JP2004018839A - Rare earth-activated fluorinated halogenated alkaline-earth metal-based stimulable phosphor and radiological image-converting panel - Google Patents
Rare earth-activated fluorinated halogenated alkaline-earth metal-based stimulable phosphor and radiological image-converting panel Download PDFInfo
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- JP2004018839A JP2004018839A JP2002180503A JP2002180503A JP2004018839A JP 2004018839 A JP2004018839 A JP 2004018839A JP 2002180503 A JP2002180503 A JP 2002180503A JP 2002180503 A JP2002180503 A JP 2002180503A JP 2004018839 A JP2004018839 A JP 2004018839A
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- stimulable phosphor
- rare earth
- earth metal
- alkaline earth
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、特に、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および放射線像変換パネルに関する。
【発明が解決しようとする課題】
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号公報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。
【０００２】
この方法は、輝尽性蛍光体を含有する放射線像変換パネル（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、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取って電気信号を得、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。そして、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、撮影毎にフィルムを消費する放射線写真法に対して、放射線像変換パネルは、繰り返して使用できるので、資源保護や経済効率の面からも有利である。
放射線像変換パネルは、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なる。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なるものと、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とがある。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。尚、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なる保護膜が設けられる。
輝尽性蛍光体は、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る。
【０００４】
この種の輝尽性蛍光体として、例えば特開昭５５−１２１４５号公報、特開昭５５−１６００７８号公報、特開昭５６−７４１７５号公報、特開昭５６−１１６７７７号公報、特開昭５７−２３６７３号公報、特開昭５７−２３６７５号公報、特開昭５８−２０６６７８号公報、特開昭５９−２７２８９号公報、特開昭５９−２７９８０号公報、特開昭５９−５６４７９号公報、特開昭５９−５６４８０号公報など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号公報、特開昭６０−８４３８１号公報、特開昭６０−１０６７５２号公報、特開昭６０−１６６３７９号公報、特開昭６０−２２１４８３号公報、特開昭６０−２２８５９２号公報、特開昭６０−２２８５９３号公報、特開昭６１−２３６７９号公報、特開昭６１−１２０８８２号公報、特開昭６１−１２０８８３号公報、特開昭６１−１２０８８５号公報、特開昭６１−２３５４８６号公報、特開昭６１−２３５４８７号公報などに記載の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号公報に記載の希土類元素付活オキシハライド蛍光体；特開昭５８−６９２８１号公報に記載のセリウム付活３価金属オキシハライド蛍光体；特開昭６０−７０４８４号公報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号公報、特開昭６０−１５７１００号公報などに記載の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号公報に記載の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号公報に記載の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号公報、特開昭６１−２１１８２号公報など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号公報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号公報に記載の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号公報に記載の２価のユーロピウム付活複合ハロゲン化物蛍光体等が知られている。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など高感度の輝尽発光を示すものとして知られている。
【０００５】
ところで、輝尽性蛍光体の製造方法は、特開平７−２３３３６９号公報や特開平９−２９１２７８号公報などで開示されている。すなわち、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（前駆体は輝尽発光を殆ど示さない。）を得、この前駆体を焼成することによって輝尽性蛍光体が得られる。
【０００６】
輝尽性蛍光体を得る為に行う焼成工程では、輝尽性蛍光体前駆体を石英ボート、アルミナルツボ、石英ルツボ等の耐熱性容器に入れ、これを電気炉の炉心に入れ、焼成する。焼成温度は４００〜１３００℃、焼成時間は０．５〜１２時間程度が一般的である。焼成雰囲気は、窒素ガス、アルゴンガス等の中性雰囲気、或いは少量の水素ガスを含む窒素ガス等の弱還元性雰囲気、又は微量の酸素を含む酸化性雰囲気が用いられる。
【０００７】
しかしながら、これら従来の輝尽性蛍光体では満足できていない。特に、高輝度で消去特性に優れた放射線像変換パネルは得られていない。
【０００８】
従って、本発明が解決しようとする課題は、高輝度で消去特性に優れた放射線像変換パネルを提供することである。
【０００９】
【課題を解決するための手段】
上記の問題点に対する研究を積み重ねて行くうちに、下記一般式（Ｉ）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を用いた放射線像変換パネルの輝度や消去特性はＢａとＯとの割合によって大きく左右されることを見出すに至った。
【００１０】
この知見を基にして本発明が達成されたものである。
【００１１】
すなわち、前記の課題は、下記一般式（Ｉ）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であって、
ＯとＢａとの表面組成比Ｏ／Ｂａが０．３〜１．４である
ことを特徴とする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によって解決される。
【００１２】
特に、下記一般式（Ｉ）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であって、
焼成後におけるＯとＢａとの表面組成比Ｏ／Ｂａが０．３〜１．４である
ことを特徴とする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によって解決される。
【００１３】
一般式（Ｉ）
Ｂａ（１−ｘ）Ｍ２（ｘ）ＦＢｒ（ｙ）Ｉ（１−ｙ）：ａＭ１，ｂＬｎ，ｃＯ
〔式中、Ｍ１はＬｉ，Ｎａ，Ｋ，Ｒｂ及びＣｓの群の中から選ばれる少なくとも１種のアルカリ金属、Ｍ２はＢｅ，Ｍｇ，Ｃａ，Ｓｒ，Ｚｎ及びＣｄの群の中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の群の中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、各々、０≦ｘ≦０．３，０≦ｙ≦０．３，０≦ａ≦０．０５，０＜ｂ≦０．２，０≦ｃ≦０．１の条件を満たす値である。〕
尚、上記ＯとＢａとの表面組成比Ｏ／Ｂａが０．３〜１．４である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は、Ｂａ量や焼成条件を考慮することで得られる。
【００１４】
そして、液相法によって得られ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の前駆体を焼成して得たものが好ましい。
【００１５】
上記特徴を有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は、従来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技術を応用することで得られる。但し、この際、注意すべき点は、ＯとＢａとの表面組成比Ｏ／Ｂａが０．３〜１．４であるようにすることである。例えば、一般式（Ｉ）で表される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前駆体を窒素ガス雰囲気６００℃以上で１００分以上加熱し、微量酸素雰囲気を導入した後、冷却する。又、一般式（Ｉ）で表される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前駆体にＢａＯを混合し、６００℃以上に加熱した後、冷却する。
【００１６】
又、前記の課題は、放射線像変換パネルにおいて、
前記放射線像変換パネルの蛍光体層の輝尽性蛍光体が上記の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である
ことを特徴とする放射線像変換パネルによって解決される。
【００１７】
【発明の実施の形態】
本発明になる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は、上記一般式（Ｉ）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であって、ＯとＢａとの表面組成比Ｏ／Ｂａが０．３〜１．４である。特に、焼成後におけるＯとＢａとの表面組成比Ｏ／Ｂａが０．３〜１．４である。更には、Ｏ／Ｂａが０．４以上であり、１．２以下である。
【００１８】
本発明になる放射線像変換パネルは、放射線像変換パネルの蛍光体層の輝尽性蛍光体が上記の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である。
【００１９】
以下、更に、詳しく説明する。
【００２０】
液相法による輝尽性蛍光体前駆体製造については、特開平１０−１４０１４８号公報、特開平１０−１４７７７８号公報、特開２００２−３８１４３号公報に記載された技術を好ましく利用できる。
【００２１】
ここで輝尽性蛍光体前駆体とは、前記一般式（Ｉ）の物質が４００℃以上の高温を経ていない状態を示し、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。
【００２２】
本発明では、例えば液相法で一般式（Ｉ）で示される輝尽性蛍光体の前駆体を合成する方法において、該液相は少なくともバリウム成分及び無機フッ化物が存在していることが好ましい。バリウム成分と無機フッ化物との反応母液中への添加の順序は特に限定されないが、無機フッ化物の添加が後であることが好ましい。又、一般式（Ｉ）で示される輝尽性蛍光体を構成する他の成分の原材料の投入順序は限定がなく、液相中に添加しても良いし、焼成時に添加しても良い。
【００２３】
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（Ｉ）で示される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無く、粒径の制御が容易である液相法により行うことが好ましい。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。
［製造法］
ＢａＩ２とＬｎのハロゲン化物を含み、前記一般式（Ｉ）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、そしてａが０でない場合、Ｍ１のハロゲン化物を含み、それらが溶解した後、バリウム濃度が３．３ｍｏｌ／Ｌ以上、好ましくは３．５ｍｏｌ／Ｌ以上で、上限として好ましくは５．０ｍｏｌ／Ｌ以下の溶液を調製する工程；
上記溶液に１〜１０００ｐｐｍの還元剤を添加する工程；
上記溶液を５０℃以上、好ましくは１００℃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、更に好ましくは１２ｍｏｌ／Ｌ以上、上限として好ましくは１５ｍｏｌ／Ｌ以下の無機弗化物（弗化アンモニウム又はアルカリ金属の弗化物）の溶液を添加し、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；
上記無機弗化物を添加しつつ、又は添加終了後、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；
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。
【００２４】
尚、本発明に係る粒子（前駆体結晶）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。
【００２５】
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。
【００２６】
以下に輝尽性蛍光体の製造法の詳細について説明する。
【００２７】
［前駆体結晶の沈澱物の作製、輝尽性蛍光体の作製］
最初に、水系媒体中を用いて弗素化合物以外の原料化合物を溶解させる。
【００２８】
すなわち、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。但し、ＢａＩ２濃度が３．３ｍｏｌ／Ｌ以上、好ましくは３．５ｍｏｌ／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良い。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、好ましくは８０℃以上に、上限として好ましくは１００℃以下に維持される。
【００２９】
そして、上記溶液に、例えば次亜リン酸、次亜リン酸塩、亜リン酸、亜リン酸塩、ヒドラジン、ヒドラジン誘導体などの還元剤が添加される。添加される還元剤の量は、還元剤の濃度が１〜１０００ｐｐｍとなる程度である。
【００３０】
次に、還元剤が添加され、しかも５０℃以上に維持された溶液に、無機フッ化物水溶液を添加し、反応させる。反応させている時の反応液の温度は５０℃以上、さらには８０℃以上に保たれていることが好ましい。添加は、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。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（Ｉ）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。
【００３１】
次に、反応液から溶媒を除去する。反応母液から溶媒を除去するとは、自然乾燥で溶媒を蒸発させるプロセスに加えて、自然乾燥による蒸発速度を超える速度で溶媒を除去するプロセスを人為的に付与することである。溶媒を除去する時期は特に問われないが、無機フッ化物溶液の添加開始直後から沈殿物（前駆体）を分離するまでの間に行うことが好ましい。ここで、添加開始直後とは、添加中及び添加終了のいずれをも意味する。
【００３２】
溶媒除去は、１回又は複数回に分けて行っても良いし、連続的に行っても良い。例えば、（１）無機フッ化物溶液の添加終了後、溶媒除去を行い、反応母液を放置する、（２）無機フッ化物溶液の添加終了後、第１回目の溶媒除去を行い、反応母液を放置後、第２回目の溶媒除去を行い、再び反応母液を放置する、（３）無機フッ化物溶液添加終了後、沈殿物を分離するまでの間、連続的に溶媒除去を行う等の工程をおこなっても良い。
【００３３】
溶媒除去の時期は、無機フッ化物溶液の添加終了後から除去を行うことが好ましく、該有機溶液添加終了後直ちに除去を開始することが更に好ましい。
【００３４】
ここで、係る溶媒とは、当業者で認知されている定義と同義であり、溶質を溶かす為に用いた成分である。例えば、本発明では溶質は少なくとも一般式（Ｉ）で表される輝尽性蛍光体を得る為に用いられた原材料や中間体、触媒、還元剤などが基本的に該当する。本発明の溶媒除去工程は、単一の溶媒を除去するだけでなく、複数の種類の溶媒が母液に含まれる場合は、それら全てが溶媒除去の対象となるが、除去の対象は限定されない。
【００３５】
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。従って、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。この為、溶媒の除去量は、除去前と除去後の質量比で５０％以下が好ましく、３０％以下がより好ましく、更には２０％以下がより好ましい。ここで、溶媒除去後とは、全ての溶媒除去工程を終えた後を指す。
【００３６】
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。溶媒の除去は、単位面積当たり２．０Ｋｇ／ｍ２・ｈｒ以上、２０．０Ｋｇ／ｍ２・ｈｒ以下の速度で行うことが好ましく、更には３．０Ｋｇ／ｍ２・ｈｒ以上、１０．０Ｋｇ／ｍ２・ｈｒ以下の速度がより好ましい。ここで、単位面積とは、反応母液が大気と接触している面積を指す。一般的に、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。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出来る。ここで、溶液を加熱とは、溶媒除去工程の反応母液温度を溶媒除去工程時にも維持する又はそれ以上の温度に上げる事を指す。反応母液を５０℃以上、特に８０℃以上に保つように加熱することが好ましい。
【００３７】
更に、生産性を上げる為、又、粒子形状を適切に保つ為、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。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。
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、空気や窒素が好ましい。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有効である。
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出来る。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。溶媒が水の場合、８６，４５０Ｐａ以下が好ましい。
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出来る。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、溶媒除去に要する時間が長くなる。これを防ぐ為、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。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号公報や特開平１１−２３５５２２号公報に記載の攪拌機を用いる方法が挙げられる。
【００３８】
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号公報に記載の方法が好ましく用いられる。
【００３９】
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。
【００４０】
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。
【００４１】
次に、蛍光体前駆体の結晶を、石英ボード、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、焼結を避けながら焼成を行う。焼成温度は４００〜１３００℃の範囲が適当であり、５００〜１０００℃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。
【００４２】
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。
【００４３】
上記液相法で得られた蛍光体前駆体結晶の乾燥・焼成工程は、本発明の特徴を有する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得る為に重要な工程である。すなわち、下記のような特徴を経ないで焼成された場合、本発明の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は得られない。
【００４４】
輝尽性蛍光体前駆体を炉芯に充填した後、炉芯内の雰囲気を０．１〜１０％の水素を含み残りが窒素である窒素／水素混合ガス雰囲気に置換する。この雰囲気置換に先立って炉芯内部の大気を排出して真空にしても良い。真空吸引には回転式ポンプ等が利用できる。炉芯を真空にした場合には、雰囲気の置換効率が高くなる。真空を経由しないで雰囲気を置換する、所謂、追出し置換の場合は、炉芯の容積の少なくとも３倍の体積の雰囲気を注入する必要がある。
【００４５】
電気炉の炉芯内を上記混合ガス雰囲気に置換した後、昇温速度が１〜５０℃／ｍｉｎで、６００℃以上に加熱する。６００℃以上に加熱することは、良好な発光特性を得ることで好ましいことである。加熱開始以降から輝尽性蛍光体の取出しまでの間、炉芯内の混合ガス雰囲気は０．１Ｌ／ｍｉｎ以上（特に、１．０〜５．０Ｌ／ｍｉｎ）の流量で流通させることが好ましい。これにより、炉芯内の雰囲気が置換されるので、炉芯内で生成する輝尽性蛍光体以外の反応生成物を排出できる。特に、反応生成物にヨウ素が含まれる場合には、ヨウ素による輝尽性蛍光体の黄色化、及び黄色化に伴う輝尽性蛍光体の劣化を防止できる。
【００４６】
６００℃以上に到達した後、そのまま１００分以上加熱する。この後、０．１〜７％の酸素と０．１〜１０％の水素を含み残りが窒素の雰囲気を導入し、そして少なくとも３０分以上保持する。この時の温度は好ましくは６００〜１３００℃、特に７００〜１０００℃である。すなわち、６００℃以上とすることによって、良好な輝尽発光特性が得られる。７００℃以上とした場合、特に放射線画像の診断で好ましい輝尽発光特性が得られる。尚、１３００℃を越えると、燒結により粒子が大きくなる傾向が有る為、１３００℃以下が好ましい。１０００℃以下の場合、特に放射線画像の診断で好ましい粒径の輝尽蛍光体が得られる。最も好ましいのは８２０℃付近の温度である。
【００４７】
雰囲気の置換は追出し置換で行い、新たに導入される雰囲気としては、水素濃度が０．１〜１０％、酸素濃度は水素濃度の２倍以下、そして残りの成分が窒素の混合ガスが好ましい。より好ましくは、水素濃度が０．１〜５％、酸素濃度が水素濃度の４０〜１５０％、残りが窒素の混合ガスである。中でも、水素が１％、酸素が１．１％、残りが窒素の混合ガスである。ここで、水素濃度を０．１％以上とするのは、還元力が得られ、発光特性を向上させることが出来る。１０％以下、特に５％以下とすることで、輝尽性蛍光体の結晶自体が還元されるのを防止できる。又、酸素濃度を水素濃度の約１１０％とした場合、輝尽発光強度が著しく向上する。
【００４８】
所望の窒素、水素、酸素の混合比に置換されるまでは、炉芯の容積の３倍以上の体積の混合ガスを導入するのが好ましい。この時から少なくとも３０分以上、好ましくは１〜５時間の間、６００℃以上で保持される。
【００４９】
上記操作の後、再び、炉芯内を０．１〜１０％の水素を含み残りが窒素の窒素／水素混合ガスに置換する。
【００５０】
炉芯内に残留した酸素を追い出す為には、昇温の時と同じ０．１〜１０％の水素を含み残りが窒素の窒素／水素混合ガスを用いることが好ましい。置換の効率を高める為、０．１〜１０％の水素を含み残りが窒素の窒素／水素混合ガスの流量を一時的に増加させても良い。炉芯の容積の１０倍の体積の新たなガスを導入した時点で酸素が追い出される。この時から３０分以上、特に３０分〜１２時間の間、６００℃以上で０．１〜１０％の水素を含み残りが窒素の窒素／水素混合ガス雰囲気が保持される。３０分以上とすることで、良好な輝尽発光特性を示す輝尽性蛍光体が得られる。尚、１２時間以下とするのは、加熱による輝尽発光特性の低下を防止する為である。
【００５１】
冷却過程は昇温過程と同様に行われる。
【００５２】
又，酸素／水素／窒素混合ガスを用いる代わりに、輝尽性蛍光体に予めＢａＯを混合して加熱しても良い。
【００５３】
上記のような焼成工程を経ることによって、目的とする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。
【００５４】
［放射線像変換パネルの作製］
本発明の放射線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る。この点からすると、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。
【００５５】
これら支持体の厚さは、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、１０〜５００μｍが好ましい。
【００５６】
支持体の表面は滑面であっても良く、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良い。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良い。
【００５７】
下引層に用いられる結合剤（結着剤）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出来る。これらの中でも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。
【００５８】
輝尽性蛍光体層は、例えば次のような方法により下引層上に形成することが出来る。
【００５９】
先ず、沃素含有輝尽性蛍光体、黄変防止の為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。
【００６０】
本発明に用いられる結合剤としては、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合剤が使用される。
【００６１】
輝尽性蛍光体用塗布液において、結合剤は輝尽性蛍光体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、得られる放射線像変換パネルの感度と鮮鋭性の点では結合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。
【００６２】
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。
【００６３】
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為の分散剤、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為の可塑剤など種々の添加剤が混合されても良い。こ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出来る。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出来る。
【００６４】
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出来る。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。
【００６５】
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。
【００６６】
放射線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、１０〜１０００μｍ程度である。特に、１０〜５００μｍがより好ましい。
【００６７】
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。
以下、具体的な実施例を挙げて本発明を説明する。
【００６８】
【実施例】
［実施例１］
ユーロピウム付活弗化沃化バリウムの輝尽性蛍光体前駆体を合成する為、ＢａＩ２水溶液（４ｍｏｌ／Ｌ濃度）２５０００ｍｌとＥｕＩ３水溶液（０．２ｍｏｌ／Ｌ濃度）２６５ｍｌとを反応容器に入れた。
【００６９】
この反応容器中の反応母液を撹拌しながら８３℃で保温した。そして、反応母液中に、弗化アンモニウム水溶液（８ｍｏｌ／Ｌ濃度）３２２０ｍｌをローラーポンプを用いて注入し、沈澱物を生成させた。
【００７０】
注入終了後も保温と攪拌を２時間ほど続け、沈殿物の熟成を行った。沈殿物をろ別後、メタノールにより洗浄し、真空乾燥することでユーロピウム付活弗化ヨウ化バリウムの結晶を７．１５Ｋｇ得た。
【００７１】
そして、燒結による粒子形状の変化、粒子間融着による粒子サイズ分布の変化を防止する為、アルミナの超微粒子粉体を０．１質量％添加し、ミキサーで充分撹拌し、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。
【００７２】
そして、結晶表面にアルミナの超微粒子粉体が均一に付着したユーロピウム付活弗化ヨウ化バリウムの結晶粉体７Ｋｇを焼成管に入れ、窒素／水素（９９／１容量％）の混合ガスを１０Ｌ／ｍｉｎの流量で６０分間流通させて雰囲気を置換した。この後、窒素／水素（９９／１容量％）の混合ガスの流量を１．５Ｌ／ｍｉｎに減じ、０．２ｒｐｍの速度で回転させながら、２０℃／ｍｉｎの昇温速度で８２０℃まで加熱した。
【００７３】
８２０℃に到達してから２時間後に、流量１．５Ｌ／ｍｉｎの窒素／水素（９９／１容量％）混合ガスに流量９０ｍＬ／ｍｉｎの窒素／酸素（８０／２０容量％）混合ガスを加えて２時間３０分間流通させながら、８２０℃に保持した。
【００７４】
この後、導入ガスを、再度、窒素／水素（９９／１容量％）混合ガスとし、流量を５Ｌ／ｍｉｎとした。そして、この条件の下で８２０℃とし、３０分間保持した。この後、５０℃に冷却した。
【００７５】
そして、焼成管の回転を止め、酸素導入ユーロピウム付活弗化沃化バリウム輝尽性蛍光体粒子を取り出した。
【００７６】
次に、上記のようにして得られた酸素導入ユーロピウム付活弗化沃化バリウム輝尽性蛍光体粒子を基にして放射線像変換パネルの製造する工程を示す。
【００７７】
蛍光体層形成材料として、上記酸素導入ユーロピウム付活弗化沃化バリウム輝尽性蛍光体粒子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、及びビスフェノールＡ型エポキシ樹脂２．０ｇを、メチルエチルケトンとトルエンとの混合（１：１）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（ＰＥＴ）フィルム上に塗布した後、１００℃で１５分間乾燥させて、蛍光体層を形成した。
【００７８】
次に、保護膜形成材料として、弗素系樹脂（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（イソシアナート、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、及びシリコーン樹脂微粉末（信越化学工業社製：ＫＭＰ−５９０，粒子径１〜２μｍ）１０ｇを、トルエンとｉ−プロピルアルコールとの混合（１：１）溶媒に添加し、塗布液を作った。
【００７９】
この塗布液を、上記のように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共に乾燥し、厚さ１０μｍの保護膜を設けた。
【００８０】
このようにして、輝尽性蛍光体層を有する放射線像変換パネルを得た。
【００８１】
［実施例２］
ユーロピウム付活弗化臭化バリウムの輝尽性蛍光体前駆体を合成する為、ＢａＢｒ２水溶液（２．５ｍｏｌ／Ｌ濃度）２８８００ｍｌとＥｕＢｒ３水溶液（０．２ｍｏｌ／Ｌ濃度）９００ｍｌと水４２３００ｍｌとを反応容器に入れた。
【００８２】
この反応容器中の反応母液を撹拌しながら６０℃で保温した。そして、反応母液中に、弗化アンモニウム水溶液（１０ｍｏｌ／Ｌ濃度）３６００ｍｌと水３６００ｍｌとの混合溶液をローラーポンプを用いて注入し、沈澱物を生成させた。
【００８３】
注入終了後も保温と攪拌を２時間ほど続け、沈殿物の熟成を行った。沈殿物をろ別後、メタノールにより洗浄し、真空乾燥することでユーロピウム付活弗化臭化バリウムの結晶を７．９２Ｋｇ得た。
【００８４】
そして、燒結による粒子形状の変化、粒子間融着による粒子サイズ分布の変化を防止する為、アルミナの超微粒子粉体を０．１質量％添加し、ミキサーで充分撹拌し、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。
【００８５】
これを焼成管に入れて実施例１と同様な焼成を行い、酸素導入ユーロピウム付活弗化臭化バリウム輝尽性蛍光体粒子を取り出した。
【００８６】
そして、この酸素導入ユーロピウム付活弗化臭化バリウム輝尽性蛍光体粒子を用いて実施例１と同様にして放射線像変換パネルを得た。
【００８７】
［実施例３］
ユーロピウム付活弗化臭化バリウムと弗化沃化バリウムとの混合物からなる輝尽性蛍光体前駆体を合成する為、反応容器に４２２４０ｍｌの水を入れ、そしてＢａＢｒ２水溶液（２．５ｍｏｌ／Ｌ濃度）２８８００ｍｌとＥｕＢｒ３水溶液（０．２ｍｏｌ／Ｌ濃度）９６０ｍｌとＣａＢｒ２・２Ｈ２Ｏを２０．４ｇ添加し、撹拌しながら６０℃で保温した。そして、この反応母液中に、弗化アンモニウム水溶液（１０ｍｏｌ／Ｌ濃度）３６０ｍｌと水３６０ｍｌとの混合溶液をローラーポンプを用いて注入し、沈澱物を生成させた。
【００８８】
注入終了後も保温と攪拌を２時間ほど続け、沈殿物の熟成を行った。沈殿物をろ別後、メタノールにより洗浄し、真空乾燥することでユーロピウム付活弗化臭化バリウムの結晶を７．９２Ｋｇ得た。
【００８９】
このユーロピウム付活弗化臭化バリウム６Ｋｇと弗化沃化バリウム１．２７Ｋｇと臭化セシウム３．６ｇとアルミナの超微粒子粉体（燒結による粒子形状の変化、粒子間融着による粒子サイズ分布の変化を防止する為、アルミナの超微粒子粉体を０．１質量％添加）とを添加し、ミキサーで充分撹拌し、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。
【００９０】
これを焼成管に入れ、実施例１と同様な焼成を行って輝尽性蛍光体粒子を得、この輝尽性蛍光体粒子を用いて実施例１と同様にして放射線像変換パネルを得た。
【００９１】
［実施例４］
ユーロピウム付活弗化沃化バリウムの輝尽性蛍光体前駆体を合成する為、ＢａＩ２水溶液（４．０ｍｏｌ／Ｌ濃度）２５０００ｍｌとＥｕＩ３水溶液（０．２ｍｏｌ／Ｌ濃度）２６５ｍｌとを反応容器に入れた。
【００９２】
この反応容器中の反応母液を撹拌しながら８３℃で保温した。そして、反応母液中に、弗化アンモニウム水溶液（８ｍｏｌ／Ｌ濃度）３２２０ｍｌをローラーポンプを用いて注入し、沈澱物を生成させた。
【００９３】
注入終了後も保温と攪拌を２時間ほど続け、沈殿物の熟成を行った。沈殿物をろ別後、メタノールにより洗浄し、真空乾燥することでユーロピウム付活弗化沃化バリウムの結晶を７．１５Ｋｇ得た。
【００９４】
そして、燒結による粒子形状の変化、粒子間融着による粒子サイズ分布の変化を防止する為、アルミナの超微粒子粉体を０．１質量％添加し、ミキサーで充分撹拌し、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。
【００９５】
この結晶表面にアルミナの超微粒子粉体が均一に付着したユーロピウム付活弗化沃化バリウムの結晶粉体７ＫｇとＢａＯ９．２ｇとを焼成管に入れ、温度が８２０℃に到達してから６０分後に、流量１．５Ｌ／ｍｉｎの窒素／水素（９９／１容量％）混合ガスに流量９０ｍＬ／ｍｉｎの窒素／酸素（８０／２０容量％）混合ガスを加えて実施例１と同様にして焼成を行い、酸素ドープのユーロピウム付活弗化沃化バリウム輝尽性蛍光体粒子を取り出した。
【００９６】
そして、この輝尽性蛍光体粒子を用いて実施例１と同様にして放射線像変換パネルを得た。
【００９７】
［比較例１］
実施例１の焼成工程において、窒素／酸素（８０／２０容量％）混合ガスを用いなかった以外は同様に行って放射線像変換パネルを得た。
【００９８】
［比較例２］
実施例１の焼成工程における焼成雰囲気を大気雰囲気とした以外は同様に行って放射線像変換パネルを得た。
【００９９】
［比較例３］
実施例２の焼成工程において、窒素／酸素（８０／２０容量％）混合ガスを用いなかった以外は同様に行って放射線像変換パネルを得た。
【０１００】
［比較例４］
実施例２の焼成工程における焼成雰囲気を大気雰囲気とした以外は同様に行って放射線像変換パネルを得た。
【０１０１】
［比較例５］
実施例３の焼成工程において、窒素／酸素（８０／２０容量％）混合ガスを用いなかった以外は同様に行って放射線像変換パネルを得た。
【０１０２】
［比較例６］
実施例３の焼成工程における焼成雰囲気を大気雰囲気とした以外は同様に行って放射線像変換パネルを得た。
【０１０３】
［比較例７］
実施例４の焼成工程において、ＢａＯ９．２ｇを用いなかった以外は同様に行って放射線像変換パネルを得た。
【０１０４】
［比較例８］
実施例４の焼成工程における焼成雰囲気を大気雰囲気とした以外は同様に行って放射線像変換パネルを得た。
【０１０５】
［比較例９］
実施例１の焼成工程において、試料温度が８２０℃に到達してから６０分後に、流量１．５Ｌ／ｍｉｎの窒素／水素（９９／１容量％）混合ガスに窒素／酸素（８０／２０容量％）混合ガスを加えて流通させた以外は同様に行って酸素ドープ・ユーロピウム付活弗化沃化バリウム輝尽性蛍光体粒子を得、これを用いて放射線像変換パネルを得た。
【０１０６】
［特性］
上記のようにして得られた放射線像変換パネルの感度及び消去特性を調べたので、その結果を表−１に示す。
【０１０７】
［感度］
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）で受光して強度を測定し、これを感度と定義する。そして、実施例２の放射線像変換パネルの感度を１００とし、相対値で表示した。
【０１０８】
［消去］
放射線像変換パネルに管電圧８０ｋＶｐのＸ線を１００ｍＲ照射した後、照射エネルギー４．３Ｊ／ｍ２の半導体レーザー光（６６０ｎｍ）を照射し、励起させ、蛍光体粒子から放射された輝尽発光を光学フィルター（Ｂ−４１０）を通して光電子増倍管で受光して初期輝尽発光量を測定した。
【０１０９】
続いて、３波長型電球色蛍光灯を用い、１００万ｌｘ・ｓｅｃの光量により消去操作を施した。
【０１１０】
消去操作後の蛍光体粒子について、初期輝尽発光量の測定と同様に行い、消去後の輝尽発光量を測定した。
【０１１１】
そして、（消去後の輝尽発光量）／（初期輝尽発光量）＝消去値として消去特性を求めた。この消去値が小さい程、消去特性は良好である。
【０１１２】
［表面組成比Ｏ／Ｂａ］
上記放射線像変換パネルに用いられ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のＯとＢａとの表面組成比Ｏ／Ｂａを、ＸＰＳ表面分析装置を用いて測定した。
【０１１３】
ＸＰＳ表面分析装置はＶＧサイエンティフィックス社のＥＳＣＡＬＡＢ−２００Ｒが用いられた。Ｘ線アノードにはＭｇを用い、出力６００Ｗ（加速電圧１５ｋＶ、エミッション電流４０ｍＡ）で測定した。エネルギー分解能は、清浄なＡｇ３ｄ５／２ピークの半値幅で規定した時、１．５〜１．７ｅＶとなるように設定した。
【０１１４】
測定を行う前に、先ず、汚染による影響を除く為、薄膜の膜厚の１０〜２０％の厚さに相当する表面層をＡｒイオンエッチングにより除去した。
【０１１５】
そして、結合エネルギー０ｅＶから１１００ｅＶの範囲をデータ取込間隔１．０ｅＶで測定し、如何なる元素が検出されるかを調べた。次に、検出された全ての元素（エッチングイオン種を除く。）において、データ取込間隔を０．２ｅＶとして最大強度を与える光電子ピークについてナロースキャンを行い、各元素のスペクトルを測定した。
【０１１６】
得られたスペクトルは、測定装置やコンピュータの違いによる含有率算出結果の違いを無くす為、ＶＡＭＡＳ−ＳＣＡ−ＪＡＰＡＮ製のＣＯＭＭＯＮ ＤＡＴＡ ＰＲＯＣＥＳＳＩＮＧ ＳＹＳＴＥＭ（Ｖｅｒ．２．３以降）上に転送した後、同ソフトで処理し、各元素含有率を原子数濃度（ａｔ％）として求めた。
【０１１７】
定量処理を行う前に、各元素についてのＣｏｕｎｔ Ｓｃａｌｅのキャリブレーションを行い、５ポイントのスムージング処理を行った。
【０１１８】
定量処理では、バックグラウンドを除去したピークエリア強度を用いた。バックグラウンド処理にはＳｈｉｒｌｅｙ法（Ｄ．Ａ．Ｓｈｉｒｌｅｙ，Ｐｈｙｓ．Ｒｅｖ．，Ｂ５，４７０９（１９７２）参照）を用いた。
【０１１９】
本発明によれば、感度および消去特性に優れた放射線像変換パネルが得られる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention particularly relates to a rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor and a radiation image conversion panel.
[Problems to be solved by the invention]
A radiation image recording / reproducing method using a stimulable phosphor described in JP-A-55-12145 or the like is known as an effective diagnostic means which replaces the conventional radiographic method.
[0002]
This method uses a radiation image conversion panel (also referred to as a stimulable phosphor sheet) containing a stimulable phosphor, and converts radiation transmitted through a subject or emitted from a subject into a stimulable phosphor. And stimulates the stimulable phosphor in a time series with electromagnetic waves such as visible light and ultraviolet rays (referred to as excitation light), and radiates the stored radiation energy as fluorescence (referred to as stimulable emission light). The fluorescent light is read photoelectrically to obtain an electric signal, and a radiation image of the subject or the subject is reproduced as a visible image based on the obtained electric signal. After the reading, the conversion panel is subjected to erasing of the remaining image and used for the next photographing.
[0003]
According to this method, there is an advantage that a radiographic image with a large amount of information can be obtained with a much smaller exposure dose than a radiographic method using a combination of a radiographic film and an intensifying screen. In addition, since the radiographic image conversion panel can be used repeatedly as compared with the radiographic method in which a film is consumed for each photographing, it is advantageous in terms of resource conservation and economic efficiency.
The radiation image conversion panel comprises only a support and a stimulable phosphor layer provided on the surface thereof or a self-supporting stimulable phosphor layer. The stimulable phosphor layer is usually composed of only a stimulable phosphor and a binder that supports the stimulable phosphor and an aggregate of the stimulable phosphor formed by a vapor deposition method or a sintering method. There are things. In addition, there is also known one in which a polymer substance is impregnated in gaps of the aggregate. In addition, on the surface of the stimulable phosphor layer on the side opposite to the support side, a protective film composed of a polymer film or an inorganic vapor-deposited film is usually provided.
As the stimulable phosphor, one that emits stimulable light in the wavelength range of 300 to 500 nm by excitation light in the range of 400 to 900 nm is generally used.
[0004]
Examples of this type of stimulable phosphor include JP-A-55-12145, JP-A-55-160078, JP-A-56-74175, JP-A-56-116777, and JP-A-56-116777. JP-A-57-23673, JP-A-57-23675, JP-A-58-206678, JP-A-59-27289, JP-A-59-27980, and JP-A-59-56479. Rare earth element-activated alkaline earth metal fluoride halide-based phosphors described in JP-A-59-56480; JP-A-59-75200; JP-A-60-84381; JP-A-60-106752, JP-A-60-166379, JP-A-60-221483, JP-A-60-228592, JP-A-60-228593, and JP-A-60-61 No. 23679, JP-A-61-120882, JP-A-61-120883, JP-A-61-120885, JP-A-61-235486, JP-A-61-235487 and the like. Described divalent europium activated alkaline earth metal fluorohalide-based phosphor; rare earth element activated oxyhalide phosphor described in JP-A-55-12144; described in JP-A-58-69281 Cerium-activated trivalent metal oxyhalide phosphor; bismuth-activated alkali metal halide phosphor described in JP-A-60-70484; JP-A-60-141783 and JP-A-60-157100 And divalent europium-activated alkaline earth metal halophosphate phosphors described in JP-A-60-157099. -Activated alkaline earth metal haloborate phosphor; divalent europium-activated alkaline earth metal hydride halide phosphor described in JP-A-60-217354; JP-A-61-21173; Cerium-activated rare earth composite halide phosphor described in JP-A-61-21182; Cerium-activated rare earth halophosphate phosphor described in JP-A-61-40390; JP-A-60-78151 A divalent europium-activated cerium rubidium halide phosphor described in the gazette; a divalent europium-activated composite halide phosphor described in JP-A-60-78151 and the like are known. Among them, a divalent europium-activated alkaline earth metal fluorohalide phosphor containing iodine, a rare earth element-activated oxyhalide phosphor containing iodine, and a bismuth-activated alkali metal halide phosphor containing iodine It is known to exhibit high-sensitivity photostimulated luminescence.
[0005]
Incidentally, a method for producing a stimulable phosphor is disclosed in JP-A-7-233369 and JP-A-9-291278. That is, the concentration of the phosphor raw material solution is adjusted to obtain a stimulable phosphor precursor in the form of fine particles (the precursor shows almost no stimulable luminescence), and the stimulable phosphor is baked by firing the precursor. The body is obtained.
[0006]
In the firing step performed to obtain the stimulable phosphor, the stimulable phosphor precursor is placed in a heat-resistant container such as a quartz boat, an alumina crucible, or a quartz crucible, placed in a core of an electric furnace, and fired. The firing temperature is generally 400 to 1300 ° C., and the firing time is generally about 0.5 to 12 hours. As the firing atmosphere, a neutral atmosphere such as nitrogen gas or argon gas, a weak reducing atmosphere such as nitrogen gas containing a small amount of hydrogen gas, or an oxidizing atmosphere containing a small amount of oxygen is used.
[0007]
However, these conventional stimulable phosphors are not satisfactory. In particular, a radiation image conversion panel having high luminance and excellent erasing characteristics has not been obtained.
[0008]
Accordingly, an object of the present invention is to provide a radiation image conversion panel having high luminance and excellent erasing characteristics.
[0009]
[Means for Solving the Problems]
As the studies on the above problems are accumulated, the luminance of a radiation image conversion panel using an oxygen-introduced rare earth-activated alkaline earth metal fluoride halide stimulable phosphor represented by the following general formula (I): It has been found that the erasing characteristics are greatly influenced by the ratio of Ba and O.
[0010]
The present invention has been achieved based on this finding.
[0011]
That is, an object of the present invention is to provide an oxygen-introduced rare earth-activated alkaline earth metal fluoride halide stimulable phosphor represented by the following general formula (I),
The problem is solved by a rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor characterized in that the surface composition ratio O / Ba of O to Ba is 0.3 to 1.4.
[0012]
In particular, an oxygen-introduced rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor represented by the following general formula (I):
The problem is solved by a rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor, wherein the surface composition ratio O / Ba of O and Ba after firing is 0.3 to 1.4. .
[0013]
General formula (I)
Ba (1-x) M2 (x) FBr (y) I (1-y) : aM1, bLn, cO
[Wherein, M1 is at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs, and M2 is at least one selected from the group consisting of Be, Mg, Ca, Sr, Zn and Cd. One kind of alkaline earth metal, Ln represents at least one kind of rare earth element selected from the group consisting of Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb; , Y, a, b and c are respectively 0 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.3, 0 ≦ a ≦ 0.05, 0 <b ≦ 0.2, 0 ≦ c ≦ 0. This value satisfies the condition of 1. ]
The rare earth activated alkaline earth metal fluoride halide stimulable phosphor having a surface composition ratio O / Ba of O to Ba of 0.3 to 1.4 is considered in consideration of the amount of Ba and the firing conditions. It is obtained by doing.
[0014]
Then, a precursor obtained by calcining a precursor of an oxygen-introduced rare earth activated alkaline earth metal fluorohalide stimulable phosphor obtained by a liquid phase method is preferable.
[0015]
The oxygen-introduced rare earth-activated alkaline earth metal fluorohalide-based stimulable phosphor having the above characteristics is a conventional technology for producing an oxygen-introduced rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor. It can be obtained by applying. However, in this case, it should be noted that the surface composition ratio O / Ba of O and Ba is set to 0.3 to 1.4. For example, the precursor of the rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor represented by the general formula (I) is heated at 600 ° C. or more in a nitrogen gas atmosphere for 100 minutes or more, and a trace oxygen atmosphere is introduced. After cooling. BaO is mixed with the precursor of the rare earth activated alkaline earth metal fluoride halide stimulable phosphor represented by the general formula (I), heated to 600 ° C. or more, and then cooled.
[0016]
Further, the above-mentioned problem is solved in a radiation image conversion panel,
The radiation image conversion panel is characterized in that the stimulable phosphor of the phosphor layer of the radiation image conversion panel is the rare earth activated alkaline earth metal fluorinated halide-based stimulable phosphor. .
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
The rare earth-activated alkaline earth metal fluorohalide-based stimulable phosphor according to the present invention is an oxygen-introduced rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor represented by the above general formula (I). And a surface composition ratio O / Ba of O to Ba is 0.3 to 1.4. In particular, the surface composition ratio O / Ba of O and Ba after firing is 0.3 to 1.4. Further, O / Ba is 0.4 or more and 1.2 or less.
[0018]
In the radiation image conversion panel according to the present invention, the stimulable phosphor of the phosphor layer of the radiation image conversion panel is the above-described rare earth activated alkaline earth metal fluoride halide stimulable phosphor.
[0019]
Hereinafter, this will be described in more detail.
[0020]
For producing the stimulable phosphor precursor by the liquid phase method, the techniques described in JP-A-10-140148, JP-A-10-147778, and JP-A-2002-38143 can be preferably used.
[0021]
Here, the stimulable phosphor precursor refers to a state in which the substance of the general formula (I) has not passed a high temperature of 400 ° C. or more, and the stimulable phosphor precursor has a stimulable luminescent property or an instantaneous luminescent property. Is hardly shown.
[0022]
In the present invention, for example, in a method for synthesizing a precursor of a stimulable phosphor represented by the general formula (I) by a liquid phase method, it is preferable that the liquid phase contains at least a barium component and an inorganic fluoride. . The order of addition of the barium component and the inorganic fluoride to the reaction mother liquor is not particularly limited, but it is preferable that the inorganic fluoride be added later. Further, there is no limitation on the order of adding the raw materials of the other components constituting the stimulable phosphor represented by the general formula (I), and they may be added to the liquid phase or may be added at the time of firing.
[0023]
In the present invention, it is preferable to obtain a precursor by the following liquid phase synthesis method. The production of the rare earth activated alkaline earth metal fluoroiodide-based stimulable phosphor represented by the general formula (I) is not a solid phase method in which control of the particle shape is difficult, but the particle size can be easily controlled. It is preferable to carry out by a liquid phase method. In particular, it is preferable to obtain a stimulable phosphor by the following liquid phase synthesis method.
[Manufacturing method]
It contains a halide of BaI 2 and Ln, and when x in the formula (I) is not 0, further comprises a halide of M2; when y is not 0, BaBr 2 ; and when a is not 0, M1. And preparing a solution having a barium concentration of 3.3 mol / L or more, preferably 3.5 mol / L or more, and preferably 5.0 mol / L or less as an upper limit after the dissolution thereof.
Adding 1 to 1000 ppm of a reducing agent to the solution;
While maintaining the solution at a temperature of 50 ° C. or higher, preferably 100 ° C. or higher, the concentration of the solution is 5 mol / L or higher, preferably 8 mol / L or higher, more preferably 12 mol / L or higher, and preferably 15 mol / L or lower as an upper limit. Adding a solution of an inorganic fluoride (ammonium fluoride or an alkali metal fluoride) to obtain a precipitate of a rare earth-activated alkaline earth metal fluoroiodide-based stimulable phosphor precursor crystal;
Removing the solvent from the reaction solution while adding the inorganic fluoride or after completion of the addition;
Separating the precursor crystal precipitate from the reaction solution;
This is a production method including a step of firing the separated precursor crystal precipitate while avoiding sintering.
[0024]
The particles (precursor crystals) according to the present invention preferably have an average particle size of 1 to 10 μm and are monodisperse, and have an average particle size of 1 to 5 μm and a distribution (%) of the average particle size. It is more preferably 20% or less, and particularly preferably one having an average particle size of 1 to 3 μm and a distribution of the average particle size of 15% or less.
[0025]
The average particle size in the present invention is obtained by randomly selecting 200 particles from an electron micrograph of a particle (crystal) and calculating the average by a sphere-equivalent volume particle size.
[0026]
The details of the method for producing the stimulable phosphor will be described below.
[0027]
[Preparation of precipitate of precursor crystal, preparation of stimulable phosphor]
First, a starting compound other than a fluorine compound is dissolved in an aqueous medium.
[0028]
That, BaI 2 and Ln halide and further M2 halides necessary, and further put M1 halide in an aqueous medium, thoroughly mixing, dissolving, to prepare an aqueous solution in which they are dissolved. However, BaI 2 concentration of 3.3 mol / L or more, preferably such that 3.5 mol / L or more, previously adjusted to quantitative ratio between BaI 2 concentration and an aqueous solvent. 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 appropriately select the barium concentration, and as a result of the study by the present inventors, it has been found that fine precursor particles can be formed at 3.3 mol / L or more. At this time, a small amount of an acid, ammonia, alcohol, a water-soluble polymer, a water-insoluble metal oxide fine particle powder or the like may be added as required. It is also a preferable embodiment to add an appropriate amount of a lower alcohol (methanol, ethanol, etc.) as long as the solubility of BaI 2 is not significantly reduced. The aqueous solution (reaction mother liquor) is maintained at 50 ° C., preferably at 80 ° C. or higher, and preferably at 100 ° C. or lower as an upper limit.
[0029]
Then, a reducing agent such as hypophosphorous acid, hypophosphite, phosphorous acid, phosphite, hydrazine, or a hydrazine derivative is added to the above solution. The amount of the reducing agent added is such that the concentration of the reducing agent is 1 to 1000 ppm.
[0030]
Next, an aqueous solution of inorganic fluoride is added to the solution to which the reducing agent has been added and which has been maintained at 50 ° C. or higher, and reacted. The temperature of the reaction solution during the reaction is preferably maintained at 50 ° C. or higher, more preferably 80 ° C. or higher. For the addition, an aqueous solution of an inorganic fluoride (ammonium fluoride, alkali metal fluoride, or the like) is injected into the stirred aqueous solution using a pipe with a pump or the like. This injection is preferably carried out in the area where the stirring is particularly violent. By the injection of the inorganic fluoride aqueous solution into the reaction mother liquor, the rare earth activated alkaline earth metal fluorohalide-based phosphor precursor crystal corresponding to the general formula (I) precipitates.
[0031]
Next, the solvent is removed from the reaction solution. To remove the solvent from the reaction mother liquor means to artificially provide a process of removing the solvent at a rate exceeding the evaporation rate by natural drying, in addition to the process of evaporating the solvent by natural drying. The timing of removing the solvent is not particularly limited, but it is preferably performed immediately after the start of the addition of the inorganic fluoride solution until the precipitate (precursor) is separated. Here, “immediately after the start of addition” means both during addition and completion of addition.
[0032]
The removal of the solvent may be performed once or in a plurality of times, or may be performed continuously. For example, (1) after the addition of the inorganic fluoride solution, the solvent is removed and the reaction mother liquor is left. (2) After the addition of the inorganic fluoride solution, the first solvent removal is performed and the reaction mother liquor is left. Thereafter, the second solvent removal is performed, and the reaction mother liquor is left again. (3) After the addition of the inorganic fluoride solution, the solvent is continuously removed until the precipitate is separated. May be.
[0033]
It is preferable to remove the solvent after the completion of the addition of the inorganic fluoride solution, and it is more preferable to start the removal immediately after the completion of the addition of the organic solution.
[0034]
Here, such a solvent has the same meaning as the definition recognized by those skilled in the art, and is a component used for dissolving a solute. For example, in the present invention, the solute basically corresponds to at least a raw material, an intermediate, a catalyst, a reducing agent, and the like used for obtaining the stimulable phosphor represented by the general formula (I). In the solvent removal step of the present invention, not only a single solvent is removed, but when a plurality of types of solvents are contained in a mother liquor, all of them are targets for solvent removal, but the targets for removal are not limited.
[0035]
The removal amount of the solvent is preferably 3% or more by mass ratio before and after the removal. Below this, the crystal may not have a desirable composition. Therefore, the removal amount is preferably 3% or more, more preferably 5% or more. In addition, even if it is excessively removed, there may be a problem in handling, such as an excessive increase in the viscosity of the reaction solution. For this reason, the removal amount of the solvent is preferably 50% or less, more preferably 30% or less, and even more preferably 20% or less by mass ratio before and after the removal. Here, “after removing the solvent” refers to after completing all the solvent removing steps.
[0036]
The time required for removing the solvent not only greatly affects the productivity, but also the shape and particle size distribution of the particles are affected by the method for removing the solvent. Therefore, the method for removing the solvent must be appropriately selected. The removal of the solvent per unit area 2.0Kg / m 2 · hr or more, it is preferably carried out at 20.0Kg / m 2 · hr or less speed, even 3.0Kg / m 2 · hr or more, 10.0 kg / M 2 · hr or less is more preferable. Here, the unit area indicates an area where the reaction mother liquor is in contact with the atmosphere. Generally, 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 an intended composition can be obtained. Here, heating the solution refers to maintaining or increasing the temperature of the reaction mother liquor in the solvent removing step even during the solvent removing step. It is preferable to heat the reaction mother liquor so as to keep it at 50 ° C. or higher, particularly 80 ° C. or higher.
[0037]
Further, it is preferable to use another solvent removal method in combination in order to increase the productivity and keep the particle shape appropriately. The method for removing the solvent used in combination is not particularly limited. In the present invention, it is preferable to select the following removal method from the viewpoint of productivity.
1. [Aeration of dry gas] The reaction vessel is made a closed type, provided with holes through which at least two or more gases can pass, and a dry gas is vented therethrough. The type of gas can be arbitrarily selected. From the viewpoint of safety, air and nitrogen are preferable. The solvent is entrained and removed from the gas depending on the saturated water vapor amount of the gas to be passed. In addition to the method of ventilating the void portion of the reaction vessel, a method of ejecting gas as bubbles into the liquid phase and absorbing the solvent into the bubbles is also effective.
2. [Depressurization] As is well known, reducing the pressure reduces the vapor pressure of the solvent. 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 the solvent. When the solvent is water, the pressure is preferably 86,450 Pa or less.
3. [Liquid film] The solvent can be removed efficiently by enlarging the evaporation area. As in the present invention, when heating and stirring using a reaction vessel of a fixed volume to cause a reaction, the heating method is a method of immersing the heating means in a liquid or mounting the heating means outside the vessel. Is common. According to this method, the heat transfer area is limited to the portion where the liquid and the heating means come into contact, and the heat transfer area decreases with the removal of the solvent, and the time required for removing the solvent becomes longer. In order to prevent this, it is effective to use a pump or a stirrer to spray the solution on the wall surface of the reaction vessel to increase the heat transfer area. The method of spraying the liquid on the wall surface of the reaction vessel to form a liquid film in this manner is known as a "wet wall". Examples of the method for forming the wetted wall include a method using a pump and a method using a stirrer described in JP-A-6-335627 and JP-A-11-235522.
[0038]
These methods may be used alone or 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 aerating a dry gas, and the like are effective. In particular, the former is preferable, and the method described in JP-A-6-335627 is preferably used.
[0039]
Next, the phosphor precursor crystals are separated from the solution by filtration, centrifugation, etc., sufficiently washed with methanol or the like, and dried.
[0040]
A sintering inhibitor such as alumina fine powder or silica fine powder is added to and mixed with the dried phosphor precursor crystal to uniformly adhere the sintering inhibitor fine powder to the crystal surface. The addition of the sintering inhibitor can be omitted by selecting the firing conditions.
[0041]
Next, the crystal of the phosphor precursor is filled in a heat-resistant container such as a quartz board, an alumina crucible, or a quartz crucible, placed in a core of an electric furnace, and fired while avoiding sintering. The firing temperature is suitably in the range of 400 to 1300C, and preferably in the range of 500 to 1000C. The firing time varies depending on the filling amount of the phosphor raw material mixture, the firing temperature, the temperature for taking out from the furnace, and the like, but generally, 0.5 to 12 hours is appropriate.
[0042]
As the firing atmosphere, a neutral atmosphere such as a nitrogen gas atmosphere, an argon gas atmosphere, a weak reducing atmosphere such as a nitrogen gas atmosphere containing a small amount of hydrogen gas, a carbon dioxide atmosphere containing carbon monoxide, or a trace amount of oxygen introduced The atmosphere is used.
[0043]
The step of drying and baking the phosphor precursor crystals obtained by the above liquid phase method is an important step for obtaining a rare earth activated alkaline earth metal fluoride halide stimulable phosphor having the features of the present invention. It is. That is, when fired without the following characteristics, the rare earth-activated alkaline earth metal fluorinated halide-based stimulable phosphor of the present invention cannot be obtained.
[0044]
After filling the stimulable phosphor precursor into the furnace core, the atmosphere in the furnace core is replaced with a nitrogen / hydrogen mixed gas atmosphere containing 0.1 to 10% of hydrogen and the balance being nitrogen. Prior to the replacement of the atmosphere, the atmosphere inside the furnace core may be exhausted to create a vacuum. A rotary pump or the like can be used for vacuum suction. When the furnace core is evacuated, the atmosphere replacement efficiency increases. In the case of the so-called purge replacement, in which the atmosphere is replaced without passing through a vacuum, it is necessary to inject an atmosphere of at least three times the volume of the furnace core.
[0045]
After the inside of the furnace core of the electric furnace is replaced with the mixed gas atmosphere, the furnace is heated to 600 ° C. or more at a temperature rising rate of 1 to 50 ° C./min. Heating to 600 ° C. or higher is preferable because good emission characteristics can be obtained. It is preferable that the mixed gas atmosphere in the furnace core be circulated at a flow rate of 0.1 L / min or more (particularly, 1.0 to 5.0 L / min) from the start of heating to the removal of the stimulable phosphor. . As a result, the atmosphere in the furnace core is replaced, so that reaction products other than the stimulable phosphor generated in the furnace core can be discharged. In particular, when iodine is contained in the reaction product, yellowing of the stimulable phosphor due to iodine and deterioration of the stimulable phosphor due to the yellowing can be prevented.
[0046]
After the temperature reaches 600 ° C. or higher, heating is continued for 100 minutes or longer. After this, an atmosphere of 0.1 to 7% oxygen and 0.1 to 10% hydrogen and the balance nitrogen is introduced and held for at least 30 minutes. The temperature at this time is preferably 600 to 1300 ° C, particularly 700 to 1000 ° C. That is, by setting the temperature to 600 ° C. or higher, good photostimulated luminescence characteristics can be obtained. When the temperature is set to 700 ° C. or higher, a photostimulated luminescence characteristic which is particularly preferable for diagnosis of a radiation image is obtained. If the temperature exceeds 1300 ° C., the particles tend to become large due to sintering. When the temperature is 1000 ° C. or lower, a stimulable phosphor having a particle size preferable for a diagnosis of a radiographic image is obtained. Most preferred is a temperature near 820 ° C.
[0047]
The replacement of the atmosphere is performed by an expelling replacement, and the newly introduced atmosphere is preferably a mixed gas of a hydrogen concentration of 0.1 to 10%, an oxygen concentration of twice or less the hydrogen concentration, and nitrogen as the remaining component. More preferably, the hydrogen concentration is 0.1 to 5%, the oxygen concentration is 40 to 150% of the hydrogen concentration, and the remainder is a mixed gas of nitrogen. Above all, a mixed gas of 1% of hydrogen, 1.1% of oxygen, and the rest is nitrogen. Here, when the hydrogen concentration is 0.1% or more, a reducing power can be obtained and the light emission characteristics can be improved. By setting the content to 10% or less, particularly 5% or less, reduction of the stimulable phosphor crystal itself can be prevented. When the oxygen concentration is about 110% of the hydrogen concentration, the photostimulated luminescence intensity is significantly improved.
[0048]
Until the mixture is replaced with a desired mixture ratio of nitrogen, hydrogen and oxygen, it is preferable to introduce a mixed gas having a volume of at least three times the volume of the furnace core. From this time, the temperature is maintained at 600 ° C. or more for at least 30 minutes or more, preferably for 1 to 5 hours.
[0049]
After the above operation, the inside of the furnace core is replaced again with a mixed gas of nitrogen / hydrogen containing 0.1 to 10% of hydrogen and the remaining nitrogen.
[0050]
In order to expel oxygen remaining in the furnace core, it is preferable to use a nitrogen / hydrogen mixed gas containing 0.1 to 10% of hydrogen, the same as at the time of temperature rise, with the balance being nitrogen. In order to increase the efficiency of the replacement, the flow rate of the nitrogen / hydrogen mixed gas containing 0.1 to 10% of hydrogen and the balance of nitrogen may be temporarily increased. Oxygen is expelled when new gas is introduced, ten times the volume of the furnace core. From this time, an atmosphere of a mixed gas of nitrogen / hydrogen containing 0.1 to 10% of hydrogen at 600 ° C. or more and the balance of nitrogen is maintained for 30 minutes or more, particularly for 30 minutes to 12 hours. By setting the time to 30 minutes or longer, a stimulable phosphor exhibiting good stimulable light emission characteristics can be obtained. The reason why the time is set to 12 hours or less is to prevent the photostimulated luminescence characteristics from deteriorating due to heating.
[0051]
The cooling process is performed in the same manner as the heating process.
[0052]
Instead of using the oxygen / hydrogen / nitrogen mixed gas, the stimulable phosphor may be mixed with BaO in advance and heated.
[0053]
Through the above calcination step, the desired rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor can be obtained.
[0054]
[Production of radiation image conversion panel]
As the support used in the radiation image storage panel of the present invention, various polymer materials, glass, metal and the like are used. Particularly, a material that can be processed into a flexible sheet or web for handling as an information recording material is preferable. From this point, plastic films such as cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, and polycarbonate films; metal sheets such as aluminum, iron, copper, and chromium; metal sheets having a coating layer of the metal oxide; Is preferred.
[0055]
The thickness of the support varies depending on the material of the support to be used and the like, but is generally 10 to 1000 μm, and preferably 10 to 500 μm from the viewpoint of handling.
[0056]
The surface of the support may be a smooth surface, or may be a mat surface for the purpose of improving the adhesion to the stimulable phosphor layer. Further, an undercoat layer may be provided on the surface on which the stimulable phosphor layer is provided for the purpose of improving the adhesiveness with the stimulable phosphor layer.
[0057]
Examples of the binder (binder) used in the undercoat layer include proteins such as gelatin, polysaccharides such as dextran, and natural polymer substances such as gum arabic; polyvinyl butyral, polyvinyl acetate, nitrocellulose, Bonds represented by synthetic polymer substances such as ethyl cellulose, vinylidene chloride-vinyl chloride copolymer, polyalkyl (meth) acrylate, vinyl chloride-vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, linear polyester, etc. Agents. Among them, particularly preferred are 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. Is a mixture of In addition, these binders may be crosslinked with a crosslinking agent.
[0058]
The stimulable phosphor layer can be formed on the undercoat layer by, for example, the following method.
[0059]
First, an iodine-containing stimulable phosphor, a compound such as a phosphite for preventing yellowing, and a binder are added to an appropriate solvent, and these are mixed well, and the phosphor particles and the binder are mixed in a binder solution. A coating liquid in which the compound particles are uniformly dispersed is prepared.
[0060]
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, vinyl chloride / vinyl chloride copolymer, polymethyl methacrylate, and vinyl chloride. -A film-forming binder usually used for a layer structure, such as a vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, or polyvinyl alcohol, is used.
[0061]
In the stimulable phosphor coating solution, the binder is used in an amount of 0.01 to 1 part by mass per 1 part by mass of the stimulable phosphor. 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 part by mass is more preferable in consideration of ease of application.
[0062]
Examples of solvents used for preparing the coating solution for the stimulable phosphor layer 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 and acetic acid Esters of lower fatty acids such as ethyl and butyl acetate with lower alcohols; 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 Hydrogen and mixtures thereof.
[0063]
The coating solution has a dispersant for improving the dispersibility of the phosphor in the coating solution, and also improves the binding force between the binder and the phosphor in the stimulable phosphor layer after formation. Various additives such as a plasticizer may be mixed. Examples of dispersants used for such purposes include phthalic acid, stearic acid, caproic acid, and lipophilic surfactants. Examples of the plasticizer include phosphoric esters such as triphenyl phosphate, tricresyl phosphate, and diphenyl phosphate; phthalic esters such as diethyl phthalate and dimethoxyethyl phthalate; ethylphthalylethyl glycolate and butylphthalylbutyl glycolate; Glycolic acid esters; polyesters of polyethylene glycol and aliphatic dibasic acid, such as polyesters of triethylene glycol and adipic acid, polyesters of diethylene glycol and succinic acid, and the like.
[0064]
The coating liquid prepared as described above is uniformly applied to the surface of the undercoat layer to form a coating film of the coating liquid. This coating operation can be performed using a normal coating means, for example, a doctor blade, a roll coater, a knife coater or the like. Next, the formed coating film is dried by gradually heating to complete the formation of the stimulable phosphor layer on the undercoat layer.
[0065]
The preparation of the coating solution for the stimulable phosphor layer is performed using a dispersing device such as a ball mill, a sand mill, an attritor, a three-roll mill, a high-speed impeller disperser, a Kady mill, and an ultrasonic disperser. The prepared coating solution is applied on a support using a coating device such as a doctor blade, a roll coater, or a knife coater, and dried to form a stimulable phosphor layer. After applying and drying the coating solution on the protective layer, the stimulable phosphor layer and the support may be bonded.
[0066]
The thickness of the stimulable phosphor layer of the radiation image conversion panel depends on the characteristics of the intended radiation image conversion panel, the type of the stimulable phosphor, the mixing ratio between the binder and the stimulable phosphor, and the like. Is about 10 to 1000 μm. In particular, 10 to 500 μm is more preferable.
[0067]
In the foregoing, examples of the stimulable phosphor such as europium-activated barium fluoroiodide have been mainly described. However, europium-activated barium fluorobromide and other stimulable phosphors represented by the above general formula (I) have been described. The phosphor can also be manufactured with reference to the above.
Hereinafter, the present invention will be described with reference to specific examples.
[0068]
【Example】
[Example 1]
In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, 25,000 ml of an aqueous solution of BaI 2 (concentration of 4 mol / L) and 265 ml of an aqueous solution of EuI 3 (concentration of 0.2 mol / L) were placed in a reaction vessel. Was.
[0069]
The reaction mother liquor in the reaction vessel was kept at 83 ° C. while stirring. Then, into the reaction mother liquor, 3220 ml of an ammonium fluoride aqueous solution (8 mol / L concentration) was injected using a roller pump to generate a precipitate.
[0070]
After completion of the injection, the temperature and the stirring were continued for about 2 hours to ripen the precipitate. The precipitate was separated by filtration, washed with methanol, and vacuum-dried to obtain 7.15 kg of europium-activated barium fluoroiodide crystals.
[0071]
Then, in order to prevent a change in particle shape due to sintering and a change in particle size distribution due to inter-particle fusion, 0.1% by mass of ultrafine alumina powder is added, and the mixture is sufficiently stirred with a mixer. Ultrafine powder was uniformly adhered.
[0072]
Then, 7 kg of europium-activated barium fluorinated iodide crystal powder having ultrafine alumina particles uniformly adhered to the crystal surface is placed in a firing tube, and 10 L of a mixed gas of nitrogen / hydrogen (99/1 volume%) is placed in the firing tube. The atmosphere was replaced by flowing at a flow rate of / min for 60 minutes. Thereafter, the flow rate of the mixed gas of nitrogen / hydrogen (99/1% by volume) is reduced to 1.5 L / min, and heated to 820 ° C. at a rate of 20 ° C./min while rotating at a rate of 0.2 rpm. did.
[0073]
Two hours after reaching 820 ° C., a nitrogen / oxygen (80/20 volume%) mixed gas at a flow rate of 90 mL / min is added to a nitrogen / hydrogen (99/1 volume%) mixed gas at a flow rate of 1.5 L / min. And maintained at 820 ° C. for 2 hours and 30 minutes.
[0074]
Thereafter, the introduced gas was again a mixed gas of nitrogen / hydrogen (99/1 volume%), and the flow rate was 5 L / min. Then, under these conditions, the temperature was set to 820 ° C., and the temperature was maintained for 30 minutes. Then, it cooled to 50 degreeC.
[0075]
Then, the rotation of the firing tube was stopped, and the oxygen-introduced europium-activated barium fluoroiodide stimulable phosphor particles were taken out.
[0076]
Next, a process for producing a radiation image conversion panel based on the oxygen-introduced europium-activated barium fluoroiodide stimulable phosphor particles obtained as described above will be described.
[0077]
As the phosphor layer forming material, 427 g of the oxygen-introduced europium-activated barium fluoroiodide stimulable phosphor particles, 15.8 g of a polyurethane resin (manufactured by Sumitomo Bayer Urethane Co., Desmolac 4125), and bisphenol A type epoxy resin 2 Was added to a mixed (1: 1) solvent of methyl ethyl ketone and toluene, and dispersed by a propeller mixer to prepare a coating solution having a viscosity of 25 to 30 PS. This coating solution was applied on a polyethylene terephthalate (PET) film with an undercoat using a doctor blade, and then dried at 100 ° C. for 15 minutes to form a phosphor layer.
[0078]
Next, as a protective film forming material, 70 g of a fluororesin (fluoroolefin-vinyl ether copolymer, manufactured by Asahi Glass Co., Ltd .: Lumiflon LF100), 25 g of a cross-linking agent (isocyanate, Desmodur Z4370 manufactured by Sumitomo Bayer Urethane Co., Ltd.), bisphenol A 5 g of epoxy resin and 10 g of silicone resin fine powder (KMP-590, manufactured by Shin-Etsu Chemical Co., Ltd., particle size 1-2 μm) are added to a mixed (1: 1) solvent of toluene and i-propyl alcohol, and coated. I made a liquid.
[0079]
This coating solution is applied to the phosphor layer previously formed as described above using a doctor blade, and then heat-treated at 120 ° C. for 30 minutes to be thermally cured and dried, and has a thickness of 10 μm. A protective film was provided.
[0080]
Thus, a radiation image conversion panel having a stimulable phosphor layer was obtained.
[0081]
[Example 2]
In order to synthesize a stimulable phosphor precursor of europium-activated barium fluorobromide, 28800 ml of an aqueous solution of BaBr 2 (concentration of 2.5 mol / L), 900 ml of an aqueous solution of EuBr 3 (concentration of 0.2 mol / L) and 42300 ml of water Was placed in a reaction vessel.
[0082]
The reaction mother liquor in the reaction vessel was kept at 60 ° C. while stirring. Then, into the reaction mother liquor, a mixed solution of 3600 ml of an aqueous solution of ammonium fluoride (10 mol / L concentration) and 3600 ml of water was injected using a roller pump to generate a precipitate.
[0083]
After completion of the injection, the temperature and the stirring were continued for about 2 hours to ripen the precipitate. The precipitate was separated by filtration, washed with methanol, and dried under vacuum to obtain 7.92 Kg of europium-activated barium fluorobromide crystals.
[0084]
Then, in order to prevent a change in particle shape due to sintering and a change in particle size distribution due to inter-particle fusion, 0.1% by mass of ultrafine alumina powder is added, and the mixture is sufficiently stirred with a mixer. Ultrafine powder was uniformly adhered.
[0085]
This was placed in a firing tube and fired in the same manner as in Example 1 to obtain oxygen-introduced europium-activated barium fluorobromide stimulable phosphor particles.
[0086]
Then, a radiation image conversion panel was obtained in the same manner as in Example 1 using the oxygen-introduced europium-activated barium fluorobromide stimulable phosphor particles.
[0087]
[Example 3]
In order to synthesize a stimulable phosphor precursor consisting of a mixture of europium-activated barium fluorobromide and barium fluoroiodide, 42240 ml of water was placed in a reaction vessel, and a BaBr 2 aqueous solution (2.5 mol / L) 28800 ml), 960 ml of an EuBr 3 aqueous solution (0.2 mol / L concentration) and 20.4 g of CaBr 2 .2H 2 O were added, and the mixture was kept at 60 ° C. with stirring. Then, into this reaction mother liquor, a mixed solution of 360 ml of an ammonium fluoride aqueous solution (10 mol / L concentration) and 360 ml of water was injected using a roller pump to generate a precipitate.
[0088]
After completion of the injection, the temperature and the stirring were continued for about 2 hours to ripen the precipitate. The precipitate was separated by filtration, washed with methanol, and dried under vacuum to obtain 7.92 Kg of europium-activated barium fluorobromide crystals.
[0089]
Ultrafine powder of europium-activated barium fluorobromide (6 kg), barium fluoride iodide (1.27 kg), cesium bromide (3.6 g) and alumina (change in particle shape due to sintering, particle size distribution due to interparticle fusion). In order to prevent the change, ultrafine alumina powder was added at 0.1% by mass), and the mixture was sufficiently stirred with a mixer to uniformly adhere the ultrafine alumina powder to the crystal surface.
[0090]
This was placed in a firing tube and baked in the same manner as in Example 1 to obtain stimulable phosphor particles. Using the stimulable phosphor particles, a radiation image conversion panel was obtained in the same manner as in Example 1. .
[0091]
[Example 4]
In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, 25000 ml of a BaI 2 aqueous solution (4.0 mol / L concentration) and 265 ml of an EuI 3 aqueous solution (0.2 mol / L concentration) were used in a reaction vessel. Put in.
[0092]
The reaction mother liquor in the reaction vessel was kept at 83 ° C. while stirring. Then, into the reaction mother liquor, 3220 ml of an ammonium fluoride aqueous solution (8 mol / L concentration) was injected using a roller pump to generate a precipitate.
[0093]
After completion of the injection, the temperature and the stirring were continued for about 2 hours to ripen the precipitate. The precipitate was separated by filtration, washed with methanol, and dried under vacuum to obtain 7.15 kg of europium-activated barium fluoroiodide crystals.
[0094]
Then, in order to prevent a change in particle shape due to sintering and a change in particle size distribution due to inter-particle fusion, 0.1% by mass of ultrafine alumina powder is added, and the mixture is sufficiently stirred with a mixer. Ultrafine powder was uniformly adhered.
[0095]
7 Kg of europium-activated barium fluoroiodide crystal powder having ultrafine alumina particles uniformly adhered to the crystal surface and 9.2 g of BaO were placed in a firing tube, and 60 minutes after the temperature reached 820 ° C. Thereafter, a mixture gas of nitrogen / oxygen (80/20% by volume) at a flow rate of 90 mL / min was added to a gas mixture of nitrogen / hydrogen (99/1 volume%) at a flow rate of 1.5 L / min, and firing was performed in the same manner as in Example 1. To obtain oxygen-doped europium-activated barium fluoroiodide stimulable phosphor particles.
[0096]
Then, a radiation image conversion panel was obtained in the same manner as in Example 1 using the stimulable phosphor particles.
[0097]
[Comparative Example 1]
A radiation image conversion panel was obtained in the same manner as in Example 1, except that the nitrogen / oxygen (80/20% by volume) mixed gas was not used in the firing step.
[0098]
[Comparative Example 2]
A radiation image conversion panel was obtained in the same manner as in Example 1, except that the baking atmosphere in the baking step was changed to an air atmosphere.
[0099]
[Comparative Example 3]
A radiation image storage panel was obtained in the same manner as in Example 2, except that the nitrogen / oxygen (80/20% by volume) mixed gas was not used in the firing step.
[0100]
[Comparative Example 4]
A radiation image storage panel was obtained in the same manner as in Example 2, except that the baking atmosphere in the baking step was changed to an air atmosphere.
[0101]
[Comparative Example 5]
A radiation image conversion panel was obtained in the same manner as in Example 3, except that the nitrogen / oxygen (80/20% by volume) mixed gas was not used in the firing step.
[0102]
[Comparative Example 6]
A radiation image conversion panel was obtained in the same manner as in Example 3, except that the baking atmosphere in the baking step was changed to an air atmosphere.
[0103]
[Comparative Example 7]
A radiation image conversion panel was obtained in the same manner as in Example 4, except that 9.2 g of BaO was not used.
[0104]
[Comparative Example 8]
A radiation image conversion panel was obtained in the same manner as in Example 4, except that the baking atmosphere in the baking step was changed to the air atmosphere.
[0105]
[Comparative Example 9]
In the firing step of Example 1, 60 minutes after the sample temperature reached 820 ° C., a nitrogen / hydrogen (99/1 volume%) mixed gas at a flow rate of 1.5 L / min was mixed with nitrogen / oxygen (80/20 volume). %) Oxygen-doped europium-activated barium fluoroiodide stimulable phosphor particles were obtained in the same manner except that a mixed gas was added and circulated, and a radiation image conversion panel was obtained using this.
[0106]
[Characteristic]
The sensitivity and erasure characteristics of the radiation image conversion panel obtained as described above were examined, and the results are shown in Table 1.
[0107]
[sensitivity]
After irradiating the radiation image conversion panel with X-rays having a tube voltage of 80 kVp, the panel is operated by operating with a He-Ne laser beam (633 nm), and the stimulated emission emitted from the phosphor layer is detected by a photodetector (spectral sensitivity S The intensity is measured by receiving light with a (-5 photoelectron image tube), and this is defined as sensitivity. Then, the sensitivity of the radiation image conversion panel of Example 2 was set to 100, and the relative values were displayed.
[0108]
[Erase]
After irradiating the radiation image conversion panel with 100 mR of X-rays having a tube voltage of 80 kVp, the panel is irradiated with a semiconductor laser beam (660 nm) having an irradiation energy of 4.3 J / m 2 to excite and emit stimulated light emitted from the phosphor particles. Light was received by a photomultiplier tube through an optical filter (B-410), and the amount of initial photostimulated luminescence was measured.
[0109]
Subsequently, an erasing operation was performed using a three-wavelength bulb-type fluorescent lamp with a light amount of 1,000,000 lx · sec.
[0110]
The phosphor particles after the erasing operation were measured in the same manner as the measurement of the initial stimulating luminescence, and the stimulating luminescence after the erasing was measured.
[0111]
Then, the erasing characteristics were determined as (stimulated luminescence amount after erasing) / (initial stimulating luminescence amount) = erasing value. The smaller the erase value, the better the erase characteristics.
[0112]
[Surface composition ratio O / Ba]
The surface composition ratio O / Ba of O to Ba of the oxygen-introduced rare earth activated alkaline earth metal fluorohalide stimulable phosphor used in the radiation image conversion panel was measured using an XPS surface analyzer. did.
[0113]
As the XPS surface analyzer, ESCALAB-200R manufactured by VG Scientific was used. The measurement was performed at an output of 600 W (acceleration voltage 15 kV, emission current 40 mA) using Mg as the X-ray anode. The energy resolution was set to be 1.5 to 1.7 eV when defined by the half width of the clean Ag3d5 / 2 peak.
[0114]
Before the measurement, first, a surface layer corresponding to a thickness of 10 to 20% of the thickness of the thin film was removed by Ar ion etching in order to remove the influence of contamination.
[0115]
Then, the range of the binding energy from 0 eV to 1100 eV was measured at a data acquisition interval of 1.0 eV to check what element was detected. Next, for all the detected elements (excluding the etching ion species), a narrow scan was performed on the photoelectron peak giving the maximum intensity with the data acquisition interval set to 0.2 eV, and the spectrum of each element was measured.
[0116]
The obtained spectrum was transferred to COMMON DATA PROCESSING SYSTEM (Ver. 2.3 or later) manufactured by VAMAS-SCA-JAPAN in order to eliminate the difference in the content calculation results due to the difference in the measurement device and computer. And the content of each element was determined as an atomic number concentration (at%).
[0117]
Before performing the quantitative processing, the Count Scale was calibrated for each element, and a 5-point smoothing processing was performed.
[0118]
In the quantitative processing, the peak area intensity from which the background was removed was used. For background processing, the Shirley method (see DA Shirley, Phys. Rev., B5, 4709 (1972)) was used.
[0119]
According to the present invention, a radiation image conversion panel having excellent sensitivity and erasing characteristics can be obtained.
Claims (3)
ＯとＢａとの表面組成比Ｏ／Ｂａが０．３〜１．４である
ことを特徴とする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。
一般式（Ｉ）
Ｂａ（１−ｘ）Ｍ２（ｘ）ＦＢｒ（ｙ）Ｉ（１−ｙ）：ａＭ１，ｂＬｎ，ｃＯ
〔式中、Ｍ１はＬｉ，Ｎａ，Ｋ，Ｒｂ及びＣｓの群の中から選ばれる少なくとも１種のアルカリ金属、Ｍ２はＢｅ，Ｍｇ，Ｃａ，Ｓｒ，Ｚｎ及びＣｄの群の中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の群の中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、各々、０≦ｘ≦０．３，０≦ｙ≦０．３，０≦ａ≦０．０５，０＜ｂ≦０．２，０≦ｃ≦０．１の条件を満たす値である。〕An oxygen-introduced rare earth-activated alkaline earth metal fluorohalide-based stimulable phosphor represented by the following general formula (I),
A rare earth activated alkaline earth metal fluorohalide-based stimulable phosphor, wherein a surface composition ratio O / Ba of O and Ba is 0.3 to 1.4.
General formula (I)
Ba (1-x) M2 (x) FBr (y) I (1-y) : aM1, bLn, cO
[Wherein, M1 is at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs, and M2 is at least one selected from the group consisting of Be, Mg, Ca, Sr, Zn and Cd. One kind of alkaline earth metal, Ln represents at least one kind of rare earth element selected from the group consisting of Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb; , Y, a, b and c are respectively 0 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.3, 0 ≦ a ≦ 0.05, 0 <b ≦ 0.2, 0 ≦ c ≦ 0. This value satisfies the condition of 1. ]
前記放射線像変換パネルの蛍光体層の輝尽性蛍光体が、請求項１又は請求項２の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である
ことを特徴とする放射線像変換パネル。In the radiation image conversion panel,
The radiation stimulable phosphor of the phosphor layer of the radiation image conversion panel is the rare earth activated alkaline earth metal fluoride halide stimulable phosphor according to claim 1 or 2. Image conversion panel.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2006054532A1 (en) * | 2004-11-22 | 2006-05-26 | Konica Minolta Medical & Graphic, Inc. | Process for producing rare earth activated alkaline earth metal fluorohalide photostimulable phosphor |
| JP2008175815A (en) * | 2006-12-21 | 2008-07-31 | Konica Minolta Medical & Graphic Inc | Radiological image conversion panel |
| JPWO2007018170A1 (en) * | 2005-08-08 | 2009-02-19 | Ｌａｂｏ Ｗｅｌｌ株式会社 | Spraying equipment |
| CN114957802A (en) * | 2022-04-14 | 2022-08-30 | 陕西科技大学 | Preparation method of rare earth fluorescent film based on cellulose photonic crystal forbidden band modulation |
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2002
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006054532A1 (en) * | 2004-11-22 | 2006-05-26 | Konica Minolta Medical & Graphic, Inc. | Process for producing rare earth activated alkaline earth metal fluorohalide photostimulable phosphor |
| JPWO2006054532A1 (en) * | 2004-11-22 | 2008-05-29 | コニカミノルタエムジー株式会社 | Method for producing rare earth activated alkaline earth metal fluoride halide stimulable phosphor |
| JPWO2007018170A1 (en) * | 2005-08-08 | 2009-02-19 | Ｌａｂｏ Ｗｅｌｌ株式会社 | Spraying equipment |
| JP2008175815A (en) * | 2006-12-21 | 2008-07-31 | Konica Minolta Medical & Graphic Inc | Radiological image conversion panel |
| CN114957802A (en) * | 2022-04-14 | 2022-08-30 | 陕西科技大学 | Preparation method of rare earth fluorescent film based on cellulose photonic crystal forbidden band modulation |
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