JP2007145676A - Method for improving surface purity of lutetium silicate crystal - Google Patents

Method for improving surface purity of lutetium silicate crystal

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JP2007145676A
JP2007145676A JP2005345549A JP2005345549A JP2007145676A JP 2007145676 A JP2007145676 A JP 2007145676A JP 2005345549 A JP2005345549 A JP 2005345549A JP 2005345549 A JP2005345549 A JP 2005345549A JP 2007145676 A JP2007145676 A JP 2007145676A
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surface
solution
acid
crystal
lutetium
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JP2005345549A
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Japanese (ja)
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Hiroaki Shidara
Masato Takahashi
広明 設楽
真人 高橋
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Oxide Corp
Toshiba Ceramics Co Ltd
東芝セラミックス株式会社
株式会社オキサイド
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Abstract

PROBLEM TO BE SOLVED: To provide a method for simply purifying the surface and surface layer thereof almost without substantially dissolving the surface of a lutetium silicate crystal (Lu2SiO5), whose use as a scintillator of a positron emission tomography device (PET device) has been considered.
SOLUTION: The surface purity of the silicic acid lutetium crystal is improved by washing the surface of the silicic acid lutetium crystal with a mixed solution of a solution whose hydrofluoric acid concentration is 0.01-50% and a solution whose nitric acid concentration is 0.01-70%.
COPYRIGHT: (C)2007,JPO&INPIT

Description

この発明は、ケイ酸ルテチウム結晶の表面純度を向上する方法に関する。 This invention relates to a method of improving the surface purity silicate lutetium crystals.

ケイ酸ルテチウム結晶(Lu 2 SiO 5 )は、陽電子放射断層撮影装置(positron emission tomography device, PET装置。)のシンチレータとして使用することが検討されているが、その表面・表層純化についてはこれまで適当なものは存在しなかった。 Silicate lutetium crystals (Lu 2 SiO 5), the positron emission tomography apparatus (positron emission tomography device, PET devices.) Although be used as a scintillator of being considered, so far suitable for the surface-surface purification such things did not exist.

シンチレータの表面を鏡面研磨するには機械的研磨があるが、多面体の場合はこれらの1面ずつを研磨しなければならず研磨コストが高く、また複雑な表面では研磨が困難であった。 Although the surface of the scintillator to mirror polishing is mechanical polishing, if the polyhedron has a high polishing cost must polished by these one side and the polishing is difficult for complex surfaces. このために、これまでは所定の形状に成形した後に表面を溶解溶液で洗浄することによって行っている。 For this, heretofore is carried out by washing the surface with a lysis solution after formed into a predetermined shape.

しかしながら、ケイ酸ルテチウム結晶はその洗浄方法がこれまで特定されていなかった。 However, silicate lutetium crystals its cleaning method has not been identified so far. 一方で、ケイ酸ルテチウム結晶の主成分であるルテチウム(Lu)を含む希土類元素の溶解方法は、硫酸、塩酸、フッ化水素酸などを用いることが知られ、これらの溶解液がこれら物質の表面のみならず全てを溶かすことが知られている。 On the other hand, methods for dissolving rare earth elements including a lutetium (Lu) which is the main component of silicate lutetium crystals is known to use sulfuric acid, hydrochloric acid, hydrofluoric acid or the like, the surface of these lysates of these substances be dissolved all not only are known. JIS の試薬ハンドブックには、ケイ酸ルテチウムは記載されていないが、ルテチウム単体は無機酸に溶解することが分かっている。 The JIS reagent Handbook, silicate lutetium is not described, lutetium alone has been found to be soluble in mineral acids. ケイ酸ルテチウム結晶の他方の主成分であるSiO 2は、フッ化水素に容易に溶解することが分かっている。 SiO 2 is the other main component of silicate lutetium crystals are found to be readily soluble in hydrogen fluoride.

シンチレータの表面加工方法の従来技術はエッチング液で表面処理するもので、そのエッチング液がオルトリン酸又はピロリン酸を一度、200℃を超える温度まで加熱することによって得られた液を主とするものがある(例えば、特許文献1参照。) Prior art method of processing the surface of the scintillator is intended to surface treatment with an etchant, the etchant orthophosphoric acid or pyrophosphoric acid once, those mainly resulting solution by heating to temperatures above 200 ° C. some (for example, see Patent Document 1.)
特開平9−110600号公報(請求項2、請求項3) JP-9-110600 discloses (claim 2, claim 3)

しかしながら、特許文献1に記載のエッチング方法では、ケイ酸ルテチウム結晶の表面を溶解することはできず、加工などにより汚染された表面の不純物の洗浄は困難であった。 However, in the etching method described in Patent Document 1, it can not be dissolving the surface of the silicate lutetium crystals, washing the impurities of contaminated surfaces due process has been difficult. この発明は、ケイ酸ルテチウム結晶の表面を限定した濃度をもったフッ化水素酸と硝酸の混合溶液で洗浄するだけで、ケイ酸ルテチウム結晶の表面を実質的にほとんど溶解することなく、その表面および表層を簡単に純化する方法を得ようとするものである。 This invention is only washed with a mixed solution of hydrofluoric acid having a concentration of limiting the surface of the silicate lutetium crystals and nitric acid without substantially little dissolving the surface of the silicate lutetium crystal, its surface and it is intended to obtain an easy way to purify the surface layer.

この発明は、ケイ酸ルテチウム結晶の表面純度を向上する方法であって、フッ化水素酸濃度が0.01〜50%の溶液と硝酸濃度が0.01〜70%の溶液の混合溶液でケイ酸ルテチウム結晶の表面を洗浄することでケイ酸ルテチウム結晶の表面純度を向上する方法(請求項1)および前記洗浄を常圧で行うことを特徴とする請求項1記載のケイ酸ルテチウム結晶の表面純度を向上する方法(請求項2)である。 This invention provides a method of improving the surface purity silicate lutetium crystals, the solution and nitric acid concentration of the hydrofluoric acid concentration from 0.01 to 50% silicate with a mixture of 0.01 to 70% solution how to improve the surface purity silicate lutetium crystals by washing the surface of lutetium crystal (claim 1) and the surface of the cleaning silicate lutetium crystal according to claim 1, characterized in that at normal pressure a method of improving the purity (claim 2).

この発明によれば、ケイ酸ルテチウム結晶の基材をほとんど溶解することなく、その表面および表層の不純物量を1/10〜1/100にも純化することができる。 According to the present invention, without substantially dissolving the substrate silicate lutetium crystals, the impurity amount of the surface and the surface layer can also be purified to 1 / 10-1 / 100. さらに、その純化処理は上記の結晶を常圧で洗浄することによって簡単に行うことができる。 Moreover, the purification process can be easily performed by washing the crystals at normal pressure. しかも、この発明では基材を実質的にほとんど溶解しないところから、基材の影響を小さくすることができ、表面の不純物情報を得ることができて表層分析が可能となるものである。 Moreover, the base material in the present invention from where not substantially less soluble, it is possible to reduce the influence of the substrate, are those which can be obtained impurities information surface it is possible to surface analysis.

この発明は、フッ化水素酸濃度が0.01〜50%の溶液と硝酸濃度が0.01〜70%の溶液の混合溶液でケイ酸ルテチウム結晶の表面を常圧で洗浄するものである。 The present invention is hydrofluoric acid concentration of the solution and nitric acid concentration of 0.01 to 50% is washed with a surface atmospheric pressure of the mixed solution in silicate lutetium crystals from 0.01 to 70% of the solution.

フッ化水素酸濃度が0.01%未満では洗浄能力が低く、またこれが50%を超えるとフッ化水素酸の蒸気が発生するため洗浄操作に不便が生じる。 Hydrofluoric acid concentration is low cleaning performance is less than 0.01%, also this inconvenience occurs washing operation for vapor hydrofluoric acid exceeds 50% is generated. 一方、硝酸濃度が0.01未満ではこれも洗浄能力が低く、またこれが70%を超えると硝酸の蒸気が発生するため洗浄操作に不便が生じる。 On the other hand, the nitric acid concentration is also cleaning ability is low and this is inconvenient occurs washing operation the steam nitric acid is generated when more than 70% is less than 0.01. これらの混合溶液でケイ酸ルテチウム結晶の表面を純化するには、例えばこの混合溶液の入った容器の中に、被洗浄物であるケイ酸ルテチウム結晶を入れて、例えば1時間放置する。 To purify the surface of the silicate lutetium crystals in these mixed solution, for example in a vessel containing the mixed solution, put silicate lutetium crystals to be cleaned, allowed to stand for example 1 hour. その後これを容器から取り出し純水で洗浄し乾燥する。 Thereafter it was washed with pure water was taken out from the vessel and dried. これによって、基材のケイ酸ルテチウム結晶の表面および表層をほとんど溶解することなく、表面の不純物を溶解して除去して表面を純化することができるものである。 Thus, without substantially dissolving the surface and surface layer of the silicate lutetium crystal substrates and is able to purify the surface by removing dissolved impurities on the surface. その結果、基材表面のNa,Al,K,Fe,Y といった不純物を大幅に低下して表面純度を大きく向上することができるものである。 As a result, those that can greatly improve the surface purity Na of the substrate surface, Al, K, Fe, impurities such as Y greatly reduced.

試料A〜Dについて、ポリテトラフルオロエチレンビーカーに、表1に示すような洗浄液を10ml入れ、1時間放置した。 Samples to D, polytetrafluoroethylene beaker, the cleaning liquid as shown in Table 1 were placed 10 ml, allowed to stand for 1 hour. その後、試料を洗浄液より取り出しこれに硫酸を0.2mlを加えてから加熱し、洗浄液が0.2mlになるまで濃縮した。 Then, this sulfate removed samples from the washing liquid is heated after the addition of 0.2 ml, the cleaning liquid was concentrated to 0.2 ml. 次にこれに水を加えて定容(100ml)してICP発光分析法で不純物を測定した。 It was then measured impurity by the ICP emission spectrometry and constant volume (100ml) by addition of water thereto. この結果を表1に示した The results are shown in Table 1

表1に示すように、各種洗浄液を用いて洗浄してその洗浄液を分析することで、基材の表面および表層近傍の不純物濃度を知ることができる。 As shown in Table 1, by analyzing the washes were washed with various cleaning liquid, it is possible to know the surface and the impurity concentration near the surface layer of the substrate. 表1では、試料A,Bでは不純物の溶出が充分でなく、また試料C,Dでは基材の溶出が大きい。 In Table 1, samples A, elution of impurities in B is not sufficient, also the sample C, and a large dissolution of the base in D.

表2は、基材のケイ酸ルテチウム結晶の溶出を出来るだけ抑え、かつ不純物溶出を多くして表面純化の洗浄をするために本発明の洗浄液を選択して洗浄したところ、洗浄液の不純物含有量は同表に示す通りであった。 Table 2, was washed by selecting a cleaning solution of the present invention to suppress as much as possible the dissolution of the silicate lutetium crystal substrates, and the cleaning of the impurities elute much to the surface purification, impurity content of the cleaning solution were as shown in the Table.

表2で示すように、この洗浄によって基材からのLuの溶出はいずれも少なく、しかもCe,Mg,Niなどの不純物の溶出が大きいことが分かる。 As shown in Table 2, at least either the dissolution of Lu from the substrate by the cleaning, moreover Ce, Mg, that elution of impurities such as Ni is large seen. 試料DについてはLuの溶出が300ppm を超えているが、この場合はAl,Ca,Ce,Naなどの溶出がさらに大きくよく純化されていることがわかる。 Although elution of Lu exceeds the 300ppm for sample D, in this case Al, Ca, Ce, it is understood that dissolution such as Na is greater better purification.

表3は、表2で用いたと同じ洗浄液を用いて、表2で述べた洗浄をすでに終えた試料A,B,C,Dを再度同じように洗浄してその洗浄液を分析したものである。 Table 3, using the same washing liquid as that used in Table 2 is a sample A which has finished already washed as described in Table 2, B, C, washed D the like again that analyze the cleaning liquid.

表3から明らかなように、この場合の洗浄液中の不純物元素含有量は殆どが1ppm以下で、表2での洗浄で不純物元素は殆ど純化されていることが分かる。 As apparent from Table 3, the impurity element contents in the washing solution in this case is most 1ppm or less, impurity elements in the cleaning of Table 2 it can be seen that almost purified. ここで溶出されているのは基材のLuが主であることがわかる。 Here what is eluted is seen that base of Lu is the main.

表4は、洗浄液に塩酸を用いた場合を参考例として示したものである。 Table 4 shows the case of using a hydrochloric acid washing liquid as a reference example. この場合は基材のLuを大きく溶解して表面純化には不適であることがわかる。 In this case, it can be seen that are not suitable for the surface purification by increasing dissolved Lu substrates.

Claims (2)

  1. ケイ酸ルテチウム結晶の表面純度を向上する方法であって、フッ化水素酸濃度が0.01〜50%の溶液と硝酸濃度が0.01〜70%の溶液の混合溶液でケイ酸ルテチウム結晶の表面を洗浄することでケイ酸ルテチウム結晶の表面純度を向上する方法。 A method of improving the surface purity silicate lutetium crystals, hydrofluoric acid concentration 0.01 to 50% solution and nitric acid concentration of silicic acid lutetium crystals with a mixed solution of 0.01 to 70% solution how to improve the surface purity silicate lutetium crystals by washing the surface.
  2. 前記洗浄を常圧で行うことを特徴とする請求項1記載のケイ酸ルテチウム結晶の表面純度を向上する方法。 How to improve the surface purity silicate lutetium crystal according to claim 1, characterized in that the cleaning at normal pressure.
JP2005345549A 2005-11-30 2005-11-30 Method for improving surface purity of lutetium silicate crystal Pending JP2007145676A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH054811A (en) * 1991-06-25 1993-01-14 Shin Etsu Handotai Co Ltd Method for cleansing polycrystalline silicon
JPH06140376A (en) * 1992-10-23 1994-05-20 Sumitomo Metal Mining Co Ltd Cleaning solution for gap crystal
JP2005532571A (en) * 2002-07-05 2005-10-27 ワシントン・ユニバーシティWashington University School of Medicine How to increase the spatial resolution of Pet scanners and devices

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH054811A (en) * 1991-06-25 1993-01-14 Shin Etsu Handotai Co Ltd Method for cleansing polycrystalline silicon
JPH06140376A (en) * 1992-10-23 1994-05-20 Sumitomo Metal Mining Co Ltd Cleaning solution for gap crystal
JP2005532571A (en) * 2002-07-05 2005-10-27 ワシントン・ユニバーシティWashington University School of Medicine How to increase the spatial resolution of Pet scanners and devices

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