film, a polyethylene terephthalate film, a polyamide film, a polyimide film, a triacetate film, A plastic film such as a polycarbonate film, a metal sheet of aluminum, iron, copper, chromium, or a metal sheet having a coating layer of the metal oxide is preferable.

  The layer thickness of these supports varies depending on the material of the support used, but is generally 20 μm to 1000 μm, and more preferably 20 μm to 500 μm from the viewpoint of handling.

  The surface of these supports may be a smooth surface, or may be a mat surface for the purpose of improving the adhesion to the photostimulable phosphor layer.

  Further, these supports may be provided with an undercoat layer on the surface on which the photostimulable phosphor layer is provided for the purpose of improving the adhesion to the photostimulable phosphor layer.

  Examples of binders used in the stimulable phosphor layer in the present invention include proteins such as gelatin, polysaccharides such as dextran, or natural high molecular substances such as gum arabic; and polyvinyl butyral, polyvinyl acetate, Represented by synthetic polymer materials such as nitrocellulose, ethyl cellulose, vinylidene chloride / vinyl chloride copolymer, polyalkyl (meth) acrylate, vinyl chloride / vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, linear polyester, etc. Can be mentioned.

  Particularly preferred among such binders are nitrocellulose, linear polyesters, polyalkyl (meth) acrylates, mixtures of nitrocellulose and linear polyesters, mixtures of nitrocellulose and polyalkyl (meth) acrylates and It is a mixture of polyurethane and polyvinyl butyral. Note that these binders may be crosslinked by a crosslinking agent. The photostimulable phosphor layer can be formed on the undercoat layer by the following method, for example.

  First, an iodine-containing stimulable phosphor, a compound such as a phosphite for preventing yellowing, and a binder are added to a suitable solvent, and these are mixed well to add phosphor particles and A coating solution in which the compound particles are uniformly dispersed is prepared.

  As the binder used in the present invention, the film-forming binder is used. In general, the binder is used in the range of 0.01 to 1 part by weight with respect to 1 part by weight of the stimulable phosphor. The However, in terms of sensitivity and sharpness of the obtained radiation image conversion panel, it is preferable that the amount of the binder is small, and a range of 0.03 to 0.2 parts by weight is more preferable in view of easy application.

  The mixing ratio of the binder to the stimulable phosphor in the coating solution (however, if the binder is an epoxy group-containing compound, it is equal to the ratio of the compound to the phosphor) is the intended radiation image conversion. Although it varies depending on the characteristics of the panel, the type of phosphor, the amount of the epoxy group-containing compound added, etc., generally examples of solvents for preparing the bonding coating solution include methanol, enotal, 1-propanol, 2-propanol, and n-butanol. Lower alcohols such as methylene chloride, ethylene chloride and other chlorine atom-containing hydrocarbons; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate and butyl acetate; Ethylene glycol ethyl ether, ethylene glycol monomethyl ether Ethers such as ether: toluene; and it can include mixtures thereof.

  Examples of the solvent used for the preparation of the stimulable phosphor layer coating solution include lower alcohols such as methanol, ethanol, isopropanol and n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, ketones such as cyclohexanone, methyl acetate, Esters of lower fatty acids and lower alcohols such as ethyl acetate and n-butyl acetate, ethers such as dioxane, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, aromatic compounds such as triol and xylol, methylene chloride, ethylene chloride, etc. Examples thereof include halogenated hydrocarbons and mixtures thereof.

  The coating solution has a dispersing agent for improving the dispersibility of the phosphor in the coating solution, and a binding force between the binder and the phosphor in the stimulable phosphor layer after formation. Various additives such as a plasticizer for improvement may be mixed. Examples of the dispersant used for such purpose include phthalic acid, stearic acid, caproic acid, lipophilic surfactant and the like. Examples of plasticizers include phosphate esters such as triphenyl phosphate, tricresyl phosphate and diphenyl phosphate; phthalate esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, etc. And a polyester of triethylene glycol and adipic acid, a polyester of polyethylene glycol and an aliphatic dibasic acid such as a polyester of diethylene glycol and succinic acid, and the like.

  Dispersants such as stearic acid, phthalic acid, caproic acid, and lipophilic surfactants for the purpose of improving the dispersibility of stimulable phosphor layer phosphor particles in the coating solution for stimulable phosphor layer May be mixed. Moreover, you may add the plasticizer with respect to a binder as needed. Examples of the plasticizer include phthalic acid esters such as diethyl phthalate and dibutyl phthalate, aliphatic dibasic acid esters such as diisodecyl succinate and dioctyl adipate, ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate And glycolic acid esters.

  The coating liquid prepared as described above is then uniformly applied to the surface of the undercoat layer to form a coating film of the coating liquid. This coating operation can be performed by using a normal coating means, for example, a doctor blade, a roll coater, a knife coater or the like.

  Next, the formed coating film is dried by gradually heating to complete the formation of the photostimulable phosphor layer on the undercoat layer. The thickness of the photostimulable phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of stimulable phosphor, the mixing ratio of the binder and the phosphor, and is usually 20 μm to 1000 μm. . However, this layer thickness is preferably 20 to 500 μm.

  The stimulable phosphor layer coating solution is prepared using a dispersing device such as a ball mill, a sand mill, an attritor, a three-roll mill, a high-speed impeller disperser, a Kady mill, and an ultrasonic disperser. The prepared coating solution is applied on a support using a coating solution such as a doctor blade, a roll coater, or a knife coater, and dried to form a photostimulable phosphor layer. The stimulable phosphor layer and the support may be adhered after the coating solution is applied on the protective layer and dried.

  The film thickness of the stimulable phosphor layer of the radiation image conversion panel of the present invention is the characteristics of the intended radiation image conversion panel, the type of stimulable phosphor, the mixing ratio of the binder and the stimulable phosphor, etc. Depending on the case, it is preferably selected from the range of 20 μm to 1000 μm, more preferably selected from the range of 20 μm to 500 μm.

The following examples illustrate the invention.
Example 1
In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, 2500 ml of BaI ₂ aqueous solution (3.5N) and 80 ml of EuI ₃ aqueous solution (0.1N) were placed in a reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 250 ml of NH ₄ F aqueous solution (8N) was injected into the reaction mother liquor using a roller pump to form a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. In order to prevent changes in particle shape due to sintering during firing, and changes in particle size distribution due to inter-particle fusion, 1% by weight of ultrafine powder of alumina is added and stirred thoroughly with a mixer. An ultrafine powder of alumina was uniformly attached. This was filled in a quartz boat and baked at 850 ° C. for 2 hours in a hydrogen gas atmosphere using a tube furnace to obtain europium-activated barium fluoroiodide phosphor particles.

  Next, an example of manufacturing a radiation image conversion panel is shown. As the phosphor layer forming material, 427 g of the europium-activated barium fluoroiodide phosphor obtained above, 15.8 g of polyurethane resin (Desmolac 4125, manufactured by Sumitomo Bayer Urethane Co., Ltd.), 2.0 g of bisphenol A type epoxy resin, methyl ethyl ketone -It added to the toluene (1: 1) mixed solvent, and it disperse | distributed with the propeller mixer, and prepared the coating liquid with a viscosity of 25-30PS. This coating solution was applied onto an undercoated polyethylene terephthalate film using a doctor blade and then dried at 100 ° C. for 15 minutes to form phosphor layers having various thicknesses.

  Next, as a protective film forming material, fluorine resin: fluoroolefin-vinyl ether copolymer (Lumiflon LF100, manufactured by Asahi Glass Co., Ltd.) 70 g, cross-linking agent: isocyanate (Desmodule Z4370, manufactured by Sumitomo Bayer Urethane Co., Ltd.) 25 g, bisphenol A type epoxy resin 5 g and 10 g of silicone resin fine powder (KMP-590, manufactured by Shin-Etsu Chemical Co., Ltd., particle size: 1 to 2 μm) were added to a toluene-isopropyl alcohol (1: 1) mixed solvent to prepare a coating solution. This coating solution is applied on the phosphor layer formed in advance as described above by using a doctor blade, and then heat-cured at 120 ° C. for 30 minutes to be thermally cured and dried to provide a protective layer having a thickness of 10 μm. A membrane was provided. By the above method, radiation image conversion panels having photostimulable phosphor layers with various thicknesses were obtained.

Reference example 1
NH4I solution (4.5 N) 2500 ml and EuI ₃ aqueous solution (0.1 N) 80 ml was placed in a reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. NH ₄ F aqueous solution (8N) 250 ml and BaI ₂ aqueous solution (3.5 N) 2500 ml were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to generate precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Example 2
2500 ml of an aqueous BaI ₂ solution (3.5 N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 250 ml of NH ₄ F aqueous solution (8N) and 80 ml of EuI ₃ aqueous solution (0.1N) were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to generate precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Reference example 2
2500 ml of aqueous NH ₄ I (4.5N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. Injecting 250 ml of NH ₄ F aqueous solution (8N), 2500 ml of BaI ₂ aqueous solution (3.5N) and 80 ml of EuI ₃ aqueous solution (0.1N) into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump, A precipitate was formed. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Example 3
2500 ml of an aqueous BaI ₂ solution (3.5 N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 250 ml of NH ₄ F aqueous solution (8N) was injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to generate precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was separated by filtration, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide crystals. After mixing the above crystal and 4.26 g of EuI ₃ , it was filled in a quartz boat and baked at 850 ° C. for 2 hours in a hydrogen gas atmosphere using a tube furnace, and activated with europium-activated barium fluoroiodide phosphor particles ( BaFI: 0.004Eu) was obtained. A panel was prepared by the method described in Example 1 using the above crystals.

Example 4
2500 ml BaI ₂ aqueous solution (3.5 N) and 125 ml EuBr ₃ aqueous solution (0.2 N) were placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 250 ml of NH ₄ F aqueous solution (8N) was injected into the reaction mother liquor using a roller pump to form a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was separated by filtration, washed with methanol, and then vacuum-dried to obtain europium-activated barium fluoroiodide (BaFI: 0.013Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Reference example 3
2500 ml of NH ₄ I aqueous solution (4.5N) and 125 ml of EuBr ₃ aqueous solution (0.2N) were placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. NH ₄ F aqueous solution (8N) 250 ml and BaI ₂ aqueous solution (3.5 N) 2500 ml were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to generate precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was separated by filtration, washed with methanol, and then vacuum-dried to obtain europium-activated barium fluoroiodide (BaFI: 0.013Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Example 5
2500 ml of an aqueous BaI ₂ solution (3.5 N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. NH ₄ F aqueous solution (8N) (250 ml) and EuBr ₃ aqueous solution (0.2N) (125 ml) were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to generate precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was separated by filtration, washed with methanol, and then vacuum-dried to obtain europium-activated barium fluoroiodide (BaFI: 0.013Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Reference example 4
2500 ml of aqueous NH ₄ I (4.5N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. NH ₄ F aqueous solution (8N) 250 ml, BaI ₂ aqueous solution (3.5 N) 2500 ml and EuBr ₃ aqueous solution (0.2 N) 125 ml were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump, A precipitate was formed. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was separated by filtration, washed with methanol, and then vacuum-dried to obtain europium-activated barium fluoroiodide (BaFI: 0.013Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Example 6
2500 ml of an aqueous BaI ₂ solution (3.5 N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 250 ml of NH ₄ F aqueous solution (8N) was injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to generate precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was separated by filtration, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide crystals. After mixing the above crystals and 10.17 g of EuBr _3, they are filled in a quartz boat and baked at 850 ° C. for 2 hours in a hydrogen gas atmosphere using a tube furnace, and europium-activated barium fluoroiodide phosphor particles (BaFI: 0.013Eu) was obtained. A panel was prepared by the method described in Example 1 using the above crystals.

Example 7
2500 ml of BaI ₂ aqueous solution (3.5N) and 80 ml of EuI ₃ aqueous solution (0.1N) were placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 250 ml of an aqueous KF solution (8N) was injected into the reaction mother liquor using a roller pump to produce a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Example 8
2500 ml BaI ₂ aqueous solution (3.5 N), 80 ml EuI ₃ aqueous solution (0.1 N), 20.5 g SrI ₂ and 0.03 g KI were placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 250 ml of NH ₄ F aqueous solution (8N) was injected into the reaction mother liquor using a roller pump to form a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate is filtered off, washed with methanol, and then vacuum dried to obtain crystals of barium fluoroiodide (BaFI: 0.0001K, 0.03Sr, 0.004Eu) activated with strontium / potassium and europium. It was. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 1
5800 ml of BaI ₂ aqueous solution (1.5N) and 80 ml of EuI ₃ aqueous solution (0.1N) were placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 250 ml of NH ₄ F aqueous solution (8N) was injected into the reaction mother liquor using a roller pump to form a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 2
2500 ml of BaI ₂ aqueous solution (3.5N) and 80 ml of EuI ₃ aqueous solution (0.1N) were placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 500 ml of NH ₄ F aqueous solution (4N) was injected into the reaction mother liquor using a roller pump to form a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 3
2500 ml of BaI ₂ aqueous solution (3.5N) and 80 ml of EuI ₃ aqueous solution (0.1N) were placed in the reactor. The reaction mother liquor in the reactor was kept warm at 25 ° C. with stirring. 250 ml of NH ₄ F aqueous solution (8N) was injected into the reaction mother liquor using a roller pump to form a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 4
2500 ml of NH ₄ I aqueous solution (4.5N) and 80 ml of EuI ₃ aqueous solution (0.1N) were placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. NH ₄ F aqueous solution (8N) (250 ml) and barium iodide aqueous solution (1.5N) (5800 ml) were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to form precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 5
2500 ml of NH ₄ I aqueous solution (4.5N) and 80 ml of EuI ₃ aqueous solution (0.1N) were placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. NH ₄ F aqueous solution (4N) 500 ml and barium iodide aqueous solution (3.5 N) 2500 ml were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to generate precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 6
2500 ml of NH ₄ I aqueous solution (2.5N) and 80 ml of EuI ₃ aqueous solution (0.1N) were placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. NH ₄ F aqueous solution (8N) 250 ml and barium iodide aqueous solution (3.5 N) 2500 ml were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to form precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 7
2500 ml of NH ₄ I aqueous solution (4.5N) and 80 ml of EuI ₃ aqueous solution (0.1N) were placed in the reactor. The reaction mother liquor in the reactor was kept warm at 25 ° C. with stirring. NH ₄ F aqueous solution (8N) 250 ml and barium iodide aqueous solution (3.5 N) 2500 ml were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to form precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 8
8750 ml of an aqueous BaI ₂ solution (1N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 250 ml of NH ₄ F aqueous solution (8N) and 80 ml of EuI ₃ aqueous solution (0.1N) were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to generate precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 9
2500 ml of an aqueous BaI ₂ solution (3.5 N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. NH ₄ F aqueous solution (4N) (500 ml) and EuI ₃ aqueous solution (0.1N) (80 ml) were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to generate precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 10
2500 ml of an aqueous BaI ₂ solution (3.5 N) was placed in the reactor. The reaction mother liquor in the reactor was kept warm at 25 ° C. with stirring. 250 ml of NH ₄ F aqueous solution (8N) and 80 ml of EuI ₃ aqueous solution (0.1N) were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to generate precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 11
2500 ml of aqueous NH ₄ I (4.5N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. NH ₄ F aqueous solution (8N) 250 ml, EuI ₃ aqueous solution (0.1N) 80 ml, and BaI ₂ aqueous solution (1.5N) 5800 ml were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump. A precipitate was formed. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 12
2500 ml of aqueous NH ₄ I (4.5N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. NH ₄ F aqueous solution (4N) 500 ml, EuI ₃ aqueous solution (0.1 N) 80 ml, and BaI ₂ aqueous solution (3.5 N) 2500 ml are injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump. A precipitate was formed. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 13
2500 ml of aqueous NH ₄ I (2.5N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. NH ₄ F aqueous solution (8N) 250 ml, EuI ₃ aqueous solution (0.1 N) 80 ml, and BaI ₂ aqueous solution (3.5 N) 2500 ml are injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump. A precipitate was formed. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 14
2500 ml of aqueous NH ₄ I (4.5N) was placed in the reactor. The reaction mother liquor in the reactor was kept warm at 25 ° C. with stirring. NH ₄ F aqueous solution (8N) 250 ml, EuI ₃ aqueous solution (0.1 N) 80 ml, and BaI ₂ aqueous solution (3.5 N) 2500 ml are injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump. A precipitate was formed. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 15
5800 ml of BaI ₂ aqueous solution (1.5N) and 80 ml of EuI ₃ aqueous solution (0.1N) were placed in the reactor. The reaction mother liquor in the reactor was kept warm at 25 ° C. with stirring. 500 ml of NH ₄ F aqueous solution (4N) was injected into the reaction mother liquor using a roller pump to form a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was filtered off, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide (BaFI: 0.004Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 16
2500 ml BaI ₂ aqueous solution (3.5 N) and 125 ml EuBr ₃ aqueous solution (0.2 N) were placed in the reactor. The reaction mother liquor in the reactor was kept warm at 25 ° C. with stirring. 250 ml of NH ₄ F aqueous solution (8N) was injected into the reaction mother liquor using a roller pump to form a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was separated by filtration, washed with methanol, and then vacuum-dried to obtain europium-activated barium fluoroiodide (BaFI: 0.013Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

Comparative Example 17
3500 ml of BaI ₂ aqueous solution (1N) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 1000 ml of NH ₄ F aqueous solution (8N) and 50 ml of EuBr ₃ aqueous solution (0.2N) were injected into the reaction mother liquor while controlling the flow rate using a high feed precision cylinder pump to generate precipitates. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was separated by filtration, washed with methanol, and then vacuum-dried to obtain europium-activated barium fluoroiodide (BaFI: 0.013Eu) crystals. A panel was prepared by the method described in Example 1 using the above crystals.

(Evaluation of radiation image conversion panel)
Regarding sensitivity, after irradiating the radiation image conversion panel with X-rays with a tube voltage of 80 KVp, the panel is operated with He-Ne laser light (633 nm) to excite it, and stimulated emission emitted from the phosphor layer is received by a photoreceiver. The light was received by (photoelectron image multiplier of spectral sensitivity S-5) and the intensity was measured. In the table below, sensitivity is shown as a relative value.

  For sharpness, the radiation image conversion panel is irradiated with X-rays with a tube voltage of 80 KVp through an MTF chart made of lead, and then excited by operating with the panel He-Ne laser light to emit stimulated luminescence emitted from the phosphor layer. Light is received by the same light receiver as above and converted into an electrical signal, which is converted from analog to digital and recorded on a magnetic tape. The magnetic tape is analyzed by a computer and the modulated transmission of the X-ray image recorded on the magnetic tape is performed. The function (MTF) was examined. The table below shows the MTF value (%) at a spatial frequency of 2 cycles / mm.

  As for graininess, the radiation image conversion panel is irradiated with X-rays with a tube voltage of 80 KVp, and then the panel is excited by operating with He-Ne laser light. The light was received by a device and converted into an electric signal, which was recorded on a normal photographic film by a film scanner, and the graininess of the obtained image was visually evaluated. In the table below, the graininess refers to the graininess of an image obtained by conventional practical X-ray photography using an intensifying screen (Konica SRO-250) and an X-ray photographic film (Konica SR-G). Shown in comparison. The symbol “◯” means a graininess equivalent to that of an image obtained by X-ray photography using the above-described intensifying screen and film, and the symbol “◎” means a graininess better than that. Further, the Δ mark means graininess that is slightly rougher than the image obtained by X-ray photography, and the X mark means graininess that is significantly rougher than that.

Claims (3)

Formula ^{_{(1) Ba 1-x M}} 2 xFI: yM 1, zLn
M ² : at least one alkaline earth metal selected from the group consisting of Sr and Ca M ¹ : at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs Ln: Ce, Pr, Sm, At least one rare earth element x, y and z selected from the group consisting of Eu, Gd, Tb, Tm and Yb is 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.05, and 0 <z ≦ 0. 2
A rare earth activated alkaline earth metal fluoroiodide photostimulable phosphor having the following steps for producing a rare earth activated alkaline earth metal fluoroiodide photostimulable phosphor represented by the formula: .
A step of preparing an aqueous solution containing a halide of M ² when x in the general formula (1) is not 0 and further containing a halide of M ¹ when y is not 0 and having a BaI ₂ concentration of 2N or more. ;
While maintaining the above aqueous solution at a temperature of 50 ° C. or higher, an aqueous solution of an inorganic fluoride having a concentration of 5 N or higher and an aqueous solution of a halide of Ln are added to the rare earth activated alkaline earth metal fluoride iodide. Obtaining a precipitate of crystalline phosphor precursor crystals;
Separating the precursor crystal precipitate from an aqueous solution;
And the process of baking the deposit of the separated precursor crystal | crystallization. 2. The method for producing a rare earth activated alkaline earth metal fluoride iodide photostimulable phosphor according to claim 1, wherein the inorganic fluoride is ammonium fluoride or an alkali metal fluoride. 3. The rare earth activated alkaline earth metal fluoride iodide photostimulable phosphor according to claim 1 or 2, wherein in the step of firing the precipitate, firing is performed while avoiding sintering of the precipitate. Manufacturing method.