JP2001019951A - Photostimulable phosphor composed of alkaline earth metal fluoride halide doped with rare earth element, its production and radiological image conversion panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photostimulable phosphor composed of an alkaline earth metal fluoride halide doped with a rare earth element, giving an image having high picture quality with extremely high sharpness in the case of using in a radiological image conversion panel and having good sensitivity and graininess. SOLUTION: The process for the production of the objective photostimulable phosphor composed of an alkaline earth metal fluoride halide doped with a rare earth element and expressed by composition formula Ba1-aMIIaFX1-bIb:cMI, dLn is characterized by the crystal growth of an alkaline earth metal fluoride iodide photostimulable phosphor precursor crystal on the surface of an iodine- free alkaline earth metal fluoride halide photostimulable phosphor precursor crystal and the baking of the product to form a mixed crystal in a single particle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor, a method for producing the same, and a radiation image conversion panel using the stimulable phosphor.

[0002]

2. Description of the Related Art As an alternative to the conventional radiographic method, for example, a radiation image recording / reproducing method using a stimulable phosphor as described in JP-A-55-12145 is known. This method uses a radiation image conversion panel (a stimulable phosphor sheet) containing a stimulable phosphor, and transmits radiation transmitted through a subject or emitted from a subject to the stimulable phosphor of the panel. The radiation energy stored in the stimulable phosphor is absorbed by the body in a time-series manner by exciting the stimulable phosphor with electromagnetic waves (excitation light) such as visible light and infrared rays. The fluorescent light is emitted (stimulated emission light), the fluorescent light is read photoelectrically to obtain an electric signal, and a radiation image of a subject or a subject is reproduced as a visible image based on the obtained electric signal. . After the reading of the panel is completed, after the remaining image is deleted, the panel is prepared for the next photographing. That is, the radiation image conversion panel can be used repeatedly.

According to the above-described radiographic image recording / reproducing method, a radiographic image having a much smaller amount of information and a much larger amount of information than a radiographic method using a combination of a conventional radiographic film and an intensifying screen. There is an advantage that can be obtained. Furthermore, in the conventional radiographic method, radiographic film is consumed for each photographing,
In this radiation image conversion method, since the radiation image conversion panel can be used repeatedly, it is advantageous also in terms of resource protection and economic efficiency.

A stimulable phosphor is a phosphor that emits stimulable light when irradiated with excitation light after being irradiated with radiation. However, in practice, the stimulable phosphor has a wavelength of 400 to 900 nm due to excitation light having a wavelength in the range of 400 to 900 nm. Is generally used. Examples of stimulable phosphors conventionally used in radiation image conversion panels include rare earth-activated alkaline earth metal fluorinated halide-based phosphors. The radiation image conversion panel used in the radiation image recording / reproducing method has, as a basic structure, a support and a stimulable phosphor layer provided on the surface of the support. However, when the stimulable phosphor layer is self-supporting, a support is not necessarily required. The stimulable phosphor layer usually comprises a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state. However, as the stimulable phosphor layer, there is also known a stimulable phosphor layer which does not include a binder formed by a vapor deposition method or a sintering method and is constituted only by an aggregate of the stimulable phosphor. Further, there is known a radiation image conversion panel having a stimulable phosphor layer in which a polymer substance is impregnated in a gap between stimulable phosphor aggregates. In any of these stimulable phosphor layers, the stimulable phosphor has a property of exhibiting stimulable luminescence when irradiated with excitation light after absorbing radiation such as X-rays. Radiation transmitted from the subject or emitted from the subject is absorbed in the stimulable phosphor layer of the radiation image conversion panel in an amount of energy proportional to the radiation dose,
On the panel, a radiation image of the subject or the subject is formed as an accumulated image of radiation energy. This accumulated image can be emitted as stimulated emission light by irradiating the excitation light, and the accumulated image of radiation energy is imaged by photoelectrically reading the stimulated emission light and converting it into an electric signal. It is possible to do.

The surface of the stimulable phosphor layer (the surface not facing the support) is usually provided with a protective film such as a polymer film or an inorganic vapor-deposited film.
The stimulable phosphor layer is protected from chemical alteration or physical impact.

The rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor has excellent sensitivity and, when used as a radiation image conversion panel, produces a radiation-reproduced image with high sharpness. It can be said that it is an excellent stimulable phosphor. However, as the radiation image recording / reproducing method has been put to practical use, there has been an increasing demand for further improving the performance of the stimulable phosphor. Then, when the particle shapes of the rare earth activated alkaline earth metal fluorohalide-based stimulable phosphors used so far were examined, they were found to consist of plate-like particles. Conventionally known methods for producing rare earth activated alkaline earth metal fluoride halide stimulable phosphors include a starting compound alkaline earth metal fluoride, an alkaline earth metal halide other than fluoride, and a rare earth element. Halide, ammonium fluoride, etc. together,
After mixing in a dry system or suspending and mixing in an aqueous medium, the mixture is added with a sintering inhibitor, if necessary, and then calcined and pulverized. Therefore, in the conventional production method, the pulverization step after firing is substantially essential, and the particles of the rare earth activated alkaline earth metal fluoride halide stimulable phosphor thus obtained are mostly contained. Were plate-like particles (hereinafter sometimes simply referred to as “plate-like phosphor”).

However, in the stimulable phosphor layer obtained by mixing such a plate-shaped phosphor with a binder resin solution, coating the mixture on a support, and drying, the plate-shaped phosphor is seen in FIG. As a result, there is a tendency that the surface of the plate-shaped phosphor and the plane of the support are arranged in parallel. When a radiation image is stored in a radiation image conversion panel having a stimulable phosphor layer on which a plate-like phosphor is disposed as described above, and the excitation light is irradiated, the excitation light and the generated stimulable luminescence are emitted in a lateral direction ( This tends to spread in a direction parallel to the plane of the support (see the horizontal arrow in FIG. 7), which causes a problem that the sharpness of the obtained radiation-reproduced image is easily reduced.

In order to suppress the decrease in the sharpness of a radiation reproduced image in the radiation image recording / reproducing method as described above, a substantially cubic stimulable phosphor disclosed in JP-A-62-86086 is used. It is conceivable to use particles.
However, the reproducibility of the method for producing the substantially cubic stimulable phosphor particles disclosed in the above publication is not sufficient for industrial use.

Japanese Patent Application Laid-Open No. Hei 7-233369 discloses a tetrahedral rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor having a controlled particle shape and particle aspect ratio (hereinafter simply referred to as "phosphor"). ) Is shown. Radiation image conversion panel having a stimulable phosphor layer on which a tetradecahedral rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor (hereinafter may be simply referred to as a "tetrahedral phosphor") is disposed. As shown in FIG. 8, in the stimulable phosphor layer, the tetradecahedral phosphor has an arrangement with less directivity, so that the undesired spread of the excitation light and the stimulable emission light in the lateral direction is reduced. Thus, the sharpness of the obtained radiation reproduction image is improved.

In the production method disclosed in the above publication, ammonium halide is used as a reaction mother liquor, and an aqueous solution of barium halide and an aqueous solution of an inorganic fluoride salt are simultaneously added to the mother liquor to cause the reaction to proceed. Luminescent phosphor is synthesized, but tends to take a particle shape having a high particle aspect ratio. On the other hand, by adding barium halide to the reaction mother liquor in advance, the aspect ratio can be made close to 1 to some extent, but the controllability of the particle shape, particle size and particle size distribution is not sufficient, and furthermore, There is a demand for improved image quality.

In order to improve the image quality of the radiation image conversion panel, it is important to control the outer shape of the phosphor particles, and it is also important to control the halogen composition ratio in the crystal. BaFX (X represents Cl or Br.) By partially substituting X of the phosphor matrix with I, the emission characteristics are greatly improved, but in the precipitation reaction of the phosphor precursor crystals in an aqueous solvent, To perform the mixed crystallization, B
It is difficult because the solubility difference between the aFX crystal and the BaFI crystal is too large. In addition, the synthesis range of BaFI crystal is narrow, and in view of industrial production efficiency, it is inevitable to take a flat crystal shape. However, there is a problem in that the particle size distribution becomes large when Ba is produced, and the flat plate-shaped BaFI crystal disadvantageously causes light scattering in the stimulable phosphor layer of the radiation image conversion panel, thereby deteriorating the image quality of the panel.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, when the present invention is used for a radiation image conversion panel, a high-quality image showing extremely high sharpness can be obtained, and at the same time, a rare-earth-activated alkaline-earth metal fluorinated halide having excellent sensitivity and granularity is obtained. It is intended to provide a depleted phosphor. Another object of the present invention is to provide a novel method for producing the stimulable phosphor, which has high controllability of the particle shape, particle size, and particle size distribution of the resulting stimulable phosphor particles. . Further, the present invention provides
An object is to provide a radiation image conversion panel using the stimulable phosphor.

[0013]

According to the present invention, as a result of intensive studies, the synthesis of a BaFX (X represents Cl or Br) phosphor precursor crystal in which the crystal outer shape is easy to control is performed first.
Then, a BaFI crystal is laminated and grown on the crystal surface, whereby a part of the X is replaced with an arbitrary I without largely changing the crystal outer shape, thereby improving the image quality of the radiation image conversion panel. Have found that a fluorohalide-based stimulable phosphor can be produced,
The present invention has been completed.

Means for solving the above problems are as follows:
It is on the street. That is, <1> basic composition formula (I): Ba_1-aM^II _aFX_1-bI_b: CM^I, DLn (I) [where M^IIIs a small number selected from the group consisting of Sr and Ca
Represents at least a kind of alkaline earth metal, M^IIs Li,
A small number selected from the group consisting of Na, K, Rb, and Cs
At least one kind of alkali metal, X is Cl or Br
At least one halogen selected from the group consisting of
Ln is Ce, Pr, Sm, Eu, Gd, Tb, T
at least one member selected from the group consisting of
Represents a rare earth element, and a, b, c and d each represent 0
≦ a ≦ 0.5, 0 <b ≦ 0.5, 0 ≦ c ≦ 0.05, 0
It represents a numerical value in the range represented by <d ≦ 0.2. ]
Alkaline earth metal fluoride halides free of iodine
Alkaline earth on the crystal surface of the stimulable phosphor precursor crystal
Metal fluoroiodide-based stimulable phosphor precursor crystal grows
And characterized by being mixed within one particle by firing
Rare earth activated alkaline earth metal fluorinated halide photostimulability
It is a phosphor. <2> The particle aspect ratio is 1.0 to 2.0,
The median diameter (Dm) of the child size is 1 to 10 μm,
And σ /, where σ is the standard deviation of the particle size distribution.
The rare earth according to <1>, wherein Dm is in a range of 50% or less.
Activated Fluorescence Fluorescence of Alkali Earth Metal Fluorohalides
Body. <3> The particle aspect ratio is 2.0 to 5.0,
The median diameter (Dm) of the child size is 1 to 20 μm,
And σ /, where σ is the standard deviation of the particle size distribution.
The rare earth according to <1>, wherein Dm is in a range of 50% or less.
Activated Fluorescence Fluorescence of Alkali Earth Metal Fluorohalides
Body. <4> Ln in the basic composition formula (I) is Ce or E
The rare earth according to any one of the above <1> to <3>, wherein u is
Activated Fluorescence Fluorescence of Alkali Earth Metal Fluorohalides
Body. <5> Basic composition formula (I): Ba_1-aM^II _aFX_1-bI_b: CM^I, DLn (I) [where M^IIIs a small number selected from the group consisting of Sr and Ca
Represents at least a kind of alkaline earth metal, M^IIs Li,
A small number selected from the group consisting of Na, K, Rb, and Cs
At least one kind of alkali metal, X is Cl or Br
At least one halogen selected from the group consisting of
Ln is Ce, Pr, Sm, Eu, Gd, Tb, T
at least one member selected from the group consisting of
Represents a rare earth element, and a, b, c and d each represent 0
≦ a ≦ 0.5, 0 <b ≦ 0.5, 0 ≦ c ≦ 0.05, 0
It represents a numerical value in the range represented by <d ≦ 0.2. ]
Having a particle aspect ratio of 1.0 to 2.0,
The median diameter (Dm) of the size is 1 to 10 μm,
Σ / D when the standard deviation of the particle size distribution is σ
a rare earth-activated alkaline earth having a m of 50% or less
A method for producing a metal fluorinated halide-based stimulable phosphor.
And BaX_TwoA water-soluble compound of Ln;
If a in (I) is not 0, then M^IIHalogenation of
Substance, nitrate, nitrite or acetate; the above basic composition formula
If c in (I) is not 0, M^IHalogenation of
, Nitrates, nitrites or acetates
And BaX after they are dissolved_TwoThe concentration is
Prepare mother liquor 1 that is less than 2.5 mol / l
A first mother liquor preparation step, and
While maintaining the temperature at
Addition of alkaline earth metal fluorinated halide
First precipitate formation for forming a precipitate of phosphor precursor crystals
And separating the precipitate of the phosphor precursor crystal from the aqueous solution.
A first separating step of separating_TwoA water-soluble compound of Ln
If a in formula (I) is not 0,
M^IIHalide, nitrate, nitrite or acetic acid
Salt; when c in the above basic composition formula (I) is not 0,
M^IHalide, nitrate, nitrite or acetic acid
A salt; a precipitate of the separated phosphor precursor crystals;
BaI in solution and after they are dissolved_Twoconcentration
Prepares a reaction mother liquor 2 of not more than 5.0 mol / l
A second mother liquor preparation step and the reaction mother liquor 2
While maintaining the temperature at ° C, add an aqueous solution of inorganic fluoride salt
By adding alkaline earth to the surface of the phosphor precursor crystal.
Metal fluorinated iodide-based stimulable phosphor precursor crystals grew
A second precipitate forming step of obtaining a precipitate, and the second precipitate
Second step of separating the precipitate obtained in the product generation step from the aqueous solution
Separation step, and the precipitate separated in the second separation step
Is fired while avoiding sintering, and mixed within one particle.
A rare earth activation method characterized by comprising:
Production of fluorinated phosphors based on rukari earth metal fluorides
Is the way. <6> Inorganic fluoride salt in the first precipitate formation step
When the aqueous solution is added, the final phosphor precursor
Assuming that the amount of the crystalline precipitate is N,
The amount of the precipitate of the phosphor precursor crystal is 0.001 N / min to 1
The addition rate is adjusted to be in the range of 0 N / min.
The rare earth according to <5>, wherein an aqueous solution of a fluoride salt is added.
Activated alkaline earth metal fluorinated halide stimulable phosphor
It is a manufacturing method of. <7> Inorganic fluoride aqueous solution in the first precipitate formation step
The addition rate of the liquid is constant or
<5> or <6>, which changes continuously or intermittently.
Rare earth activated alkaline earth metal fluoride halides
This is a method for producing a luminescent phosphor. <8> First precipitation generation step and second precipitation generation step
In the process, the inorganic fluoride salts are, respectively, ammonium fluoride
<5> to <7, which are fluorides of metals or alkali metals.
Rare earth activated alkaline earth metal fluoride according to any one of>
This is a method for producing a halide stimulable phosphor. <9> Basic composition formula (I): Ba_1-aM^IIaFX_1-bI_b: CM^I, DLn (I) [where M^IIIs a small number selected from the group consisting of Sr and Ca
Represents at least a kind of alkaline earth metal, M^IIs Li,
A small number selected from the group consisting of Na, K, Rb, and Cs
At least one kind of alkali metal, X is Cl or Br
At least one halogen selected from the group consisting of
Ln is Ce, Pr, Sm, Eu, Gd, Tb, T
at least one member selected from the group consisting of
Represents a rare earth element, and a, b, c and d each represent 0
≦ a ≦ 0.5, 0 <b ≦ 0.5, 0 ≦ c ≦ 0.05, 0
It represents a numerical value in the range represented by <d ≦ 0.2. ]
Having a particle aspect ratio of 2.0 to 5.0,
The median diameter (Dm) of the is from 1 to 20 μm;
Σ / D when the standard deviation of the particle size distribution is σ
a rare earth-activated alkaline earth having a m of 50% or less
A method for producing a metal fluorinated halide-based stimulable phosphor.
And NH_FourX: a water-soluble compound of Ln; the above basic composition formula
If a in (I) is not 0, then M^IIHalogenation of
Substance, nitrate, nitrite or acetate; the above basic composition formula
If c in (I) is not 0, M^IHalogenation of
, Nitrates, nitrites or acetates
And the NH after they have dissolved_FourX concentration is
Prepare reaction mother liquor 1 that is less than 4.5 mol / l
A first mother liquor preparation step, and
While maintaining the temperature at
BaX_TwoSimultaneously with the aqueous solution of
Elementary and BaX_TwoTo maintain a constant molar ratio with
And alkaline earth metal fluoride halide stimulable fluorescence
Precipitate forming step for forming a precipitate of a body precursor crystal
Separating the precipitate of the phosphor precursor crystal from the aqueous solution
A first separation step;_TwoA water-soluble compound of Ln;
When a in the above basic composition formula (I) is not 0, M^II
Halides, nitrates, nitrites or acetates of
When c in the basic composition formula (I) is not 0, M^Iof
Halides, nitrates, nitrites or acetates;
A precipitate of separated phosphor precursor crystals;
And the BaI after they are dissolved_TwoThe concentration is 5.
Second mother for preparing reaction mother liquor 2 of 0 mol / l or less
A liquid preparation step, and the reaction mother liquor 2 is heated to a temperature of
Add an aqueous solution of inorganic fluoride salt to this while maintaining the temperature
The phosphor precursor crystal has an alkaline earth metal
Precipitates of fluorinated iodide-based stimulable phosphor precursor crystals grown
A second precipitate forming step of obtaining the second precipitate, and the second precipitate forming step
Second separation for separating the precipitate obtained in the process from the aqueous solution
And separating the precipitate separated in the second separation step.
Sintering process to avoid sintering and mix crystals in one particle
Rare earth activated alkaline earth characterized by comprising
A method for producing a metal fluorinated halide-based stimulable phosphor.
You. <10> Inorganic fluoride salt in first precipitate formation step
Aqueous solution and BaX_TwoWhen adding the aqueous solution of
When the amount of the obtained phosphor precursor crystal precipitate is N
The amount of precipitates of the phosphor precursor crystals formed during the addition
In the range of 0.001 N / min to 10 N / min.
By adjusting the acceleration, an aqueous solution of inorganic fluoride salt and BaX_Two
Rare earth activated aluminum according to <9>, wherein an aqueous solution of
Preparation of potassium fluorinated halide stimulable phosphor
Is the law. <11> Inorganic fluoride water in the first precipitate formation step
Solution and BaX_TwoThe addition rate of the aqueous solution
, The constant speed or continuous, intermittent
Rare earth activated alkaline earth metal according to 9> or <10>
This is a method for producing a fluorohalide-based stimulable phosphor. <12> First precipitation generation step and second precipitation generation
Each of the inorganic fluoride salts in the process is treated with ammonium fluoride.
From <9>, which is a fluoride of
11> The rare earth activated alkaline earth metal according to any one of
This is a method for producing a fluorohalide-based stimulable phosphor. <13> Having a stimulable phosphor layer containing a stimulable phosphor
A radiation image conversion panel, wherein the stimulable phosphor is <1.
Rare earth activated alkaline earth according to any one of> to <4>
It is a fluorinated metal-based stimulable phosphor.
This is a radiation image conversion panel. <14> Basic composition formula (I): Ba_1-aM^II _aFX_1-bI_b: CM^I, DLn (I) [where M^IIIs a small number selected from the group consisting of Sr and Ca
Represents at least a kind of alkaline earth metal, M^IIs Li,
A small number selected from the group consisting of Na, K, Rb, and Cs
At least one kind of alkali metal, X is Cl or Br
At least one halogen selected from the group consisting of
Ln is Ce, Pr, Sm, Eu, Gd, Tb, T
at least one member selected from the group consisting of
Represents a rare earth element, and a, b, c and d each represent 0
≦ a ≦ 0.5, 0 <b ≦ 0.5, 0 ≦ c ≦ 0.05, 0
It represents a numerical value in the range represented by <d ≦ 0.2. ]
Having a particle aspect ratio of 1.0 to 2.0,
The median diameter (Dm) of the size is 1 to 10 μm,
Σ / D when the standard deviation of the particle size distribution is σ
a rare earth-activated alkaline earth having a m of 50% or less
A method for producing a metal fluorinated halide-based stimulable phosphor.
And BaX_TwoWhen a in the basic composition formula (I) is not 0;
If M^IIHalide, nitrate, nitrite if
Or acetate; when c in the above basic composition formula (I) is not 0
Also has M^IHalides, nitrates, nitrites or
Is an aqueous solution containing acetate; and
BaX after_TwoWhen the concentration is 2.5 mol / L or less
A first mother liquor preparation step for preparing a reaction mother liquor 1
While maintaining the mother liquor 1 at a temperature of 20-100 ° C.,
Add an aqueous solution of an inorganic fluoride salt to form an alkaline earth metal fluoride.
Precipitates of halide halide stimulable phosphor precursor crystals
First precipitate forming step to be performed, and the phosphor precursor crystal
A first separation step of separating the precipitate of
I_TwoWhen a in the above basic composition formula (I) is not 0,
To M^IIHalide, nitrate, nitrite or acetic acid
Salt; when c in the above basic composition formula (I) is not 0,
M^IHalide, nitrate, nitrite or acetic acid
A salt; a precipitate of the separated phosphor precursor crystals;
BaI in solution and after they are dissolved_Twoconcentration
Prepares a reaction mother liquor 2 of not more than 5.0 mol / l
A second mother liquor preparation step and the reaction mother liquor 2
While maintaining the temperature at ° C, add an aqueous solution of inorganic fluoride salt
By adding alkaline earth to the surface of the phosphor precursor crystal.
Metal fluorinated iodide-based stimulable phosphor precursor crystals grew
A second precipitate forming step of obtaining a precipitate, and the second precipitate
Second step of separating the precipitate obtained in the product generation step from the aqueous solution
Separation step, and the precipitate separated in the second separation step
Is fired while avoiding sintering, and mixed within one particle.
Baking step, the first mother liquor preparation step, and
And in one of the second mother liquor preparation steps,
A rare earth activation agent characterized by adding a water-soluble compound.
Production of fluorinated phosphors based on rukari earth metal fluorides
Is the way. <15> Basic composition formula (I): Ba_1-aM^IIaFX_1-bI_b: CM^I, DLn (I) [where M^IIIs a small number selected from the group consisting of Sr and Ca
Represents at least a kind of alkaline earth metal, M^IIs Li,
A small number selected from the group consisting of Na, K, Rb, and Cs
At least one kind of alkali metal, X is Cl or Br
At least one halogen selected from the group consisting of
Ln is Ce, Pr, Sm, Eu, Gd, Tb, T
at least one member selected from the group consisting of
Represents a rare earth element, and a, b, c and d each represent 0
≦ a ≦ 0.5, 0 <b ≦ 0.5, 0 ≦ c ≦ 0.05, 0
It represents a numerical value in the range represented by <d ≦ 0.2. ]
Having a particle aspect ratio of 2.0 to 5.0,
The median diameter (Dm) of the is from 1 to 20 μm;
Σ / D when the standard deviation of the particle size distribution is σ
a rare earth-activated alkaline earth having a m of 50% or less
A method for producing a metal fluorinated halide-based stimulable phosphor.
And NH_FourX: when a in the above basic composition formula (I) is not 0
If M^IIHalide, nitrate, nitrite if
Or acetate; when c in the above basic composition formula (I) is not 0
Also has M^IHalides, nitrates, nitrites or
Is an aqueous solution containing acetate; and
NH after_FourX concentration is less than 4.5 mol / l
A first mother liquor preparation step for preparing a reaction mother liquor 1
While maintaining the mother liquor 1 at a temperature of 20-100 ° C.,
Aqueous solution of inorganic fluoride salt and BaX_TwoAt the same time
And inorganic fluoride salt fluorine and BaX_TwoThe molar ratio with
And alkaline earth metal fluoride.
Generates precipitates of stimulable phosphor precursor crystals
Forming a first precipitate, and depositing the phosphor precursor crystal.
A first separation step of separating the deposit from the aqueous solution;
I_TwoWhen a in the above basic composition formula (I) is not 0,
To M^IIHalide, nitrate, nitrite or acetic acid
Salt; when c in the above basic composition formula (I) is not 0,
M^IHalide, nitrate, nitrite or acetic acid
A salt; a precipitate of the separated phosphor precursor crystals;
BaI in solution and after they are dissolved _Twoconcentration
Prepares a reaction mother liquor 2 of not more than 5.0 mol / l
A second mother liquor preparation step and the reaction mother liquor 2
While maintaining the temperature at 0 ° C.,
A liquid is added to the surface of the phosphor precursor crystal to form an alkali.
An earth metal fluoroiodide-based stimulable phosphor precursor crystal grows
A second precipitate forming step of obtaining a separated precipitate;
Separation of the precipitate obtained in the deposition process from the aqueous solution
Separation step 2 and the precipitate separated in the second separation step
Is fired while avoiding sintering, and mixed within one particle.
Baking step, the first mother liquor preparation step, and
And in one of the second mother liquor preparation steps,
A rare earth activation agent characterized by adding a water-soluble compound.
Production of fluorinated phosphors based on rukari earth metal fluorides
Is the way.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. Rare earth activated alkaline earth metal fluorinated halide stimulable phosphor The rare earth activated alkaline earth metal fluorinated halide stimulable phosphor of the present invention (hereinafter simply referred to as "stimulable phosphor") Is a basic composition formula (I): Ba _{1 -a} M ^II _a FX _{1 -b} I _b : cM ^I , dLn (I) [where M ^II is selected from the group consisting of Sr and Ca Represents at least one alkaline earth metal, and M ^I is Li,
X represents at least one alkali metal selected from the group consisting of Na, K, Rb, and Cs; X represents at least one halogen selected from the group consisting of Cl and Br; Ln represents Ce, Pr, Sm, Eu, Gd, Tb, T
represents at least one rare earth element selected from the group consisting of m and Yb, a, b, c and d each represent 0
≦ a ≦ 0.5, 0 <b ≦ 0.5, 0 ≦ c ≦ 0.05, 0
It represents a numerical value in the range represented by <d ≦ 0.2. ]. The stimulable phosphor represented by the basic composition formula (I) is:
For the purpose of further improving the stimulable light emission amount, the erasing property, and the like, the composition may contain the following various additional components. For example,
Nonmetallic elements represented by B, O, S, Al, Ge, Sn
, Mg, Fe, Ni, Cu, Ag
And the like. The amount of these additional components is preferably 1000 ppm or less based on the stimulable phosphor represented by the basic composition formula (I).

The stimulable phosphor represented by the basic composition formula (I) usually has an aspect ratio in the range of 1.0 to 5.0. When the particle aspect ratio of the stimulable phosphor of the present invention is 1.0 to 2.0, the median diameter (Dm) of the particle size is 1 to 10 μm (more preferably, 2 to 7 μm).
m), and σ / Dm when the standard deviation of the particle size distribution is σ is 50% or less (more preferably 40 / Dm).
% Or less). On the other hand, when the particle aspect ratio is 2.0 to 5.0, the median diameter (Dm) of the particle size is 1 to 20 μm (more preferably, 2 to 20 μm).
And the standard deviation of the particle size distribution is σ / Dm of 50% or less (more preferably 40% or less). Also,
Examples of the shape of the particle include a rectangular parallelepiped, a regular hexahedron, a regular octahedron, an intermediate polyhedron, a tetrahedron, and the like.
Although a facepiece type is preferred, the effects of the present invention can be achieved without being necessarily limited to the tetrahedral shape as long as they satisfy the above particle aspect ratio, particle size and particle size distribution. In the basic composition formula (I), Ln is preferably Ce or Eu from the viewpoint of improving light emission characteristics (sensitivity, erasing characteristics, response, and the like).

The stimulable phosphor of the present invention is an alkaline earth metal fluorohalide-based stimulable phosphor precursor crystal not containing iodine (BaFX crystal: X represents Cl or Br).
Characterized in that an alkaline earth metal fluoroiodide-based stimulable phosphor precursor crystal (BaFI crystal) grew on the crystal surface and was crystallized in one grain by firing. In the precipitation reaction of the phosphor precursor crystals in an aqueous solvent, these B
To achieve the mixed crystal of aFX crystal and BaFI crystal, B
Although the solubility difference between the aFX crystal and the BaFI crystal is too large, it is difficult, but the BaFX (X
Represents Cl or Br. ) The stimulable phosphor of the present invention, in which a part of the X is substituted by an arbitrary I, by first synthesizing a phosphor precursor crystal and then growing a BaFI crystal on the crystal surface. Obtainable. The stimulable phosphor of the present invention can be advantageously used as a stimulable phosphor material for forming a stimulable phosphor layer of a radiation image conversion panel, and greatly changes the crystal shape of a BaFX crystal. In addition, since I (iodine atom) is introduced, the image quality of the radiation image conversion panel can be improved.

Manufacturing Method The stimulable phosphor of the present invention is manufactured by the following two manufacturing methods (A) and (B). Depending on the production method (A), the particle aspect ratio is 1.0 to 2.0.
Is obtained, and depending on the production method (B),
A stimulable phosphor having a particle aspect ratio of 2.0 to 5.0 is obtained.

(A) BaX ₂ ; a water-soluble compound of Ln;
When a in the above basic composition formula (I) is not 0, M ^II
Halides, nitrate, nitrite or acetate; c halides further M ^I when non-zero the formula (I), nitrate, nitrite or acetate; an aqueous solution containing, and, BaX ₂ after they are dissolved
A first mother liquor preparation step of preparing a reaction mother liquor 1 having a concentration of 2.5 mol / liter or less;
While maintaining the temperature at 100 ° C., an aqueous solution of an inorganic fluoride salt is added thereto to form an alkaline earth metal fluoride halide-based stimulable phosphor precursor crystal (preferably a substantially cubic to tetradecahedral type). A first precipitate forming step of forming a precipitate of crystal), a first separating step of separating the precipitate of the phosphor precursor crystal from an aqueous solution, BaI ₂ ; a water-soluble compound of Ln; When a in formula (I) is not 0, a halide, nitrate, nitrite or acetate of M ^II ; and when c of the above basic composition formula (I) is not 0, a halide or nitrate of M ^I is further added. , Nitrite or acetate; an aqueous solution containing the separated precipitates of the phosphor precursor crystals, and having a BaI ₂ concentration of 5.0 mol / L or less after dissolving them. Second mother liquor preparation step to be prepared And reacting mother liquor 2 with 20 to 100
An aqueous solution of an inorganic fluoride salt was added thereto while maintaining the temperature at ℃, and an alkaline earth metal iodide fluoride was formed on the surface of the phosphor precursor crystal (preferably a substantially cubic to tetradecahedral crystal). Precipitate forming step of obtaining a precipitate in which a fluoride-based stimulable phosphor precursor crystal has grown, and a second separating step of separating the precipitate obtained in the second precipitate forming step from an aqueous solution And baking the precipitate separated in the second separation step while avoiding sintering to form a mixed crystal within one particle. A method for producing a halide halide stimulable phosphor.
In producing the stimulable phosphor represented by the basic composition formula (I), for the purpose of further improving the stimulable light emission amount, the erasing characteristics, and the like,
Various additional components as described below can also be added. For example, non-metallic elements represented by B, O, S, Al, G
e, amphoteric elements represented by Sn, Mg, Fe, Ni, C
and metal elements represented by u and Ag. The amount of these additional components is preferably 1000 ppm or less based on the stimulable phosphor represented by the basic composition formula (I).

(B) NH ₄ X; a water-soluble compound of Ln;
When a in the above basic composition formula (I) is not 0, M ^II
Halides, nitrate, nitrite or acetate; c halides further M ^I when non-zero the formula (I), nitrate, nitrite or acetate; an aqueous solution containing, and, NH ₄ X after they are dissolved
A first mother liquor preparation step for preparing a reaction mother liquor 1 having a concentration of 4.5 mol / l or less;
While maintaining the temperature at 100 ° C., an aqueous solution of an inorganic fluoride salt and an aqueous solution of BaX ₂ were simultaneously added thereto and added so as to maintain a constant molar ratio of fluorine of the inorganic fluoride salt to BaX _2. And an alkaline earth metal fluorinated halide-based stimulable phosphor precursor crystal (preferably substantially cubic to 1
A first precipitate forming step of forming a precipitate of (tetrahedral type crystal), a first separating step of separating the precipitate of the phosphor precursor crystal from an aqueous solution, and a water-soluble compound of BaI ₂ ; Ln. When a in the above basic composition formula (I) is not 0, further halides, nitrates, nitrites or acetates of M ^II ; and when c in the above basic composition formula (I) is not 0, further addition of M ^I An aqueous solution containing a halide, a nitrate, a nitrite or an acetate; a precipitate of the separated phosphor precursor crystal, and having a BaI ₂ concentration of 5.0 mol / liter or less after dissolving them. A second mother liquor preparation step of preparing a reaction mother liquor 2;
While maintaining the temperature at 0 ° C., an aqueous solution of an inorganic fluoride salt is added thereto to form an alkaline earth metal fluoride on the surface of the phosphor precursor crystal (preferably a substantially cubic to tetradecahedral crystal). A second precipitate forming step of obtaining a precipitate in which the iodide-based stimulable phosphor precursor crystal has grown, and a second separation of separating the precipitate obtained in the second precipitate forming step from an aqueous solution Step and the precipitate separated in the second separation step,
And baking while avoiding sintering to form a mixed crystal within one particle. A method for producing a rare earth activated alkaline earth metal fluoride halide stimulable phosphor, comprising: In the production of the stimulable phosphor represented by the basic composition formula (I), the following various additives may be added for the purpose of further improving the stimulable light emission amount, the erasing characteristics and the like. For example, a non-metallic element represented by B, O, S, A
amphoteric elements represented by l, Ge, Sn, Mg, Fe, N
Metal elements typified by i, Cu, Ag, and the like.
The amount of these additional components is preferably 1000 ppm or less based on the stimulable phosphor represented by the basic composition formula (I).

In the present invention, the term "aqueous solution" means a solution obtained by dissolving a "solute" in an "aqueous medium". Also,
The term “aqueous medium” is a concept including not only water, but also a liquid having a high affinity for water (eg, alcohol or the like) alone or as a mixture thereof, or a mixture of these and water. Of these, water is most preferred. Therefore, the term “aqueous solution” in the present invention is a concept including all the solutions prepared by the “aqueous medium” of the present invention, and it is most preferable to use water as the “aqueous medium”. On the other hand, “solute” refers to the type of aqueous solution (raw material solution, reaction mother liquor,
And an aqueous solution for addition. The manufacturing methods (A) and (B) will be described separately for each process.

[Production method (A)] i) First mother liquor preparation step First, a raw material compound other than a fluorine compound is dissolved using an aqueous medium to prepare a reaction mother liquor 1. That is, water-soluble compounds of BaX ₂ and Ln, and optionally halides of M ^{I I,} nitrate, nitrite or acetate salt, if necessary, a halide of M ^I, nitrate, nitrite or acetate The salt is placed in an aqueous medium, mixed well, and dissolved to prepare an aqueous solution (reaction mother liquor 1) in which these components are dissolved. At this time, the quantitative ratio between BaX ₂ and the aqueous solvent is adjusted so that the BaX ₂ concentration becomes 2.5 mol / liter or less. Examples of the water-soluble compound of Ln include halides (chlorides, bromides, etc.), nitrates, acetates and the like of the rare earth elements. However, when a water-soluble compound of Ln is added in the second mother liquor preparation step described below,
In the step of preparing a mother liquor, the water-soluble compound of Ln may not be added. The reaction mother liquor 1 may optionally contain a small amount of acid, ammonia, a water-soluble polymer, water-insoluble metal oxide fine particles, or the like. The obtained reaction mother liquor 1 is maintained at 20 to 100 ° C., preferably 40 to 80 ° C., and is stirred.

Ii) First Precipitate Formation Step The reaction mother liquor 1 is maintained at a temperature of 20 to 100 ° C.
Then, an aqueous solution of an inorganic fluoride salt was added to the well-known metering solution.
Such as precision cylinder pumps and precision gear pumps
Pump, tube pump, diaphragm pump, etc.
Add. Of these, the precision cylinder
And alkaline earth metal halogen fluoride
Nitride-based stimulable phosphor precursor crystal (preferably a substantially cubic
To a tetradecahedral crystal). Inorganic fluoride
Salts include ammonium fluoride and alkali metal fluoride.
Substances, alkaline earth metal fluorides, transition metal fluorides, fluorides
Hydrofluoric acid, etc., among which solubility, emission characteristics,
Ammonium fluoride and alkali
Metal fluorides are preferred. An aqueous solution of the inorganic fluoride salt;
In both cases, an aqueous solution of Ln and, if necessary, M^IIWater of
Solution and, if necessary, M ^IAt the same time
You can also.

Upon addition of the aqueous solution of the inorganic fluoride salt, the finally obtained alkaline earth metal fluorohalide-based stimulable phosphor precursor crystal (preferably, approximately cubic to 14
Assuming that the amount of the precipitate of (hedral type crystal) is N, the amount of the precipitate of the phosphor precursor crystal generated during the addition is 0.001.
N / min to 10 N / min (more preferably 0.01 N
/ Min. To 1.0 N / min.), And adding an aqueous solution of an inorganic fluoride salt. If the addition speed is higher than the above, it may not be possible to take sufficient time for uniform mixing, while if the addition speed is lower than the above, the residence time in the reaction cell may be too long and crystal growth may occur in the cell. There is. In order to precisely adjust the rate of addition, it is preferable to add with a precision cylinder pump. Further, this addition is usually performed at a constant addition rate, but the addition rate is an nth order function (n
= 1, 2, 3), and may change continuously or intermittently as an exponential function or a differential function. This addition is preferably carried out in the region where the stirring is particularly vigorous.

Iii) First Separation Step Precipitation of alkaline earth metal fluorohalide-based stimulable phosphor precursor crystals (preferably substantially cubic to tetradecahedral crystals) obtained as described above The substance is separated from the aqueous solution by a separation means such as suction filtration, pressure filtration, and centrifugation. The separated precipitate of the phosphor precursor crystal is sufficiently washed with a lower alcohol such as methanol and dried.

Iv) Second mother liquor preparation step Next, the following starting compounds are dissolved using an aqueous medium,
A reaction mother liquor 2 is prepared. That is, a water-soluble compound of BaI ₂ and Ln, a precipitate of the phosphor precursor crystal separated in the first separation step, and, if necessary, a halide, nitrate, nitrite or acetate of M ^II , and if necessary, a halide of M ^I, nitrate, nitrite or acetate, placed thoroughly mixed in the aqueous medium, it is dissolved,
An aqueous solution in which these components are dissolved (reaction mother liquor 2) is prepared. At this time, the amount ratio of BaI ₂ to the aqueous solvent is adjusted so that the BaI ₂ concentration is 5.0 mol / liter or less. Examples of the water-soluble compound of Ln include those similar to those in the first mother liquor preparation step. However, when the water-soluble compound of Ln is added in the first mother liquor preparation step, the water-soluble compound of Ln may not be added in the second mother liquor preparation step. The reaction mother liquor 2 may optionally contain a small amount of acid, ammonia, water-soluble polymer, water-insoluble metal oxide fine particles, or the like. The reaction mother liquor 2 obtained above has a temperature of 20 to 100 ° C., preferably 40 to 100 ° C.
Maintain at 80 ° C. and stir.

V) Second Precipitate Forming Step While maintaining the reaction mother liquor 2 at a temperature of 20 to 100 ° C., an aqueous solution of an inorganic fluoride salt is added to the reaction liquid and used in the first precipitate forming step. Add using a metering pump.
Among these, the addition is preferably carried out using a precision cylinder pump, and the alkaline earth metal fluorohalide-based stimulable phosphor precursor crystals (preferably, substantially cubic to 1
An alkaline earth metal fluoroiodide-based stimulable phosphor precursor crystal is grown on the surface of the (tetrahedral crystal) to obtain a precipitate. As the inorganic fluoride salt, those used in the first precipitate forming step can be used. Along with the aqueous solution of the inorganic fluoride salt, an aqueous solution of Ln and, if necessary, M
^II aqueous, if necessary, may be added an aqueous solution of M ^I simultaneously.

When the amount of the precipitate of the stimulable phosphor precursor crystal represented by the basic composition formula (I) finally obtained is defined as M when the aqueous solution of the inorganic fluoride salt is added, The amount of the phosphor precursor crystal precipitate formed therein is 0.001.
M / min to 10 M / min (more preferably 0.01 M
/ Min. To 1.0 M / min.), And the aqueous solution of the inorganic fluoride salt is preferably added. If the addition speed is higher than the above-mentioned rate, uniform mixing may not be performed, or BaFI may independently form nuclei, and crystal growth may not occur on the surface of the BaFBr crystal. On the other hand, if the addition rate is lower than the above, crystal growth may occur in the cell. In order to precisely adjust the rate of addition, it is preferable to add with a precision cylinder pump. Further, this addition is usually performed at a constant addition rate, but the addition rate is continuously or intermittently represented by an n-order function (n = 1, 2, 3), an exponential function, or a differential function with respect to the addition time. May be changed. This addition is preferably carried out in the region where the stirring is particularly vigorous.

Vi) Second Separation Step The precipitate obtained in the second precipitate formation step is separated from the aqueous solution by separation means such as suction filtration, pressure filtration, and centrifugation. The separated precipitate of the phosphor precursor crystal is sufficiently washed with a lower alcohol such as methanol and dried.

Vii) Firing Step The precipitate of the phosphor precursor crystal separated in the second separation step is fired while avoiding sintering. As a method of avoiding sintering, for example, alumina,
A method of adding a sintering inhibitor composed of a fine powder of a metal oxide such as silica, zirconia, titania, magnesia and the like, mixing the mixture, and sintering the mixture to uniformly adhere the sintering inhibitor fine powder to the crystal surface is used. The addition of the sintering inhibitor can be omitted by appropriately adjusting the firing conditions.

As a specific firing method, a phosphor precursor crystal having fine particles of a sintering inhibitor attached to the surface thereof, if necessary, is placed in a heat-resistant container such as a quartz boat, an alumina boat, a quartz crucible, or an alumina crucible. Filling and placing in a furnace core such as an electric furnace. Firing temperature is 400 ~ 130
A range of 0 ° C is preferable, and a range of 500 to 1000 ° C is more preferable. The firing time depends on the amount of the phosphor precursor crystal filled,
Generally, 0.5 to 12 hours is appropriate, although it depends on the firing temperature and the unloading temperature. The firing atmosphere may be a neutral atmosphere such as a nitrogen gas atmosphere or an argon gas atmosphere, a nitrogen gas atmosphere containing a small amount of hydrogen gas, a weak reducing atmosphere such as a carbon dioxide atmosphere containing carbon monoxide, or a trace oxygen introduction atmosphere. Used. By the above-mentioned calcination, the desired rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor represented by the basic composition formula (I) is obtained.

[Production method (B)] i) First mother liquor preparation step First, a raw material compound other than a fluorine compound is dissolved using an aqueous medium to prepare a reaction mother liquor 1. That, NH ₄ water-soluble compound X and Ln, and optionally halides of M ^{I I,} nitrate, nitrite or acetate salt, if necessary, a halide of M ^I, nitrate, nitrite or The acetate is placed in an aqueous medium, mixed well, and dissolved to prepare an aqueous solution (reaction mother liquor 1) in which these components are dissolved. At this time, the amount ratio between NH ₄ X and the aqueous solvent is adjusted so that the NH ₄ X concentration is 4.5 mol / L or less, preferably 3.0 mol / L or more and 4.5 mol / L or less. deep. Examples of the water-soluble compound of Ln include those similar to those in the above-mentioned production method (A). However, when the water-soluble compound of Ln is added in the second mother liquor preparation step described below, the water-soluble compound of Ln may not be added in the first mother liquor preparation step. To the reaction mother liquor, a small amount of acid, ammonia, a water-soluble polymer, a water-insoluble metal oxide fine particle powder or the like may be added as required. The obtained reaction mother liquor 1 is maintained at 20 to 100 ° C., preferably 40 to 80 ° C., and is stirred.

Ii) First Precipitate Formation Step While maintaining the reaction mother liquor 1 at a temperature of 20 to 100 ° C., an aqueous solution of an inorganic fluoride salt and an aqueous solution of BaX ₂ are simultaneously added to the reaction solution. Is added using the known metering pump used in the production method (A) so that the molar ratio of fluorine to BaX ₂ is kept constant. Among these, a precipitate of an alkaline earth metal fluorohalide-based stimulable phosphor precursor crystal (preferably a substantially cubic or tetradecahedral crystal) is preferably added by using a precision cylinder pump. obtain. With an aqueous solution of the inorganic fluoride salts, aqueous solutions of Ln and optionally, an aqueous solution of M ^II, if necessary, may be added an aqueous solution of M ^I simultaneously.

When an aqueous solution of an inorganic fluoride salt and an aqueous solution of BaX ₂ are added, a finally obtained alkaline earth metal fluorinated halide-based stimulable phosphor precursor crystal (preferably a substantially cubic to tetradecahedral type) is used. The amount of the precipitate of the phosphor precursor crystal generated during the addition is in the range of 0.001 N / min to 10 N / min (more preferably 0.01 N / Min to 1.0 N / min), and the aqueous solution of the inorganic fluoride salt and the aqueous solution of BaX ₂ are preferably added. If the addition speed is higher than the above, it may not be possible to take sufficient time for uniform mixing, while if the addition speed is lower than the above, the residence time in the reaction cell may be too long and crystal growth may occur in the cell. There is. In order to precisely adjust the rate of addition, it is preferable to add with a precision cylinder pump. Further, this addition is usually performed at a constant addition rate, but the addition rate is an n-order function (n = 1,
2, 3), may change continuously or intermittently as an exponential function or a differential function. This addition is preferably carried out in the region where the stirring is particularly vigorous.

Iii) First separation step Precipitation of alkaline earth metal fluorohalide-based stimulable phosphor precursor crystals (preferably substantially cubic to tetradecahedral crystals) obtained as described above The substance is separated from the aqueous solution by a separation means such as suction filtration, pressure filtration, and centrifugation. The separated precipitate of the phosphor precursor crystal is sufficiently washed with a lower alcohol such as methanol and dried.

In the same manner as in the production method (A), the desired mother liquor is passed through iv) a second mother liquor preparation step, v) a second precipitate formation step, vi) a second separation step, and vii) a baking step. A rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor represented by the basic composition formula (I) is obtained.

Next, a method for manufacturing a radiation image conversion panel using the stimulable phosphor of the present invention will be described. The stimulable phosphor of the present invention is contained in the stimulable phosphor layer of the radiation image storage panel.
Usually, it comprises a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state. The stimulable phosphor layer may further contain other stimulable phosphors and / or additives such as coloring agents.

A method for manufacturing a radiation image conversion panel will be described by taking, as an example, a case where the stimulable phosphor layer is composed of a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state.

The stimulable phosphor layer can be formed on a support by the following known method. First, a stimulable phosphor and a binder are added to a solvent and mixed well to prepare a coating solution in which the stimulable phosphor is uniformly dispersed in a binder solution. The mixing ratio between the binder and the stimulable phosphor in the coating solution varies depending on the intended characteristics of the radiation image conversion panel, the type of the stimulable phosphor, and the like. Is selected from the range of 1: 1 to 1: 100, especially 1: 8 to 1:40.
It is preferable to select from the range. Next, the coating solution containing the stimulable phosphor and the binder prepared as described above is uniformly applied to the surface of the support to form a coating film. This coating operation can be performed by using ordinary coating means, for example, a doctor blade, a roll coater, a knife coater, or the like.

The support can be arbitrarily selected from those conventionally known as materials for supports of radiation image conversion panels. In known radiation image conversion panels, photostimulation is used to enhance the bond between the support and the photostimulable phosphor layer or to improve the sensitivity or image quality (sharpness, granularity) of the radiation image conversion panel. A polymer material such as gelatin is applied to the surface of the support on which the conductive phosphor layer is provided to provide an adhesion-imparting layer, or a light-reflective layer made of a light-reflective material such as titanium dioxide, or carbon black. It is known to provide a light absorbing layer or the like made of a light absorbing substance. The support used in the present invention can also be provided with these various layers, and the configuration thereof can be arbitrarily selected according to the purpose, use, and the like of a desired radiation image conversion panel. Furthermore, Japanese Patent Laid-Open No. 58
As described in JP-A-200200, the surface of the support on the stimulable phosphor layer side (the surface of the support on the stimulable phosphor layer side) is used for the purpose of improving the sharpness of the obtained image. When an adhesiveness-imparting layer, a light-reflecting layer, a light-absorbing layer, or the like is provided, the surface thereof may have fine irregularities.

After forming a coating on the support as described above, the coating is dried to form a stimulable phosphor layer on the support. The thickness of the stimulable phosphor layer varies depending on the intended properties of the radiation image conversion panel, the type of the stimulable phosphor, the mixing ratio between the binder and the stimulable phosphor, and the like.
μm to 1 mm. The layer thickness is preferably 50 to 500 μm. Note that the stimulable phosphor layer does not necessarily need to be formed by directly applying a coating solution on the support as described above. After forming the phosphor layer by applying and drying the liquid, this is pressed onto the support, or even if the support and the stimulable phosphor layer are joined by using an adhesive or the like. Good.

As described above, a protective film is usually provided on the stimulable phosphor layer. The protective film is formed by applying a solution prepared by dissolving a transparent organic polymer substance such as a cellulose derivative or polymethyl methacrylate in an appropriate solvent onto the stimulable phosphor layer. A protective film forming sheet such as an organic polymer film such as polyethylene terephthalate or a transparent glass plate is separately formed and provided on the surface of the stimulable phosphor layer using a suitable adhesive,
Alternatively, an inorganic compound formed on a stimulable phosphor layer by vapor deposition or the like is used. Further, the protective film may be formed of a coating film of a fluorine-based resin soluble in an organic solvent, in which a perfluoroolefin resin powder or a silicone resin powder is dispersed and contained.

For the purpose of improving the sharpness of the obtained image, at least one of the layers constituting the radiation image conversion panel absorbs excitation light and does not absorb stimulated emission light. Coloring agent, or an independent colored intermediate layer may be provided (Japanese Patent Publication No. 54-1979).
No. 23400).

According to the above-mentioned method, a rare earth activated alkaline earth metal fluorinated halide stimulable phosphor obtained by the production method of the present invention and a binder containing and supporting the same in a dispersed state are obtained. And a radiation image conversion panel provided with a stimulable phosphor layer comprising

[0045]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. Example 1 To synthesize a stimulable phosphor precursor of europium-activated barium fluorobromide, 1200 ml of an aqueous solution of BaBr ₂ (2.5 mol / l) and an aqueous solution of EuBr ₃ (0.2 mol / l) 37.5 ml, 2.98 g of KBr, 3.54 g of CaBr ₂ .2H ₂ O, and 1762.5 ml of water were placed in a 4 liter reactor. The reaction mother liquor (BaBr ₂ concentration of 1.0
(Mol / liter) at 60 ° C.
The screw-type stirring blade with a diameter of 45 mm provided with a mixing chamber of 00 ml was rotated at 500 rpm to stir the reaction mother liquor 1 so as to generate an upward flow from the mixing chamber.

150 ml of an aqueous solution of ammonium fluoride (10 mol / l) and 150 ml of water are mixed, and 300 ml of the mixture is placed in a mixing chamber in the reaction mother liquor 1 kept warm under the above stirring, and a precision cylinder pump is provided. 5ml using
/ Minute to form a precipitate. After completion of the addition, the mixture was kept warm and stirred for 2 hours to ripen the precipitate. Next, the precipitate was separated by filtration and washed with 2 liters of methanol. Next, the washed precipitate is taken out, dried in vacuum at 120 ° C. for 4 hours, and then barium fluorobromide (Ba _0.99 Ca _0.01 FBr added with europium-activated potassium calcium:
0.0002K, 0.005Eu ²⁺ )
g was obtained. (Sediment 1)

Subsequently, in order to grow a stimulable phosphor precursor of europium-activated barium fluoroiodide on the crystal surface of the stimulable phosphor precursor crystal, a BaI ₂ aqueous solution (4.0 mol / mol) was used. Liter) 2000 ml, 3.75 ml of EuI ₃ aqueous solution (0.2 mol / l), KI 4.
15g, CaI ₂ · 3.3H ₂ O The 0.53 g, and the fluoride barium bromide _{(Ba 0.99 Ca 0.01 FBr: 0} .
0002K, 0.005 Eu) in 200.8 g
Placed in a liter volume reactor. The reaction mother liquor 2 (BaI ₂ concentration of 4.0 mol / l) in this reactor was added to 60
C., and a screw stirring blade having a diameter of 45 mm and a mixing chamber having a volume of about 100
The reaction mother liquor 2 was stirred at a rotation speed of rpm to generate an upward flow from the mixing chamber.

15 ml of an aqueous solution of ammonium fluoride (10 mol / l) and 85 ml of water were mixed.
00 ml was added to the mixing chamber in the reaction mother liquor 2 kept warm under the above stirring at an addition rate of 1 ml / min using a precision cylinder pump to produce a precipitate. After completion of the addition, the mixture was kept warm and stirred for 2 hours to ripen the precipitate. Next, the precipitate was filtered off and washed with 2 liters of 2-propanol. The washed precipitate is taken out, dried in vacuum at 150 ° C. for 4 hours, and then barium fluorobromide (Ba _0.99 Ca _0.01 FBr: 0.00) added with europium-activated potassium calcium.
02K, europium-activated potassium calcium added fluoride barium iodide on the crystal surface of 0.005Eu ²⁺⁾ (Ba
Europium-activated potassium calcium-added barium fluorobromide iodide (Ba _0.99 Ca _0.01 FBr _0.85 ) on which _0.99 Ca _0.01 FI: 0.0002K, 005Eu ²⁺ ) crystal has grown.
About 240 g of I _0.15 : 0.0002K, 0.005Eu ²⁺ ) crystals were obtained. (Sediment 2)

In order to prevent a change in particle shape due to sintering during firing and a change in particle size due to fusion between particles, 1% by weight of ultrafine alumina powder is added to the crystals of the precipitate 2. The mixture was sufficiently mixed with a mixer to uniformly adhere ultrafine alumina powder to the crystal surface. This is 100
g, and then calcined in a tube furnace at 800 ° C. for 2 hours in a nitrogen gas atmosphere, using europium-activated potassium calcium-added barium fluorobromoiodide phosphor particles (Ba _0.99 Ca _0.01 FBr _0.85). I _0.15 : 0.0
002K, 0.005 Eu ²⁺ ). Observation of the obtained phosphor particles with a scanning electron microscope revealed that most of the particles were obtained by growing BaFI crystals on tetradecahedral particles having an aspect ratio of 1. A photograph of the phosphor particles at a magnification of 1550 times by an electron microscope is shown in FIG. 1 as a drawing. Also,
FIG. 2 is a schematic diagram showing the shape of a tetrahedral particle having an aspect ratio of 1. In the obtained phosphor particles, BaFI crystals were mainly grown on the black crystal plane of the tetradecahedral particles in FIG.

Example 2 In order to synthesize a stimulable phosphor precursor of europium-activated barium fluorobromide, NH _{4 was used.}
1780 ml of Br aqueous solution (4.5 mol / l), E
uBr ₃ aqueous solution (0.2 mol / L) 12.5 m
1, 2.0 g of KBr and 2.36 of CaBr ₂ .2H ₂ O
g and 207.5 ml of water were placed in a 4 liter volume reactor. The reaction mother liquor 1 (NH ₄ Br concentration: 4.0 mol / l) in this reactor was kept at 60 ° C., and was provided with a mixing chamber having a volume of about 100 ml and a diameter of 45 mm.
By rotating the screw-type stirring blade at 500 rpm,
The reaction mother liquor 1 was stirred so as to generate an upward flow from the mixing chamber.

100 ml of an aqueous solution of ammonium fluoride (10 mol / l) and 400 ml of an aqueous solution of BaBr ₂ (2.5 mol / l) were prepared. Using a separate precision cylinder pump, NH ₄ F was added at a rate of ₂ ml / min and BaBr ₂ was added at a rate of 8 ml / min in a mixing chamber in the reaction mother liquor 1 which was kept warm under the above stirring. Was added. This addition produced a precipitate. After completion of the addition, the mixture was kept warm and stirred for 2 hours to ripen the precipitate. Next, the precipitate was separated by filtration and washed with 2 liters of methanol. The washed precipitate is taken out, dried under vacuum at 120 ° C. for 4 hours, and barium fluorobromide (Ba _0.99 Ca _0.01 FBr: 0.0002) containing potassium calcium activated by europium.
About 230 g of a crystal of ⁽ K, 0.005 Eu ²⁺ ) was obtained. (Sediment 3)

Subsequently, in order to grow a stimulable phosphor precursor of europium-activated barium fluoroiodide on the crystal surface of the stimulable phosphor precursor crystal, a BaI ₂ aqueous solution (4.0 mol / mol) was used. Liter) 2000 ml, 3.75 ml of EuI ₃ aqueous solution (0.2 mol / l), KI 4.
15g, CaI ₂ · 3.3H ₂ O The 0.53 g, and the fluoride barium bromide _{(Ba 0.99 Ca 0.01 FBr: 0} .
200.8 g of 0002K, 0.005 Eu ²⁺ ) crystals were placed in a 4 liter volume reactor. The reaction mother liquor 2 (BaI ₂ concentration of 4.0 mol / l) in this reactor was added to 6
The temperature was maintained at 0 ° C., and a screw-type stirring blade having a diameter of 45 mm and a mixing chamber having a volume of about 100 ml was provided around the stirring blade.
The reaction mother liquor 2 was stirred at 0 rpm to generate an upward flow from the mixing chamber.

A mixture of 15 ml of an aqueous solution of ammonium fluoride (10 mol / l) and 85 ml of water was mixed.
00 ml was added to the mixing chamber in the reaction mother liquor 2 kept warm under the above stirring at an addition rate of 1 ml / min using a precision cylinder pump to produce a precipitate. After completion of the addition, the mixture was kept warm and stirred for 2 hours to ripen the precipitate. Next, the precipitate was filtered off and washed with 2 liters of 2-propanol. The washed precipitate is taken out, dried in vacuum at 150 ° C. for 4 hours, and then barium fluorobromide (Ba _0.99 Ca _0.01 FBr: 0.00) added with europium-activated potassium calcium.
02K, europium-activated potassium calcium added fluoride barium iodide on the crystal surface of 0.005Eu ²⁺⁾ (Ba
Europium-activated potassium calcium-added barium fluorobromide iodide (Ba _0.99 Ca _0.01 FBr _0.85 ) on which _0.99 Ca _0.01 FI: 0.0002K, 005Eu ²⁺ ) crystal has grown.
About 240 g of I _0.15 : 0.0002K, 0.005Eu ²⁺ ) crystals were obtained. (Sediment 4)

In order to prevent a change in particle shape due to sintering during firing and a change in particle size due to fusion between particles, 1% by weight of ultrafine alumina powder is added to the crystals of the precipitate 4. The mixture was sufficiently mixed with a mixer to uniformly adhere the ultrafine alumina powder to the crystal surface. This is 100
g, and then calcined in a tube furnace at 800 ° C. for 2 hours in a nitrogen gas atmosphere, using europium-activated potassium calcium-added barium fluorobromoiodide phosphor particles (Ba _0.99 Ca _0.01 FBr _0.85). I _0.15 : 0.0
002K, 0.005 Eu ²⁺ ). Observation of the obtained phosphor particles with a scanning electron microscope revealed that most of the particles were BaFI crystals grown on columnar tetradecahedral particles having an aspect ratio of 3. A photograph of the phosphor particles at a magnification of 2800 times by an electron microscope is shown in FIG. 3 as a drawing. FIG. 4 is a schematic diagram showing the shape of columnar tetrahedral particles having an aspect ratio of 3. The obtained phosphor particles are made of BaF
The I crystal mainly grew on the crystallographic plane of the columnar tetrahedral particle shown in FIG. 4 shown in black.

(Comparative Example 1) Precipitate 1 obtained in Example 1
Changes in particle shape due to sintering during firing,
Aluminum to prevent particle size change due to fusion
1% by weight of ultra-fine particles of Na
Mix and uniformly disperse ultrafine alumina powder on the crystal surface
Attached. Take 100g of this and fill it into a quartz boat
Using a tube furnace in a nitrogen gas atmosphere at 800 ° C.
Bake for 2 hours in europium activated potassium calcium
Added barium fluorobromide phosphor particles (Ba_0.99Ca _0.01F
Br: 0.0002K, 0.005Eu²⁺) Got. Profit
The observed phosphor particles were observed with a scanning electron microscope.
Most of them have the shape of a tetrahedron with an aspect ratio of 1.
Was. Magnification of the phosphor particles by an electron microscope is 1550.
A magnified photograph is shown in the drawing as FIG.

(Comparative Example 2) Precipitate 3 obtained in Example 2
1% by weight of ultra-fine alumina powder was added to the crystal of Example 1 in order to prevent a change in particle shape due to sintering during sintering and a change in particle size due to fusion between particles. Then, ultrafine alumina powder was uniformly adhered to the crystal surface. 100 g of this was filled in a quartz boat and placed in a tube furnace at 800 ° C. in a nitrogen gas atmosphere.
Bake for 2 hours and add europium-activated potassium calcium-added barium fluorobromide phosphor particles (Ba _0.99 Ca _0.01 F)
Br: 0.0002K, 0.005Eu ²⁺ ). Observation of the obtained phosphor particles with a scanning electron microscope revealed that most of the particles were in the form of a columnar tetrahedron having an aspect ratio of 3. Magnification 28 of this phosphor particle by an electron microscope
A photograph at a magnification of 00 is shown in the drawing as FIG.

Comparative Example 3 In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, BaI was used.
₂ aqueous solution (4.0 mol / l) 2000 ml, Eu
25 ml of I ₃ aqueous solution (0.2 mol / l), 4.15 g of KI and 3.53 g of CaI ₂ .3H ₂ O
Placed in a liter volume reactor. The reaction mother liquor (BaI ₂ concentration 4.0 mol / l) in this reactor was
And a 45-mm diameter screw-type stirring blade having a mixing chamber with a volume of about 100 ml
The reaction mother liquor was stirred so as to generate an upward flow from the mixing chamber by rotating at pm.

Using a precision cylinder pump, 100 ml of 100 ml of an aqueous solution of ammonium fluoride (10 mol / l) was introduced into the mixing chamber in the reaction mother liquor kept warm under stirring.
A precipitate was formed at an addition rate of 1 / min. After completion of the addition, the mixture was kept warm and stirred for 2 hours to ripen the precipitate. Next, the precipitate was filtered off and washed with 2 liters of 2-propanol. Remove the washed sediment,
Vacuum drying for europium-activated potassium calcium-added barium fluoroiodide (Ba _0.99 Ca _0.01 FI: 0.
About 280 g of 0002K, 0.005 Eu ²⁺ ) crystals were obtained.

17.5 g of the crystals of the precipitate and Example 1
And 82.5 g of the crystals of the precipitate 1 obtained in the above step, and in order to prevent a change in particle shape due to sintering during sintering and a change in particle size due to fusion between particles, alumina ultrafine powder is used. Was added by 1% by weight, and the mixture was sufficiently mixed with a mixer to uniformly adhere ultrafine alumina powder to the crystal surface. This was filled in a quartz boat, and calcined at 800 ° C. for 2 hours in a nitrogen gas atmosphere using a tube furnace to prepare europium-activated potassium calcium-added barium fluorobromoiodide phosphor particles (Ba _0.99 Ca _0.01 FBr _0.85 I). _0.15 :
0.0002K, 0.005Eu2 ⁺ ).

The phosphors obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were evaluated as follows. [Measurement of Phosphor Particle Shape and the Like] The particle size (median diameter) and the particle size distribution were measured using a light diffraction type particle size distribution measuring device (LA-500, manufactured by Horiba, Ltd.). As the median diameter, a value measured by the above device was used, and the particle size distribution was calculated from a distribution table measured by the above device (FIG. 9). The particle shape and the particle aspect ratio are measured by a scanning electron microscope (JEOL Ltd., J
(SM-5400LV). The average value was obtained by actually measuring the aspect ratio of 200 points of the particles of the photograph obtained by the above apparatus, and the average value was calculated. Table 1 shows the evaluation results.

[0061]

[Table 1]

[Evaluation of Light Emission Characteristics of Phosphor] <Evaluation of Sensitivity> The obtained phosphor was subjected to 80 kV and 100 mR.
Of X-rays, a He-Ne laser beam (wavelength: 6)
(32.8 nm) at 12.4 J / m ² , the stimulated emission intensity emitted from the phosphor was measured, and the sensitivity was evaluated using the stimulated emission intensity (the phosphor of Comparative Example 1 was used). The stimulated emission intensity shown was taken as a sensitivity of 100 and relatively evaluated.) Table 2 shows the evaluation results.

[0063]

[Table 2]

Next, using the phosphors obtained in Example 1 and Comparative Examples 1 and 3, a radiation image conversion panel was produced by the following procedure and evaluated as follows. 356 g of the phosphor obtained in Example 1 and Comparative Examples 1 and 3, and a polyurethane resin (“Desmolac 412” manufactured by Sumitomo Bayer Urethane Co., Ltd.)
5 ") 15.8 g and bisphenol A type epoxy resin 2.0 g were added to a mixed solvent of methyl ethyl ketone-toluene (1: 1) and dispersed using a propeller mixer, and a phosphor layer coating solution having a viscosity of 25 to 30 PS was prepared. Prepared. This phosphor layer coating solution was applied on a polyethylene terephthalate film with an undercoat using a doctor blade, and then dried at 100 ° C. for 15 minutes to form stimulable phosphor layers of various thicknesses.

Next, a fluorine-based resin (fluoroolefin-
Vinyl ether copolymer: 70 g of "Lumiflon LF-100" manufactured by Asahi Glass Co., Ltd.), a crosslinking agent (isocyanate:
Sumitomo Bayer Urethane Co., Ltd., “Death Module Z4
370 ") 25 g, bisphenol A type epoxy resin 5
g, and 10 g of a silicone resin powder (particle size: 1 to 2 μm: “KMP-590” manufactured by Shin-Etsu Chemical Co., Ltd.) are added to a mixed solvent of toluene and isopropyl alcohol (1: 1). Prepared. This protective layer coating solution is applied onto a stimulable phosphor layer formed in advance using a doctor blade, then heat-treated at 120 ° C. for 30 minutes to be thermally cured and dried, and has a thickness of 10 μm. Was provided. By the method described above, radiation image conversion panels having stimulable phosphor layers of various thicknesses were obtained.

[Evaluation Method of Radiation Image Conversion Panel] <Evaluation of Sensitivity> The produced radiation image conversion panel was irradiated with X-rays having a tube voltage of 80 kV, and then scanned with a He-Ne laser beam (wavelength: 632.8 nm). Then, the photostimulated luminescence intensity emitted from the phosphor layer was measured, and the sensitivity was evaluated using the photostimulated luminescence intensity (the photostimulated luminescence intensity indicated by the panel of Comparative Example 1 was set to a sensitivity of 100, and was relatively determined). evaluated.). <Evaluation of Sharpness> X-rays having a tube voltage of 80 kV were applied to the produced radiation image conversion panel through a CTF chart, and then scanned with a He-Ne laser beam to obtain an image of a CTF chart. A contrast transfer function (CTF) was measured from the obtained image, and evaluated by a CTF value at a spatial frequency of 2 cycles / mm. <Granularity> A tube voltage of 80 was applied to the produced radiation image conversion panel.
After uniform irradiation with X-rays of kV, scanning was performed with a He-Ne laser beam to obtain a uniform exposure image. The graininess of the obtained image signal was evaluated using the RMS value (the RMS value shown by the panel of Comparative Example 1 was set to 100 and the graininess was relatively evaluated). Table 3 shows the above evaluation results.

[0067]

[Table 3]

On the crystal surface of the BaFBr-based phosphor precursor, B
In Examples 1 and 2 in which an aFI-based phosphor precursor crystal was grown at 15 mol%, as shown in Table 1, B
The particle aspect ratio, the particle size, and the particle size distribution are not largely changed as compared with the BaFBr crystal in which the aFI crystal is not grown (Comparative Examples 1 and 2). In Comparative Example 3 in which the particles were mixed, the particle aspect ratio, the particle size, and the particle size distribution were different due to the particle mixing. In the emission characteristics of the phosphor, as shown in Table 2, Br
In Examples 1 and 2 in which was substituted with I by 15 mol%, the sensitivity was significantly improved as compared with Comparative Examples 1 and 2 in which I was not substituted. Further, as shown in Table 3, the image quality of the radiation image conversion panel including the phosphors of Examples 1 and 2 was well balanced in sensitivity, sharpness, and granularity. The image quality of the radiation image conversion panel including the phosphor in which the irregular shaped particles were mixed due to the mixing tended to deteriorate.

[0069]

As described above, when the rare-earth activated alkaline earth metal fluoride halide-based stimulable phosphor contained in the radiation image conversion panel contains iodine, the solubility difference with other halides is too large. Although simple mixed crystal formation by a precipitation reaction in an aqueous solvent was difficult, the present invention enabled mixed crystal formation in one particle with a change in particle shape suppressed in an aqueous solvent. Thus, according to the present invention, when used in a radiation image conversion panel, a high-quality image exhibiting extremely high sharpness can be obtained, and a rare-earth activated alkaline earth metal halogen fluoride having excellent sensitivity and granularity can be obtained. A stimulable phosphor can be provided. Further, according to the present invention, it is possible to provide a novel method for producing the stimulable phosphor, which has high controllability of the particle shape, particle size, and particle size distribution of the obtained stimulable phosphor particles. . Further, according to the present invention, the emission characteristics of the stimulable phosphor are improved by adding iodine, and the stimulable phosphor is used in a radiation image conversion panel, whereby light scattering in the stimulable phosphor layer is improved. Image quality (especially sharpness and structural noise)
Can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a view showing an electron micrograph of a rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor obtained in Example 1.

FIG. 2 is a schematic view showing the shape of a tetrahedral particle having an aspect ratio of 1.

FIG. 3 is a view showing an electron micrograph of the rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor obtained in Example 2.

FIG. 4 is a schematic view showing the shape of a columnar tetrahedral particle having an aspect ratio of 3.

5 is a view showing an electron micrograph of the rare earth activated alkaline earth metal fluorinated halide stimulable phosphor obtained in Comparative Example 1. FIG.

6 is a view showing an electron micrograph of the rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor obtained in Comparative Example 2. FIG.

FIG. 7 shows the arrangement of a conventional plate-like rare earth activated alkaline earth metal fluorinated halide-based stimulable phosphor in a stimulable phosphor layer of a radiation image conversion panel, and the arrangement in the stimulable phosphor layer. It is a figure which shows the direction of light conduction typically.

FIG. 8 is a diagram schematically showing an arrangement of rare earth activated alkaline earth metal fluorohalide-based stimulable phosphors in a phosphor layer of a radiation image conversion panel and a direction of photoconductivity in the phosphor layer. It is.

FIG. 9 is a graph showing the particle size distribution of the rare earth activated alkaline earth metal fluorohalide-based stimulable phosphors obtained in Examples and Comparative Examples.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G083 AA03 BB01 DD02 DD11 DD15 EE02 EE03 4H001 CA04 CA08 CF02 XA09 XA17 XA20 XA35 XA38 XA53 XA56 YA03 YA11 YA19 YA37 YA55 YA58 YA59 YA62 YA63 YA64 YA65

Claims (15)

[Claims] 1. Basic composition formula (I): Ba _{1 -a} M ^II _a FX _{1 -b} I _b : cM ^I , dLn (I) [where M ^II is selected from the group consisting of Sr and Ca Represents at least one alkaline earth metal, wherein M ^I is Li,
X represents at least one alkali metal selected from the group consisting of Na, K, Rb, and Cs; X represents at least one halogen selected from the group consisting of Cl and Br; Ln represents Ce, Pr, Sm, Eu, Gd, Tb, T
represents at least one rare earth element selected from the group consisting of m and Yb, a, b, c and d each represent 0
≦ a ≦ 0.5, 0 <b ≦ 0.5, 0 ≦ c ≦ 0.05, 0
It represents a numerical value in the range represented by <d ≦ 0.2. And an alkaline earth metal fluorinated iodide-based stimulable phosphor precursor crystal having no iodine is formed on the crystal surface of the alkaline earth metal fluorinated halide-based stimulable phosphor precursor crystal. A rare earth activated alkaline earth metal fluorinated halide stimulable phosphor characterized by being grown and mixed in one particle by firing. 2. When the particle aspect ratio is 1.0 to 2.0, the median diameter (Dm) of the particle size is 1 to 10 μm, and the standard deviation of the particle size distribution is σ / The rare earth activated alkaline earth metal fluorinated halide-based stimulable phosphor according to claim 1, wherein Dm is in a range of 50% or less. 3. When the particle aspect ratio is 2.0 to 5.0, the median diameter (Dm) of the particle size is 1 to 20 μm, and the standard deviation of the particle size distribution is σ / The rare earth activated alkaline earth metal fluorinated halide-based stimulable phosphor according to claim 1, wherein Dm is in a range of 50% or less. 4. Ln in the basic composition formula (I) is Ce
4. The rare earth activated alkaline earth metal fluoride halide stimulable phosphor according to claim 1, which is Eu or Eu. 5. Basic composition formula (I): Ba _{1 -a} M ^II _a FX _{1 -b} I _b : cM ^I , dLn (I) wherein M ^II is selected from the group consisting of Sr and Ca Represents at least one alkaline earth metal, and M ^I is Li,
X represents at least one alkali metal selected from the group consisting of Na, K, Rb, and Cs; X represents at least one halogen selected from the group consisting of Cl and Br; Ln represents Ce, Pr, Sm, Eu, Gd, Tb, T
represents at least one rare earth element selected from the group consisting of m and Yb, a, b, c and d each represent 0
≦ a ≦ 0.5, 0 <b ≦ 0.5, 0 ≦ c ≦ 0.05, 0
It represents a numerical value in the range represented by <d ≦ 0.2. Σ when the particle aspect ratio is 1.0 to 2.0, the median diameter (Dm) of the particle size is 1 to 10 μm, and the standard deviation of the particle size distribution is σ. D
A method for producing a rare earth-activated alkaline earth metal fluorohalide-based stimulable phosphor, wherein m is in the range of 50% or less, wherein BaX ₂ ; a water-soluble compound of Ln;
Halides of further M ^II is in the case of a is not 0, nitrate, nitrite or acetate; c halides further M ^I when non-zero the formula (I), nitrate, nitrite or A first mother liquor preparation step of preparing a reaction mother liquor 1 which is an aqueous solution containing acetic acid salt and having a BaX ₂ concentration of 2.5 mol / liter or less after dissolving them; While maintaining a temperature of 20-100 ° C,
A first precipitate forming step of adding an aqueous solution of an inorganic fluoride salt thereto to form a precipitate of an alkaline earth metal fluorohalide-based stimulable phosphor precursor crystal; A first separation step of separating a precipitate of crystals from an aqueous solution; BaI ₂ ; a water-soluble compound of Ln;
Halides of further M ^II is in the case of a is not 0, nitrate, nitrite or acetate; c halides further M ^I when non-zero the formula (I), nitrate, nitrite or A second step of preparing a reaction mother liquor 2 which is an aqueous solution containing an acetate salt; a precipitate of the separated phosphor precursor crystal; and having a BaI ₂ concentration of 5.0 mol / liter or less after dissolution. An aqueous solution of an inorganic fluoride salt is added to the reaction mother liquor 2 while maintaining the reaction mother liquor 2 at a temperature of 20 to 100 ° C., so that an alkaline earth metal fluoride is formed on the surface of the phosphor precursor crystal. A second precipitate forming step of obtaining a precipitate in which the iodide-based stimulable phosphor precursor crystal has grown, and a second step of separating the precipitate obtained in the second precipitate forming step from an aqueous solution A separating step; and a separation step performed in the second separating step. A rare earth-activated alkaline earth metal fluorohalide-based stimulable phosphor characterized by comprising a firing step of firing the precipitate while avoiding sintering to form a mixed crystal in one particle. Method. 6. When the amount of the precipitate of the phosphor precursor crystal finally obtained is N when the aqueous solution of the inorganic fluoride salt is added in the first precipitate formation step, the precipitate is formed during the addition. The amount of the precipitate of the phosphor precursor crystal is 0.001 N /
The rare earth-activated alkaline earth metal fluorohalide-based stimulable phosphor according to claim 5, wherein the aqueous solution of the inorganic fluoride salt is added by adjusting the addition rate so as to be in the range of 10 to 10 N / min. Production method. 7. The rare earth activated alkali according to claim 5, wherein the rate of addition of the inorganic fluoride aqueous solution in the first precipitate formation step changes at a constant rate or continuously or intermittently with the addition time. A method for producing an earth metal fluorohalide-based stimulable phosphor. 8. The method according to claim 5, wherein the inorganic fluoride salt in the first precipitate forming step and the second precipitate forming step is ammonium fluoride or a fluoride of an alkali metal, respectively. For producing a rare earth activated alkaline earth metal fluorinated halide stimulable phosphor. 9. Basic composition formula (I): Ba _{1 -a} M ^II aFX _{1 -b} I _b : cM ^I , dLn (I) wherein M ^II is selected from the group consisting of Sr and Ca at least one rare earth metal, M ^I is Li,
X represents at least one alkali metal selected from the group consisting of Na, K, Rb, and Cs; X represents at least one halogen selected from the group consisting of Cl and Br; Ln represents Ce, Pr, Sm, Eu, Gd, Tb, T
represents at least one rare earth element selected from the group consisting of m and Yb, a, b, c and d each represent 0
≦ a ≦ 0.5, 0 <b ≦ 0.5, 0 ≦ c ≦ 0.05, 0
It represents a numerical value in the range represented by <d ≦ 0.2. Σ when the particle aspect ratio is 2.0 to 5.0, the median diameter (Dm) of the particle size is 1 to 20 μm, and the standard deviation of the particle size distribution is σ. D
A method for producing a rare earth-activated alkaline earth metal fluorohalide-based stimulable phosphor, wherein m is in the range of 50% or less, wherein NH ₄ X; a water-soluble compound of Ln;
Halides of further M ^II is in the case of a is not 0, nitrate, nitrite or acetate; c halides further M ^I when non-zero the formula (I), nitrate, nitrite or A first mother liquor preparation step of preparing a reaction mother liquor 1 which is an aqueous solution containing acetate; and having an NH ₄ X concentration of 4.5 mol / liter or less after dissolving them; While maintaining the temperature at 20-100 ° C.
To this, an aqueous solution of an inorganic fluoride salt and an aqueous solution of BaX ₂ are added simultaneously, and the molar ratio between the fluorine of the inorganic fluoride salt and BaX ₂ is kept constant. Precipitate forming step of forming a precipitate of a fluoride-based stimulable phosphor precursor crystal; a first separating step of separating the precipitate of the phosphor precursor crystal from an aqueous solution; BaI ₂ ; Ln A water-soluble compound of the formula:
Halides of further M ^II is in the case of a is not 0, nitrate, nitrite or acetate; c halides further M ^I when non-zero the formula (I), nitrate, nitrite or A second step of preparing a reaction mother liquor 2 which is an aqueous solution containing an acetate salt; a precipitate of the separated phosphor precursor crystal; and having a BaI ₂ concentration of 5.0 mol / liter or less after dissolution. An aqueous solution of an inorganic fluoride salt is added to the reaction mother liquor 2 while maintaining the temperature of the reaction mother liquor 2 at a temperature of 20 to 100 ° C., so that an alkaline earth metal fluoride A second precipitate forming step of obtaining a precipitate in which the iodide-based stimulable phosphor precursor crystal has grown, and a second step of separating the precipitate obtained in the second precipitate forming step from an aqueous solution Separated in the separation step and the second separation step And baking the precipitate while avoiding sintering to form a mixed crystal within one particle; and producing a rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor. Method. 10. The method according to claim 1, wherein the amount of the precipitate of the phosphor precursor crystals finally obtained is N when the aqueous solution of the inorganic fluoride salt and the aqueous solution of BaX ₂ are added in the first precipitate formation step. The addition rate was adjusted so that the amount of the precipitates of the phosphor precursor crystals formed during the addition was in the range of 0.001 N / min to 10 N / min, and the aqueous solution of inorganic fluoride salt and B
method for producing a rare earth activated alkaline earth metal fluorohalide stimulable phosphor according to claim 9 adding an aqueous solution of aX _2. 11. The method according to claim 9, wherein the rate of addition of the aqueous solution of inorganic fluoride and the aqueous solution of BaX ₂ in the first precipitate formation step changes at a constant rate or continuously or intermittently with the addition time. For producing a rare earth activated alkaline earth metal fluorinated halide stimulable phosphor. 12. The method according to claim 9, wherein the inorganic fluoride salt in the first precipitate forming step and the second precipitate forming step is ammonium fluoride or a fluoride of an alkali metal, respectively. For producing a rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor according to the present invention. 13. A radiation image conversion panel having a stimulable phosphor layer containing a stimulable phosphor, wherein the stimulable phosphor is a rare earth-activated alkaline earth according to any one of claims 1 to 4. A radiation image conversion panel comprising a metal fluorinated halide stimulable phosphor. 14. A basic composition formula (I): Ba _{1 -a} M ^II _a FX _{1 -b} I _b : cM ^I , dLn (I) where M ^II is selected from the group consisting of Sr and Ca Represents at least one alkaline earth metal, wherein M ^I is Li,
X represents at least one alkali metal selected from the group consisting of Na, K, Rb, and Cs; X represents at least one halogen selected from the group consisting of Cl and Br; Ln represents Ce, Pr, Sm, Eu, Gd, Tb, T
represents at least one rare earth element selected from the group consisting of m and Yb, a, b, c and d each represent 0
≦ a ≦ 0.5, 0 <b ≦ 0.5, 0 ≦ c ≦ 0.05, 0
It represents a numerical value in the range represented by <d ≦ 0.2. Σ when the particle aspect ratio is 1.0 to 2.0, the median diameter (Dm) of the particle size is 1 to 10 μm, and the standard deviation of the particle size distribution is σ. D
A method for producing a rare earth-activated alkaline earth metal fluorohalide-based stimulable phosphor, wherein m is in the range of 50% or less, wherein BaX ₂ ; Is an aqueous solution further containing a halide, nitrate, nitrite or acetate of M ^II ; and when c of the basic composition formula (I) is not 0, further containing a halide, nitrate, nitrite or acetate of M ^I. A first mother liquor preparation step of preparing a reaction mother liquor 1 having a BaX ₂ concentration of 2.5 mol / liter or less after dissolution of the mother liquor; While maintaining
A first precipitate forming step of adding an aqueous solution of an inorganic fluoride salt thereto to form a precipitate of an alkaline earth metal fluorohalide-based stimulable phosphor precursor crystal; A first separation step of separating the precipitate of crystals from the aqueous solution; BaI ₂ ; if a in the above basic composition formula (I) is not 0, further halides, nitrates, nitrites or acetates of M ^II ; c halides further M ^I when non-zero basic composition formula (I), the nitrate, nitrite or acetate; precipitation of the separated phosphor precursor crystals; an aqueous solution containing, and they A second mother liquor preparation step of preparing a reaction mother liquor 2 having a BaI ₂ concentration of 5.0 mol / liter or less after dissolving the, and maintaining the reaction mother liquor 2 at a temperature of 20 to 100 ° C. To an aqueous solution of an inorganic fluoride salt, A second precipitate forming step of obtaining a precipitate in which an alkaline earth metal fluoroiodide-based stimulable phosphor precursor crystal has grown on the surface of the phosphor precursor crystal, and the second precipitate forming step A second separation step of separating the precipitate obtained in step 2 from the aqueous solution; and a baking step of baking the precipitate separated in the second separation step while avoiding sintering to form a mixed crystal in one particle. Characterized in that a water-soluble compound of Ln is added in one of the first mother liquor preparation step and the second mother liquor preparation step. A method for producing a stimulable phosphor. 15. A basic composition formula (I): Ba _{1 -a} M ^II aFX _{1 -b} I _b : cM ^I , dLn (I) wherein M ^II is selected from the group consisting of Sr and Ca at least one rare earth metal, M ^I is Li,
X represents at least one alkali metal selected from the group consisting of Na, K, Rb, and Cs; X represents at least one halogen selected from the group consisting of Cl and Br; Ln represents Ce, Pr, Sm, Eu, Gd, Tb, T
represents at least one rare earth element selected from the group consisting of m and Yb, a, b, c and d each represent 0
≦ a ≦ 0.5, 0 <b ≦ 0.5, 0 ≦ c ≦ 0.05, 0
It represents a numerical value in the range represented by <d ≦ 0.2. Σ when the particle aspect ratio is 2.0 to 5.0, the median diameter (Dm) of the particle size is 1 to 20 μm, and the standard deviation of the particle size distribution is σ. D
A method for producing a rare earth-activated alkaline earth metal fluorohalide-based stimulable phosphor, wherein m is in the range of 50% or less, wherein NH ₄ X; a in the above basic composition formula (I) is not 0 An aqueous solution further containing a halide, nitrate, nitrite or acetate of M ^II ; and if c of the above basic composition formula (I) is not 0, further containing a halide, nitrate, nitrite or acetate of M ^I And a first mother liquor preparation step of preparing a reaction mother liquor 1 having an NH ₄ X concentration of 4.5 mol / liter or less after dissolving them, While maintaining the temperature
An aqueous solution of an inorganic fluoride salt and an aqueous solution of BaX ₂ are simultaneously added thereto so as to keep the molar ratio of fluorine of the inorganic fluoride salt to BaX ₂ constant, and the alkaline earth metal halogen fluoride is added. A first precipitate forming step of forming a precipitate of a fluoride-based stimulable phosphor precursor crystal, a first separating step of separating the precipitate of the phosphor precursor crystal from an aqueous solution, and BaI ₂ ; When a in the basic composition formula (I) is not 0, a halide, nitrate, nitrite or acetate of M ^II ; and when c in the above basic composition formula (I) is not 0, further a halide of M ^I , A nitrate, a nitrite or an acetate; an aqueous solution containing the separated precipitate of the phosphor precursor crystal, and having a BaI ₂ concentration of 5.0 mol / l or less after dissolving them. Mother liquor preparation step for preparing the second liquid While maintaining the reaction mother liquor 2 at a temperature of 20 to 100 ° C., an aqueous solution of an inorganic fluoride salt is added to the reaction mother liquor 2 so that an alkaline earth metal fluorinated iodide A second precipitate forming step of obtaining a precipitate in which the stimulable phosphor precursor crystal has grown, a second separating step of separating the precipitate obtained in the second precipitate forming step from an aqueous solution, A baking step of baking the precipitate separated in the second separation step while avoiding sintering to form a mixed crystal within one particle, the first mother liquid preparation step, and the second mother liquid A method for producing a rare earth-activated alkaline earth metal fluorohalide-based stimulable phosphor, wherein a water-soluble compound of Ln is added in one of the preparation steps.