JPH07252476A - Production of fluorescent material and ceramics - Google Patents
Production of fluorescent material and ceramicsInfo
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- JPH07252476A JPH07252476A JP4388194A JP4388194A JPH07252476A JP H07252476 A JPH07252476 A JP H07252476A JP 4388194 A JP4388194 A JP 4388194A JP 4388194 A JP4388194 A JP 4388194A JP H07252476 A JPH07252476 A JP H07252476A
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- rare earth
- sensitivity
- component
- phosphor
- scintillator
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、Ｘ線などの放射線を検
出する放射線検出器に用いられるシンチレータに係り、
特に多結晶焼結体の希土類オキシ硫化物から成るセラミ
ックシンチレータに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scintillator used in a radiation detector for detecting radiation such as X-rays,
In particular, it relates to a ceramic scintillator made of a rare earth oxysulfide of a polycrystalline sintered body.
【０００２】[0002]
【従来の技術】従来、Ｘ線ＣＴ装置などに設けられる放
射線検出器として、シンチレータを用いた検出器が広く
使用されている。シンチレータはＸ線などの放射線の刺
激によって可視光に近い波長の電磁波を放射する物質
で、シンチレータ材料としては、ＮａＩ，ＣｓＩ，Ｃｄ
ＷＯ4 などの単結晶、特公昭５９−４５０２２号公報に
示されるＢａＦＣｌ：Ｅｕ，ＬａＯＢｒ：Ｔｂ，Ｃｓ
Ｉ：Ｔｌ，ＣａＷＯ4 及びＣｄＷＯ4 のセラミックス、
特開昭５９−２７２８３号公報に示される立方晶系希土
類酸化物セラミックス、特開昭５８−２０４０８８号公
報に示されるＧｄ2 Ｏ2 Ｓ：Ｐｒ等の希土類オキシ硫化
物セラミックス等が知られている。2. Description of the Related Art Conventionally, a detector using a scintillator has been widely used as a radiation detector provided in an X-ray CT apparatus or the like. A scintillator is a substance that emits an electromagnetic wave having a wavelength close to visible light when stimulated by radiation such as X-rays, and scintillator materials include NaI, CsI, and Cd.
Single crystals such as WO 4, BaFCl: Eu, LaOBr: Tb, Cs disclosed in JP-B-59-45022.
I: Ceramics of Tl, CaWO 4 and CdWO 4 ,
The cubic rare earth oxide ceramics disclosed in JP-A-59-27283 and the rare earth oxysulfide ceramics such as Gd 2 O 2 S: Pr disclosed in JP-A-58-204088 are known. .
【０００３】この中でも特に、化学式（Ｍ1-a Ｐｒa ）
2 Ｏ2 Ｓ（ただし、ＭはＹ，Ｌａ，Ｇｄから成る群の中
から選ばれる少なくとも一種の希土類元素を表す）で表
されるプラセオジム（Ｐｒ）で付活された希土類オキシ
硫化物セラミックス，（Ｍ1-b Ｔｂb ）2 Ｏ2 Ｓで表さ
れるテルビウム（Ｔｂ）で付活された希土類オキシ硫化
物セラミックスまたは（Ｍ1-c Ｅｕc ）2 Ｏ2 Ｓで表さ
れるユーロピウム（Ｅｕ）で付活された希土類オキシ硫
化物セラミックスはその高い発光効率などのためにシン
チレータ材料として好適であり、特に、ＭがＧｄである
希土類オキシ硫化物セラミックスはＸ線吸収係数が大き
いのでＸ線検出用シンチレータとして好ましい。なお、
Ｐｒの付活濃度ａ、Ｔｂの付活濃度ｂ、及びＥｕの付活
濃度ｃは低すぎても高すぎても発光効率が低下してしま
うので、 ０．０００１≦ａ≦０．００５ ０．００１ ≦ｂ≦０．２ ０．００１ ≦ｃ≦０．２ であることが好ましいとされている。Among them, especially, the chemical formula (M 1-a Pr a )
2 O 2 S (provided that M represents at least one rare earth element selected from the group consisting of Y, La, and Gd), and the rare earth oxysulfide ceramics activated with praseodymium (Pr), ( Terbium (Tb) activated rare earth oxysulfide ceramics represented by M 1-b Tb b ) 2 O 2 S or europium (Eu) represented by (M 1-c Eu c ) 2 O 2 S The rare-earth oxysulfide ceramics activated in (1) are suitable as scintillator materials because of their high luminous efficiency, and in particular, the rare-earth oxysulfide ceramics in which Md is Gd have a large X-ray absorption coefficient and therefore are used for X-ray detection Preferred as a scintillator. In addition,
If the activation concentration a of Pr, the activation concentration b of Tb, and the activation concentration c of Eu are too low or too high, the light emission efficiency will decrease, so 0.0001 ≦ a ≦ 0.0050. It is said that it is preferable that 001 ≤ b ≤ 0.2 0.001 ≤ c ≤ 0.2.
【０００４】このようなセラミックシンチレータは高い
検出感度を得るために透光性であることが要求され、こ
の目的にかなうような透光性に優れた希土類オキシ硫化
物セラミックスは、特開昭６２−２７５０７２号公報に
示されるように、原料となる希土類オキシ硫化物の蛍光
体粉を金属性気密容器に封入し、熱間静水圧プレス処理
（ＨＩＰ法）を施すことにより製造することができる。Such a ceramic scintillator is required to have a light-transmitting property in order to obtain a high detection sensitivity, and a rare earth oxysulfide ceramic having an excellent light-transmitting property which meets this purpose is disclosed in Japanese Patent Laid-Open No. 62-62. As disclosed in Japanese Patent No. 275072, it can be manufactured by enclosing phosphor powder of a rare earth oxysulfide as a raw material in a metal airtight container and performing hot isostatic pressing (HIP method).
【０００５】ところで、希土類オキシ流化物の蛍光体
は、一般に、M.R.Royce, et al. : Extended Abstr. El
ectrochem. Soc. Paper 86, P.201 (1969, spring)等に
示されるように、硫化剤として硫黄、フラックスとして
Ｎａ2 ＣＯ3 等のアルカリ金属化合物及びＫ3 ＰＯ4 等
のリン酸塩を用いる方法により製造される。この方法に
より製造された希土類オキシ硫化物蛍光体は、結晶性に
優れ、輝度が高く、粒径もそろっており、希土類オキシ
硫化物セラミックスを製造する上での原料としても適し
ている。しかしながら、上述したようなフラックスの使
用に起因して、蛍光体中にアルカリ金属元素及びリン酸
が混入してしまうことが避けられなかった。また、製造
するときの容器などに石英あるいはガラス容器を用いる
ことがあるため、ＳｉＯ2 も混入してしまうことが避け
られない。従って、この蛍光体を用いて希土類オキシ硫
化物セラミックシンチレータを製造する場合には、透光
性に優れ、高い検出感度のセラミックシンチレータが得
られるが、セラミックス中に原料蛍光体や焼結助剤等か
らアルカリ金属元素及びリン酸イオンの形でのリン、シ
リカの形でのシリコンが混入することが避けられなかっ
た。By the way, phosphors of rare earth oxyfluoride are generally used in MR Royce, et al .: Extended Abstr.
As shown in ectrochem. Soc. Paper 86, P.201 (1969, spring), sulfur is used as a sulfiding agent, alkali metal compounds such as Na 2 CO 3 and phosphate such as K 3 PO 4 are used as a flux. Manufactured by the method. The rare earth oxysulfide phosphor manufactured by this method has excellent crystallinity, high brightness, and uniform particle size, and is suitable as a raw material for manufacturing rare earth oxysulfide ceramics. However, it is unavoidable that the phosphor is mixed with the alkali metal element and phosphoric acid due to the use of the flux as described above. Further, since a quartz or glass container is sometimes used as a container at the time of manufacturing, it is inevitable that SiO 2 is also mixed in. Therefore, when a rare earth oxysulfide ceramic scintillator is manufactured using this phosphor, a ceramic scintillator having excellent translucency and high detection sensitivity can be obtained. Therefore, it was unavoidable that alkali metal elements, phosphorus in the form of phosphate ions, and silicon in the form of silica were mixed.
【０００６】本発明者等は、このようにアルカリ金属元
素やリン、シリコンを多く含む希土類オキシ硫化物蛍光
体を用いて作製したセラミックシンチレータにおいて
は、検出器に用いた場合に、実用上の問題になる程度の
放射線照射に伴う感度低下現象を見いだした（特願平２
−３８３５４号）。特に、リンの存在によって特性が大
きく変わることもわかっている。しかし、原料中のリン
の存在が焼結時の結晶成長を円滑に進行させ、このため
に結晶性が良好で透光性に優れた希土類オキシ硫化物セ
ラミックスが得られることも考えられる。実際、意図的
にリンの含有量の極端に少ない蛍光体を原料に用いて希
土類オキシ硫化物セラミックスを製造したところ、かえ
って放射線照射に伴う感度低下現象が大きくなってしま
い、実用的ではなかった。The inventors of the present invention have practical problems in using a ceramic scintillator made of a rare earth oxysulfide phosphor containing a large amount of alkali metal elements, phosphorus and silicon as described above, when it is used as a detector. It was found that the sensitivity decrease phenomenon due to radiation irradiation to the extent that
-38354). In particular, it has been found that the presence of phosphorus significantly changes the characteristics. However, it is conceivable that the presence of phosphorus in the raw material facilitates the crystal growth during sintering, and for this reason, rare earth oxysulfide ceramics having good crystallinity and excellent translucency can be obtained. In fact, when a rare earth oxysulfide ceramics was intentionally produced by using a phosphor having an extremely low phosphorus content as a raw material, the sensitivity decrease phenomenon due to radiation irradiation was rather large, which was not practical.
【０００７】一方、原料蛍光体を作る上で、上に述べた
ようなフラックスを水洗し、その後蛍光体を乾燥する工
程が入るが、この乾燥工程で希土類酸硫化物が酸化され
希土類オキシ硫酸塩が生成される可能性が避けられな
い。この硫酸塩不純物を多く含む原料蛍光体を使ってセ
ラミックスを製造すると、この場合も放射線照射に伴う
感度低下現象が大きくなることが明らかになった。これ
は、希土類オキシ硫酸塩の存在により、希土類オキシ硫
化物セラミックスのストイキオメトリーが若干ずれるた
めであると考えられる。On the other hand, in producing the raw material phosphor, there is a step of washing the flux as described above with water and then drying the phosphor. In this drying step, the rare earth oxysulfide is oxidized and the rare earth oxysulfate is formed. Is unavoidably generated. It was revealed that when the raw material phosphor containing a large amount of sulfate impurities is used to manufacture ceramics, the sensitivity decrease phenomenon due to radiation irradiation becomes large in this case as well. It is considered that this is because the stoichiometry of the rare earth oxysulfide ceramics is slightly deviated due to the presence of the rare earth oxysulfate.
【０００８】[0008]
【発明が解決しようとする課題】以上のように、従来の
希土類オキシ酸硫化物セラミックシンチレータにおいて
は、感度は十分であるが、蛍光体中に残留するリン酸塩
やオキシ硫酸ガドリニウムのために放射線照射に伴う感
度低下が大きいという問題があった。また逆に、リン酸
を含まない希土類オキシ硫化物セラミックスシンチレー
タにおいては、結晶性の悪さなどが起因となって放射線
照射に伴う感度低下が大きくなってしまうという問題が
あった。As described above, in the conventional rare earth oxyoxysulfide ceramic scintillator, the sensitivity is sufficient, but due to the phosphate and gadolinium oxysulfate remaining in the phosphor, the radiation is reduced. There was a problem that the sensitivity was greatly reduced due to irradiation. On the contrary, in the rare earth oxysulfide ceramics scintillator containing no phosphoric acid, there was a problem that the sensitivity was greatly decreased due to the irradiation of radiation due to poor crystallinity.
【０００９】本発明は上記した従来技術の課題を解決す
るためになされたもので、その目的とするところは、放
射線照射に伴う感度低下が少ない希土類オキシ硫化物蛍
光体とこの蛍光体を用いたセラミックスシンチレータの
製造方法を提供することにある。The present invention has been made in order to solve the above-mentioned problems of the prior art, and an object of the present invention is to use a rare earth oxysulfide phosphor and a phosphor thereof in which the sensitivity is not significantly decreased by the irradiation of radiation. It is to provide a method for manufacturing a ceramic scintillator.
【００１０】[0010]
【課題を解決するための手段と作用】本発明者らは、上
記目的を達成すべく鋭意研究を重ねた結果、希土類オキ
シ硫化物原料蛍光体中のリン酸成分と硫酸成分の含有量
を特定の範囲に制限することにより、この原料蛍光体を
用いて得られたセラミックスシンチレータの放射線、と
くにＸ線照射に伴う感度低下を低減することができるこ
とを見いだし、本発明を完成するに至った。[Means and Actions for Solving the Problems] As a result of intensive studies to achieve the above-mentioned object, the present inventors have determined the contents of phosphoric acid component and sulfuric acid component in the rare earth oxysulfide raw material phosphor. It was found that the decrease in the sensitivity of the ceramic scintillator obtained by using this raw material phosphor, particularly the X-ray irradiation, can be reduced by limiting the range to the above range, and the present invention has been completed.
【００１１】すなわち、本発明の希土類オキシ硫化物蛍
光体は、化学式（Ｍ，Ｎ）2 Ｏ2 Ｓ（ただし、ＭはＹ，
Ｌａ及びＧｄから成る群の中から選ばれる少なくとも１
種の元素、ＮはＰｒ，Ｔｂ及びＥｕから成る群の中から
選ばれる少なくとも１種の元素を示す）で表され、微量
成分として、ＰＯ4 成分のｐｐｍ濃度（ｘ）及びＳＯ4
成分のｐｐｍ濃度（ｙ）を、各々１０≦ｘ≦１５０、ｙ
≦１００の範囲で含むことを特徴とする。That is, the rare earth oxysulfide phosphor of the present invention has the chemical formula (M, N) 2 O 2 S (where M is Y,
At least one selected from the group consisting of La and Gd
Element, N represents at least one element selected from the group consisting of Pr, Tb and Eu), and as a minor component, ppm concentration of PO 4 component (x) and SO 4
The ppm concentration (y) of the component is 10 ≦ x ≦ 150, y
It is characterized in that it is included in the range of ≦ 100.
【００１２】この蛍光体は希土類オキシ硫化物セラミッ
クシンチレータの原料である。ＰＯ4 成分のｐｐｍ濃度
（ｘ）は、この蛍光体を王水分解した後、ＩＣＰ発光分
光法により得られる。また、ＳＯ4 のｐｐｍ濃度（ｙ）
は、蛍光体を水に溶出させた後、ＩＣＰ発光分光法（あ
るいはイオンクロマトグラフ）により得られる。This phosphor is a raw material for a rare earth oxysulfide ceramic scintillator. The ppm concentration (x) of the PO 4 component can be obtained by ICP emission spectroscopy after decomposing this phosphor with aqua regia. Also, the SO 4 ppm concentration (y)
Can be obtained by ICP emission spectroscopy (or ion chromatography) after eluting the phosphor in water.
【００１３】また、本発明のセラミックスの製造方法
は、この蛍光体を用いて１３００℃〜１８００℃。１０
００気圧以上の圧力下で、熱間静水圧法を用いて行なう
ことを特徴とする。Further, the method for producing ceramics of the present invention uses this phosphor at 1300 ° C. to 1800 ° C. 10
It is characterized in that the hydrostatic pressure method is used under a pressure of at least 00 atm.
【００１４】以下に、本発明をさらに詳しく説明する。
上述のように、希土類オキシ硫化物セラミックスの原料
となる希土類オキシ硫化物蛍光体を製造する際に、結晶
性を高め、粉体の粒度分布を整えるためにアルカリ金属
化合物やリン酸塩、シリカなどをフラックスとして用い
る。この結果、希土類オキシ硫化物蛍光体粉中には必然
的にアルカリ金属元素及びリン酸イオン、シリカが混入
し、この蛍光体を原料にして得られた希土類オキシ硫化
物セラミックシンチレータ中にもアルカリ金属元素及び
リン酸イオン、シリカが存在する。また、原料蛍光体中
のフラックスを水洗し、乾燥する工程で、希土類オキシ
硫化物が酸化して希土類オキシ硫酸塩ができるが、原料
蛍光体が焼結した後もわずかなストイキオメトリのずれ
となって、結晶欠陥として残る。このような残留フラッ
クスやストイキオメトリのずれは、放射線照射に伴う感
度低下をひきおこす。すなわち、希土類オキシ硫化物セ
ラミックス中のアルカリ金属、シリカ、燐酸イオン、酸
素あるいは硫黄欠陥は、放射線を照射する際に電子トラ
ップとして働き、発光中心であるプラセオジムイオン、
テルビウムイオン、ユーロピウムイオンの発光再結合効
率が小さくなってしまうために感度低下がおこると考え
られる。The present invention will be described in more detail below.
As described above, when a rare earth oxysulfide phosphor, which is a raw material for rare earth oxysulfide ceramics, is manufactured, alkali metal compounds, phosphates, silica, etc. are added to enhance crystallinity and adjust the particle size distribution of powder. Is used as flux. As a result, the rare earth oxysulfide phosphor powder is inevitably mixed with alkali metal elements, phosphate ions, and silica, and the rare earth oxysulfide ceramic scintillator obtained using this phosphor as a raw material also contains alkali metal. There are elements, phosphate ions and silica. Also, in the process of washing the flux in the raw material phosphor with water and drying, the rare earth oxysulfide is oxidized to form a rare earth oxysulfate, but even after the raw material phosphor is sintered, there is a slight deviation in stoichiometry. And remain as crystal defects. Such residual flux and deviation of stoichiometry cause a decrease in sensitivity due to radiation irradiation. That is, the alkali metal, silica, phosphate ion, oxygen or sulfur defect in the rare earth oxysulfide ceramics functions as an electron trap when irradiated with radiation, and praseodymium ion, which is the emission center,
It is considered that the sensitivity is lowered because the radiative recombination efficiency of terbium ions and europium ions becomes small.
【００１５】しかし、適量のアルカリ金属元素、シリカ
及び燐酸塩は原料蛍光体粉が焼結する際に焼結を促進さ
せる焼結助剤としての働きをすると考えられ、とくに燐
酸塩については、適量のリン酸イオンを含む蛍光体粉か
ら得られた希土類オキシ硫化物セラミックシンチレータ
は、微密で、ストイキオメトリのずれによる酸素欠陥、
いおう欠陥が少ないため、電子トラップが少なく、放射
線照射に伴う感度低下が小さい。However, it is considered that a proper amount of alkali metal element, silica and phosphate acts as a sintering aid for promoting the sintering when the raw material phosphor powder is sintered. The rare earth oxysulfide ceramic scintillator obtained from the phosphor powder containing the phosphate ion of is very fine and has an oxygen defect due to the deviation of stoichiometry,
Since there are few defects, there are few electron traps, and the decrease in sensitivity due to radiation irradiation is small.
【００１６】[0016]
【実施例】以下に、本発明の実施例と比較例について説
明する。 実施例１ プラセオジムとガトリニウムの共沈酸化物（（Ｇｄ，Ｐ
ｒ）2 Ｏ3 ）１６０ｇと硫黄３２ｇとを、炭酸ナトリウ
ム（ＮａＣＯ3 ）３２ｇと燐酸カリウム（Ｋ3ＰＯ4 ）
８ｇからなる溶融型フラックスと混合し、アルミナるつ
ぼ中で１１００℃で５時間焼成し、Ｇｄ2 Ｏ2 Ｓ：Ｐｒ
蛍光体を得た。その後、水でフラックス及び過剰の硫黄
化合物を洗い流し、さらに温水洗浄を繰り返し、濾過し
て、低温乾燥することにより組成式（Ｇｄ0.9993Ｐｒ
0.0007）2 Ｏ2 Ｓで表される蛍光体粉を得た。EXAMPLES Examples of the present invention and comparative examples will be described below. Example 1 Co-precipitated oxide of praseodymium and gatrinium ((Gd, P
r) 2 O 3 ) 160 g and sulfur 32 g, sodium carbonate (NaCO 3 ) 32 g and potassium phosphate (K 3 PO 4 ).
It was mixed with 8 g of melt type flux and baked in an alumina crucible at 1100 ° C. for 5 hours to obtain Gd 2 O 2 S: Pr.
A phosphor was obtained. After that, the flux and excess sulfur compounds are washed away with water, and washing with warm water is repeated, filtration and low-temperature drying are carried out to obtain a compositional formula (Gd 0.9993 Pr
A phosphor powder represented by 0.0007 ) 2 O 2 S was obtained.
【００１７】この蛍光体の一部を王水に溶解し、ＩＣＰ
発光分光法によりＰＯ4 成分濃度を測定したところ、７
０ｐｐｍであった。また、この蛍光体の別の一部を水に
溶出し、ＩＣＰ発光分光法によりＳＯ4 成分濃度を測定
したところ、４０ｐｐｍであった。A part of this phosphor is dissolved in aqua regia and ICP is added.
When the PO 4 component concentration was measured by emission spectroscopy, it was 7
It was 0 ppm. Another part of this phosphor was eluted in water, and the SO 4 component concentration was measured by ICP emission spectroscopy. As a result, it was 40 ppm.
【００１８】さらに、この蛍光体を原料として冷間プレ
スによる成形を行った後、この蛍光体を金属製気密容器
に封入し、アルゴン雰囲気下で温度１４６０℃、圧力２
０００気圧、処理時間３時間のＨＩＰ処理を施し、その
後Ｈ2 ３％を含むＮ2 の混合雰囲気下、１３５０℃、２
４時間の熱処理を施すことにより実施例１のセラミック
シンチレータを得た。Further, this phosphor was used as a raw material and was molded by cold pressing. Then, the phosphor was sealed in a metal airtight container, and the temperature was 1460 ° C. and the pressure was 2 in an argon atmosphere.
HIP treatment was performed at 000 atm for a treatment time of 3 hours, and thereafter, in a mixed atmosphere of N 2 containing 3% of H 2 at 1350 ° C. for 2 hours.
The ceramic scintillator of Example 1 was obtained by performing heat treatment for 4 hours.
【００１９】このセラミックシンチレータの気孔率は
０．１％以下であり、透光性に優れ、感度が高かった。
このシンチレータを２ｍｍの厚さに成形してシリコンフ
ォトダイオード上に密着させて検出器を作成したとこ
ろ、１２０ｋＶｐの管電圧のＸ線に対するこの検出器の
感度は、ＣｄＷＯ4 単結晶シンチレータを用いて同一の
形状で構成した検出器に比べて１．６倍という高い値で
あった。The porosity of this ceramic scintillator was 0.1% or less, and it was excellent in translucency and high in sensitivity.
When this scintillator was molded to a thickness of 2 mm and adhered on a silicon photodiode to make a detector, the sensitivity of this detector to X-rays with a tube voltage of 120 kVp was the same using a CdWO 4 single crystal scintillator. The value was 1.6 times higher than that of the detector configured in the above shape.
【００２０】また、この（Ｇｄ，Ｐｒ）2 Ｏ2 Ｓセラミ
ックシンチレータに管電圧１２０ｋＶｐ，５００レント
ゲンのＸ線を曝射し、その前後で管電圧１２０ｋＶｐ，
約０．０１レントゲンのＸ線を照射した際の感度を比較
した。その結果を表１に示す。表１から明らかなよう
に、Ｘ線曝射後の感度は曝射前に比べて０．７％しか低
下せず、ＣｄＷＯ4 単結晶シンチレータについて同様の
条件で測定した感度低下１．０％にくらべ性能が上がっ
ており、Ｘ線照射に伴う感度低下についても実用上全く
問題がないレベルであった。The (Gd, Pr) 2 O 2 S ceramic scintillator was exposed to an X-ray of a tube voltage of 120 kVp, 500 roentgen, and a tube voltage of 120 kVp, before and after the exposure.
The sensitivities when irradiated with X-rays of about 0.01 roentgen were compared. The results are shown in Table 1. As is clear from Table 1, the sensitivity after X-ray irradiation was reduced by only 0.7% as compared with that before exposure, and the sensitivity was decreased to 1.0% when measured under the same conditions for the CdWO 4 single crystal scintillator. The performance was higher than that of the conventional one, and there was no problem in practical use with respect to the decrease in sensitivity due to X-ray irradiation.
【００２１】実施例２ ＨＩＰ処理を施した後、熱処理を施さない以外は、実施
例１と同様にして（Ｇｄ0.9993Ｐｒ0.0007）2 Ｏ2 Ｓを
得、これを用いて蛍光体セラミックシンチレータを得
た。そのＰＯ4 成分濃度、ＳＯ4 成分濃度および感度低
下を表１に示す。Example 2 (Gd 0.9993 Pr 0.0007 ) 2 O 2 S was obtained in the same manner as in Example 1 except that after the HIP treatment, no heat treatment was performed. Using this, a phosphor ceramic scintillator was obtained. It was Table 1 shows the PO 4 component concentration, the SO 4 component concentration and the sensitivity decrease.
【００２２】実施例３ Ｇｄ2 Ｏ2 Ｐｒ蛍光体を得た後の温水洗浄の回数を少な
くする以外は、実施例１と同様にして（Ｇｄ0.9993Ｐｒ
0.0007）2 Ｏ2 Ｓを得、これを用いてセラミックシンチ
レータを得た。そのＰＯ4 成分濃度、ＳＯ4 成分濃度お
よび感度低下を表１に示す。Example 3 The procedure of Example 1 was repeated except that the number of washings with warm water after obtaining the Gd 2 O 2 Pr phosphor was reduced (Gd 0.9993 Pr).
0.0007 ) 2 O 2 S was obtained, and this was used to obtain a ceramic scintillator. Table 1 shows the concentration of the PO 4 component, the concentration of the SO 4 component and the decrease in sensitivity.
【００２３】実施例４ Ｇｄ2 Ｏ2 Ｐｒ蛍光体を得た後の温水洗浄の回数を少な
くする以外は、実施例１と同様にして（Ｇｄ0.9993Ｐｒ
0.0007）2 Ｏ2 Ｓを得、これを用いてセラミックシンチ
レータを得た。そのＰＯ4 成分濃度、ＳＯ4 成分濃度お
よび感度低下を表１に示す。Example 4 The procedure of Example 1 was repeated except that the number of times of washing with warm water after obtaining the Gd 2 O 2 Pr phosphor was reduced (Gd 0.9993 Pr).
0.0007 ) 2 O 2 S was obtained, and this was used to obtain a ceramic scintillator. Table 1 shows the concentration of the PO 4 component, the concentration of the SO 4 component and the decrease in sensitivity.
【００２４】比較例１ Ｇｄ2 Ｏ2 Ｓ：Ｐｒ蛍光体は、プラセオジムとガドリニ
ウムの共沈酸化物（（Ｇｄ，Ｐｒ）2 Ｏ3 ））１６０ｇ
と硫黄３２ｇとを、炭酸ナトリウム（ＮａＣＯ3 ）３２
ｇと燐酸カリウム（Ｋ3 ＰＯ4 ）８ｇからなる溶融型フ
ラックスと混合し、アルミナるつぼ中で１１００℃で５
時間焼成し、その後、水でフラックス及び過剰の硫黄化
合物を洗い流して、組成式（Ｇｄ0.9993Ｐｒ0.0007）2
Ｏ2 Ｓで表される蛍光体粉を得た。Comparative Example 1 A Gd 2 O 2 S: Pr phosphor is 160 g of a coprecipitated oxide of praseodymium and gadolinium ((Gd, Pr) 2 O 3 )).
And 32 g of sulfur, sodium carbonate (NaCO 3 ) 32
g and a molten flux of potassium phosphate (K 3 PO 4 ) 8 g, and mixed in an alumina crucible at 1100 ° C. for 5
After firing for a period of time, the flux and excess sulfur compounds are washed away with water, and the composition formula (Gd 0.9993 Pr 0.0007 ) 2
A phosphor powder represented by O 2 S was obtained.
【００２５】この蛍光体の一部を王水に溶解し、ＩＣＰ
発光分光法によりＰＯ4 成分濃度を測定したところ、２
６０ｐｐｍであった。また、この蛍光体の別の一部を水
に溶出し、ＩＣＰ発光分光法によりＳＯ4 成分濃度を測
定したところ、１３０ｐｐｍであった。A part of this phosphor is dissolved in aqua regia and ICP is added.
When the concentration of PO 4 component was measured by emission spectroscopy, it was 2
It was 60 ppm. Another part of this phosphor was eluted in water, and the SO 4 component concentration was measured by ICP emission spectroscopy. As a result, it was 130 ppm.
【００２６】さらに、この蛍光体を原料として冷間プレ
スによる成形を行った後、この蛍光体を金属製気密容器
に封入し、アルゴン雰囲気下で温度１４２０℃、圧力１
５００気圧、処理時間３時間のＨＩＰ処理を施すことに
より比較例１のセラミックシンチレータを得た。このセ
ラミックシンチレータの気孔率は０．１％以下であり、
透光性に優れ、そのために感度が高かった。例えば、こ
のシンチレータを２ｍｍの厚さに成形してシリコンフォ
トダイオード上に密着させて検出器を作成したところ、
１２０ｋＶｐの管電圧のＸ線に対するこの検出器の感度
は、ＣｄＷＯ4単結晶シンチレータを用いて同一の形状
で構成した検出器に比べて１．５倍という高い値であっ
た。Further, this phosphor is used as a raw material and molded by cold pressing, and then the phosphor is sealed in a metal airtight container, and the temperature is 1420 ° C. and the pressure is 1 in an argon atmosphere.
A ceramic scintillator of Comparative Example 1 was obtained by performing HIP treatment at 500 atmospheric pressure for 3 hours. The porosity of this ceramic scintillator is 0.1% or less,
It had excellent translucency and therefore high sensitivity. For example, when this scintillator was molded to a thickness of 2 mm and adhered onto a silicon photodiode to form a detector,
The sensitivity of this detector to X-rays with a tube voltage of 120 kVp was as high as 1.5 times that of a detector constructed in the same shape using a CdWO 4 single crystal scintillator.
【００２７】また、この（Ｇｄ，Ｐｒ）2 Ｏ2 Ｓセラミ
ックシンチレータに管電圧１２０ｋＶｐ，５００レント
ゲンのＸ線を曝射し、その前後で管電圧１２０ｋＶｐ，
約０．０１レントゲンのＸ線を照射した際の感度を比較
したところ、Ｘ線曝射後の感度は曝射前に比べて３％ほ
ど低下しており、Ｘ線照射に伴う感度低下が大きいため
実際のＣＴに組み込むことはできなかった。Further, this (Gd, Pr) 2 O 2 S ceramic scintillator was exposed to an X-ray of a tube voltage of 120 kVp, 500 roentgen, and before and after that, a tube voltage of 120 kVp,
Comparing the sensitivities when X-rays of about 0.01 roentgen were compared, the sensitivities after X-ray irradiation were reduced by about 3% as compared with those before the exposure, and the sensitivity decrease due to X-ray irradiation was large. Therefore, it could not be incorporated into an actual CT.
【００２８】 表 １ ＰＯ4 (ppm) ＳＯ4 (ppm) セラミック 感度低下(%) 作成後の熱処理 実施例１ ７０ ４０ 有り ０．７ ２ ７０ ４０ 無し ０．９ ３ ４３ ３０ 有り １．０ ４ ６０ ５０ 無し ０．８ 比較例１ ２６０ １３０ 無し ３Table 1 PO 4 (ppm) SO 4 (ppm) Ceramics Sensitivity reduction (%) Heat treatment after preparation Example 1 70 40 Yes 0.7 2 70 40 No 0.9 3 43 30 Yes 1.0 4 60 50 None 0.8 Comparative Example 1 260 130 None 3
【００２９】[0029]
【発明の効果】以上説明したように、本発明の原料蛍光
体を使って製造したセラミックシンチレータは、透光性
に優れて感度が高く、かつ、放射線照射に伴う感度低下
が少ない。従って、本発明のシンチレータをＸ線検出器
等の放射線検出器に適用すれば、検出感度が高く、か
つ、放射線照射に伴う感度低下が少ない検出器を得るこ
とができる。As described above, the ceramic scintillator manufactured by using the raw material phosphor of the present invention is excellent in translucency and high in sensitivity, and is less sensitive to radiation irradiation. Therefore, when the scintillator of the present invention is applied to a radiation detector such as an X-ray detector, it is possible to obtain a detector having high detection sensitivity and less deterioration in sensitivity due to radiation irradiation.
フロントページの続き (72)発明者 横田 和人 神奈川県横浜市磯子区新杉田町８番地 株 式会社東芝横浜事業所内 (72)発明者 福田 幸洋 神奈川県横浜市磯子区新杉田町８番地 株 式会社東芝横浜事業所内Front page continuation (72) Inventor Kazuto Yokota 8 Shinsita-cho, Isogo-ku, Yokohama, Kanagawa, Ltd. Toshiba Corporation Yokohama office (72) Inventor Yukihiro Fukuda Shin-Sugita-cho, Isogo-ku, Yokohama, Kanagawa Inside the Yokohama office
Claims (2)
Ｙ，Ｌａ及びＧｄから成る群の中から選ばれる少なくと
も１種の元素、ＮはＰｒ，Ｔｂ及びＥｕから成る群の中
から選ばれる少なくとも１種の元素を示す）で表され、
微量成分として、ＰＯ4 成分のｐｐｍ濃度（ｘ）及びＳ
Ｏ4 成分のｐｐｍ濃度（ｙ）を、各々１０≦ｘ≦１５
０、ｙ≦１００の範囲で含むことを特徴とする希土類オ
キシ硫化物蛍光体。1. A compound of the general formula (M, N) 2 O 2 S (where M is at least one element selected from the group consisting of Y, La and Gd, and N is a group consisting of Pr, Tb and Eu). Represents at least one element selected from among
As a trace component, ppm concentration (x) of PO 4 component and S
The ppm concentration (y) of O 4 component is 10 ≦ x ≦ 15, respectively.
A rare earth oxysulfide phosphor containing 0 or y ≦ 100.
８００℃，１０００気圧以上の圧力で、熱間静水圧法に
より焼成することを特徴とするセラミックスシンチレー
タの製造方法。2. The phosphor according to claim 1 at 1300 ° C. to 1 ° C.
A method for producing a ceramic scintillator, which comprises firing at 800 ° C. and a pressure of 1000 atm or more by a hot isostatic method.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4388194A JP3260541B2 (en) | 1994-03-15 | 1994-03-15 | Phosphor powder, ceramic scintillator and method for producing the same |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4388194A JP3260541B2 (en) | 1994-03-15 | 1994-03-15 | Phosphor powder, ceramic scintillator and method for producing the same |
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| Publication Number | Publication Date |
|---|---|
| JPH07252476A true JPH07252476A (en) | 1995-10-03 |
| JP3260541B2 JP3260541B2 (en) | 2002-02-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4388194A Expired - Lifetime JP3260541B2 (en) | 1994-03-15 | 1994-03-15 | Phosphor powder, ceramic scintillator and method for producing the same |
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| Country | Link |
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| JP (1) | JP3260541B2 (en) |
Cited By (9)
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|---|---|---|---|---|
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09202880A (en) * | 1995-11-21 | 1997-08-05 | Toshiba Corp | Ceramic scintillator, radioactive ray detector using the same and radioactive ray inspector |
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