JP3959984B2 - Oxygen-introduced rare earth activated alkaline earth metal fluoride halide photostimulable phosphor, method for producing the same, and radiation image conversion panel - Google Patents
Oxygen-introduced rare earth activated alkaline earth metal fluoride halide photostimulable phosphor, method for producing the same, and radiation image conversion panel Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は酸素導入希土類付活アルカリ土類金属弗化沃化物系輝尽性蛍光体とその輝尽性蛍光体の製造方法、及び前記輝尽性蛍光体を用いた放射線画像変換パネルに関する。
【０００２】
【従来の技術】
従来の放射線写真法に代わる有効な診断手段として、特開昭５５−１２１４５号等に記載の輝尽性蛍光体を用いる放射線画像記録再生方法が知られている。この方法は、輝尽性蛍光体を含有する放射線画像変換パネル（蓄積性蛍光体シートとも呼ばれる）を利用するもので、被写体を透過した、又は被検体から発せられた放射線を輝尽性蛍光体に吸収させ、可視光線、紫外線などの電磁波（励起光と言う）で時系列的に輝尽性蛍光体を励起して、蓄積されている放射線エネルギーを蛍光（輝尽発光光と言う）として放射させ、この蛍光を光電的に読みとって電気信号を得、得られた電気信号に基づいて被写体又は被検体の放射線画像を可視画像として再生するものである。読取り後の変換パネルは、残存画像の消去が行われ、次の撮影に供される。
【０００３】
この方法によれば、放射線写真フィルムと増感紙とを組み合わせて用いる放射線写真法に比して、遙かに少ない被爆線量で情報量の豊富な放射線画像が得られる利点がある。又、放射線写真法では撮影毎にフィルムを消費するのに対して、放射線画像変換パネルは繰り返し使用されるので、資源保護や経済効率の面からも有利である。
【０００４】
放射線画像変換パネルは、支持体とその表面に設けられた輝尽性蛍光体層、又は自己支持性の輝尽性蛍光体層のみから成り、輝尽性蛍光体層は通常輝尽性蛍光体とこれを分散支持する結合材から成るものと、蒸着法や焼結法によって形成される輝尽性蛍光体の凝集体のみから構成されるものがある。又、該凝集体の間隙に高分子物質が含浸されているものも知られている。更に、輝尽性蛍光体層の支持体側とは反対側の表面には、通常、ポリマーフィルムや無機物の蒸着膜から成る保護膜が設けられる。
【０００５】
輝尽性蛍光体としては、通常、４００〜９００ｎｍの範囲にある励起光によって、波長３００〜５００ｎｍの範囲にある輝尽発光を示すものが一般的に利用され、特開昭５５−１２１４５号、同５５−１６００７８号、同５６−７４１７５号、同５６−１１６７７７号、同５７−２３６７３号、同５７−２３６７５号、同５８−２０６６７８号、同５９−２７２８９号、同５９−２７９８０号、同５９−５６４７９号、同５９−５６４８０号等に記載の希土類元素付活アルカリ土類金属弗化ハロゲン化物系蛍光体；特開昭５９−７５２００号、同６０−８４３８１号、同６０−１０６７５２号、同６０−１６６３７９号、同６０−２２１４８３号、同６０−２２８５９２号、同６０−２２８５９３号、同６１−２３６７９号、同６１−１２０８８２号、同６１−１２０８８３号、同６１−１２０８８５号、同６１−２３５４８６号、同６１−２３５４８７号等に記載の２価のユーロピウム付活アルカリ土類金属弗化ハロゲン化物系蛍光体；特開昭５５−１２１４４号に記載の希土類元素付活オキシハロゲン化物蛍光体；特開昭５８−６９２８１号に記載のセリウム付活３価金属オキシハロゲン化物蛍光体；特開昭６０−７０４８４号に記載のビスマス付活アルカリ金属ハロゲン化物蛍光体；特開昭６０−１４１７８３号、同６０−１５７１００号等に記載の２価のユーロピウム付活アルカリ土類金属ハロ燐酸塩蛍光体；特開昭６０−１５７０９９号に記載の２価のユーロピウム付活アルカリ土類金属ハロ硼酸塩蛍光体；特開昭６０−２１７３５４号に記載の２価のユーロピウム付活アルカリ土類金属水素化ハロゲン化物蛍光体；特開昭６１−２１１７３号、同６１−２１１８２号等に記載のセリウム付活希土類複合ハロゲン化物蛍光体；特開昭６１−４０３９０号に記載のセリウム付活希土類ハロ燐酸塩蛍光体；特開昭６０−７８１５１号に記載の２価のユーロピウム付活ハロゲン化セリウム・ルビジウム蛍光体；特開昭６０−７８１５１号に記載の２価のユーロピウム付活複合ハロゲン化物蛍光体等が挙げられ、中でも、沃素を含有する２価のユーロピウム付活アルカリ土類金属弗化ハロゲン化物蛍光体、沃素を含有する希土類元素付活オキシハロゲン化物蛍光体及び沃素を含有するビスマス付活アルカリ金属ハロゲン化物蛍光体等が知られているが、依然、高輝度の輝尽性蛍光体が要求されている。
【０００６】
又、輝尽性蛍光体を利用する放射線画像変換方法の利用が進むにつれて、得られる放射線画像の画質の向上、例えば鮮鋭度の向上や粒状性の向上が更に求められるようになって来た。
【０００７】
先に記載の輝尽性蛍光体の製造方法は、固相法あるいは焼結法と呼ばれる方法で、焼成後の粉砕が必須であり、感度、画像性能に影響する粒子形状の制御が困難であるという問題を有する。放射線画像の画質向上の手段の中で、輝尽性蛍光体の微粒子化と微粒子化された輝尽性蛍光体の粒径を揃えること、即ち、粒径分布を狭くすることが有効である。
【０００８】
特開平７−２３３３６９号、同９−２９１２７８号等で開示されている液相からの輝尽性蛍光体の製造法は、蛍光体原料溶液の濃度を調整して微粒子状の輝尽性蛍光体前駆体を得る方法であり、粒径分布の揃った輝尽性蛍光体粉末の製造法として有効である。又、放射線被爆量の低減という観点から、希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の内、沃素含有量が高いものが好ましいことが知られている。これは、臭素に比べて沃素がＸ線吸収率が高いためである。
【０００９】
上記の様に液相で製造されるアルカリ土類金属弗化沃化物系輝尽性蛍光体は、輝度、粒状性の点で有利であるが、液相にて前駆体結晶を得る場合、以下の様な問題を持っている。即ち、特開平１０−８８１２５号、同９−２９１２７８号の記載に見られるように、
１）沃化バリウムを水あるいは有機溶媒に溶解し、この液を攪拌しながら無機弗化物の溶液を添加する、
２）弗化アンモニウムを水に溶解し、この液を攪拌しながら沃化バリウムの溶液を添加する、
方法が有効である。
【００１０】
しかし、１）の方法では、溶液中に過剰の沃化バリウムを存在させておく必要があり、そのため投入した沃化バリウムと固液分離後に得られる弗化沃化バリウムの化学量論比は０．４前後と小さい値であることが多い。つまり、投入した沃化バリウムに対し、アルカリ土類金属弗化沃化物系輝尽性蛍光体の収率は４０％程度であることが多い。
【００１１】
又、２）の方法でも、無機弗化物に対して過剰の沃化バリウムを必要とし、収率が低い。このように、弗化沃化バリウムの液相合成は収率が低く、生産性が悪いという問題を有している。収率を上げるために母液中の沃化バリウム濃度を下げると粒子の肥大化を招き、これは画質特性上好ましくない。
【００１２】
希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体、特にアルカリ土類金属弗化沃化物系輝尽性蛍光体の収率を上げる試みとしては、特開平１１−２９３２４号に、反応母液の濃度と弗素源を添加した後、濃縮することにより基本組成式ＢａＦＩ：ｘＬｎ（Ｌｎ：Ｃｅ、Ｐｒ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｔｍ及びＹｂから選ばれる少なくとも１種の希土類元素、ｘは０＜ｘ≦０．１の数値を表す）で示される希土類元素含有角状弗化沃化バリウム結晶を得る方法が開示されている。
【００１３】
しかし、本発明者らが追試を行った結果、記載通りＢａＦＩ角状結晶は生成したものの、自然蒸発による濃縮を用いるため著しく生産性が低く、工業的には現実的ではないことが判った。又、得られる角状結晶も粒径が大きく、かつ粒径分布が広いため画像特性が悪く、実用に供することが出来ないことが判った。
【００１４】
【発明が解決しようとする課題】
本発明の課題は、まず、粒径分布の揃った酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体を生産性良く得ることであり、更に微粒子化され粒径分布の揃った前記輝尽性蛍光体をバリウムハロゲン化物より高い収率で得ることであり、更にそれらを用いた高感度・高画質の放射線画像変換パネルを提供することである。
【００１５】
【課題を解決するための手段】
上記本発明の課題は、下記の構成により達成される。
【００１６】
（１）下記一般式（１）で示される酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の製造方法であり、無機弗化物水溶液とアルカリ金属ハロゲン化物水溶液を添加した後、該反応母液中のバリウム濃度が３．３ｍｏｌ／Ｌ以上の溶液から溶媒を除去することにより輝尽性蛍光体前駆体を得ることを特徴とする、酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の製造方法。
【００１７】
一般式（１） Ｂａ(1-x)Ｍ2(x)ＦＢｒ(y)Ｉ(1-y)：ａＭ1，ｂＬｎ，ｃＯ
式中、Ｍ1はＬｉ，Ｎａ，Ｋ，Ｒｂ及びＣｓから選ばれる少なくとも１種のアルカリ金属、Ｍ2はＢｅ，Ｍｇ，Ｓｒ及びＣａから選ばれる少なくとも１種のアルカリ土類金属、ＬｎはＣｅ，Ｐｒ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｔｍ，Ｄｙ，Ｈｏ，Ｎｄ，Ｅｒ及びＹｂから選ばれる少なくとも１種の希土類元素を表し、ｘ，ｙ，ａ，ｂ及びｃは、それぞれ０≦ｘ≦０．３，０≦ｙ≦０．３，０≦ａ≦０．０５，０＜ｂ≦０．２，０＜ｃ≦０．１である。
【００１８】
（２）前記一般式（１）で示される酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の製造方法であり、バリウムハロゲン化物水溶液と無機弗化物水溶液とアルカリ金属ハロゲン化物水溶液を添加した後、該反応母液中のバリウム濃度が３．３ｍｏｌ／Ｌ以上の溶液から溶媒を除去することにより輝尽性蛍光体前駆体を得ることを特徴とする、酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の製造方法。
【００１９】
（３）前記一般式（１）で示される酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の製造方法であり、該反応母液中のバリウム濃度が３．３ｍｏｌ／Ｌ以上の溶液から溶媒を除去した後にアルカリ金属ハロゲン化物水溶液を添加することにより輝尽性蛍光体前駆体を得ることを特徴とする、酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の製造方法。
【００２０】
（４）反応液の質量が（溶媒除去後／溶媒除去前）≦０．９７であることを特徴とする（１）、（２）又は（３）記載の酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の製造方法。
【００２１】
（５）反応溶媒を除去する方法が人為的操作を加えたものであることを特徴とする（１）〜（４）の何れか１項記載の酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の製造方法。
【００２２】
（６）反応溶媒を除去する方法が乾燥気体を通気させる方法であることを特徴とする（１）〜（５）の何れか１項記載の酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の製造方法。
【００２３】
（７）溶媒除去の作業中、溶液が濡れ壁を形成することを特徴とする（１）〜（６）の何れか１項記載の酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の製造方法。
【００２４】
（８）前記（１）〜（７）の何れか１項記載の製造方法によって得られたことを特徴とする酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体。
【００２５】
（９）前記（８）に記載の酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体を含む蛍光体層を有することを特徴とする放射線画像変換パネル。
【００２６】
【発明の実施の形態】
本発明の酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体の製造方法の代表的な態様を以下に詳しく説明する。
【００２７】
液相法による輝尽性蛍光体前駆体製造については、特願平８−２６５５２５号に記載された前駆体製造方法、特願平８−２６６７１８号に記載された前駆体製造装置が好ましく利用できる。ここで輝尽性蛍光体前駆体とは、前記一般式（１）の物質が６００℃以上の高温を経ていない状態であって、輝尽性蛍光体前駆体は、輝尽発光性や瞬時発光性を殆ど示さない。
【００２８】
本発明では以下の液相合成法により前駆体を得ることが好ましい。
前記一般式（１）で示される酸素導入希土類付活アルカリ土類金属弗化沃化物系輝尽性蛍光体の製造は、粒子形状の制御が難しい固相法ではなく、粒径の制御が容易である液相法により行うものである。特に、下記の液相合成法により輝尽性蛍光体を得ることが好ましい。
【００２９】
（製造法１）
ＢａＩ2とＬｎのハロゲン化物を含み、前記一般式（１）のｘが０でない場合には、更にＭ2のハロゲン化物を、ｙが０でない場合はＢａＢｒ2を、それらが溶解した後、ＢａＩ2濃度が３．３ｍｏｌ／Ｌ以上、好ましくは４．０ｍｏｌ／Ｌ以上の溶液を調製する工程；
上記溶液を５０℃以上、好ましくは８０℃以上の温度に維持しながら、これに濃度５ｍｏｌ／Ｌ以上、好ましくは８ｍｏｌ／Ｌ以上の無機弗化物（弗化アンモニウム又はアルカリ金属の弗化物）の水溶液、及びａが０でない場合はＭ1のハロゲン化物の水溶液を添加して、希土類付活アルカリ土類金属弗化沃化物系輝尽性蛍光体前駆体結晶の沈澱物を得る工程；
上記添加終了後、反応液から溶媒を除去する工程；
上記前駆体結晶沈澱物を反応液から分離する工程；
そして、分離した前駆体結晶沈澱物を焼結を避けながら焼成する工程
を含む製造方法である。
【００３０】
（製造法２）
Ｌｎのハロゲン化物を含み、前記一般式（１）のｘが０でない場合には、更にＭ2のハロゲン化物を、ｙが０でない場合はＢａＢｒ2を溶解した溶液を調製する工程；
上記溶液を５０℃以上、好ましくは８０℃以上の温度に維持しながら、これにＢａＩ2濃度が３．３ｍｏｌ／Ｌ以上、好ましくは４．０ｍｏｌ／Ｌ以上の溶液、及び濃度５ｍｏｌ／Ｌ以上、好ましくは８ｍｏｌ／Ｌ以上の無機弗化物水溶液（弗化アンモニウム又はアルカリ金属の弗化物）の水溶液、及びａが０でない場合はＭ1のハロゲン化物を添加して希土類付活アルカリ土類金属弗化沃化物系輝尽性蛍光体前駆体結晶の沈澱物を得る工程；
上記添加終了後、反応液から溶媒を除去する工程；
上記前駆体結晶沈澱物を反応液から分離する工程；
そして、分離した前駆体結晶沈澱物を焼結を避けながら焼成する工程
を含む製造方法である。
【００３１】
（製造法３）
ＢａＩ2とＬｎのハロゲン化物を含み、前記一般式（１）のｘが０でない場合には、更にＭ2のハロゲン化物を、ｙが０でない場合はＢａＢｒ2を、それらが溶解した後、ＢａＩ2濃度が３．３ｍｏｌ／Ｌ以上、好ましくは４．０ｍｏｌ／Ｌ以上の溶液を調製する工程；
上記溶液を５０℃以上、好ましくは８０℃以上の温度に維持しながら、これに濃度５ｍｏｌ／Ｌ以上、好ましくは８ｍｏｌ／Ｌ以上の無機弗化物（弗化アンモニウム又はアルカリ金属の弗化物）の水溶液を添加して、希土類付活アルカリ土類金属弗化沃化物系輝尽性蛍光体前駆体結晶の沈澱物を得る工程；
上記添加終了後、反応液から溶媒を除去する工程；
ａが０でない場合はＭ1のハロゲン化物の水溶液を添加する工程；
上記溶液を５０℃以上、好ましくは８０℃以上の温度に維持する工程；
上記前駆体結晶沈澱物を反応液から分離する工程；
そして、分離した前駆体結晶沈澱物を焼結を避けながら焼成する工程
を含む製造方法である。
【００３２】
尚、本発明に係る粒子（結晶）は、平均粒径が１〜１０μｍで、かつ単分散性のものが好ましく、平均粒径が１〜５μｍ、平均粒径の分布（％）が２０％以下のものがより好ましく、特に平均粒径が１〜３μｍ、平均粒径の分布が１５％以下のものが良い。
【００３３】
本発明における平均粒径とは、粒子（結晶）の電子顕微鏡写真より無作為に粒子２００個を選び、球換算の体積粒子径で平均を求めたものである。
【００３４】
以下に輝尽性蛍光体の製造法の詳細について説明する。
（前駆体結晶の沈澱物の作製、輝尽性蛍光体の作製）
製造法１は、水系媒体中を用いて、弗素化合物及びアルカリ金属ハロゲン化物以外の原料化合物を溶解させる。即ち、ＢａＩ2とＬｎのハロゲン化物、そして必要により更にＭ2のハロゲン化物を水系媒体中に入れ、充分に混合し、溶解させて、それらが溶解した水溶液を調製する。ただし、ＢａＩ2濃度が３．３ｍｏｌ／Ｌ以上、好ましくは４．０ｍｏｌ／Ｌ以上となるように、ＢａＩ2濃度と水系溶媒との量比を調整しておく。この時、バリウム濃度が低いと、所望の組成の前駆体が得られないか、得られても粒子が肥大化する。よって、バリウム濃度は適切に選択する必要があり、本発明者らの検討の結果、３．３ｍｏｌ／Ｌ以上で微細な前駆体粒子を形成することができることが判った。この時、所望により少量の酸、アンモニア、アルコール、水溶性高分子ポリマー、水不溶性金属酸化物微粒子粉体などを添加してもよい。ＢａＩ2の溶解度が著しく低下しない範囲で低級アルコール（メタノール、エタノール等）を適当量添加しておくのも好ましい態様である。この水溶液（反応母液）は５０℃以上に維持される。
【００３５】
次に、この５０℃以上に維持され、撹拌されている水溶液に、無機弗化物（弗化アンモニウム、アルカリ金属の弗化物など）の水溶液及びアルカリ金属ハロゲン化物の水溶液をポンプ付きのパイプ等を用いて注入する。この注入は、撹拌が特に激しく実施されている領域部分に行うのが好ましい。この無機弗化物水溶液の反応母液への注入によって、前記一般式（１）に該当する希土類付活アルカリ土類金属弗化ハロゲン化物系蛍光体前駆体結晶が沈澱する。
【００３６】
製造法２は、水系媒体中を用いてＢａI2水溶液、弗素化合物の水溶液、アルカリ金属ハロゲン化物の水溶液を準備しておき、これらを同時或いは順次混合により、希土類付活アルカリ土類金属弗化ハロゲン化物系蛍光体前駆体結晶を得るものである。即ち、ＢａＩ2とＬｎのハロゲン化物、そして必要により更にＭ2のハロゲン化物、そして更にＭ1のハロゲン化物を水系媒体中に入れ、充分に混合し、溶解させて、それらが溶解した水溶液を調製する。ただし、ＢａＩ2濃度が３．３ｍｏｌ／Ｌ以上、好ましくは４．０ｍｏｌ／Ｌ以上となるように、ＢａＩ2濃度と水系溶媒との量比を調整しておく。この時、バリウム濃度が低いと、所望の組成の前駆体が得られないか、得られても粒子が肥大化する。よって、バリウム濃度は適切に選択する必要があり、本発明者らの検討の結果、３．３ｍｏｌ／Ｌ以上で微細な前駆体粒子を形成することができることが判った。この時、所望により少量の酸、アンモニア、アルコール、水溶性高分子ポリマー、水不溶性金属酸化物微粒子粉体などを添加してもよい。ＢａＩ2の溶解度が著しく低下しない範囲で低級アルコール（メタノール、エタノール等）を適当量添加しておくのも好ましい態様である。この水溶液（反応母液）は５０℃に維持され、ポンプ付きのパイプ等を用いて注入する。
【００３７】
一方、無機弗化物（弗化アンモニウム、アルカリ金属の弗化物など）の水溶液をポンプ付きのパイプ等を用いて注入する。
【００３８】
これら準備された水溶液を、反応容器に同時或いは若干の時間のずれを生じて注入されるが、撹拌が特に激しく実施されている領域部分に行うのが好ましい。これらのＢａＩ2水溶液及び無機弗化物水溶液の反応容器への注入によって、前記一般式（１）に該当する希土類付活アルカリ土類金属弗化ハロゲン化物系蛍光体前駆体結晶が沈澱する。
【００３９】
製造法３は、水系媒体中を用いて、弗素化合物及びアルカリ金属ハロゲン化物以外の原料化合物を溶解させる。即ち、ＢａＩ2とＬｎのハロゲン化物、そして必要により更にＭ2のハロゲン化物を水系媒体中に入れ、充分に混合し、溶解させて、それらが溶解した水溶液を調製する。ただし、ＢａＩ2濃度が３．３ｍｏｌ／Ｌ以上、好ましくは４．０ｍｏｌ／Ｌ以上となるように、ＢａＩ2濃度と水系溶媒との量比を調整しておく。この時、バリウム濃度が低いと、所望の組成の前駆体が得られないか、得られても粒子が肥大化する。よって、バリウム濃度は適切に選択する必要があり、本発明者らの検討の結果、３．３ｍｏｌ／Ｌ以上で微細な前駆体粒子を形成することができることが判った。この時、所望により少量の酸、アンモニア、アルコール、水溶性高分子ポリマー、水不溶性金属酸化物微粒子粉体などを添加してもよい。ＢａＩ2の溶解度が著しく低下しない範囲で低級アルコール（メタノール、エタノール等）を適当量添加しておくのも好ましい態様である。この水溶液（反応母液）は５０℃以上に維持される。
【００４０】
次に、この５０℃以上に維持され、撹拌されている水溶液に、無機弗化物（弗化アンモニウム、アルカリ金属の弗化物など）の水溶液をポンプ付きのパイプ等を用いて注入する。この注入は、撹拌が特に激しく実施されている領域部分に行うのが好ましい。
【００４１】
次に反応液から溶媒を除去する。溶媒を除去する時期は特に問わないが、最も好ましいのは無機弗化物溶液を添加し終えた直後から除去を始める態様である。
【００４２】
溶媒の除去量は、除去前と除去後の質量比で３％以上が好ましい。これ以下では結晶が好ましい組成に成りきらない場合がある。そのため除去量は３％以上が好ましく、５％以上がより好ましい。又、除去し過ぎても、反応溶液の粘度が過剰に上昇するなど、ハンドリングの面で不都合が生じる場合がある。そのため、溶媒の除去量は、除去前と除去後の質量比で５０％以下が好ましい。
【００４３】
適当量の溶媒を除去した後、アルカリ金属ハロゲン化物水溶液を添加し、更に撹拌を行い希土類付活アルカリ土類金属弗化ハロゲン化物系蛍光体前駆体結晶を得る。
【００４４】
溶媒の除去に要する時間は、生産性に大きく影響するばかりでなく、粒子の形状、粒径分布も溶媒の除去方法に影響されるので、除去方法は適切に選択する必要がある。本発明においては、自然蒸発以外の人為的操作を加えた方法を用いる。溶媒の除去に際しては、溶液を加熱し、溶媒を蒸発する方法が選択されるが、本発明においても、この方法は有用である。溶媒の除去により、意図した組成の前駆体を得ることができる。
【００４５】
更に、生産性を上げるため、又、粒子形状を適切に保つため、他の溶媒除去方法を併用することが好ましい。併用する溶媒の除去方法は特に問わない。逆浸透膜などの分離膜を用いる方法を選択することも可能である。本発明では生産性の面から、以下の除去方法を選択することが好ましい。
【００４６】
１．乾燥気体を通気
反応容器を密閉型とし、少なくとも２箇所以上の気体が通過できる孔を設け、そこから乾燥気体を通気する。気体の種類は任意に選ぶことができる。安全性の面から、空気、窒素が好ましい。通気する気体の飽和水蒸気量に依存して溶媒が気体に同伴、除去される。反応容器の空隙部分に通気する方法の他、液相中に気体を気泡として噴出させ、気泡中に溶媒を吸収させる方法も、又、有効である。
【００４７】
２．減圧
よく知られるように、減圧にすることで溶媒の蒸気圧は低下する。蒸気圧降下により効率的に溶媒を除去することができる。減圧度としては溶媒の種類により適宜選択することができる。
【００４８】
３．液膜
蒸発面積を拡大することにより溶媒の除去を効率的に行うことができる。本発明のように、一定容積の反応容器を用いて加熱、攪拌し、反応を行わせる場合、加熱方法としては、加熱手段を液体中に浸漬するか、容器の外側に加熱手段を装着する方法が一般的である。該方法によると、伝熱面積は液体と加熱手段が接触する部分に限定され、溶媒除去に伴い伝熱面積が減少し、よって、溶媒除去に要する時間が長くなる。これを防ぐため、ポンプ又は攪拌機を用いて反応容器の壁面に散布し、伝熱面積を増大させる方法が有効である。
【００４９】
このように反応容器壁面に液体を散布し、液膜を形成する方法は“濡れ壁”として知られている。濡れ壁の形成方法としては、ポンプを用いる方法の他、特開平６−３３５６２７号、同１１−２３５５２２号に記載の攪拌機を用いる方法が挙げられる。
【００５０】
これらの方法は単独のみならず、組み合わせて用いても構わない。液膜を形成する方法と容器内を減圧にする方法の組合せ、液膜を形成する方法と乾燥気体を通気する方法の組合せ等が有効である。特に前者が好ましく、特開平６−３３５６２７号に記載の方法が好ましく用いられる。
【００５１】
次に、上記の蛍光体前駆体結晶を、濾過、遠心分離などにより溶液から分離し、メタノール等で充分に洗浄し、乾燥する。この乾燥蛍光体前駆体結晶に、アルミナ微粉末、シリカ微粉末などの焼結防止剤を添加、混合し、結晶表面に焼結防止剤微粉末を均一に付着させる。尚、焼成条件を選ぶことにより焼結防止剤の添加を省略することも可能である。
【００５２】
次に、蛍光体前駆体の結晶を、石英ポート、アルミナ坩堝、石英坩堝などの耐熱性容器に充填し、電気炉の炉心に入れて焼結を避けながら焼成を行う。焼成温度は４００〜１，３００℃の範囲が適当であり、５００〜１，０００℃の範囲が好ましい。焼成時間は、蛍光体原料混合物の充填量、焼成温度及び炉からの取出し温度などによっても異なるが、一般には０．５〜１２時間が適当である。
【００５３】
焼成雰囲気としては、窒素ガス雰囲気、アルゴンガス雰囲気等の中性雰囲気、あるいは少量の水素ガスを含有する窒素ガス雰囲気、一酸化炭素を含有する二酸化炭素雰囲気などの弱還元性雰囲気、あるいは微量酸素導入雰囲気が利用される。焼成方法については、特開２０００−８０３４号に記載の方法が好ましく用いられる。
【００５４】
上記の焼成によって目的の酸素導入希土類付活アルカリ土類金属弗化ハロゲン化物系輝尽性蛍光体が得られる。
【００５５】
（放射線画像変換パネルの作製）
本発明の放射線画像変換パネルに用いられる支持体としては、各種高分子材料、ガラス、金属等が用いられる。特に情報記録材料としての取扱い上、可撓性のあるシート又はウェブに加工できるものが好適であり、この点から言えばセルロースアセテート、ポリエステル、ポリエチレンテレフタレート、ポリアミド、ポリイミド、トリアセテート、ポリカーボネートフィルム等のプラスチックフィルム；アルミニウム、鉄、銅、クロム等の金属シート又は該金属酸化物の被覆層を有する金属シート等が好ましい。
【００５６】
これら支持体の層厚は、用いる支持体の材質等によって異なるが、一般的には１０〜１０００μｍであり、取扱い上の点から、更に好ましくは１０〜５００μｍである。
【００５７】
これら支持体の表面は滑面であってもよいし、輝尽性蛍光体層との接着性を向上させる目的でマット面としてもよい。更に、輝尽性蛍光体層との接着性を向上させる目的で、輝尽性蛍光体層が設けられる面に下引層を設けてもよい。
【００５８】
輝尽性蛍光体層に用いられる結合剤の例としては、ゼラチン等の蛋白質、デキストラン等のポリサッカライド、又はアラビアゴムのような天然高分子物質；ポリビニルブチラール、ポリ酢酸ビニル、ニトロセルロース、エチルセルロース、塩化ビニリデン・塩化ビニルコポリマー、ポリアルキル（メタ）アクリレート、塩化ビニル・酢酸ビニルコポリマー、ポリウレタン、セルロースアセテートブチレート、ポリビニルアルコール、線状ポリエステル等のような合成高分子物質などにより代表される結合剤を挙げることができる。これらの中で特に好ましいものは、ニトロセルロース、線状ポリエステル、ポリアルキル（メタ）アクリレート、ニトロセルロースと線状ポリエステルとの混合物、ニトロセルロースとポリアルキル（メタ）アクリレートとの混合物及びポリウレタンとポリビニルブチラールとの混合物である。尚、これらの結合剤は、架橋剤によって架橋されたものでもよい。
【００５９】
輝尽性蛍光体層は、例えば次のような方法により下塗層上に形成することができる。
【００６０】
まず、沃素含有輝尽性蛍光体、黄変防止のための亜燐酸エステル等の化合物及び結合剤を適当な溶剤に添加し、これらを充分に混合して結合剤溶液中に蛍光体粒子及び該化合物の粒子が均一に分散した塗布液を調製する。
【００６１】
本発明に用いられる結着剤としては、例えばゼラチンの如き蛋白質、デキストランの如きポリサッカライド又はアラビアゴム、ポリビニルブチラール、ポリ酢酸ビニル、ニトロセルロース、エチルセルロース、塩化ビニルデン・塩化ビニルコポリマー、ポリメチルメタクリレート、塩化ビニル・酢酸ビニルコポリマー、ポリウレタン、セルロースアセテートブチレート、ポリビニルアルコール等のような、通常、層構成に用いられる造膜性の結着剤が使用される。
【００６２】
一般に、結着剤は輝尽性蛍光体１質量部に対して０．０１〜１質量部の範囲で使用される。しかしながら、得られる放射線画像変換パネルの感度と鮮鋭性の点では結着剤は少ない方が好ましく、塗布の容易さとの兼合いから０．０３〜０．２質量部の範囲がより好ましい。
【００６３】
塗布液における結合剤と輝尽性蛍光体との混合比（ただし、結合剤全部がエポキシ基含有化合物である場合には、該化合物と蛍光体との比率に等しい）は、目的とする放射線画像変換パネルの特性、蛍光体の種類、エポキシ基含有化合物の添加量などによって異なるが、一般には、結合塗布液調製用の溶剤例として、メタノール、エノタール、１−プロパノール、２−プロパノール、ブタノール等の低級アルコール；メチレンクロライド、エチレンクロライド等の塩素原子含有炭化水素；アセトン、メチルエチルケトン、メチルイソブチルケトン等のケトン；酢酸メチル、酢酸エチル、酢酸ブチル等の低級脂肪酸と低級アルコールとのエステル；ジオキサン、エチレングリコールエチルエーテル、エチレングリコールモノメチルエーテル等のエーテル；トルエン；そして、それらの混合物を挙げることができる。
【００６４】
輝尽性蛍光体層用塗布液の調製に用いられる溶剤例としては、メタノール、エタノール、１−プロパノール、ブタノール等の低級アルコール；アセトン、メチルエチルケトン、メチルイソブチルケトン、シクロヘキサノン等のケトン；酢酸メチル、酢酸エチル、酢酸ブチル等の低級脂肪酸と低級アルコールとのエステル；ジオキサン、エチレングリコールモノエチルエーテル、エチレングリコールモノメチルエーテル等のエーテル；トリオール、キシロール等の芳香族化合物；メチレンクロライド、エチレンクロライド等のハロゲン化炭化水素及びそれらの混合物などが挙げられる。
【００６５】
尚、塗布液には、該塗布液中における蛍光体の分散性を向上させるための分散剤、又、形成後の輝尽性蛍光体層中における結合剤と蛍光体との結合力を向上させるための可塑剤など、種々の添加剤が混合されてもよい。そのような目的に用いられる分散剤の例としては、フタル酸、ステアリン酸、カプロン酸、親油性界面活性剤などを挙げることができる。又、可塑剤の例としては、燐酸トリフェニル、燐酸トリクレジル、燐酸ジフェニルなどの燐酸エステル；フタル酸ジエチル、フタル酸ジメトキシエチル等のフタル酸エステル；グリコール酸エチルフタリルエチル、グリコール酸ブチルフタリルブチルなどのグリコール酸エステル；トリエチレングリコールとアジピン酸とのポリエステル、ジエチレングリコールとコハク酸とのポリエステル等のポリエチレングリコールと脂肪族二塩基酸とのポリエステル等を挙げることができる。
【００６６】
上記のように調製した塗布液を、下塗層の表面に均一に塗布することにより塗布液の塗膜を形成する。この塗布操作は通常の塗布手段、例えばドクターブレード、ロールコーター、ナイフコーター等を用いて行うことができる。次いで、形成された塗膜を徐々に加熱することにより乾燥し、下塗層上への輝尽性蛍光体層の形成を完了する。
【００６７】
輝尽性蛍光体層用塗布液の調製は、ボールミル、サンドミル、アトライター、三本ロールミル、高速インペラー分散機、Ｋａｄｙミル、及び超音波分散機などの分散装置を用いて行われる。調製された塗布液をドクターブレード、ロールコーター、ナイフコーター等の塗布装置を用いて支持体上に塗布し、乾燥することにより輝尽性蛍光体層が形成される。前記塗布液を保護層上に塗布・乾燥した後に輝尽性蛍光体層と支持体とを接着してもよい。
【００６８】
放射線画像変換パネルの輝尽性蛍光体層の膜厚は、目的とする放射線画像変換パネルの特性、輝尽性蛍光体の種類、結着剤と輝尽性蛍光体との混合比等によって異なるが、１０〜１，０００μｍの範囲から選ばれるのが好ましく、１０〜５００μｍの範囲から選ばれるのがより好ましい。
【００６９】
以上、ユーロピウム付活弗化沃化バリウム等の輝尽性蛍光体の例について主に説明したが、ユーロピウム付活弗化臭化バリウム、その他の前記一般式（Ｉ）で表される輝尽性蛍光体についても、上記を参照して製造することが出来る。
【００７０】
【実施例】
以下、実施例を挙げて本発明を例証するが、本発明はこれらに限定されるものではない。
【００７１】
実施例１
ユーロピウム付活弗化ヨウ化バリウムの輝尽性蛍光体前駆体を合成するために、２つの孔をもつ耐圧容器にＢａＩ2水溶液（４．２ｍｏｌ／Ｌ）２５００ｍｌとＥｕＩ3水溶液（０．２ｍｏｌ／Ｌ）２６．５ｍｌを反応器に入れた。この反応器中の反応母液を撹拌しながら８３℃で保温した。弗化アンモニウム水溶液（１３ｍｏｌ／Ｌ）４５０ｍｌとヨウ化カリウム水溶液（８ｍｏｌ／Ｌ）１５０ｍＬを同時に反応母液中にローラーポンプを用いて注入し、沈澱物を生成させた。注入終了後乾燥空気を１０Ｌ／ｍｉｎの割合で２０分間通気した。通気前後の溶液の質量比は０．９４であった。そのままの温度で９０分間攪拌した。９０分攪拌した後ろ過しエタノール２０００ｍｌで洗浄した。回収した前駆体の質量を計測し、投入したＢａＩ2量と比較することにより収率を求めた。上記の操作によって得た沈殿物についてＸ線回折測定を行った。Ｘ線はＣｕ−Ｋα線を用いた。次いで得られた沈殿物の平均粒径を測定した。
【００７２】
実施例２
ユーロピウム付活弗化ヨウ化バリウムの輝尽性蛍光体前駆体を合成するために、２つの孔をもつ耐圧容器にＮＨ4Ｉ水溶液（４．２ｍｏｌ／Ｌ）５００ｍｌとＥｕＩ3水溶液（０．２ｍｏｌ／Ｌ）２６．５ｍｌを反応器に入れた。この反応器中の反応母液を撹拌しながら８３℃で保温した。ヨウ化バリウム水溶液（４．２ｍｏｌ／Ｌ）４５００ｍｌと弗化アンモニウム水溶液（１３ｍｏｌ／Ｌ）４５０ｍｌとヨウ化カリウム水溶液（８ｍｏｌ／Ｌ）１５０ｍｌを同時に反応母液中にローラーポンプを用いて注入し、沈澱物を生成させた。注入終了後乾燥空気を１０Ｌ／ｍｉｎの割合で２０分間通気した。通気前後の溶液の質量比は０．９２であった。そのままの温度で９０分間攪拌した。９０分攪拌した後ろ過しエタノール２０００ｍｌで洗浄した。回収した前駆体の質量を計測し、投入したＢａＩ2量と比較することにより収率を求めた。上記の操作によって得た沈殿物についてＸ線回折測定を行った。Ｘ線はＣｕ−Ｋα線をもちいた。ついで得た沈殿物の平均粒径を測定した。
【００７３】
実施例３
ユーロピウム付活弗化ヨウ化バリウムの輝尽性蛍光体前駆体を合成するために、２つの孔をもつ耐圧容器にＢａＩ2水溶液（４．２ｍｏｌ／Ｌ）２５００ｍｌとＥｕＩ3水溶液（０．２ｍｏｌ／Ｌ）２６．５ｍｌを反応器に入れた。この反応器中の反応母液を撹拌しながら８３℃で保温した。弗化アンモニウム水溶液（１３ｍｏｌ／Ｌ）４５０ｍｌを反応母液中にローラーポンプを用いて注入し、沈澱物を生成させた。注入終了後乾燥空気を１０Ｌ／ｍｉｎの割合で２０分間通気した。通気前後の溶液の質量比は０．９２であった。次にヨウ化カリウム水溶液（８ｍｏｌ／Ｌ）１５０ｍｌを添加した後、そのままの温度で９０分間攪拌した。９０分攪拌した後ろ過しエタノール２０００ｍｌで洗浄した。回収した前駆体の質量を計測し、投入したＢａＩ2量と比較することにより収率を求めた。上記の操作によって得た沈殿物についてＸ線回折測定を行った。Ｘ線はＣｕ−Ｋα線をもちいた。ついで得た沈殿物の平均粒径を測定した。
【００７４】
実施例４
弗化アンモニウムの添加終了後、循環アスピレーターを用いて反応容器内の圧力を７４５ｈＰａとし、溶媒の減圧濃縮を行った。１５分間濃縮を行った。濃縮前後の反応溶液の質量比は０．９２であった。これ以外は実施例１と同様の操作を行い、沈殿物を得た。実施例１と同様に収率を計算し、沈殿物のＸ線回折、平均粒径測定を行った。
【００７５】
実施例５
弗化アンモニウムの添加終了後、ポンプを用いて反応容器壁面に反応液を散布し、液膜を形成させつつ溶媒を蒸発させた。この操作を１５分間行った。濃縮前後の反応溶液の質量比は０．９４であった。これ以外は実施例１と同様の操作を行い、沈殿物を得た。実施例１と同様に収率を計算し、沈殿物のＸ線回折、平均粒径測定を行った。
【００７６】
実施例６
ユーロピウム付活弗化ヨウ化バリウムの輝尽性蛍光体前駆体を合成するために、２つの孔をもつ耐圧容器にＢａＩ2水溶液（４．２ｍｏｌ／Ｌ）２５００ｍｌとＥｕＩ3水溶液（０．２ｍｏｌ／Ｌ）２６．５ｍｌを反応器に入れた。この反応器中の反応母液を撹拌しながら８３℃で保温した。弗化アンモニウム水溶液（１３ｍｏｌ／Ｌ）４５０ｍｌとヨウ化カリウム水溶液（８ｍｏｌ／Ｌ）１３５ｍｌとヨウ化ナトリウム水溶液（８ｍｏｌ／Ｌ）１５ｍｌを同時に反応母液中にローラーポンプを用いて注入し、沈澱物を生成させた。注入終了後乾燥空気を１０Ｌ／ｍｉｎの割合で２０分間通気した。通気前後の溶液の質量比は０．９３であった。そのままの温度で９０分間攪拌した。９０分攪拌した後ろ過しエタノール２０００ｍｌで洗浄した。回収した前駆体の質量を計測し、投入したＢａＩ2量と比較することにより収率を求めた。上記の操作によって得た沈殿物についてＸ線回折測定を行った。Ｘ線はＣｕ−Ｋα線をもちいた。ついで得た沈殿物の平均粒径を測定した。
【００７７】
比較例１
ユーロピウム付活弗化ヨウ化バリウムの輝尽性蛍光体前駆体を合成するために、ＢａＩ2水溶液（４．２ｍｏｌ／Ｌ）２５００ｍｌとＥｕＩ3水溶液（０．２ｍｏｌ／Ｌ）２６．５ｍｌを反応器に入れた。この反応器中の反応母液を撹拌しながら８３℃で保温した。弗化アンモニウム水溶液（１３ｍｏｌ／Ｌ）４５０ｍｌとヨウ化カリウム水溶液（８ｍｏｌ／Ｌ）１５０ｍＬを同時に反応母液中にローラーポンプを用いて注入し、沈澱物を生成させた。注入終了後そのままの温度で９０分間攪拌した。９０分攪拌した後ろ過しエタノール２０００ｍｌで洗浄した。回収した前駆体の質量を計測し、投入したＢａＩ2量と比較することにより収率を求めた。上記の操作によって得た沈殿物についてＸ線回折測定を行った。ついで得た沈殿物の平均粒径を測定した。
【００７８】
比較例２
反応母液に注入する弗化アンモニウム水溶液の量を６００ｍｌとすること以外は比較例１と同様にして沈殿物を得た。実施例１と同様に収率を計算し、沈殿物のＸ線回折、平均粒径測定を行った。
【００７９】
比較例３
反応母液に注入する弗化アンモニウム水溶液の量を６００ｍｌとし、弗化アンモニウム溶液を注入した後、自然蒸発により溶液を濃縮した。１５時間濃縮を行った。濃縮前後の反応溶液の質量比は０．８７であった。これ以外は比較例１と同様にして沈殿物を得た。実施例１と同様に収率を計算し、沈殿物のＸ線回折、平均粒径測定を行った。
【００８０】
比較例４
ユーロピウム付活弗化ヨウ化バリウムの輝尽性蛍光体前駆体を合成するために、２つの孔をもつ耐圧容器にＢａＩ2水溶液（２．５ｍｏｌ／Ｌ）４０００ｍｌとＥｕＩ3水溶液（０．２ｍｏｌ／Ｌ）２６．５ｍｌを反応器に入れた。この反応器中の反応母液を撹拌しながら８３℃で保温した。弗化アンモニウム水溶液（１３ｍｏｌ／Ｌ）４５０ｍｌとヨウ化カリウム水溶液（８ｍｏｌ／Ｌ）１５０ｍｌを同時に反応母液中にローラーポンプを用いて注入し、沈澱物を生成させた。注入終了後乾燥空気を１０Ｌ／ｍｉｎの割合で２０分間通気した。通気前後の溶液のし質量比は０．９４であった。そのままの温度で９０分間攪拌した。９０分攪拌した後ろ過しエタノール２０００ｍｌで洗浄した。回収した前駆体の質量を計測し、投入したＢａＩ2量と比較することにより収率を求めた。上記の操作によって得た沈殿物についてＸ線回折測定を行った。Ｘ線はＣｕ−Ｋα線をもちいた。ついで得た沈殿物の平均粒径を測定した。
【００８１】
比較例５
ユーロピウム付活弗化ヨウ化バリウムの輝尽性蛍光体前駆体を合成するために、２つの孔をもつ耐圧容器にＮＨ4Ｉ水溶液（２．５ｍｏｌ／Ｌ）５００ｍｌとＥｕＩ3水溶液（０．２ｍｏｌ／Ｌ）２６．５ｍｌを反応器に入れた。この反応器中の反応母液を撹拌しながら８３℃で保温した。ヨウ化バリウム水溶液と弗化アンモニウム水溶液（１３ｍｏｌ／Ｌ）４５０ｍｌとヨウ化カリウム水溶液（８ｍｏｌ／Ｌ）１５０ｍｌを同時に反応母液中にローラーポンプを用いて注入し、沈澱物を生成させた。注入終了後乾燥空気を１０Ｌ／ｍｉｎの割合で２０分間通気した。通気前後の溶液の質量比は０．９２であった。そのままの温度で９０分間攪拌した。９０分攪拌した後ろ過しエタノール２０００ｍｌで洗浄した。回収した前駆体の質量を計測し、投入したＢａＩ2量と比較することにより収率を求めた。上記の操作によって得た沈殿物についてＸ線回折測定を行った。Ｘ線はＣｕ−Ｋα線をもちいた。ついで得た沈殿物の平均粒径を測定した。
【００８２】
比較例６
ユーロピウム付活弗化ヨウ化バリウムの輝尽性蛍光体前駆体を合成するために、２つの孔をもつ耐圧容器にＢａＩ2水溶液（２．５ｍｏｌ／Ｌ）４０００ｍｌとＥｕＩ3水溶液（０．２ｍｏｌ／Ｌ）２６．５ｍｌを反応器に入れた。この反応器中の反応母液を撹拌しながら８３℃で保温した。弗化アンモニウム水溶液（１３ｍｏｌ／Ｌ）４５０ｍｌを反応母液中にローラーポンプを用いて注入し、沈澱物を生成させた。注入終了後乾燥空気を１０Ｌ／ｍｉｎの割合で２０分間通気した。通気前後の溶液の質量比は０．９１であった。次にヨウ化カリウム水溶液（８ｍｏｌ／Ｌ）１５０ｍｌを添加した後、そのままの温度で９０分間攪拌した。９０分攪拌した後ろ過しエタノール２０００ｍｌで洗浄した。回収した前駆体の質量を計測し、投入したＢａＩ2量と比較することにより収率を求めた。上記の操作によって得た沈殿物についてＸ線回折測定を行った。Ｘ線はＣｕ−Ｋα線をもちいた。ついで得た沈殿物の平均粒径を測定した。
【００８３】
上記の結果を表１にまとめて示す。
Ｘ線回折の結果から、２θ＝２９．４°のピークを副生成物であるＢａＦ2と同定した。
【００８４】
表１中、収率とは以下で規定される値である。
収率＝（回収前駆体質量／Ｂａ量から求めた理論収量）×１００
表１から明らかなように、反応液から溶媒を除去することにより、粒子の肥大化を防ぎつつ高収率で、前駆体を得ることができる。
【００８５】
上記実施例１から６および比較例１から６について保温焼結により粒子形状の変化、粒子間融着による粒子サイズ分布の変化を防止するために、アルミナの超微粒子粉体を１質量％添加し、ミキサーで充分撹拌して、結晶表面にアルミナの超微粒子粉体を均一に付着させた。これを石英ボートに充填して、チューブ炉を用いて水素ガス雰囲気中、８５０℃で２時間焼成してユーロピウム付活弗化ヨウ化バリウム蛍光体粒子を得た。
【００８６】
次に放射線像変換パネルの製造例を示す。
蛍光体層形成材料として、上記で得たユーロピウム付活弗化ヨウ化バリウム蛍光体４２７ｇ、ポリウレタン樹脂（住友バイエルウレタン社製、デスモラック４１２５）１５．８ｇ、ビスフェノールＡ型エポキシ樹脂２．０ｇをメチルエチルケトン−トルエン（１：１）混合溶媒に添加し、プロペラミキサーによって分散し、粘度２５〜３０ＰＳの塗布液を調製した。この塗布液をドクターブレードを用いて下塗付きポリエチレンテレフタレートフィルム上に塗布したのち、１００℃で１５分間乾燥させて、蛍光体層を形成した。
【００８７】
次に、保護膜形成材料として、フッ素系樹脂：フルオロオレフィン−ビニルエーテル共重合体（旭硝子社製ルミフロンＬＦ１００）７０ｇ、架橋剤：イソシアネート（住友バイエルウレタン社製デスモジュールＺ４３７０）２５ｇ、ビスフェノールＡ型エポキシ樹脂５ｇ、およびシリコーン樹脂微粉末（ＫＭＰ−５９０、信越化学工業社製、粒子径１〜２μｍ）１０ｇをトルエン−イソプロピルアルコール（１：１）混合溶媒に添加し、塗布液を作った。この塗布液を上記のようにして予め形成しておいた蛍光体層上にドクターブレードを用いて塗布し、次に１２０℃で３０分間熱処理して熱硬化させるとともに乾燥し、厚さ１０μｍの保護膜を設けた。以上の方法により、輝尽性蛍光体層を有する放射線像変換パネルを得た。
【００８８】
（放射線像変換パネルの評価）
感度については、放射線像変換パネルに管電圧８０ｋＶｐのＸ線を照射した後、パネルをＨｅ−Ｎｅレーザー光（６３３ｎｍ）で操作して励起し、蛍光体層から放射される輝尽発光を受光器（分光感度Ｓ−５の光電子像倍管）で受光してその強度を測定した。下記の表において輝度は比較例１を１００としたときの相対値で示されている。
【００８９】
鮮鋭度については、放射線像変換パネルに鉛製のＭＴＦチャートを通して管電圧８０ｋＶｐのＸ線を照射した後パネルをＨｅ−Ｎｅレーザー光で操作して励起し、蛍光体層から放射される輝尽発光を上記と同じ受光器で受光して電気信号に変換し、これをアナログ／デジタル変換して磁気テープに記録し、磁気テープをコンピューターで分析して磁気テープに記録されているＸ線像の変調伝達関数（ＭＴＦ）を調べた。下記の表には空間周波数２サイクル／ｍｍにおけるＭＴＦ値の比較例１を１００とした時の相対値が示されている。
【００９０】
【表１】
表１から明らかなように、本発明の製造方法によれば、微細な輝尽性蛍光体前駆体を高収率で得ることが可能である。
【００９２】
本発明に係る放射線画像変換パネルは、輝度、鮮鋭度において優れている。
【００９３】
【発明の効果】
本発明によれば、輝度、鮮鋭性に優れた放射線画像変換パネルに必要な酸素導入希土類付活アルカリ土類金属弗化沃化物系輝尽性蛍光体を、高い生産性で得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oxygen-introduced rare earth activated alkaline earth metal fluoroiodide stimulable phosphor, a method for producing the stimulable phosphor, and a radiation image conversion panel using the stimulable phosphor.
[0002]
[Prior art]
A radiation image recording / reproducing method using a stimulable phosphor described in Japanese Patent Application Laid-Open No. 55-12145 is known as an effective diagnostic means in place of conventional radiography. This method uses a radiation image conversion panel (also referred to as a storage phosphor sheet) containing a stimulable phosphor, and transmits the radiation transmitted through the subject or emitted from the subject. The stimulable phosphor is excited in time series by electromagnetic waves (referred to as excitation light) such as visible light and ultraviolet light, and the stored radiation energy is emitted as fluorescence (referred to as stimulated emission light). The fluorescence is photoelectrically read to obtain an electrical signal, and a radiographic image of the subject or subject is reproduced as a visible image based on the obtained electrical signal. The conversion panel after reading is subjected to erasure of the remaining image and used for the next photographing.
[0003]
According to this method, there is an advantage that a radiographic image having a large amount of information can be obtained with a much smaller exposure dose than radiography using a combination of a radiographic film and an intensifying screen. In contrast, the radiographic method consumes a film every time it is taken, whereas the radiographic image conversion panel is used repeatedly, which is advantageous in terms of resource protection and economic efficiency.
[0004]
The radiation image conversion panel comprises only a support and a photostimulable phosphor layer provided on the surface or a self-supporting photostimulable phosphor layer, and the photostimulable phosphor layer is usually a stimulable phosphor. And those composed only of aggregates of stimulable phosphors formed by vapor deposition or sintering. Also known is a polymer material impregnated in the gaps between the aggregates. Further, a protective film made of a polymer film or an inorganic vapor deposition film is usually provided on the surface of the photostimulable phosphor layer opposite to the support side.
[0005]
As the photostimulable phosphor, those that exhibit photostimulated luminescence in the wavelength range of 300 to 500 nm by excitation light in the range of 400 to 900 nm are generally used. 55-160078, 56-74175, 56-116777, 57-23673, 57-23675, 58-206678, 59-27289, 59-27980, 59 -56479, 59-56480, etc .; rare earth element activated alkaline earth metal fluoride halide phosphors; JP-A-59-75200, JP-A-60-84381, JP-A-60-106752, 60-166379, 60-222143, 60-228592, 60-228593, 61-23679, 61-120 Divalent europium-activated alkaline earth metal fluorohalide phosphors described in 82, 61-120883, 61-120585, 61-235486, 61-235487, etc .; Rare earth element activated oxyhalide phosphor described in JP-A-55-12144; cerium-activated trivalent metal oxyhalide phosphor described in JP-A-58-69281; described in JP-A-60-70484 Bismuth-activated alkali metal halide phosphors; divalent europium-activated alkaline earth metal halophosphate phosphors described in JP-A-60-14183, JP-A-60-157100, etc .; JP-A-60-157099 A divalent europium-activated alkaline earth metal haloborate phosphor described in JP-A-60-217354 Lucari earth metal hydride halide phosphor: cerium-activated rare earth composite halide phosphor described in JP-A-61-2173, JP-A-61-21182, etc .; with cerium described in JP-A-61-139090 Active rare earth halophosphate phosphor; divalent europium activated cerium / rubidium phosphor described in JP-A-60-78151; divalent europium-activated composite halogen described in JP-A-60-78151 In particular, divalent europium activated alkaline earth metal fluoride halide phosphors containing iodine, rare earth element activated oxyhalide phosphors containing iodine, and bismuth containing iodine. Activated alkali metal halide phosphors and the like are known, but high brightness photostimulable phosphors are still required.
[0006]
In addition, as the use of radiographic image conversion methods using photostimulable phosphors has progressed, further improvements in image quality of the obtained radiographic images, such as improvement in sharpness and graininess, have been further demanded.
[0007]
The method for producing a photostimulable phosphor described above is a method called a solid phase method or a sintering method, and pulverization after firing is essential, and it is difficult to control the particle shape that affects sensitivity and image performance. Have the problem. Among the means for improving the image quality of the radiation image, it is effective to make the stimulable phosphor finer and to equalize the particle diameter of the microstimulated phosphor, that is, to narrow the particle size distribution.
[0008]
The method for producing a photostimulable phosphor from a liquid phase disclosed in JP-A-7-233369, 9-291278, etc. comprises adjusting the concentration of the phosphor raw material solution to form a particulate stimulable phosphor. This is a method for obtaining a precursor, and is effective as a method for producing a photostimulable phosphor powder having a uniform particle size distribution. Further, from the viewpoint of reducing the radiation exposure amount, it is known that among rare earth activated alkaline earth metal fluoride halide stimulable phosphors, those having a high iodine content are preferable. This is because iodine has a higher X-ray absorption rate than bromine.
[0009]
The alkaline earth metal fluoroiodide-based stimulable phosphor produced in the liquid phase as described above is advantageous in terms of luminance and granularity, but when obtaining a precursor crystal in the liquid phase, Have problems like That is, as seen in the description of JP-A-10-88125 and JP-A-9-291278,
1) Dissolve barium iodide in water or an organic solvent, and add a solution of inorganic fluoride while stirring this solution.
2) Ammonium fluoride is dissolved in water, and a solution of barium iodide is added while stirring this solution.
The method is effective.
[0010]
However, in the method 1), it is necessary to make excess barium iodide exist in the solution. Therefore, the stoichiometric ratio of the charged barium iodide and the barium fluoroiodide obtained after solid-liquid separation is 0. In many cases, the value is as small as around .4. That is, the yield of the alkaline earth metal fluoroiodide stimulable phosphor is often about 40% with respect to the charged barium iodide.
[0011]
The method 2) also requires an excess of barium iodide relative to the inorganic fluoride, and the yield is low. Thus, the liquid phase synthesis of barium fluoroiodide has the problems of low yield and poor productivity. Lowering the barium iodide concentration in the mother liquor to increase the yield leads to particle enlargement, which is undesirable from the standpoint of image quality.
[0012]
As an attempt to increase the yield of rare earth activated alkaline earth metal fluoride halide photostimulable phosphors, particularly alkaline earth metal fluoride iodide photostimulable phosphors, JP-A-11-29324 describes After adding the concentration of the reaction mother liquor and the fluorine source and concentrating, at least one rare earth element selected from the basic composition formula BaFI: xLn (Ln: Ce, Pr, Sm, Eu, Gd, Tb, Tm and Yb, A method for obtaining a rare earth element-containing prismatic barium fluoroiodide crystal represented by the following formula is disclosed: x represents a numerical value of 0 <x ≦ 0.1.
[0013]
However, as a result of a further examination by the present inventors, it was found that although BaFI square crystals were produced as described, productivity was remarkably low due to the use of concentration by natural evaporation, and this was not practical from an industrial viewpoint. Also, it was found that the obtained square crystals have a large particle size and a wide particle size distribution, so that the image characteristics are poor and cannot be put to practical use.
[0014]
[Problems to be solved by the invention]
An object of the present invention is to obtain an oxygen-introduced rare earth-activated alkaline earth metal fluoride halide photostimulable phosphor having a uniform particle size distribution with high productivity, and further to a finer particle size distribution. It is to obtain the same photostimulable phosphor with higher yield than barium halide, and to provide a high-sensitivity and high-quality radiation image conversion panel using them.
[0015]
[Means for Solving the Problems]
The object of the present invention is achieved by the following constitution.
[0016]
(1) A method for producing an oxygen-introduced rare earth activated alkaline earth metal fluoride halide photostimulable phosphor represented by the following general formula (1), wherein an inorganic fluoride aqueous solution and an alkali metal halide aqueous solution are added Thereafter, the stimulable phosphor precursor is obtained by removing the solvent from the solution having a barium concentration of 3.3 mol / L or more in the reaction mother liquor, and is characterized in that the oxygen-introduced rare earth activated alkaline earth metal fluoride is obtained. For producing a halide-based photostimulable phosphor.
[0017]
General formula (1) Ba (1-x) M 2 (x) FBr (y) I (1-y) : AM 1 , BLn, cO
Where M 1 Is at least one alkali metal selected from Li, Na, K, Rb and Cs, M 2 Is at least one alkaline earth metal selected from Be, Mg, Sr and Ca, Ln is at least one selected from Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb. X, y, a, b, and c are each represented by 0 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.3, 0 ≦ a ≦ 0.05, and 0 <b ≦ 0.2. , 0 <c ≦ 0.1.
[0018]
(2) A method for producing an oxygen-introduced rare earth activated alkaline earth metal fluoride halide photostimulable phosphor represented by the general formula (1), comprising a barium halide aqueous solution, an inorganic fluoride aqueous solution and an alkali metal halogen. An oxygen-introduced rare earth activation, characterized in that a stimulable phosphor precursor is obtained by removing a solvent from a solution having a barium concentration of 3.3 mol / L or more in the reaction mother liquor after adding an aqueous solution of the compound. A method for producing an alkaline earth metal fluoride halide photostimulable phosphor.
[0019]
(3) A method for producing an oxygen-introduced rare earth activated alkaline earth metal fluoride halide photostimulable phosphor represented by the general formula (1), wherein the barium concentration in the reaction mother liquor is 3.3 mol / L. A stimulable phosphor precursor is obtained by adding an alkali metal halide aqueous solution after removing the solvent from the above solution, and an oxygen-introduced rare earth activated alkaline earth metal fluoride halide-based stimulant For producing fluorescent phosphor.
[0020]
(4) The oxygen-introduced rare earth activated alkaline earth metal according to (1), (2) or (3), wherein the mass of the reaction solution is (after solvent removal / before solvent removal) ≦ 0.97 A method for producing a fluorinated halide-based stimulable phosphor.
[0021]
(5) The oxygen-introduced rare earth activated alkaline earth metal halogen fluoride according to any one of (1) to (4), wherein the method for removing the reaction solvent is an artificial operation. Method for producing a fluoride-based stimulable phosphor.
[0022]
(6) The oxygen-introducing rare earth activated alkaline earth metal fluorohalide according to any one of (1) to (5), wherein the method of removing the reaction solvent is a method of passing dry gas A method for producing a photostimulable phosphor.
[0023]
(7) The oxygen-introduced rare earth-activated alkaline earth metal fluorohalide-based glitter according to any one of (1) to (6), wherein the solution forms a wet wall during the solvent removal operation A method for producing an exhaustive phosphor.
[0024]
(8) An oxygen-introduced rare earth activated alkaline earth metal fluoride halide photostimulable phosphor obtained by the production method according to any one of (1) to (7).
[0025]
(9) A radiation image conversion panel comprising a phosphor layer containing the oxygen-introduced rare earth activated alkaline earth metal fluoride halide stimulable phosphor according to (8).
[0026]
DETAILED DESCRIPTION OF THE INVENTION
A typical embodiment of the method for producing the oxygen-introduced rare earth activated alkaline earth metal fluoride halide photostimulable phosphor of the present invention will be described in detail below.
[0027]
For the production of stimulable phosphor precursors by the liquid phase method, the precursor production method described in Japanese Patent Application No. 8-265525 and the precursor production apparatus described in Japanese Patent Application No. 8-266718 can be preferably used. . Here, the photostimulable phosphor precursor is a state in which the substance of the general formula (1) has not passed through a high temperature of 600 ° C. or higher, and the photostimulable phosphor precursor is a phosphorescent light emitting property or an instantaneous light emitting device. It shows little sex.
[0028]
In the present invention, the precursor is preferably obtained by the following liquid phase synthesis method.
Production of the oxygen-introduced rare earth activated alkaline earth metal fluoroiodide-based stimulable phosphor represented by the general formula (1) is not a solid phase method in which the particle shape is difficult to control, but the particle size is easily controlled. The liquid phase method is used. In particular, it is preferable to obtain a photostimulable phosphor by the following liquid phase synthesis method.
[0029]
(Production method 1)
BaI 2 And a halide of Ln, and when x in the general formula (1) is not 0, M 2 When y is not 0, BaBr 2 After they have dissolved, BaI 2 Preparing a solution having a concentration of 3.3 mol / L or more, preferably 4.0 mol / L or more;
An aqueous solution of inorganic fluoride (ammonium fluoride or alkali metal fluoride) having a concentration of 5 mol / L or more, preferably 8 mol / L or more, while maintaining the above solution at a temperature of 50 ° C. or more, preferably 80 ° C. or more. And M if a is not 0 1 Adding a rare earth-activated alkaline earth metal fluoroiodide-based stimulable phosphor precursor crystal precipitate;
Removing the solvent from the reaction solution after completion of the addition;
Separating the precursor crystal precipitate from the reaction solution;
And firing the separated precursor crystal precipitate while avoiding sintering
It is a manufacturing method containing.
[0030]
(Production method 2)
In the case where a halide of Ln is contained and x in the general formula (1) is not 0, M 2 When y is not 0, BaBr 2 Preparing a solution in which is dissolved;
While maintaining the above solution at a temperature of 50 ° C. or higher, preferably 80 ° C. or higher, 2 A solution having a concentration of 3.3 mol / L or more, preferably 4.0 mol / L or more, and an inorganic fluoride aqueous solution (ammonium fluoride or alkali metal fluoride) having a concentration of 5 mol / L or more, preferably 8 mol / L or more. Aqueous solution and M if a is not 0 1 A rare earth activated alkaline earth metal fluoroiodide-based stimulable phosphor precursor crystal precipitate;
Removing the solvent from the reaction solution after completion of the addition;
Separating the precursor crystal precipitate from the reaction solution;
And firing the separated precursor crystal precipitate while avoiding sintering
It is a manufacturing method containing.
[0031]
(Production method 3)
BaI 2 And a halide of Ln, and when x in the general formula (1) is not 0, M 2 When y is not 0, BaBr 2 After they have dissolved, BaI 2 Preparing a solution having a concentration of 3.3 mol / L or more, preferably 4.0 mol / L or more;
An aqueous solution of inorganic fluoride (ammonium fluoride or alkali metal fluoride) having a concentration of 5 mol / L or more, preferably 8 mol / L or more, while maintaining the above solution at a temperature of 50 ° C. or more, preferably 80 ° C. or more. Adding a rare earth activated alkaline earth metal fluoroiodide-based stimulable phosphor precursor crystal precipitate;
Removing the solvent from the reaction solution after completion of the addition;
M if a is not 0 1 Adding an aqueous solution of a halide of
Maintaining the solution at a temperature of 50 ° C. or higher, preferably 80 ° C. or higher;
Separating the precursor crystal precipitate from the reaction solution;
And firing the separated precursor crystal precipitate while avoiding sintering
It is a manufacturing method containing.
[0032]
The particles (crystals) according to the present invention preferably have an average particle size of 1 to 10 μm and are monodisperse, have an average particle size of 1 to 5 μm and an average particle size distribution (%) of 20% or less. The average particle size is preferably 1 to 3 μm, and the average particle size distribution is preferably 15% or less.
[0033]
The average particle diameter in the present invention is obtained by randomly selecting 200 particles from an electron micrograph of particles (crystals) and obtaining an average by volume particle diameter in terms of sphere.
[0034]
Details of the method for producing the photostimulable phosphor will be described below.
(Preparation of precursor crystal precipitate, preparation of stimulable phosphor)
In the production method 1, a raw material compound other than a fluorine compound and an alkali metal halide is dissolved in an aqueous medium. That is, BaI 2 And Ln halides, and optionally further M 2 In an aqueous medium, and thoroughly mixed and dissolved to prepare an aqueous solution in which they are dissolved. However, BaI 2 BaI so that the concentration is 3.3 mol / L or more, preferably 4.0 mol / L or more. 2 The ratio between the concentration and the aqueous solvent is adjusted. At this time, if the barium concentration is low, a precursor having a desired composition cannot be obtained, or even if obtained, the particles are enlarged. Therefore, it is necessary to select the barium concentration appropriately, and as a result of the study by the present inventors, it was found that fine precursor particles can be formed at 3.3 mol / L or more. At this time, a small amount of acid, ammonia, alcohol, water-soluble polymer, water-insoluble metal oxide fine particle powder or the like may be added as desired. BaI 2 It is also a preferred embodiment that an appropriate amount of lower alcohol (methanol, ethanol, etc.) is added within a range in which the solubility of is not significantly reduced. This aqueous solution (reaction mother liquor) is maintained at 50 ° C. or higher.
[0035]
Next, an aqueous solution of inorganic fluoride (ammonium fluoride, alkali metal fluoride, etc.) and an aqueous solution of alkali metal halide are used in the aqueous solution maintained at 50 ° C. and stirred, using a pipe with a pump, etc. Inject. This injection is preferably carried out in the region where the stirring is particularly intense. By injecting the inorganic fluoride aqueous solution into the reaction mother liquor, a rare earth activated alkaline earth metal fluoride halide phosphor crystal corresponding to the general formula (1) is precipitated.
[0036]
Production method 2 uses BaI in an aqueous medium. 2 An aqueous solution, an aqueous solution of a fluorine compound, and an aqueous solution of an alkali metal halide are prepared, and these are simultaneously or sequentially mixed to obtain a rare earth activated alkaline earth metal fluoride halide based phosphor precursor crystal. That is, BaI 2 And Ln halides, and optionally further M 2 Halides, and even M 1 In an aqueous medium, and thoroughly mixed and dissolved to prepare an aqueous solution in which they are dissolved. However, BaI 2 BaI so that the concentration is 3.3 mol / L or more, preferably 4.0 mol / L or more. 2 The ratio between the concentration and the aqueous solvent is adjusted. At this time, if the barium concentration is low, a precursor having a desired composition cannot be obtained, or even if obtained, the particles are enlarged. Therefore, it is necessary to select the barium concentration appropriately, and as a result of the study by the present inventors, it was found that fine precursor particles can be formed at 3.3 mol / L or more. At this time, a small amount of acid, ammonia, alcohol, water-soluble polymer, water-insoluble metal oxide fine particle powder or the like may be added as desired. BaI 2 It is also a preferred embodiment that an appropriate amount of lower alcohol (methanol, ethanol, etc.) is added within a range in which the solubility of is not significantly reduced. This aqueous solution (reaction mother liquor) is maintained at 50 ° C. and injected using a pipe with a pump or the like.
[0037]
On the other hand, an aqueous solution of inorganic fluoride (ammonium fluoride, alkali metal fluoride, etc.) is injected using a pipe with a pump or the like.
[0038]
These prepared aqueous solutions are injected into the reaction vessel at the same time or with a slight time lag, but it is preferable to carry out in the region where stirring is particularly intense. These BaI 2 By injecting the aqueous solution and the aqueous inorganic fluoride solution into the reaction vessel, the rare earth activated alkaline earth metal fluoride halide phosphor crystal corresponding to the general formula (1) is precipitated.
[0039]
In the production method 3, a raw material compound other than a fluorine compound and an alkali metal halide is dissolved in an aqueous medium. That is, BaI 2 And Ln halides, and optionally further M 2 In an aqueous medium, and thoroughly mixed and dissolved to prepare an aqueous solution in which they are dissolved. However, BaI 2 BaI so that the concentration is 3.3 mol / L or more, preferably 4.0 mol / L or more. 2 The ratio between the concentration and the aqueous solvent is adjusted. At this time, if the barium concentration is low, a precursor having a desired composition cannot be obtained, or even if obtained, the particles are enlarged. Therefore, it is necessary to select the barium concentration appropriately, and as a result of the study by the present inventors, it was found that fine precursor particles can be formed at 3.3 mol / L or more. At this time, a small amount of acid, ammonia, alcohol, water-soluble polymer, water-insoluble metal oxide fine particle powder or the like may be added as desired. BaI 2 It is also a preferred embodiment that an appropriate amount of lower alcohol (methanol, ethanol, etc.) is added within a range in which the solubility of is not significantly reduced. This aqueous solution (reaction mother liquor) is maintained at 50 ° C. or higher.
[0040]
Next, an aqueous solution of inorganic fluoride (ammonium fluoride, alkali metal fluoride, etc.) is injected into the aqueous solution maintained at 50 ° C. or higher and stirred using a pipe with a pump or the like. This injection is preferably carried out in the region where the stirring is particularly intense.
[0041]
Next, the solvent is removed from the reaction solution. The timing for removing the solvent is not particularly limited, but the most preferable mode is that the removal is started immediately after the addition of the inorganic fluoride solution.
[0042]
The removal amount of the solvent is preferably 3% or more by mass ratio before and after the removal. Below this, the crystals may not have a preferred composition. Therefore, the removal amount is preferably 3% or more, and more preferably 5% or more. Moreover, even if it removes too much, inconvenience may arise in terms of handling, such as an excessive increase in the viscosity of the reaction solution. Therefore, the removal amount of the solvent is preferably 50% or less in terms of the mass ratio before and after removal.
[0043]
After removing an appropriate amount of the solvent, an alkali metal halide aqueous solution is added and further stirred to obtain a rare earth activated alkaline earth metal fluoride halide phosphor precursor crystal.
[0044]
The time required for removing the solvent not only greatly affects the productivity, but also the shape of the particles and the particle size distribution are affected by the method of removing the solvent, so the removal method must be appropriately selected. In the present invention, a method to which an artificial operation other than natural evaporation is added is used. When removing the solvent, a method of heating the solution and evaporating the solvent is selected. This method is also useful in the present invention. By removing the solvent, a precursor having the intended composition can be obtained.
[0045]
Furthermore, in order to increase productivity and to keep the particle shape appropriately, it is preferable to use other solvent removal methods in combination. The method for removing the solvent used in combination is not particularly limited. It is also possible to select a method using a separation membrane such as a reverse osmosis membrane. In the present invention, it is preferable to select the following removal method from the viewpoint of productivity.
[0046]
1. Vent dry gas
The reaction vessel is of a sealed type, provided with holes through which at least two or more gases can pass, and dried gas is vented from there. The kind of gas can be selected arbitrarily. Air and nitrogen are preferable from the viewpoint of safety. Depending on the amount of saturated water vapor in the gas to be vented, the solvent is entrained in the gas and removed. In addition to the method of venting the void of the reaction vessel, a method of jetting gas as bubbles in the liquid phase and absorbing the solvent in the bubbles is also effective.
[0047]
2. Decompression
As is well known, the vapor pressure of the solvent is reduced by reducing the pressure. The solvent can be efficiently removed by the vapor pressure drop. The degree of reduced pressure can be appropriately selected depending on the type of solvent.
[0048]
3. Liquid film
The solvent can be efficiently removed by enlarging the evaporation area. As in the present invention, when a reaction is carried out by heating and stirring using a constant volume reaction vessel, the heating method is a method of immersing the heating means in a liquid or mounting the heating means outside the container. Is common. According to this method, the heat transfer area is limited to a portion where the liquid and the heating means are in contact with each other, and the heat transfer area is reduced as the solvent is removed, and thus the time required for solvent removal is increased. In order to prevent this, a method of increasing the heat transfer area by spraying on the wall surface of the reaction vessel using a pump or a stirrer is effective.
[0049]
Such a method of spraying a liquid on the reaction vessel wall surface to form a liquid film is known as a “wetting wall”. Examples of the method for forming the wet wall include a method using a stirrer described in JP-A-6-335627 and JP-A-11-235522, in addition to a method using a pump.
[0050]
These methods may be used not only alone but also in combination. A combination of a method of forming a liquid film and a method of reducing the pressure in the container, a combination of a method of forming a liquid film and a method of ventilating dry gas, and the like are effective. The former is particularly preferable, and the method described in JP-A-6-335627 is preferably used.
[0051]
Next, the phosphor precursor crystals are separated from the solution by filtration, centrifugation, etc., washed thoroughly with methanol or the like, and dried. A sintering inhibitor such as alumina fine powder or silica fine powder is added to and mixed with the dried phosphor precursor crystal, and the fine powder of sintering inhibitor is uniformly attached to the crystal surface. In addition, it is also possible to omit the addition of the sintering inhibitor by selecting the firing conditions.
[0052]
Next, the phosphor precursor crystals are filled in a heat-resistant container such as a quartz port, an alumina crucible, or a quartz crucible, and placed in the core of an electric furnace to be fired while avoiding sintering. The range of 400-1300 degreeC is suitable for a calcination temperature, and the range of 500-1000 degreeC is preferable. The firing time varies depending on the filling amount of the phosphor raw material mixture, the firing temperature, the removal temperature from the furnace, etc., but generally 0.5 to 12 hours is appropriate.
[0053]
As the firing atmosphere, a neutral atmosphere such as a nitrogen gas atmosphere or an argon gas atmosphere, a weakly reducing atmosphere such as a nitrogen gas atmosphere containing a small amount of hydrogen gas, a carbon dioxide atmosphere containing carbon monoxide, or a small amount of oxygen introduced The atmosphere is used. As the firing method, the method described in JP-A No. 2000-8034 is preferably used.
[0054]
The target oxygen-introduced rare earth activated alkaline earth metal fluoride halide photostimulable phosphor can be obtained by the above firing.
[0055]
(Production of radiation image conversion panel)
As the support used in the radiation image conversion panel of the present invention, various polymer materials, glass, metal and the like are used. Particularly suitable for information recording materials are materials that can be processed into flexible sheets or webs. From this point, plastics such as cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate film, etc. Film: A metal sheet of aluminum, iron, copper, chromium or the like or a metal sheet having a coating layer of the metal oxide is preferred.
[0056]
The layer thickness of these supports varies depending on the material of the support to be used, but is generally 10 to 1000 μm, and more preferably 10 to 500 μm from the viewpoint of handling.
[0057]
The surface of these supports may be a smooth surface, or may be a mat surface for the purpose of improving the adhesion to the stimulable phosphor layer. Furthermore, an undercoat layer may be provided on the surface on which the photostimulable phosphor layer is provided for the purpose of improving the adhesion with the photostimulable phosphor layer.
[0058]
Examples of binders used in the photostimulable phosphor layer include proteins such as gelatin, polysaccharides such as dextran, or natural polymer materials such as gum arabic; polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, Binders represented by synthetic polymer materials such as vinylidene chloride / vinyl chloride copolymer, polyalkyl (meth) acrylate, vinyl chloride / vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, linear polyester, etc. Can be mentioned. Among these, nitrocellulose, linear polyester, polyalkyl (meth) acrylate, a mixture of nitrocellulose and linear polyester, a mixture of nitrocellulose and polyalkyl (meth) acrylate, and polyurethane and polyvinyl butyral are particularly preferable. And a mixture. These binders may be crosslinked by a crosslinking agent.
[0059]
The photostimulable phosphor layer can be formed on the undercoat layer by the following method, for example.
[0060]
First, an iodine-containing photostimulable phosphor, a compound such as a phosphite for preventing yellowing, and a binder are added to a suitable solvent, and these are mixed well to combine the phosphor particles and the phosphor in the binder solution. A coating solution in which compound particles are uniformly dispersed is prepared.
[0061]
Examples of the binder used in the present invention include proteins such as gelatin, polysaccharides such as dextran or gum arabic, polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethyl cellulose, vinylidene chloride / vinyl chloride copolymer, polymethyl methacrylate, and chloride. Usually, a film-forming binder such as vinyl / vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol or the like is used for the layer structure.
[0062]
Generally, a binder is used in 0.01-1 mass part with respect to 1 mass part of stimulable fluorescent substance. However, in terms of sensitivity and sharpness of the obtained radiation image conversion panel, it is preferable that the amount of the binder is small, and the range of 0.03 to 0.2 parts by mass is more preferable from the viewpoint of easy application.
[0063]
The mixing ratio of the binder to the stimulable phosphor in the coating solution (however, when the entire binder is an epoxy group-containing compound, it is equal to the ratio of the compound to the phosphor) is the target radiation image Although it varies depending on the characteristics of the conversion panel, the type of phosphor, the amount of the epoxy group-containing compound added, etc., in general, examples of solvents for preparing the bond coating liquid include methanol, enotal, 1-propanol, 2-propanol, butanol Lower alcohols; Chlorine atom-containing hydrocarbons such as methylene chloride and ethylene chloride; Ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; Esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate, and butyl acetate; Dioxane, ethylene glycol Such as ethyl ether, ethylene glycol monomethyl ether, etc. Ether; toluene; and it can include mixtures thereof.
[0064]
Examples of solvents used for the preparation of the stimulable phosphor layer coating solution include: lower alcohols such as methanol, ethanol, 1-propanol, and butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; methyl acetate, acetic acid Esters of lower fatty acids and lower alcohols such as ethyl and butyl acetate; ethers such as dioxane, ethylene glycol monoethyl ether and ethylene glycol monomethyl ether; aromatic compounds such as triol and xylol; halogenated carbonization such as methylene chloride and ethylene chloride Examples thereof include hydrogen and a mixture thereof.
[0065]
In addition, in the coating liquid, a dispersing agent for improving the dispersibility of the phosphor in the coating liquid, and the binding force between the binder and the phosphor in the photostimulable phosphor layer after formation are improved. Various additives such as plasticizers for the purpose may be mixed. Examples of the dispersant used for such purpose include phthalic acid, stearic acid, caproic acid, lipophilic surfactant and the like. Examples of plasticizers include phosphoric esters such as triphenyl phosphate, tricresyl phosphate and diphenyl phosphate; phthalic esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalyl ethyl glycolate and butyl phthalyl butyl glycolate Examples include glycolic acid esters such as: polyesters of triethylene glycol and adipic acid, polyesters of polyethylene glycol and aliphatic dibasic acid such as polyesters of diethylene glycol and succinic acid, and the like.
[0066]
The coating liquid of the coating liquid is formed by uniformly coating the coating liquid prepared as described above on the surface of the undercoat layer. This coating operation can be performed using a normal coating means such as a doctor blade, a roll coater, a knife coater, or the like. Next, the formed coating film is dried by gradually heating to complete the formation of the photostimulable phosphor layer on the undercoat layer.
[0067]
The stimulable phosphor layer coating solution is prepared using a dispersing device such as a ball mill, a sand mill, an attritor, a three-roll mill, a high-speed impeller disperser, a Kady mill, and an ultrasonic disperser. The prepared coating solution is coated on a support using a coating device such as a doctor blade, a roll coater, or a knife coater, and dried to form a photostimulable phosphor layer. The stimulable phosphor layer and the support may be bonded after the coating solution is applied and dried on the protective layer.
[0068]
The thickness of the photostimulable phosphor layer of the radiation image conversion panel varies depending on the characteristics of the intended radiation image conversion panel, the type of stimulable phosphor, the mixing ratio of the binder and the stimulable phosphor, etc. Is preferably selected from the range of 10 to 1,000 μm, and more preferably selected from the range of 10 to 500 μm.
[0069]
In the foregoing, examples of stimulable phosphors such as europium-activated barium fluoride iodide have been mainly described, but europium-activated barium fluoride bromide and other stimuli represented by the above general formula (I) are described. The phosphor can also be manufactured with reference to the above.
[0070]
【Example】
Hereinafter, the present invention will be illustrated with reference to examples, but the present invention is not limited thereto.
[0071]
Example 1
In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, a BaI was placed in a pressure vessel with two holes. 2 2500 ml of aqueous solution (4.2 mol / L) and EuI Three 26.5 ml of an aqueous solution (0.2 mol / L) was placed in the reactor. The reaction mother liquor in this reactor was kept at 83 ° C. with stirring. 450 mL of an aqueous ammonium fluoride solution (13 mol / L) and 150 mL of an aqueous potassium iodide solution (8 mol / L) were simultaneously injected into the reaction mother liquor using a roller pump to produce a precipitate. After the injection, dry air was aerated at a rate of 10 L / min for 20 minutes. The mass ratio of the solution before and after aeration was 0.94. The mixture was stirred for 90 minutes at the same temperature. The mixture was stirred for 90 minutes, filtered and washed with 2000 ml of ethanol. Measure the mass of the recovered precursor and put BaI into 2 The yield was determined by comparing with the amount. X-ray diffraction measurement was performed on the precipitate obtained by the above operation. X-rays were Cu-Kα rays. Subsequently, the average particle diameter of the obtained precipitate was measured.
[0072]
Example 2
In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, a pressure vessel with two holes is fitted with NH. Four 500 ml of aqueous I solution (4.2 mol / L) and EuI Three 26.5 ml of an aqueous solution (0.2 mol / L) was placed in the reactor. The reaction mother liquor in this reactor was kept at 83 ° C. with stirring. A barium iodide aqueous solution (4.2 mol / L) 4500 ml, an ammonium fluoride aqueous solution (13 mol / L) 450 ml and a potassium iodide aqueous solution (8 mol / L) 150 ml were simultaneously injected into the reaction mother liquor using a roller pump, and the precipitate Was generated. After the injection, dry air was aerated at a rate of 10 L / min for 20 minutes. The mass ratio of the solution before and after aeration was 0.92. The mixture was stirred for 90 minutes at the same temperature. The mixture was stirred for 90 minutes, filtered and washed with 2000 ml of ethanol. Measure the mass of the recovered precursor and put BaI into 2 The yield was determined by comparing with the amount. X-ray diffraction measurement was performed on the precipitate obtained by the above operation. X-rays were Cu-Kα rays. Subsequently, the average particle diameter of the obtained precipitate was measured.
[0073]
Example 3
In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, a BaI was placed in a pressure vessel with two holes. 2 2500 ml of aqueous solution (4.2 mol / L) and EuI Three 26.5 ml of an aqueous solution (0.2 mol / L) was placed in the reactor. The reaction mother liquor in this reactor was kept at 83 ° C. with stirring. 450 ml of an aqueous ammonium fluoride solution (13 mol / L) was injected into the reaction mother liquor using a roller pump to form a precipitate. After the injection, dry air was aerated at a rate of 10 L / min for 20 minutes. The mass ratio of the solution before and after aeration was 0.92. Next, 150 ml of an aqueous potassium iodide solution (8 mol / L) was added, followed by stirring at the same temperature for 90 minutes. The mixture was stirred for 90 minutes, filtered and washed with 2000 ml of ethanol. Measure the mass of the recovered precursor and put BaI into 2 The yield was determined by comparing with the amount. X-ray diffraction measurement was performed on the precipitate obtained by the above operation. X-rays were Cu-Kα rays. Subsequently, the average particle diameter of the obtained precipitate was measured.
[0074]
Example 4
After completion of the addition of ammonium fluoride, the pressure in the reaction vessel was set to 745 hPa using a circulating aspirator, and the solvent was concentrated under reduced pressure. Concentration was performed for 15 minutes. The mass ratio of the reaction solution before and after concentration was 0.92. Except this, the same operation as in Example 1 was performed to obtain a precipitate. The yield was calculated in the same manner as in Example 1, and the X-ray diffraction and average particle size of the precipitate were measured.
[0075]
Example 5
After completion of the addition of ammonium fluoride, the reaction solution was sprayed onto the reaction vessel wall surface using a pump to evaporate the solvent while forming a liquid film. This operation was performed for 15 minutes. The mass ratio of the reaction solution before and after concentration was 0.94. Except this, the same operation as in Example 1 was performed to obtain a precipitate. The yield was calculated in the same manner as in Example 1, and the X-ray diffraction and average particle size of the precipitate were measured.
[0076]
Example 6
In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, a BaI was placed in a pressure vessel with two holes. 2 2500 ml of aqueous solution (4.2 mol / L) and EuI Three 26.5 ml of an aqueous solution (0.2 mol / L) was placed in the reactor. The reaction mother liquor in this reactor was kept at 83 ° C. with stirring. Ammonium fluoride aqueous solution (13 mol / L) 450 ml, potassium iodide aqueous solution (8 mol / L) 135 ml, and sodium iodide aqueous solution (8 mol / L) 15 ml were simultaneously injected into the reaction mother liquor using a roller pump to form a precipitate. I let you. After the injection, dry air was aerated at a rate of 10 L / min for 20 minutes. The mass ratio of the solution before and after aeration was 0.93. The mixture was stirred for 90 minutes at the same temperature. The mixture was stirred for 90 minutes, filtered and washed with 2000 ml of ethanol. Measure the mass of the recovered precursor and put BaI into 2 The yield was determined by comparing with the amount. X-ray diffraction measurement was performed on the precipitate obtained by the above operation. X-rays were Cu-Kα rays. Subsequently, the average particle diameter of the obtained precipitate was measured.
[0077]
Comparative Example 1
In order to synthesize a stimulable phosphor precursor of europium activated barium fluoroiodide, BaI 2 2500 ml of aqueous solution (4.2 mol / L) and EuI Three 26.5 ml of an aqueous solution (0.2 mol / L) was placed in the reactor. The reaction mother liquor in this reactor was kept at 83 ° C. with stirring. 450 mL of an aqueous ammonium fluoride solution (13 mol / L) and 150 mL of an aqueous potassium iodide solution (8 mol / L) were simultaneously injected into the reaction mother liquor using a roller pump to produce a precipitate. After completion of the injection, the mixture was stirred at the same temperature for 90 minutes. The mixture was stirred for 90 minutes, filtered and washed with 2000 ml of ethanol. Measure the mass of the recovered precursor and put BaI into 2 The yield was determined by comparing with the amount. X-ray diffraction measurement was performed on the precipitate obtained by the above operation. Subsequently, the average particle diameter of the obtained precipitate was measured.
[0078]
Comparative Example 2
A precipitate was obtained in the same manner as in Comparative Example 1 except that the amount of the aqueous ammonium fluoride solution poured into the reaction mother liquor was 600 ml. The yield was calculated in the same manner as in Example 1, and the X-ray diffraction and average particle size of the precipitate were measured.
[0079]
Comparative Example 3
The amount of the ammonium fluoride aqueous solution injected into the reaction mother liquor was 600 ml, and after the ammonium fluoride solution was injected, the solution was concentrated by natural evaporation. Concentration was performed for 15 hours. The mass ratio of the reaction solution before and after concentration was 0.87. Except this, it carried out similarly to the comparative example 1, and obtained the deposit. The yield was calculated in the same manner as in Example 1, and the X-ray diffraction and average particle size of the precipitate were measured.
[0080]
Comparative Example 4
In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, a BaI was placed in a pressure vessel with two holes. 2 4000 ml of aqueous solution (2.5 mol / L) and EuI Three 26.5 ml of an aqueous solution (0.2 mol / L) was placed in the reactor. The reaction mother liquor in this reactor was kept at 83 ° C. with stirring. 450 ml of an aqueous ammonium fluoride solution (13 mol / L) and 150 ml of an aqueous potassium iodide solution (8 mol / L) were simultaneously injected into the reaction mother liquor using a roller pump to form a precipitate. After the injection, dry air was aerated at a rate of 10 L / min for 20 minutes. The mass ratio of the solution before and after aeration was 0.94. The mixture was stirred for 90 minutes at the same temperature. The mixture was stirred for 90 minutes, filtered and washed with 2000 ml of ethanol. Measure the mass of the recovered precursor and put BaI into 2 The yield was determined by comparing with the amount. X-ray diffraction measurement was performed on the precipitate obtained by the above operation. X-rays were Cu-Kα rays. Subsequently, the average particle diameter of the obtained precipitate was measured.
[0081]
Comparative Example 5
In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, a pressure vessel with two holes is fitted with NH. Four 500 ml of aqueous solution I (2.5 mol / L) and EuI Three 26.5 ml of an aqueous solution (0.2 mol / L) was placed in the reactor. The reaction mother liquor in this reactor was kept at 83 ° C. with stirring. A barium iodide aqueous solution, an ammonium fluoride aqueous solution (13 mol / L) 450 ml and a potassium iodide aqueous solution (8 mol / L) 150 ml were simultaneously injected into the reaction mother liquor using a roller pump to form a precipitate. After the injection, dry air was aerated at a rate of 10 L / min for 20 minutes. The mass ratio of the solution before and after aeration was 0.92. The mixture was stirred for 90 minutes at the same temperature. The mixture was stirred for 90 minutes, filtered and washed with 2000 ml of ethanol. Measure the mass of the recovered precursor and put BaI into 2 The yield was determined by comparing with the amount. X-ray diffraction measurement was performed on the precipitate obtained by the above operation. X-rays were Cu-Kα rays. Subsequently, the average particle diameter of the obtained precipitate was measured.
[0082]
Comparative Example 6
In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, a BaI was placed in a pressure vessel with two holes. 2 4000 ml of aqueous solution (2.5 mol / L) and EuI Three 26.5 ml of an aqueous solution (0.2 mol / L) was placed in the reactor. The reaction mother liquor in this reactor was kept at 83 ° C. with stirring. 450 ml of an aqueous ammonium fluoride solution (13 mol / L) was injected into the reaction mother liquor using a roller pump to form a precipitate. After the injection, dry air was aerated at a rate of 10 L / min for 20 minutes. The mass ratio of the solution before and after aeration was 0.91. Next, 150 ml of an aqueous potassium iodide solution (8 mol / L) was added, followed by stirring at the same temperature for 90 minutes. The mixture was stirred for 90 minutes, filtered and washed with 2000 ml of ethanol. Measure the mass of the recovered precursor and put BaI into 2 The yield was determined by comparing with the amount. X-ray diffraction measurement was performed on the precipitate obtained by the above operation. X-rays were Cu-Kα rays. Subsequently, the average particle diameter of the obtained precipitate was measured.
[0083]
The results are summarized in Table 1.
From the result of X-ray diffraction, a peak at 2θ = 29.4 ° is obtained as a by-product, BaF. 2 Was identified.
[0084]
In Table 1, the yield is a value specified below.
Yield = (Theoretical yield determined from recovered precursor mass / Ba amount) × 100
As is clear from Table 1, by removing the solvent from the reaction solution, the precursor can be obtained in a high yield while preventing the particles from being enlarged.
[0085]
In Examples 1 to 6 and Comparative Examples 1 to 6, in order to prevent changes in the particle shape due to thermal insulation sintering and changes in the particle size distribution due to fusion between particles, 1% by mass of ultrafine powder of alumina was added. The mixture was sufficiently stirred with a mixer to uniformly adhere the ultrafine powder of alumina to the crystal surface. This was filled in a quartz boat and baked at 850 ° C. for 2 hours in a hydrogen gas atmosphere using a tube furnace to obtain europium-activated barium fluoroiodide phosphor particles.
[0086]
Next, an example of manufacturing a radiation image conversion panel is shown.
As the phosphor layer-forming material, 427 g of the europium-activated barium fluoroiodide phosphor obtained above, 15.8 g of polyurethane resin (Desmolac 4125, manufactured by Sumitomo Bayer Urethane Co., Ltd.), 2.0 g of bisphenol A type epoxy resin, methyl ethyl ketone -It added to the toluene (1: 1) mixed solvent, and it disperse | distributed with the propeller mixer, and prepared the coating liquid with a viscosity of 25-30PS. This coating solution was applied onto an undercoated polyethylene terephthalate film using a doctor blade and then dried at 100 ° C. for 15 minutes to form a phosphor layer.
[0087]
Next, as a protective film forming material, fluorine resin: fluoroolefin-vinyl ether copolymer (Lumiflon LF100, manufactured by Asahi Glass Co., Ltd.) 70 g, cross-linking agent: isocyanate (Desmodule Z4370, manufactured by Sumitomo Bayer Urethane Co., Ltd.) 25 g, bisphenol A type epoxy resin 5 g and 10 g of silicone resin fine powder (KMP-590, manufactured by Shin-Etsu Chemical Co., Ltd., particle size: 1 to 2 μm) were added to a toluene-isopropyl alcohol (1: 1) mixed solvent to prepare a coating solution. This coating solution is applied on the phosphor layer formed in advance as described above by using a doctor blade, and then heat-cured at 120 ° C. for 30 minutes to be thermally cured and dried to provide a protective layer having a thickness of 10 μm. A membrane was provided. By the above method, a radiation image conversion panel having a stimulable phosphor layer was obtained.
[0088]
(Evaluation of radiation image conversion panel)
Regarding sensitivity, after irradiating the radiation image conversion panel with X-rays with a tube voltage of 80 kVp, the panel is excited by operating with a He-Ne laser beam (633 nm) to receive the stimulated emission emitted from the phosphor layer. The light was received by (photoelectron image multiplier of spectral sensitivity S-5) and the intensity was measured. In the following table, the luminance is shown as a relative value when the comparative example 1 is 100.
[0089]
Regarding the sharpness, the radiation image conversion panel is irradiated with X-rays with a tube voltage of 80 kVp through a lead MTF chart, and then the panel is excited by operating with a He-Ne laser beam, and then the stimulated emission emitted from the phosphor layer. Is received by the same light receiver as above and converted into an electrical signal, which is converted from analog to digital and recorded on a magnetic tape. The magnetic tape is analyzed by a computer and the X-ray image recorded on the magnetic tape is modulated. The transfer function (MTF) was examined. The table below shows relative values when the comparative example 1 of the MTF value at a spatial frequency of 2 cycles / mm is taken as 100.
[0090]
[Table 1]
As apparent from Table 1, according to the production method of the present invention, a fine stimulable phosphor precursor can be obtained in high yield.
[0092]
The radiation image conversion panel according to the present invention is excellent in brightness and sharpness.
[0093]
【The invention's effect】
According to the present invention, an oxygen-introduced rare earth-activated alkaline earth metal fluoroiodide photostimulable phosphor necessary for a radiation image conversion panel excellent in luminance and sharpness can be obtained with high productivity.
Claims (9)
一般式（１） Ｂａ(1-x)Ｍ2(x)ＦＢｒ(y)Ｉ(1-y)：ａＭ1，ｂＬｎ，ｃＯ
〔式中、Ｍ1はＬｉ，Ｎａ，Ｋ，Ｒｂ及びＣｓから選ばれる少なくとも１種のアルカリ金属、Ｍ2はＢｅ，Ｍｇ，Ｓｒ及びＣａから選ばれる少なくとも１種のアルカリ土類金属、ＬｎはＣｅ，Ｐｒ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｔｍ，Ｄｙ，Ｈｏ，Ｎｄ，Ｅｒ及びＹｂから選ばれる少なくとも１種の希土類元素を表し、ｘ，ｙ，ａ，ｂ及びｃは、それぞれ０≦ｘ≦０．３，０≦ｙ≦０．３，０≦ａ≦０．０５，０＜ｂ≦０．２，０＜ｃ≦０．１である。〕A method for producing an oxygen-introduced rare earth activated alkaline earth metal fluoride halide photostimulable phosphor represented by the following general formula (1), comprising adding an inorganic fluoride aqueous solution and an alkali metal halide aqueous solution, A stimulable phosphor precursor is obtained by removing a solvent from a solution having a barium concentration of 3.3 mol / L or more in a reaction mother liquor, characterized in that an oxygen-introduced rare earth activated alkaline earth metal fluoride halide is obtained. A method for producing a photostimulable phosphor.
General formula (1) Ba (1-x) M 2 (x) FBr (y) I (1-y) : aM 1 , bLn, cO
[Wherein M 1 is at least one alkali metal selected from Li, Na, K, Rb and Cs, M 2 is at least one alkaline earth metal selected from Be, Mg, Sr and Ca, and Ln is This represents at least one rare earth element selected from Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er, and Yb, where x, y, a, b, and c are each 0 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.3, 0 ≦ a ≦ 0.05, 0 <b ≦ 0.2, 0 <c ≦ 0.1. ]
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