JP4334822B2 - Method for producing melted and solidified europium halide - Google Patents

Description

【００７７】
（２）放射線像変換パネルの製造
臭化セシウム（ＣｓＢｒ）粉末７５ｇをジルコニア製粉末成形用ダイス（内径：３５ｍｍ）に入れ、粉末金型プレス成形機（テーブルプレスＴＢ−５型、エヌピーエーシステム(株)製）にて５０ＭＰａの圧力で加圧し、タブレット（直径：３５ｍｍ、厚み：２０ｍｍ）に成形した。このとき、ＣｓＢｒ粉末に掛かった圧力は約４０ＭＰａであった。次に、このタブレットに真空乾燥機にて温度２００℃で２時間の真空乾燥処理を施した。
【００７８】
支持体として、順にアルカリ洗浄、純水洗浄、およびＩＰＡ洗浄を施した合成石英基板を用意し、蒸着装置内の基板ホルダーに設置した。蒸発源として、上記ＥｕＢｒ_mタブレットとＣｓＢｒタブレットを装置内の所定位置に配置した。その後、装置内を排気して１×１０^-3Ｐａの真空度とした。このとき、真空排気装置として、クライオパネルおよびディフュージョンポンプの組合せを用いた。次いで、基板の蒸着面とは反対側に位置したシーズヒータで、石英基板を２００℃に加熱した。蒸発源それぞれに、電子銃から加速電圧４．０ｋＶの電子線を照射して、４μｍ／分の速度で共蒸着させ、ＣｓＢｒ：Ｅｕ輝尽性蛍光体を堆積させた。このとき、各々の電子銃のエミッション電流（ＣｓＢｒ：１００ｍＡ、ＥｕＢｒ_m：５０ｍＡ）を調整して、輝尽性蛍光体におけるＥｕ／Ｃｓモル濃度比が０．００３／１となるようにした。
【００７９】
蒸着終了後に、装置内を大気圧に戻し、装置から基板を取り出した。基板上には、蛍光体の柱状結晶がほぼ垂直方向に密に林立した構造の蛍光体層（層厚：約４００μｍ、面積１０ｃｍ×１０ｃｍ）が形成されていた。
このようにして、共蒸着により支持体と蛍光体層とからなる本発明に係る放射線像変換パネルを製造した。
【００８０】
［実施例２］
実施例１において、臭化アンモニウムを１０：２（ＥｕＢｒ_m：ＮＨ₄Ｂｒ）の重量比で添加したこと以外は実施例１と同様にして、タブレット状の臭化ユーロピウム溶融凝固体を得た。次いで、このＥｕＢｒ_mタブレットを用いたこと以外は実施例１と同様にして、支持体と蛍光体層とからなる本発明に係る放射線像変換パネルを製造した。
【００８１】
［実施例３］
実施例１において、臭化アンモニウムを１０：３（ＥｕＢｒ_m：ＮＨ₄Ｂｒ）の重量比で添加したこと以外は実施例１と同様にして、タブレット状の臭化ユーロピウム溶融凝固体を得た。次いで、このＥｕＢｒ_mタブレットを用いたこと以外は実施例１と同様にして、支持体と蛍光体層とからなる本発明に係る放射線像変換パネルを製造した。
【００８２】
［実施例４］
実施例１において、臭化アンモニウムを１０：６（ＥｕＢｒ_m：ＮＨ₄Ｂｒ）の重量比で添加したこと以外は実施例１と同様にして、タブレット状の臭化ユーロピウム溶融凝固体を得た。次いで、このＥｕＢｒ_mタブレットを用いたこと以外は実施例１と同様にして、支持体と蛍光体層とからなる本発明に係る放射線像変換パネルを製造した。
【００８３】
［比較例１］
実施例１において、臭化アンモニウムを添加しなかったこと以外は実施例１と同様にして、タブレット状の臭化ユーロピウム溶融凝固体を得た。次いで、このＥｕＢｒ_mタブレットを用いたこと以外は実施例１と同様にして、支持体と蛍光体層とからなる比較のための放射線像変換パネルを製造した。
【００８４】
［比較例２］
実施例１において、ＥｕＢｒ_m蒸発源として粉末状の臭化ユーロピウム原料を粉末金型プレス成形機でタブレット状に成形したものを用いたこと以外は実施例１と同様にして、支持体と蛍光体層とからなる比較のための放射線像変換パネルを製造した。
【００８５】
［臭化ユーロピウム溶融凝固体の性能評価１］
共蒸着の際のＥｕＢｒ_mの蒸着レート（蒸着流の相対速度）を、水晶振動子にて測定した。得られた結果をまとめて表２に示す。
【００８６】
【表２】

【００８７】
表２の結果から明らかなように、本発明の方法に従ってＮＨ₄Ｂｒの存在下で製造したＥｕＢｒ_m溶融凝固体（実施例１〜４）はいずれも、ＮＨ₄Ｂｒの不在下で製造した比較のためのＥｕＢｒ_m溶融凝固体（比較例１）に比べて、ＥｕＯＢｒの含有量が極めて少なく、その結果、蒸着時における蒸着レートが顕著に安定した。
【００８８】
一方、比較のためのＥｕＢｒ_m溶融凝固体（比較例１）は、中央部と周縁部とで組成が大きく異なり、中央部は主としてＥｕＯＢｒから構成されていて蒸着レートが安定し難かった。また、溶融しなかった比較のためのＥｕＢｒ_mタブレット（比較例２）も、ＥｕＯＢｒの含有量が多くて蒸着レートの制御が不可能であり、そして含水量が多かったために蒸着中に突沸を生じた。
さらに、比較例１と２の比較により、加熱溶融の際にＮＨ₄Ｂｒを添加しないと、ＥｕＢｒ_mと反応系中に微量存在するＨ₂Ｏ、Ｏ₂との反応でＥｕＯＢｒが生成するために、返ってＥｕＯＢｒの含有量が増加することが分かる。
【００８９】
［実施例５〜８］
実施例１〜４それぞれにおいて、各蒸発源に電子線を照射する代りに、抵抗加熱器に１２０Ａの電流を流して蒸発源を加熱したこと以外は各実施例と同様にして、支持体と蛍光体層とからなる本発明に係る放射線像変換パネルを製造した。
【００９０】
［比較例３、４］
比較例１、２それぞれにおいて、各蒸発源に電子線を照射する代りに、抵抗加熱器に１２０Ａの電流を流して蒸発源を加熱したこと以外は各比較例と同様にして、支持体と蛍光体層とからなる比較のための放射線像変換パネルを製造した。
【００９１】
［臭化ユーロピウム溶融凝固体の性能評価２］
共蒸着の際のＥｕＢｒ_mの蒸着レート（蒸着流の相対速度）を、水晶振動子にて測定した。得られた結果をまとめて表３に示す。
【００９２】
【表３】

【００９３】
表３から明らかなように、蒸着法を抵抗加熱法に変えても同様の結果が得られた。すなわち、本発明の方法に従ってＮＨ₄Ｂｒの存在下で製造したＥｕＢｒ_m溶融凝固体（実施例５〜８）はいずれも、ＮＨ₄Ｂｒの不在下で製造した比較のためのＥｕＢｒ_m溶融凝固体（比較例３）および溶融しなかった比較のためのＥｕＢｒ_mタブレット（比較例４）に比べて、ＥｕＯＢｒの含有量が極めて少なく、その結果、蒸着時における蒸着レートが顕著に安定した。
【００９４】
【発明の効果】
本発明により、ハロゲンの存在下で、特にハロゲン化アンモニウムを用いて、粉末状のハロゲン化ユーロピウムを溶融したのち冷却することにより、酸化ハロゲン化ユーロピウムの混入が顕著に低減した純度の高いハロゲン化ユーロピウム溶融凝固体を得ることができる。そして、この高純度のハロゲン化ユーロピウム溶融凝固体を蒸発源として用いて蒸着法により蛍光体層を形成することにより、蛍光体組成が均一で、不純物の混入していない均質な蛍光体層を有する放射線像変換パネルを製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a high-purity europium halide melt and solidified body. In particular, the present invention relates to a method for producing a melted and solidified europium halide which is useful as an evaporation source when a deposited europium halide layer is formed on a substrate by vapor deposition.
[0002]
[Prior art]
Europium halide is known as a raw material of a phosphor activated with europium. For example, WO 01/0356 A1 discloses, as a method for producing a phosphor screen made of europium-activated cesium halide stimulable phosphor, two kinds of europium compounds such as cesium halide and europium halide. A method of binary deposition on a substrate using two evaporation sources is disclosed. According to this method, the cesium halide, which is the matrix component of the phosphor, and the europium compound, which is the activator component, are simultaneously heated to evaporate and scatter, and react to form the phosphor and deposit on the substrate surface. Thus, a vapor deposition film of the phosphor is formed.
[0003]
In general, europium halides are in powder form, including commercial products, and when used for vapor deposition as they are, they are highly hygroscopic, so bumping easily occurs due to contained moisture and halogens liberated by heating. It is difficult to form a vapor deposition film having a uniform composition and a good shape. Europium halide is also mixed with oxide halides such as odor oxides.
[0004]
It is known that when europium halide is heated in the presence of water or oxygen, it is difficult to obtain pure europium halide because europium oxide halide is easily formed. That is, it is difficult to obtain a pure europium halide melt solidified body simply by heating and melting and cooling the europium halide.
[0005]
On the other hand, the stimulable phosphor such as the stimulable phosphor absorbs and accumulates part of the radiation energy when irradiated with radiation such as X-rays, and then emits electromagnetic waves (excitation light) such as visible light and infrared light. When irradiated, it has the property of emitting light in accordance with the accumulated radiation energy. A radiation image conversion panel (also referred to as a stimulable phosphor sheet) is a sheet containing a stimulable phosphor, and includes a support and a phosphor layer provided thereon as a basic structure. However, a support is not necessarily required when the phosphor layer is self-supporting. In addition, a protective layer is usually provided on the upper surface of the phosphor layer (the surface not facing the support) to protect the phosphor layer from chemical alteration or physical impact.
[0006]
In particular, when the phosphor layer of the radiation image conversion panel is formed by the vapor deposition method, the phosphor layer does not contain a binder and is composed only of the phosphor, and between the columnar crystals of the phosphor. There are voids (cracks). For this reason, it is possible to increase the entrance efficiency of the excitation light and the extraction efficiency of the emitted light, so that the sensitivity is high, and scattering of the excitation light in the plane direction can be prevented, so that a high sharpness image can be provided. .
[0007]
The radiation image conversion panel is advantageously used in a radiation image recording / reproducing method. In the radiation image recording / reproducing method, the radiation image conversion panel is irradiated with radiation transmitted through the subject or emitted from the subject, and the radiation image information of the subject is once accumulated and recorded, and then excitation of laser light or the like is performed on the panel. This method consists of scanning light and emitting it sequentially as emitted light, and reading the emitted light photoelectrically to obtain an image signal, which has been widely used in recent years. After the reading of the panel is completed, the remaining radiation energy is erased, and then the panel is prepared and used repeatedly for the next imaging.
[0008]
[Problems to be solved by the invention]
When the phosphor layer of the radiation image conversion panel is formed by the vapor deposition method, if the europium halide containing a large amount of oxide is used as the evaporation source, the vapor deposition rate (evaporation flow rate) is not stable, and as a result It has now been found that a vapor deposited film having a europium concentration and a uniform phosphor composition cannot be formed. In addition, a homogeneous vapor deposition film cannot be formed due to the mixing of impurities. Furthermore, a radiation image conversion panel having such a phosphor layer tends to give a radiation image with a lowered image quality.
[0009]
Also, if the moisture content of the evaporation source europium halide exceeds a certain value, troubles such as bumping of the evaporation source during vapor deposition are likely to occur, and the moisture pressure in the vapor deposition atmosphere increases and becomes unstable. . As a result, the shape of the columnar crystals of the obtained deposited film is impaired, or so-called “light emission unevenness” is generated in which the amount of light emission is locally non-uniform when the entire phosphor layer is excited.
[0010]
Accordingly, it is an object of the present invention to provide a method for producing a high purity europium halide melt solidified body.
Another object of the present invention is to provide a high-purity europium halide solidified body useful as an evaporation source.
[0011]
Furthermore, the present invention also provides a method for producing a radiation image conversion panel having a phosphor layer having good columnar crystallinity and a uniform light emission amount. That is, this invention provides the manufacturing method of the radiographic image conversion panel which gives a high quality radiographic image.
[0012]
[Means for Solving the Problems]
The present invention lies in a method for producing a europium halide melt solidified body comprising heating and melting europium halide in the presence of a halogen source and then cooling.
[0013]
In the present invention, europium halide means a compound represented by the following general formula (I).
EuX _m (I)
[Wherein X represents at least one halogen selected from the group consisting of F, Cl, Br and I, and m represents a numerical value in the range of 2.0 ≦ m ≦ 3.0]
[0014]
The present invention also resides in a melted solidified europium halide having a content of europium halide halide of 10% by weight or less for use as an evaporation source in a vapor deposition method.
[0015]
The present invention further provides a multi-source deposition on a substrate of a substance generated by irradiating an electron beam and / or resistance heating each of a plurality of evaporation sources separately containing at least a phosphor base material component and an activator component. Thus, in the method for manufacturing a radiation image conversion panel including the step of forming a phosphor layer, the above-mentioned europium halide molten solidified body is used as an evaporation source containing an activator component of the phosphor. There is also a method for manufacturing a conversion panel.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
In the method for producing a europium halide melt-solidified body of the present invention, it is preferable to add and mix ammonium halide as a halogen source to europium halide. The ammonium halide is preferably added at a weight ratio in the range of 10: 0.1 to 10:10 (the latter: the former) with respect to the europium halide, and the halogens of both compounds are preferably the same. In particular, the halogen is preferably bromine.
[0017]
It is preferable to heat and melt a mixture of europium halide and ammonium halide in an atmosphere having a moisture content of 5.0 × 10 ⁻⁵ mol / L or less and an oxygen concentration of 1.0 × 10 ⁻⁵ mol / L or less. And it is preferable to heat and melt in an inert gas atmosphere or a reducing gas atmosphere. The molten europium halide is preferably cooled in a vacuum, in an inert gas atmosphere or in a reducing gas atmosphere.
[0018]
The reaction system containing this mixture is preferably dried before being melted by heating, and particularly preferably dried by heating at a temperature of 50 to 400 ° C. at a vacuum degree of 100 Pa or higher.
[0019]
Both are preferably dried before mixing, and particularly preferably dried by heating at a temperature of 50 to 400 ° C. under vacuum.
[0020]
Alternatively, it is preferable to heat and melt europium halide in an atmosphere containing halogen gas or hydrogen halide gas as halogen. The halogen gas or hydrogen halide gas is preferably contained in the melting atmosphere in the range of 1 × 10 ^{−6 to} 1 × 10 ⁵ Pa, and the halogen of the halogen gas or hydrogen halide gas and the halogen of europium halide are the same. It is preferable that In particular, the halogen is preferably bromine.
[0021]
Europium halide is preferably melted by heating in an atmosphere having a moisture content of 5.0 × 10 ⁻⁵ mol / L or less and an oxygen concentration of 1.0 × 10 ⁻⁵ or less, and halogen gas or hydrogen halide gas It is preferable to heat and melt in an inert gas atmosphere or a reducing gas atmosphere. The molten europium halide is preferably cooled in a vacuum, in an inert gas atmosphere or in a reducing gas atmosphere.
[0022]
The reaction system containing the europium halide is preferably dried before heating and melting, and particularly preferably dried by heating at a temperature of 50 to 400 ° C. at a vacuum degree of 100 Pa or higher.
[0023]
It is preferable to dry the europium halide before heating and melting, and it is particularly preferable to dry by heating at a temperature of 50 to 400 ° C. under vacuum.
[0024]
In the europium halide melt solidified body produced by the above method, the content of europium oxide halide is preferably 10% by weight or less, and the water content is preferably 0.5% by weight or less.
[0025]
In the melted and solidified europium halide of the present invention, the content of the europium oxide halide is preferably 3% by weight or less, particularly preferably 1% by weight or less. Further, the water content is preferably 0.5% by weight or less.
[0026]
In the method for producing a radiation image conversion panel of the present invention, the phosphor is preferably a phosphor containing europium as an activator, and in particular, a europium activated alkali metal halide system having the following basic composition formula (II): A stimulable phosphor is preferred.
[0027]
M ^I X · aM ^II X ' ₂ · bM ^III X " ₃ : zEu (II)
[Wherein M ^I represents at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs; M ^II represents Be, Mg, Ca, Sr, Ba, Ni, Cu, Zn, and Cd. M ^III represents Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, and at least one alkaline earth metal or divalent metal selected from the group consisting of Represents at least one rare earth element or trivalent metal selected from the group consisting of Tm, Yb, Lu, Al, Ga and In; X, X ′ and X ″ are from the group consisting of F, Cl, Br and I, respectively. Represents at least one selected halogen; and a, b, and z represent numerical values in the range of 0 ≦ a <0.5, 0 ≦ b <0.5, and 0 <z <1.0, respectively.
[0028]
Below, the manufacturing method of the europium halide melt-solidified body of this invention is described in detail.
[0029]
The europium halide raw material used in the present invention is a compound represented by the following general formula (I), and europium may be divalent, trivalent, or a mixture thereof. . This europium halide raw material is generally a powder.
EuX _m (I)
[Wherein X represents at least one halogen selected from the group consisting of F, Cl, Br and I, and m represents a numerical value in the range of 2.0 ≦ m ≦ 3.0]
[0030]
In the present invention, the halogen source includes ammonium halide (NH ₄ X ′, where X ′ is F, Cl, Br and / or I), halogen alone (F, Cl, Br and / or I), or halogen Hydrogen fluoride gas (HX ′) can be used. The ammonium halide may be used as a solid or may be vaporized and used as a gas. Halogen alone can be used in gaseous, liquid or solid form depending on the type and operating conditions. It is preferable that the halogen of the ammonium halide, the hydrogen halide gas or the halogen simple substance is the same as the halogen of the europium halide. A particularly preferred halogen is bromine (X, X ′ = Br).
[0031]
When solid ammonium halide is used as the halogen source, it is preferable that the EuX _m raw material and NH ₄ X ′ are preliminarily dried to remove moisture as much as possible. The drying treatment can be performed, for example, by heating each compound at a temperature of 50 to 400 ° C. for about 1 to 10 hours under vacuum using a vacuum dryer or the like.
[0032]
Next, the dried EuX _m raw material and NH ₄ X ′ are mixed. The mixing is preferably performed under dry air. NH ₄ X ′ is preferably added at a weight ratio in the range of 10: 0.1 to 10:10 (the latter: the former) with respect to the EuX _m raw material, and particularly preferably 10: 1 to 10: 5 ( The latter is the weight ratio in the range of the former.
[0033]
The mixture was then platinum crucible of EuX _m feedstock and NH ₄ X ', an alumina crucible was filled in a heat resistant vessel such as a quartz boat, and heated to a temperature above the melting point of EuX _m placed in the furnace core of the electric furnace Melt. Prior to heating, the inside of the furnace core loaded with the mixture is preferably dried. For example, drying is performed by heating at a vacuum degree of 100 Pa or higher, preferably 10 Pa or higher, at a temperature of 50 to 400 ° C. for about 10 minutes to 12 hours. Can do.
[0034]
The melting temperature is generally in the range of 500 to 2000 ° C. As the melting atmosphere, an inert gas atmosphere such as nitrogen gas or a reducing gas atmosphere such as hydrogen gas is generally used. The water content in the molten atmosphere is generally 5.0 × 10 ⁻⁵ mol / L or less, preferably 5.0 × 10 ⁻⁶ mol / L or less. The oxygen concentration in the molten atmosphere is generally 1.0 × 10 ⁻⁵ mol / L or less, preferably 1.0 × 10 ⁻⁶ mol / L or less. The melting time is generally from 30 minutes to 12 hours.
[0035]
EuX during heat melting _m forms a equilibrium with oxides europium halide (EuOX) by water or oxygen present in the reaction system. By allowing the halogen source NH ₄ X ′ to be present in the reaction system, this equilibrium state can be shifted to the EuX _m side (if there is no NH ₄ X ′, EuOX is further generated). That is, it is possible to reduce by controlling the by-product amount of EuOX by reaction of EuX _m and H ₂ O, and O _2. However, if there is an excessive amount of NH ₄ X ′, EuXm approaches EuX ₃ . Furthermore, the halogen source NH ₄ X ′ can convert EuOX contained in the EuX _m raw material into EuX ₂ .
[0036]
Next, the melted EuX _m is cooled and solidified. Cooling is preferably performed under vacuum, in an inert gas atmosphere, or in a reducing gas atmosphere. The added NH ₄ X ′ sublimates into a gas during the heating process and is removed during the cooling process.
[0037]
In this manner, melting and solidification of EuX _m is obtained. However, the Eu valence of the obtained EuX _m melted solidified body, that is, _m , may be slightly different from the raw material EuX _m depending on the amount of NH ₄ X ′, melting conditions, and the like. By selecting the shape of the heat-resistant container such as a crucible to be used, the EuX _m melted solidified body can be formed into a desired shape such as a tablet. Further, the EuX _m melted solidified body can be stored and stored for several weeks to several months by vacuum packaging with an aluminum film in a dry gas atmosphere.
[0038]
As described above, gaseous, liquid or solid halogen (F, Cl, Br and / or I) or hydrogen halide gas (HX ′) can be used as the halogen source.
[0039]
In this case, the heating and melting the EuX _m feedstock in an atmosphere containing X _'2 gas or HX' gas. Preferably, it is melted by heating in an inert gas atmosphere containing X ′ ₂ gas or HX ′ gas or in a reducing gas atmosphere. X ′ ₂ gas or HX ′ gas is preferably contained in the melting atmosphere in the range of 1 × 10 ^{−6 to} 1 × 10 ⁵ Pa. Alternatively, in the presence of a liquid halogen (Br ₂₎ or solid silver (I _2), is heated and melted EuX _m raw materials or reducing gas atmosphere in an inert gas atmosphere. However, similarly to the above, the amount of water in the molten atmosphere is generally 5.0 × 10 ⁻⁵ mol / L or less, preferably 5.0 × 10 ⁻⁶ mol / L or less. The oxygen concentration in the molten atmosphere is generally 1.0 × 10 ⁻⁵ mol / L or less, preferably 1.0 × 10 ⁻⁶ mol / L or less.
[0040]
An EuX _m melted solidified body can be obtained by heating and melting the EuX _m raw material under the same conditions and operations as described above and then cooling. Also, prior to heating, to a powdery EuX _m feedstock may be dried, it may be dried in a furnace core loaded with EuX _m feedstock.
[0041]
In this way, a high purity europium halide (EuX _m ) melt-solidified body can be obtained. In other words, is not less than 10% by weight oxide content of europium halide (EuOX), also the water content is a EuX _m melt solidified body is 0.5 wt% or less, can be preferably obtained. More preferably, can EuOX content obtain EuX _m melt solidified body is 3 wt% or less, particularly preferably, may EuOX content obtain EuX _m melt solidified body is not more than 1 wt%. Here, EuOX content, as described later in Examples, by X-ray diffraction method, and calculates the ratio of EuOX peak area (100 plane) / EuX ₂ peak area (211 plane), obtained from the calibration curve Value. The water content is a value calculated from the weight loss at a temperature of 50 to 150 ° C. by thermogravimetric analysis, as will be described later in Examples.
[0042]
Hereinafter, a method for producing the radiation image conversion panel of the present invention using the EuX _m melted solidified body will be described by taking as an example the case where the phosphor is a storage phosphor.
[0043]
The substrate for forming the vapor deposition film usually serves also as a support for the radiation image conversion panel, and can be arbitrarily selected from known materials as a support for the conventional radiation image conversion panel. A quartz glass sheet, a sapphire glass sheet; a metal sheet made of aluminum, iron, tin, chromium or the like; a resin sheet made of aramid or the like. In a known radiation image conversion panel, in order to improve the sensitivity or image quality (sharpness, graininess) of the panel, a light reflecting layer made of a light reflecting material such as titanium dioxide, or a light absorbing material such as carbon black It is known to provide a light absorption layer made of or the like. These various layers can also be provided for the substrate used in the present invention, and the configuration thereof can be arbitrarily selected according to the desired purpose and application of the radiation image conversion panel. Further, for the purpose of enhancing the columnar crystallinity, an auxiliary layer such as a surface on the phosphor layer side of the substrate (an undercoat layer (adhesion imparting layer) on the surface of the phosphor layer side of the substrate, a light reflecting layer or a light absorbing layer) is provided. If it is provided, the surface of those auxiliary layers may be finely formed).
[0044]
In the present invention, the stimulable phosphor is a phosphor activated with at least europium. In general, a stimulable phosphor that exhibits stimulated emission in a wavelength range of 300 to 500 nm when irradiated with excitation light having a wavelength in the range of 400 to 900 nm is preferable.
[0045]
Among these, basic composition formula (II):
M ^I X · aM ^II X ' ₂ · bM ^III X " ₃ : zEu (II)
The europium activated alkali metal halide photostimulable phosphor represented by the formula (1) is particularly preferred. M ^I represents at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs, and M ^II consists of Be, Mg, Ca, Sr, Ba, Ni, Cu, Zn, and Cd. at least one rare earth element or trivalent metal selected from the group, M ^III is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm Represents at least one rare earth element or trivalent metal selected from the group consisting of Yb, Lu, Al, Ga and In. X, X ′ and X ″ each represent at least one halogen selected from the group consisting of F, Cl, Br and I. a, b and z are 0 ≦ a <0.5 and 0 ≦ b <, respectively. It represents a numerical value within the range of 0.5 and 0 <z <1.0.
[0046]
M ^I in the basic composition formula (II) preferably contains at least Cs. X preferably contains at least Br. In addition, in the basic composition formula (II), if necessary, a metal oxide such as aluminum oxide, silicon dioxide, zirconium oxide or the like is added in an amount of 0.5 mol or less with respect to 1 mol of M ^I. May be added.
[0047]
First, as an evaporation source, an evaporation source including at least a matrix component of the phosphor is prepared in addition to the above-described europium halide (EuX _m ) molten solidified body that is an activator component of the stimulable phosphor. This evaporation source may be composed of only a host component of the phosphor or a mixture with an additive component or the like according to the desired phosphor composition. Further, the matrix component of the phosphor may be a compound itself constituting the matrix, or may be a mixture of two or more raw materials that can react to become a matrix compound. Further, the number of evaporation sources may be three or more. Multi-source vapor deposition is preferable because the vapor deposition rate can be controlled when the vapor pressures of the respective components of the phosphor are greatly different.
[0048]
EuX _m melt solidified body used as the evaporation source in the present invention is generally EuOX content of 10 wt% or less. Preferably, the EuOX content is 3% by weight or less, and particularly preferably, the EuOX content is 1% by weight or less. By suppressing the EuOX content to such a low value, the deposition rate can be stabilized.
[0049]
Further, EuX _m melt solidified body preferably has a water content of 0.5 wt% or less. Furthermore, it is preferable that other phosphor components such as a phosphor matrix component serving as an evaporation source have a water content of 0.5% by weight or less. In the case where the matrix component and the activator component of the phosphor are hygroscopic such as CsBr and EuBr, for example, they easily contain moisture. It is important from the standpoint of preventing bumping to keep the water content of the evaporation source at such a low value. The dehydration of the evaporation source is several tens of minutes at a temperature equal to or higher than the melting point of the phosphor component by heat-treating the phosphor component in a temperature range of 100 to 300 ° C. under reduced pressure or in an atmosphere not containing moisture such as a nitrogen atmosphere It can be carried out by heating and melting for several hours.
[0050]
Furthermore, EuX _m melt-solidified body is preferably a molar ratio of Eu ²⁺ is 70% or more. In general, Eu compounds contain a mixture of Eu ²⁺ and Eu ^3+, but the desired stimulating luminescence (or even instantaneous luminescence) is a phosphor using Eu ²⁺ as an activator. Because it is emitted from. That is, m is preferably a numerical value within a range of 2.0 ≦ m ≦ 2.3. Although m is desirably 2.0, oxygen tends to be mixed when trying to approach 2.0. Therefore, in practice, the state where m is around 2.2 and the ratio of halogen X is relatively high is stable. X is preferably bromine.
[0051]
The relative density of the evaporation source is preferably 80% or more, more preferably 90% or more and 100% or less. Here, the relative density means the ratio of the actual density of the evaporation source to the density specific to the phosphor or its raw material. If the evaporation source is in a powder state with a low relative density, there will be inconveniences such as powder scattering during vapor deposition, or the film thickness of the vapor deposition film will be non-uniform without evaporating uniformly from the surface of the evaporation source. Or Therefore, in order to realize stable vapor deposition, it is desirable that the density of the evaporation source is high to some extent. In order to obtain the above relative density, generally, the powder is pressure-molded at a pressure of 20 MPa or more, or is heated and melted at a temperature of the melting point or more to form a tablet (tablet). However, the evaporation source is not necessarily in the form of a tablet.
[0052]
An evaporation source, particularly an evaporation source including a phosphor matrix component, has an alkali metal impurity (that is, an alkali metal other than the constituent elements of the phosphor) of 10 ppm or less, and an alkaline earth metal impurity (that is, a phosphor). The content of (alkaline earth metal other than the constituent elements) is preferably 1 ppm or less. Such an evaporation source can be prepared by using a raw material having a low impurity content such as an alkali metal or an alkaline earth metal. As a result, it is possible to form a vapor-deposited film with few impurities and to increase the amount of light emitted from such a vapor-deposited film.
[0053]
The evaporation source and the substrate are installed in a vapor deposition apparatus, and the inside of the apparatus is evacuated to a vacuum degree of about 1 × 10 ⁻⁵ to 1 × 10 ⁻² Pa. At this time, an inert gas such as Ar gas, Ne gas, or N ₂ gas may be introduced while maintaining the degree of vacuum at this level. Further, the moisture pressure in the atmosphere in the apparatus is preferably set to 7.0 × 10 ⁻³ Pa or less by using a cryopump, a combination of a diffusion pump and a cold trap or the like.
[0054]
In forming the vapor-deposited phosphor layer, for example, each of a plurality of evaporation sources separately containing at least a phosphor base component and an activator component is irradiated with an electron beam or resistance-heated, or one of the electron beam Irradiation is performed, and a substance generated by applying resistance heating to the other is vapor-deposited on the substrate. Note that, when heating one evaporation source, electron beam irradiation and resistance heating may be used in combination.
[0055]
The plurality of vapor deposition sources may be three or more evaporation sources including a base component, one or more activator components, and, optionally, one or more additive components. In this case, the heating methods of the respective evaporation sources may be the same, or two or three or more may use the same heating method, and others may use different heating methods. Alternatively, all evaporation sources may be heated by different heating methods. Needless to say, in heating, electron beam irradiation and resistance heating may be used in combination.
[0056]
In the following description, an example of heating and evaporating two evaporation sources, ie, a matrix component evaporation source and an activator component evaporation source, by electron beam irradiation using an electron gun will be described.
[0057]
Electron beams are generated from two electron guns, respectively, and irradiated to each evaporation source. At this time, it is desirable to set the acceleration voltage of the electron beam to 1.5 kV or more and 5.0 kV or less. By irradiation with an electron beam, the matrix component, activator component, and the like of the stimulable phosphor that is the evaporation source are heated to evaporate and scatter, and react to form the phosphor and deposit on the substrate surface. At this time, the evaporation rate of each evaporation source may be controlled by adjusting the acceleration voltage of each electron beam. The deposition rate of the phosphor, that is, the deposition rate is generally in the range of 0.1 to 1000 μm / min, and preferably in the range of 1 to 100 μm / min. Alternatively, each deposition source can be heated by resistance heating. Alternatively, either one can be irradiated with an electron beam and the other can be subjected to resistance heating treatment.
[0058]
In the present invention, the EuX _m melted and solidified body, which is the evaporation source of the activator component, has a high purity containing almost no EuOX or moisture, and therefore does not cause trouble such as bumping and has a stable deposition rate. Can be deposited. Therefore, a uniform vapor deposition film can be formed.
[0059]
Two or more phosphor layers can be formed by performing electron beam irradiation in a plurality of times. Further, the deposition target (substrate) may be cooled or heated as necessary during vapor deposition, or the phosphor layer may be heat-treated (annealed) after vapor deposition.
[0060]
Instead of using two electron guns, two evaporation sources are placed in close proximity, and the electron beam from one electron gun is controlled using a two-point controller, so that each evaporation source has an electron alternately. It is also possible to employ a method of irradiating a line.
[0061]
Alternatively, prior to forming the deposited film made of the stimulable phosphor, a deposited film made only of the phosphor base material may be formed. As a result, it is possible to obtain a vapor deposition film with even better columnar crystallinity. Note that additives such as an activator in the vapor-deposited film made of the phosphor diffuse into the vapor-deposited film made of the phosphor matrix, particularly by heating during vapor deposition and / or heat treatment after vapor deposition. May not always be clear.
[0062]
In addition, when using the resistance heating method, a vapor deposition apparatus equipped with a resistance heater is used to heat the evaporation source by passing an electric current through the resistance heater to form the matrix component of the stimulable phosphor that is the evaporation source. And activator components are evaporated and scattered.
[0063]
In this way, a layer is obtained in which columnar crystals made of a stimulable phosphor are grown substantially in the thickness direction. The layer thickness of the phosphor layer is usually in the range of 50 to 1000 μm, preferably in the range of 200 μm to 700 mm.
[0064]
The substrate does not necessarily have to serve as a support for the radiation image conversion panel. After forming the phosphor layer, the phosphor layer is peeled off from the substrate and bonded to the prepared support using an adhesive or the like. A method of providing a phosphor layer on a support may be used. Alternatively, the support (substrate) may not be attached to the phosphor layer.
[0065]
It is desirable to provide a protective layer on the surface of the phosphor layer in order to facilitate transportation and handling of the radiation image conversion panel and avoid characteristic changes. It is desirable that the protective layer be transparent so that it does not affect the incidence of excitation light and emission of emitted light, and the radiation image conversion panel is sufficiently protected from physical impacts and chemical effects given from the outside. It is desirable to be chemically stable, highly moisture-proof, and have high physical strength.
[0066]
As the protective layer, a solution prepared by dissolving a transparent organic polymer substance such as cellulose derivative, polymethyl methacrylate, organic solvent-soluble fluorine-based resin in an appropriate solvent is applied on the phosphor layer. Formed, or separately formed a protective layer forming sheet such as an organic polymer film such as polyethylene terephthalate or a transparent glass plate, and provided with an appropriate adhesive on the surface of the phosphor layer, or inorganic A compound formed on the phosphor layer by vapor deposition or the like is used. In addition, in the protective layer, various additives such as light scattering fine particles such as magnesium oxide, zinc oxide, titanium dioxide and alumina, slipping agents such as perfluoroolefin resin powder and silicone resin powder, and crosslinking agents such as polyisocyanate. May be dispersed and contained. The thickness of the protective layer is generally in the range of about 0.1 to 20 μm when it is made of a polymer substance, and is in the range of 100 to 1000 μm when it is made of an inorganic compound such as glass.
[0067]
A fluororesin coating layer may be further provided on the surface of the protective layer in order to increase the stain resistance of the protective layer. The fluororesin coating layer can be formed by coating a fluororesin solution prepared by dissolving (or dispersing) a fluororesin in an organic solvent on the surface of the protective layer and drying. Although the fluororesin may be used alone, it is usually used as a mixture of a fluororesin and a resin having a high film forming property. In addition, an oligomer having a polysiloxane skeleton or an oligomer having a perfluoroalkyl group can be used in combination. The fluororesin coating layer can be filled with a fine particle filler in order to reduce interference unevenness and further improve the image quality of the radiation image. The thickness of the fluororesin coating layer is usually in the range of 0.5 μm to 20 μm. In forming the fluororesin coating layer, additive components such as a cross-linking agent, a hardener, and a yellowing inhibitor can be used. In particular, the addition of a crosslinking agent is advantageous for improving the durability of the fluororesin coating layer.
[0068]
Although the radiation image conversion panel according to the present invention is obtained as described above, the configuration of the panel of the present invention may include various known modifications. For example, for the purpose of improving the sharpness of the obtained image, at least one of the layers may be colored with a colorant that absorbs excitation light and does not absorb emitted light.
[0069]
Further, in the present invention, the phosphor is not limited to the stimulable phosphor, and the radiation image conversion panel is also a stimulable phosphor (energy storing fluorescence) as described in JP-A-2001-255610. And a phosphor screen containing a phosphor (radiation absorbing phosphor) that absorbs radiation and emits light in the ultraviolet to visible region.
[0070]
【Example】
In the following examples, the EuOBr content of the sample was prepared separately after calculating the ratio of the EuOBr peak area (100 planes) / EuBr ₂ peak area (211 planes) of the sample by X-ray diffraction (XRD). was determined based on the following calibration curve prepared using a known EuOBr · EuBr ₂ mixture was.
[0071]
Calibration curve: EuOBr content (% by weight) =
52.0 × EuOBr peak area (100 faces) / EuBr ₂ peak area (211 faces)
[0072]
The moisture content of the sample was increased in a nitrogen flow (200 cc / min) atmosphere using a differential thermothermal gravimetric simultaneous measurement device (TG / DTA320 type, manufactured by Seiko Denshi Kogyo Co., Ltd.) according to thermogravimetric analysis. The temperature was increased from room temperature to 300 ° C. at a temperature rate of 10 ° C./min, and the weight loss of the sample was measured.
[0073]
[Example 1]
(1) Production of europium bromide melt solidified powder Ammonium bromide (NH ₄ Br, product of Kanto Chemical Co., Inc.) was vacuum dried at 150 ° C. for 1 hour in a vacuum dryer. This ammonium bromide was added to europium bromide (EuBr _m , m = 2.2, manufactured by Furuuchi Chemical Co., Ltd.) at a weight ratio of 10: 1 (EuBr _m : NH ₄ Br) and then mixed under dry air did. The water content of the obtained powdery mixture was 0.6% by weight or more. This mixture was filled in a double platinum crucible, placed on a quartz boat, and this quartz boat was placed together with the core of the tube furnace. The inside of the furnace core was heated for 1 hour at a temperature of 200 ° C. and a degree of vacuum of 54 to 6.6 Pa, and dried to obtain a dry powder having a moisture content of 0.33% by weight or less.
[0074]
Next, nitrogen gas was introduced into the furnace core to normal pressure, and the mixture was melted at a temperature of 800 ° C. for 1 hour. Next, the obtained melt was naturally cooled for 30 minutes while evacuating the inside of the furnace core. Thus, a tablet-like (diameter: 30 mm, thickness: 5 mm) europium bromide melt-solidified body was obtained.
[0075]
The atmosphere in the furnace core before and after vacuum drying (before the start of melting) was as shown in Table 1. However, the moisture content is a value calculated on the assumption that the residual pressure in the furnace core is entirely based on moisture, and the oxygen content and the nitrogen content are all air (N ₂ : O ₂ = 80:20) and calculated.
[0076]
[Table 1]

[0077]
(2) Production of Radiation Image Conversion Panel 75 g of cesium bromide (CsBr) powder was placed in a zirconia powder molding die (inner diameter: 35 mm), and a powder mold press molding machine (table press TB-5, NPA system ( The product was manufactured under the pressure of 50 MPa and formed into a tablet (diameter: 35 mm, thickness: 20 mm). At this time, the pressure applied to the CsBr powder was about 40 MPa. Next, this tablet was vacuum dried at a temperature of 200 ° C. for 2 hours with a vacuum dryer.
[0078]
As a support, a synthetic quartz substrate subjected to alkali cleaning, pure water cleaning, and IPA cleaning in order was prepared and placed on a substrate holder in a vapor deposition apparatus. As the evaporation source was placed at a predetermined position in the apparatus the EuBr _m tablet and CsBr tablet. Thereafter, the inside of the apparatus was evacuated to a vacuum degree of 1 × 10 ⁻³ Pa. At this time, a combination of a cryopanel and a diffusion pump was used as an evacuation apparatus. Next, the quartz substrate was heated to 200 ° C. with a sheathed heater located on the side opposite to the deposition surface of the substrate. Each of the evaporation sources was irradiated with an electron beam with an acceleration voltage of 4.0 kV from an electron gun and co-evaporated at a rate of 4 μm / min to deposit a CsBr: Eu stimulable phosphor. At this time, the emission current (CsBr: 100 mA, EuBr _m : 50 mA) of each electron gun was adjusted so that the Eu / Cs molar concentration ratio in the photostimulable phosphor was 0.003 / 1.
[0079]
After vapor deposition, the inside of the apparatus was returned to atmospheric pressure, and the substrate was taken out from the apparatus. On the substrate, a phosphor layer (layer thickness: about 400 μm, area 10 cm × 10 cm) having a structure in which the columnar crystals of the phosphor were densely planted substantially vertically was formed.
Thus, the radiation image conversion panel which concerns on this invention which consists of a support body and a fluorescent substance layer by co-evaporation was manufactured.
[0080]
[Example 2]
In the same manner as in Example 1 except that ammonium bromide was added at a weight ratio of 10: 2 (EuBr _m : NH ₄ Br) in Example 1, a tablet-like europium bromide melt solidified body was obtained. Then, except for the use of this EuBr _m tablet in the same manner as in Example 1, to produce a radiation image storage panel according to the present invention comprising a support and a phosphor layer.
[0081]
[Example 3]
In the same manner as in Example 1 except that ammonium bromide was added at a weight ratio of 10: 3 (EuBr _m : NH ₄ Br) in Example 1, a tablet-like europium bromide melt solidified body was obtained. Then, except for the use of this EuBr _m tablet in the same manner as in Example 1, to produce a radiation image storage panel according to the present invention comprising a support and a phosphor layer.
[0082]
[Example 4]
In the same manner as in Example 1 except that ammonium bromide was added at a weight ratio of 10: 6 (EuBr _m : NH ₄ Br) in Example 1, a tablet-like europium bromide melt solidified body was obtained. Then, except for the use of this EuBr _m tablet in the same manner as in Example 1, to produce a radiation image storage panel according to the present invention comprising a support and a phosphor layer.
[0083]
[Comparative Example 1]
In Example 1, a tablet-like europium bromide melt solidified body was obtained in the same manner as in Example 1 except that ammonium bromide was not added. Then, except for the use of this EuBr _m tablet in the same manner as in Example 1, to produce a radiation image storage panel for comparison comprising a support and a phosphor layer.
[0084]
[Comparative Example 2]
In Example 1, a support and a phosphor were used in the same manner as in Example 1 except that a powdery europium bromide raw material formed into a tablet shape by a powder mold press molding machine was used as the EuBr _m evaporation source. A comparative radiation image conversion panel consisting of layers was produced.
[0085]
[Performance Evaluation 1 of Europium Bromide Melt Solids]
Evaporation rate of EuBr _m during co-evaporation (relative rate of vapor deposition flow) was measured by a crystal oscillator. The results obtained are summarized in Table 2.
[0086]
[Table 2]

[0087]
As is clear from the results in Table 2, all EuBr _m melted solids (Examples 1 to 4) produced in the presence of NH ₄ Br according to the method of the present invention were compared in the absence of NH ₄ Br. Compared with the EuBr _m melted solidified body for comparison (Comparative Example 1), the content of EuOBr was extremely small, and as a result, the deposition rate during deposition was remarkably stabilized.
[0088]
On the other hand, the EuBr _m solidified solid for comparison (Comparative Example 1) has a composition that differs greatly between the central part and the peripheral part, and the central part is mainly composed of EuOBr, and the deposition rate is difficult to stabilize. In addition, the EuBr _m tablet for comparison that did not melt (Comparative Example 2) also had a high EuOBr content, and the deposition rate could not be controlled, and because of the high water content, bumping occurred during the deposition. It was.
Further, according to the comparison between Comparative Examples 1 and 2, if NH ₄ Br is not added at the time of heating and melting, EuOBr is produced by the reaction of EuBr _m with H ₂ O and O ₂ present in a very small amount in the reaction system. In return, the content of EuOBr increases.
[0089]
[Examples 5 to 8]
In each of Examples 1 to 4, in the same manner as in each Example, except that the evaporation source was heated by supplying a current of 120 A to the resistance heater instead of irradiating each evaporation source with the electron beam, the support and the fluorescence were supplied. A radiation image conversion panel according to the present invention comprising a body layer was produced.
[0090]
[Comparative Examples 3 and 4]
In each of Comparative Examples 1 and 2, in the same manner as in each Comparative Example except that the evaporation source was heated by supplying a current of 120 A to the resistance heater instead of irradiating each evaporation source with an electron beam, A comparative radiation image conversion panel comprising a body layer was produced.
[0091]
[Performance Evaluation 2 of Europium Bromide Solidified Solids]
Evaporation rate of EuBr _m during co-evaporation (relative rate of vapor deposition flow) was measured by a crystal oscillator. The results obtained are summarized in Table 3.
[0092]
[Table 3]

[0093]
As is clear from Table 3, the same result was obtained even when the vapor deposition method was changed to the resistance heating method. That is, the EuBr _m melted solids produced in the presence of NH ₄ Br according to the method of the present invention (Examples 5 to 8) were all EuBr _m melted solids for comparison produced in the absence of NH ₄ Br. (Comparative example 3) and compared to EuBr _m tablet for comparison that did not melt (Comparative example 4), the content of EuOBr is extremely small, as a result, deposition rate during deposition was remarkably stable.
[0094]
【The invention's effect】
According to the present invention, high-purity europium halide in which contamination of europium oxide is remarkably reduced by melting powdery europium halide in the presence of halogen, in particular using ammonium halide, and then cooling. A melt-solidified body can be obtained. Then, by forming a phosphor layer by vapor deposition using this high-purity europium halide melt and solidified body as an evaporation source, the phosphor composition is uniform and has a homogeneous phosphor layer free of impurities A radiation image conversion panel can be manufactured.

Claims (37)

A method for producing a europium halide melt solidified body comprising heating and melting europium halide in the presence of a halogen source and then cooling. The method for producing a europium halide melt solidified body according to claim 1, wherein the europium halide is heated and melted substantially in the absence of water and oxygen. The method for producing a solidified europium halide solidified body according to claim 1 or 2, wherein ammonium halide is used as a halogen source, and this is added to and mixed in advance with europium halide. The method for producing a europium halide melt solidified body according to claim 3, wherein the ammonium halide is added to the europium halide in a weight ratio in the range of 10: 0.1 to 10:10 (the latter: the former). The method for producing a europium halide melt solidified body according to claim 3 or 4, wherein the halogen of europium halide and the halogen of ammonium halide are the same. The europium halide according to any one of claims 3 to 5, wherein a mixture of the europium halide and the ammonium halide is heated and melted in an atmosphere having a moisture content of 5.0 x 10 ^-5 mol / L or less. A method for producing a melt-solidified body. The europium halide according to any one of claims 3 to 6, wherein a mixture of europium halide and ammonium halide is heated and melted in an atmosphere having an oxygen concentration of 1.0 x 10 ^-5 mol / L or less. A method for producing a melt-solidified body. The method for producing a melted solidified europium halide solid body according to any one of claims 3 to 7, wherein a mixture of europium halide and ammonium halide is heated and melted in an inert gas atmosphere or a reducing gas atmosphere. The method for producing a melted and solidified europium halide solid body according to any one of claims 3 to 8, wherein the melted europium halide is cooled in a vacuum, in an inert gas atmosphere or in a reducing gas atmosphere. The method for producing a melted solidified europium halide solid body according to any one of claims 3 to 9, wherein a reaction system containing a mixture of europium halide and ammonium halide is dried before heating and melting. 11. The europium halide melt solidification according to claim 10, wherein the reaction system containing a mixture of europium halide and ammonium halide is dried by heating at a temperature of 50 to 400 ° C. at a vacuum degree of 100 Pa or higher. Body manufacturing method. The method for producing a solidified europium halide solidified body according to any one of claims 3 to 11, wherein the europium halide and / or ammonium halide is dried before mixing. The method for producing a europium halide melt solidified body according to claim 12, wherein the europium halide and / or ammonium halide is dried by heating at a temperature of 50 to 400 ° C under vacuum. The method for producing a europium halide melt solidified body according to any one of claims 3 to 13, wherein the europium halide is europium bromide. The method for producing a solidified europium halide solidified body according to claim 1 or 2, wherein the europium halide is heated and melted in an atmosphere containing a halogen gas or a hydrogen halide gas as a halogen source. The method for producing a melted and solidified europium halide solid body according to claim 15, wherein the halogen gas or hydrogen halide gas is contained in the molten atmosphere in the range of 1 x 10 ^{-6 to} 1 x 10 ⁵ Pa. The method for producing a solidified europium halide solidified body according to claim 15 or 16, wherein the halogen of the europium halide is the same as the halogen gas or the halogen of the hydrogen halide gas. 18. The method for producing a europium halide melt solidified body according to claim 15, wherein the europium halide is heated and melted in an atmosphere having a moisture content of 5.0 × 10 ⁻⁵ mol / L or less. 19. The method for producing a europium halide melt solidified body according to claim 15, wherein the europium halide is heated and melted in an atmosphere having an oxygen concentration of 1.0 × 10 ⁻⁵ mol / L or less. The method for producing a solidified europium halide solidified body according to any one of claims 15 to 19, wherein the europium halide is heated and melted in an inert gas atmosphere containing a halogen gas or a hydrogen halide gas or in a reducing gas atmosphere. . 21. The method for producing a solidified europium halide solidified body according to any one of claims 15 to 20, wherein the melted europium halide is cooled in a vacuum, under an inert gas atmosphere or under a reducing gas atmosphere. The method for producing a melted and solidified europium halide solid body according to any one of claims 15 to 21, wherein the reaction system containing the europium halide is dried before heating and melting. 23. The method for producing a europium halide melt solidified body according to claim 22, wherein the reaction system containing the europium halide is dried by heating at a temperature of 50 to 400 ° C. at a vacuum degree of 100 Pa or higher. The method for producing a europium halide melt solidified body according to any one of claims 15 to 23, wherein the europium halide is dried before heating and melting. The method for producing a europium halide melt solidified body according to claim 24, wherein the europium halide is dried by heating at a temperature of 50 to 400 ° C under vacuum. 26. The method for producing a melted solidified europium halide according to any one of claims 15 to 25, wherein the europium halide is europium bromide. 27. The method for producing a europium halide melt solidified body according to any one of claims 1 to 26, wherein a europium halide melt solidified body having a europium oxide content of 10% by weight or less is obtained. 28. The method for producing a europium halide melt solidified body according to any one of claims 1 to 27, wherein a molten europium halide solidified body having a water content of 0.5% by weight or less is obtained. A europium halide melt solidified body having a content of europium oxide halide of 10% by weight or less for use as an evaporation source in a vapor deposition method. 30. The europium halide melt solidified body according to claim 29, wherein the content of europium oxide halide is 3% by weight or less. The europium halide melt-solidified product according to claim 30, wherein the content of europium oxide halide is 1% by weight or less. 32. The europium halide melt-solidified body according to any one of claims 29 to 31, wherein the water content is 0.5% by weight or less. A phosphor layer is formed by subjecting a plurality of evaporation sources including at least a phosphor base material component and an activator component to each of a plurality of evaporation sources and performing a multi-source vapor deposition on the substrate. A method for producing a radiation image conversion panel including a step of forming a solidified europium halide solidified body according to any one of claims 29 to 32 as an evaporation source including an activator component of the phosphor. A method of manufacturing a radiation image conversion panel. 35. The method for producing a radiation image conversion panel according to claim 33, wherein the europium halide melt-solidified body is produced by the method according to any one of claims 3 to 14. 34. The method for producing a radiation image conversion panel according to claim 33, wherein the europium halide melt-solidified body is produced by the method according to any one of claims 15 to 26. 36. The method for producing a radiation image conversion panel according to any one of claims 33 to 35, wherein the phosphor is a phosphor containing europium as an activator. The phosphor has the basic composition formula (II):
M ^I X · aM ^II X ' ₂ · bM ^III X " ₃ : zEu (II)
[Wherein M ^I represents at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs; M ^II represents Be, Mg, Ca, Sr, Ba, Ni, Cu, Zn and Cd. Represents at least one alkaline earth metal or divalent metal selected from the group consisting of: M ^III represents Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Represents at least one rare earth element or trivalent metal selected from the group consisting of Tm, Yb, Lu, Al, Ga and In; X, X ′ and X ″ are from the group consisting of F, Cl, Br and I, respectively. Represents at least one selected halogen; and a, b, and z represent numerical values in the range of 0 ≦ a <0.5, 0 ≦ b <0.5, and 0 <z <1.0, respectively.
37. The method for producing a radiation image conversion panel according to claim 36, which is a europium-activated alkali metal halide-based stimulable phosphor having the following.