JP2008143726A - Polycrystalline transparent y2o3 ceramics and its production method - Google Patents

Polycrystalline transparent y2o3 ceramics and its production method Download PDF

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JP2008143726A
JP2008143726A JP2006329949A JP2006329949A JP2008143726A JP 2008143726 A JP2008143726 A JP 2008143726A JP 2006329949 A JP2006329949 A JP 2006329949A JP 2006329949 A JP2006329949 A JP 2006329949A JP 2008143726 A JP2008143726 A JP 2008143726A
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Akio Ikesue
明生 池末
Yuji Iwamoto
雄二 岩本
Tsukasa Hirayama
司 平山
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Japan Fine Ceramics Center
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Abstract

<P>PROBLEM TO BE SOLVED: To provide polycrystalline transparent Y<SB>2</SB>O<SB>3</SB>ceramics for electron beam fluorescence which is excellent in mass productivity and quality in image and by which superior quality in image can be obtained especially as an electron beam scintillator, and to provide its production method. <P>SOLUTION: The polycrystalline transparent Y<SB>2</SB>O<SB>3</SB>ceramics for electron beam fluorescence consists of a polycrystalline sintered body whose main ingredient is Y<SB>2</SB>O<SB>3</SB>, which has a porosity of 0.1% or less, which has a mean crystalline particle diameter of 5-300 μm and which contains a lanthanide element (Tb, Eu and the like). The method for producing the polycrystalline transparent Y<SB>2</SB>O<SB>3</SB>ceramics for electron beam fluorescence has a primary baking step to obtain a primary baked body by baking a formed body including Y<SB>2</SB>O<SB>3</SB>powders and lanthanide oxide powders at 1,500-1,800°C under an oxygen atmosphere and a secondary baking step to additionally bake the primary baked body at 1,600-1,800°C and 49-198 MPa. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は電子線蛍光用多結晶透明Yセラミックス及びその製造方法に関する。更に詳しくは、量産性に優れ、且つ画質に優れ、特に電子線シンチレータとして優れた画質が得られる電子線蛍光用多結晶透明Yセラミックス及びその製造方法に関する。 The present invention relates to a polycrystalline transparent Y 2 O 3 ceramic for electron beam fluorescence and a method for producing the same. More specifically, the present invention relates to a polycrystalline transparent Y 2 O 3 ceramic for electron beam fluorescence, which is excellent in mass productivity, excellent in image quality, and particularly excellent in image quality as an electron beam scintillator, and a method for producing the same.

YAG(イットリウム・アルミニウム・ガーネット)に代表されるガーネット構造酸化物の蛍光粉末や、Ce及び/又はTbを添加したYAG等の電子線蛍光材料は、その市場の大半を占める重要な材料である。
これらの電子線蛍光材料としては、YAG等のガーネット構造酸化物に代表される蛍光体が用いられている。これら検出材料としては、(1)電子線蛍光材料を粉末化した上で、この粉末にバインダーを加えて基体に塗布してなる「粉末系材料」や、(2)電子線蛍光材料からなる単結晶を1mm以下の厚さに研磨・加工して用いた単結晶系材料が知られている。更に、(3)YAG等のガーネット構造を有する電子線検出材料以外では、単結晶Yを電子線検出材料として用いる技術が知られている。
A fluorescent powder of a garnet structure oxide represented by YAG (yttrium, aluminum, garnet) and an electron beam fluorescent material such as YAG added with Ce and / or Tb are important materials that occupy most of the market.
As these electron beam fluorescent materials, phosphors typified by garnet structure oxides such as YAG are used. These detection materials include (1) a “powder material” obtained by pulverizing an electron beam fluorescent material, and then adding a binder to the powder and applying the powder to a substrate, or (2) a single material made of an electron beam fluorescent material. There is known a single crystal material in which a crystal is polished and processed to a thickness of 1 mm or less. Furthermore, a technique using single crystal Y 2 O 3 as an electron beam detection material is known other than (3) an electron beam detection material having a garnet structure such as YAG.

上記(1)の粉末系材料では、Ce及び/又はTb等の蛍光元素をガーネット構造のホストに固溶させた電子線蛍光材料を用いるのが一般的である。この粉末系材料では、上記電子線蛍光材料等を粉末化し、有機バインダーと共に基材に塗布して蛍光板とし、この蛍光板に電子線が照射された際に発する蛍光特性を利用する。代表的な応用例としてはSEMの画像検出器が知られている。
しかし、この粉末系材料は、検出器の低価格化を実現できる反面、塗布された蛍光粉末の連続性が欠如(即ち、蛍光物質がドット状に分散)しているために、得られる画像にザラツキ(画質の荒さ)を生じるという問題がある。更に、蛍光粉末と共に用いられる有機系バインダーは、長時間にわたって電子線に曝されると変質及び分解を生じ、得られる画像に"焼きつき"(分解領域の画像ムラ)を生じ、画質の安定性及びメンテナンスを要する等の問題もある。
In the powder-based material (1), an electron beam fluorescent material in which a fluorescent element such as Ce and / or Tb is dissolved in a garnet structure host is generally used. In this powder-based material, the above-mentioned electron beam fluorescent material or the like is pulverized and applied to a base material together with an organic binder to form a fluorescent plate, and the fluorescent characteristic emitted when the fluorescent plate is irradiated with an electron beam is used. As a typical application example, an SEM image detector is known.
However, this powder-based material can reduce the price of the detector, but the lack of continuity of the applied fluorescent powder (that is, the fluorescent substance is dispersed in the form of dots), resulting in an obtained image. There is a problem of causing roughness (roughness in image quality). In addition, organic binders used with fluorescent powders can be altered and decomposed when exposed to an electron beam for a long time, resulting in "burn-in" (image unevenness in the decomposed area) in the resulting image and image quality stability. There are also problems such as requiring maintenance.

上記(2)の単結晶系材料では、Ce及び/又はTb等を蛍光元素とするYAG系単結晶材料が用いるのが一般的である。この単結晶系材料は、粉末系材料の欠点を克服する面を有する反面、Ce含有YAG単結晶は、YAG単結晶中でのCeイオン(Ce4+)の偏析係数が0.1〜0.2と小さいためCeイオンを添加したYAG単結晶を作製することが容易ではない。また、単結晶YAGを製造するには、育成温度は約2000℃と高温を要し、且つ育成速度は0.1〜0.3mm/時間と極めて遅い。このことから1本の単結晶を製造するのに約1ケ月程も要し、更には、得られる単結晶YAG中の蛍光元素が均一とはなり難い。更に、上記単結晶中への蛍光元素の均一分散が困難であることに加えて、添加濃度は0.5〜1原子%程度(特にCe元素の場合)が限界である。これらのことからYAG単結晶を製造できたとしても、歩留まりが非常に小さく、単結晶系材料として利用できるものは極めて少ない。更に、単結晶YAGを製造する際には極めて高価なイリジウム坩堝を要する。このため得られる単結晶YAGは高価となることは勿論、生産性の面でも満足すべき効率が得られ難いのが現状である。単結晶系材料には、これらの製造上の種々の問題がある。 In the single crystal material (2), a YAG single crystal material having Ce and / or Tb or the like as a fluorescent element is generally used. While this single crystal material has a surface that overcomes the disadvantages of the powder material, Ce-containing YAG single crystal has a segregation coefficient of Ce ions (Ce 4+ ) in the YAG single crystal of 0.1 to 0.2. Therefore, it is not easy to produce a YAG single crystal to which Ce ions are added. Further, in order to produce single crystal YAG, the growth temperature requires a high temperature of about 2000 ° C., and the growth rate is extremely slow, 0.1 to 0.3 mm / hour. Therefore, it takes about one month to produce one single crystal, and furthermore, the fluorescent element in the obtained single crystal YAG is difficult to be uniform. Further, in addition to the difficulty of uniformly dispersing the fluorescent element in the single crystal, the addition concentration is limited to about 0.5 to 1 atomic% (especially in the case of Ce element). For these reasons, even if a YAG single crystal can be manufactured, the yield is very small, and there are very few materials that can be used as a single crystal material. Furthermore, when manufacturing single crystal YAG, an extremely expensive iridium crucible is required. For this reason, the single crystal YAG obtained is not only expensive, but it is difficult to obtain satisfactory efficiency in terms of productivity. There are various problems in manufacturing these single crystal materials.

上記(3)の単結晶Yは、融点が2400℃と極めて高温であることから、量産を行うには、高品質の単結晶育成技術として不向きなベルヌイ法に依存しなければならない。このため、実用的な高品位の単結晶が製造できない。更に、Yは2280℃付近で六方晶から立方晶への相転移を生じるために、直径1cm程度を超えるような大きな単結晶を得ることが極めて困難である。このように単結晶Yには、製造上の種々の問題や利用制限があるという問題がある。 Since the single crystal Y 2 O 3 of (3) has an extremely high melting point of 2400 ° C., mass production must rely on the Bernoulli method, which is not suitable as a high-quality single crystal growth technique. For this reason, a practical high-quality single crystal cannot be produced. Furthermore, since Y 2 O 3 causes a phase transition from a hexagonal crystal to a cubic crystal at around 2280 ° C., it is extremely difficult to obtain a large single crystal having a diameter exceeding about 1 cm. As described above, the single crystal Y 2 O 3 has various problems in production and problems of use.

本発明は、上記実情に鑑みてなされたものであり、量産性に優れ、且つ画質に優れ、特に電子線シンチレータとして優れた画質が得られる電子線蛍光用多結晶透明Yセラミックス及びその製造方法を提供することを目的とする。 The present invention has been made in view of the above-mentioned circumstances, and is excellent in mass productivity, excellent in image quality, and in particular, a polycrystalline transparent Y 2 O 3 ceramic for electron beam fluorescence capable of obtaining an excellent image quality as an electron beam scintillator, and its An object is to provide a manufacturing method.

本発明は、以下に示す通りである。
(1)Yを主成分とする多結晶焼結体からなる電子線蛍光用多結晶透明Yセラミックスであって、
該多結晶焼結体は、気孔率が0.1%以下であり、平均結晶粒子径が5〜300μmであり、且つ、ランタニド元素を含有することを特徴とする電子線蛍光用多結晶透明Yセラミックス。
(2)Zr及びCaのうちの少なくとも一方を含有し、
Zr及びCaの含有量は、Yとランタニド元素との酸化物換算合計量に対して、各々酸化物換算で1000質量ppm以下である上記(1)に記載の電子線蛍光用多結晶透明Yセラミックス。
(3)Zr及びCaの両元素を含有し、且つZr及びCaの両方が含まれる複酸化物を含有する上記(1)又は(2)に記載の電子線蛍光用多結晶透明Yセラミックス。
(4)Zr及びCaの両元素を含有し、ZrとCaとのモル比Zr/Caは0.5〜2.0である上記(1)乃至(3)のうちのいずれかに記載の電子線蛍光用多結晶透明Yセラミックス。
(5)上記(1)乃至(4)のうちのいずれかに記載の電子線蛍光用多結晶透明Yセラミックスの製造方法であって、
粉末及びランタニド酸化物粉末を含有する成形体を、酸素雰囲気下1500〜1800℃で焼成して一次焼成体を得る一次焼成工程と、
該一次焼成体を更に温度1600〜1800℃且つ圧力49〜198MPaで焼成する二次焼成工程と、を備えることを特徴とする電子線蛍光用多結晶透明Yセラミックスの製造方法。
The present invention is as follows.
(1) A polycrystalline transparent Y 2 O 3 ceramic for electron beam fluorescence comprising a polycrystalline sintered body containing Y 2 O 3 as a main component,
The polycrystalline sintered body has a porosity of 0.1% or less, an average crystal particle diameter of 5 to 300 μm, and contains a lanthanide element. 2 O 3 ceramics.
(2) contains at least one of Zr and Ca,
The content of Zr and Ca is 1000 mass ppm or less in terms of oxide with respect to the total amount in terms of oxide of Y and the lanthanide element, respectively. The polycrystalline transparent Y 2 for electron beam fluorescence according to the above (1) O 3 ceramics.
(3) The polycrystalline transparent Y 2 O 3 for electron beam fluorescence according to the above (1) or (2), which contains both elements of Zr and Ca and contains a double oxide containing both Zr and Ca. Ceramics.
(4) The electron according to any one of (1) to (3), which contains both elements of Zr and Ca, and the molar ratio Zr / Ca of Zr and Ca is 0.5 to 2.0. Polycrystalline transparent Y 2 O 3 ceramics for line fluorescence.
(5) A method for producing polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence according to any one of (1) to (4) above,
A primary firing step of obtaining a primary fired body by firing a molded body containing Y 2 O 3 powder and a lanthanide oxide powder at 1500 to 1800 ° C. in an oxygen atmosphere;
And a secondary firing step of further firing the primary fired body at a temperature of 1600 to 1800 ° C. and a pressure of 49 to 198 MPa. A method for producing polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence.

本発明の電子線蛍光用多結晶透明Yセラミックスによれば、電子線蛍光用多結晶透明Yセラミックスは量産性に優れる。また、高濃度に蛍光元素(ランタニド元素)を含有させることができ、更には、蛍光元素を電子線蛍光用多結晶透明Yセラミックスの全域にわたって非常に分散性よく均一に含有させることができる。加えて大型の蛍光材料を容易に得ることができる。このため極めて画質に優れた映像を得ることができ、特にシンチレータ用材料として適している。また、バインダー等を用いないためにシンチレータの品質劣化がなく、シンチレータの長寿命化を達することができ、メンテナンスを行う必要がない。本発明の電子線蛍光用多結晶透明Yセラミックスによれば、上記優れた特性を、高価な単結晶育成装置を用いることなく得ることができる。 According to the electronic-ray fluorescence for polycrystalline transparent Y 2 O 3 ceramics of the present invention, an electron beam fluorescence polycrystalline transparent Y 2 O 3 ceramics is excellent in mass productivity. Further, a fluorescent element (lanthanide element) can be contained at a high concentration, and furthermore, the fluorescent element can be uniformly contained with good dispersibility over the entire area of the polycrystalline transparent Y 2 O 3 ceramic for electron beam fluorescence. it can. In addition, a large fluorescent material can be easily obtained. For this reason, it is possible to obtain an image with extremely excellent image quality, and it is particularly suitable as a scintillator material. Further, since no binder or the like is used, the quality of the scintillator is not deteriorated, the life of the scintillator can be extended, and no maintenance is required. According to the polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence of the present invention, the above excellent characteristics can be obtained without using an expensive single crystal growing apparatus.

Zr及びCaのうちの少なくとも一方を含有し、Zr及びCaの含有量が、Yとランタニド元素との酸化物換算合計量に対して、各々酸化物換算で1000質量ppm以下である場合は、より透明なY焼結体を作製でき、その結果、Y焼結体中の光散乱を減少されて光学特性を向上させることができる。
Zr及びCaの両元素を含有し、且つZr及びCaの両方が含まれる複酸化物を含有する場合は、更に透明なY焼結体を作製でき、その結果、Y焼結体中の光散乱を更に減少さて、光学特性(とりわけ画質)を向上させることができる。
Zr及びCaの両元素を含有し、ZrとCaとのモル比Zr/Caが0.5〜2.0である場合は、特に透明なY焼結体を作製でき、その結果、Y焼結体中の光散乱を特に減少さて、光学特性(とりわけ画質)を向上させることができる。
When it contains at least one of Zr and Ca, and the content of Zr and Ca is 1000 mass ppm or less in terms of oxide with respect to the total amount in terms of oxide of Y and lanthanide element, A transparent Y 2 O 3 sintered body can be produced, and as a result, light scattering in the Y 2 O 3 sintered body can be reduced and optical characteristics can be improved.
It contains both elements of Zr and Ca, when containing a mixed oxide of and includes both Zr and Ca, can produce a more transparent Y 2 O 3 sintered body, as a result, Y 2 O 3 sintered Optical scattering (especially image quality) can be improved by further reducing light scattering in the aggregate.
When both elements of Zr and Ca are contained and the molar ratio Zr / Ca of Zr and Ca is 0.5 to 2.0, a particularly transparent Y 2 O 3 sintered body can be produced. Light scattering in the Y 2 O 3 sintered body can be particularly reduced to improve optical properties (especially image quality).

本発明の電子線蛍光用多結晶透明Yセラミックスの製造方法によれば、前記優れた特性を、高価な単結晶育成装置を用いることなく得ることができる。特に焼結法を用いることで、材料自体の融点よりも低い温度で焼結することができる。また、焼結時間は数〜数十時間程度と短くでき、電子線蛍光用多結晶透明Yセラミックスの製造に要するエネルギー量を格段に小さくできる。更に、一台の焼結炉で多数の焼結体(電子線蛍光用多結晶透明Yセラミックス)を製造できる。また、ニアネットシェイプ技術を用いることで、実使用形状に近いシンチレータを効率良く製造できる。これらのことから、量産性及び経済性(コスト低減、希土類資源の有効利用、消費エネルギー削減)等に優れている。 According to the method for producing polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence of the present invention, the excellent characteristics can be obtained without using an expensive single crystal growing apparatus. In particular, by using a sintering method, sintering can be performed at a temperature lower than the melting point of the material itself. In addition, the sintering time can be shortened to about several to several tens of hours, and the amount of energy required for producing polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence can be remarkably reduced. Furthermore, a large number of sintered bodies (polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence) can be produced in one sintering furnace. Further, by using the near net shape technology, it is possible to efficiently manufacture a scintillator close to an actual use shape. From these, it is excellent in mass productivity and economy (cost reduction, effective use of rare earth resources, energy consumption reduction) and the like.

本発明について、以下詳細に説明する。
[1]電子線蛍光用多結晶透明Yセラミックス
本発明の電子線蛍光用多結晶透明Yセラミックスは、Yを主成分とする多結晶焼結体からなる電子線蛍光用多結晶透明Yセラミックスであって、該多結晶焼結体は、気孔率が0.1%以下であり、平均結晶粒子径が5〜300μmであり、且つ、ランタニド元素を含有することを特徴とする。
The present invention will be described in detail below.
[1] the electron-ray fluorescence for polycrystalline transparent Y 2 O 3 ceramic electron beam fluorescent polycrystalline transparent Y 2 O 3 ceramics of the present invention, an electron beam of a polycrystalline sintered body composed mainly of Y 2 O 3 A polycrystalline transparent Y 2 O 3 ceramic for fluorescence, wherein the polycrystalline sintered body has a porosity of 0.1% or less, an average crystal particle diameter of 5 to 300 μm, and contains a lanthanide element It is characterized by doing.

本発明の電子線蛍光用多結晶透明Yセラミックス(以下、単に「本セラミックス」ともいう)は、Yを主成分とする。この本セラミックスに含有されるYは特に限定されないが、通常、本セラミックス全体(100原子%として)に対して85原子%以上(通常99.5原子%以下)である。 The polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence of the present invention (hereinafter also simply referred to as “the present ceramics”) contains Y 2 O 3 as a main component. Y 2 O 3 contained in this ceramic is not particularly limited, but is usually 85 atomic% or more (usually 99.5 atomic% or less) with respect to the entire ceramic (as 100 atomic%).

また、本セラミックスは、ランタニド元素を含有する。このランタニド元素は、本セラミックス中において蛍光元素として機能できる。含有されるランタニド元素の種類は特に限定されず、La、Ce、Pr、Nd、Pm、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb及びLuが挙げられる。これらは1種のみが含有されてもよく、2種以上が含有されてもよい。これらのなかでは、Ce、Pr、Pm、Sm、Eu、Tb、Dy、Ho、Er、Tm及びYbが好ましく、更には、Tb及びEuが特に好ましい。   In addition, the present ceramic contains a lanthanide element. This lanthanide element can function as a fluorescent element in the present ceramics. The kind of lanthanide element contained is not particularly limited, and examples thereof include La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Only 1 type may contain these and 2 or more types may contain. Among these, Ce, Pr, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb are preferable, and Tb and Eu are particularly preferable.

これらランタニド元素の含有形態は特に限定されず、各ランタニド元素の酸化物、例えば、CeO、Pr11、Pm、Sm、Eu、Tb、Dy、Ho、Er、Tm及びYb等として含有することができる。また、これら以外の酸化数の酸化物(価数)として含有されてもよく、異なる酸化数(価数)の酸化物が混在してもよい。更に、各種複酸化物を形成して含有されてもよい。
また、ランタニド元素の含有量は特に限定されないが、ランタニド元素の酸化物換算による含有量は、多結晶焼結体に含有されるイットリウム元素の酸化物換算による全量に対して0.5原子%〜15原子%(より好ましくは0.5原子%〜10原子%、更に好ましくは0.5原子%〜8原子%)であることが好ましい。この範囲では、電子線蛍光材料に適し、特にシンチレータに適した適度な発光を得ることができる。この上記ランタニド元素の酸化物換算による含有量とは、本セラミックスを(Y1−xReで表した場合にランタニド元素Reが占有する割合xを百分率換算した値である。
尚、ランタニド元素の含有量の算出に際する上記ランタニド元素の酸化物換算は、各々最も安定な酸化物として換算するものとする。即ち、例えば、La、CeO、Pr11、Nd、Pm、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb及びLuである。同様に、本セラミックス中に含有されるYについても同様であり、Yとして酸化物換算するものとする。
The containing form of these lanthanide elements is not particularly limited, and oxides of each lanthanide element, such as CeO 2 , Pr 6 O 11 , Pm 2 O 3 , Sm 2 O 3 , Eu 2 O 3 , Tb 2 O 3 , Dy 2 O 3 , Ho 2 O 3 , Er 2 O 3 , Tm 2 O 3 and Yb 2 O 3 can be contained. Moreover, it may contain as an oxide (valence) of oxidation numbers other than these, and the oxide of a different oxidation number (valence) may be mixed. Furthermore, various double oxides may be formed and contained.
Further, the content of the lanthanide element is not particularly limited, but the content of the lanthanide element in terms of oxide is 0.5 atomic% to the total amount of oxide of the yttrium element contained in the polycrystalline sintered body It is preferably 15 atomic% (more preferably 0.5 atomic% to 10 atomic%, still more preferably 0.5 atomic% to 8 atomic%). In this range, it is possible to obtain appropriate light emission suitable for an electron beam fluorescent material and particularly suitable for a scintillator. The content of the lanthanide element in terms of oxide is a value obtained by converting the ratio x occupied by the lanthanide element Re when the present ceramic is represented by (Y 1-x Re x ) 2 O 3 as a percentage.
The oxide conversion of the lanthanide element when calculating the content of the lanthanide element is calculated as the most stable oxide. That is, for example, La 2 O 3 , CeO 2 , Pr 6 O 11 , Nd 2 O 3 , Pm 2 O 3 , Sm 2 O 3 , Eu 2 O 3 , Gd 2 O 3 , Tb 2 O 3 , Dy 2 O 3 , Ho 2 O 3 , Er 2 O 3 , Tm 2 O 3 , Yb 2 O 3 and Lu 2 O 3 . Similarly, the same applies to Y contained in the present ceramic, and it is assumed to be converted to oxide as Y 2 O 3 .

更に、本セラミックスは、多結晶体である。即ち、拡大視した場合に結晶粒子が複数確認できるものである。更に、これらの結晶粒子の平均粒径(平均結晶粒子径)は5〜300μmである。この平均結晶粒子径が5μm未満であると十分な透明性が得られ難く(例えば、400〜800nmの波長領域における70%以上の透過率が得難く)なる傾向にある。一方、300μmを超える結晶粒径となると、結晶粒径が大きくなり過ぎ、蛍光元素(ランタニド元素)を十分に均一に固溶させることが困難となる傾向にある。更に、結晶間の粒界相に蛍光元素が偏析し、透明なセラミックスを得難く(例えば、400〜800nmの波長領域における70%以上の透過率が得難く)なる傾向にある。また、残留気孔径が大きくなる傾向にある。大きな残留気孔を有するとこの部分では電子線検出を行うことがでず、画質の低下に繋がるため好ましくない。この平均結晶粒子径は特に5〜200μmであることが好ましい。   Furthermore, this ceramic is a polycrystal. That is, a plurality of crystal particles can be confirmed when magnified. Furthermore, the average particle diameter (average crystal particle diameter) of these crystal particles is 5 to 300 μm. When the average crystal particle diameter is less than 5 μm, sufficient transparency is hardly obtained (for example, it is difficult to obtain a transmittance of 70% or more in a wavelength region of 400 to 800 nm). On the other hand, when the crystal grain size exceeds 300 μm, the crystal grain size becomes too large, and it tends to be difficult to sufficiently uniformly dissolve the fluorescent element (lanthanide element). Further, the fluorescent element segregates in the grain boundary phase between crystals, and it tends to be difficult to obtain transparent ceramics (for example, it is difficult to obtain a transmittance of 70% or more in a wavelength region of 400 to 800 nm). Further, the residual pore diameter tends to increase. If there are large residual pores, electron beam detection cannot be performed at this portion, which leads to a decrease in image quality, which is not preferable. The average crystal particle size is particularly preferably 5 to 200 μm.

また、本セラミックスの気孔率は0.1%以下である。即ち、本セラミックスの相対密度は理論密度の99.0%以上である。セラミックスの相対密度が理論密度の99.9%未満であると、透明性が不十分となる傾向にあり、電子線蛍光材料、特に電子線シンチレータとして用いた場合の画質低下をまねく。この相対密度は、目的とする同じ化学組成の単結晶と多結晶とを学振法又はX線法により測定し、これら両者(単結晶及び多結晶)の密度を比較することで求める。上記方法が困難である場合には、セラミックスの任意断面に存在する気孔を、顕微鏡及び/又はSEMで表面観察し、得られた画像から面積(又は体積)換算解析して求めるものとする。   Moreover, the porosity of this ceramic is 0.1% or less. That is, the relative density of this ceramic is 99.0% or more of the theoretical density. If the relative density of the ceramic is less than 99.9% of the theoretical density, the transparency tends to be insufficient, leading to a reduction in image quality when used as an electron beam fluorescent material, particularly an electron beam scintillator. This relative density is obtained by measuring the target single crystal and polycrystal of the same chemical composition by the Gakushin method or the X-ray method, and comparing the density of both of them (single crystal and polycrystal). When the above method is difficult, the pores existing in an arbitrary cross section of the ceramic are surface-observed with a microscope and / or SEM, and are determined by area (or volume) conversion analysis from the obtained image.

更に、本セラミックスは透明である。透明とは、可視光範囲に含まれる少なくとも特定の波長に対する透過率が65%以上であることを意味する。透過率が高い波長範囲は特に限定されないが400〜800nmの範囲であることが好ましい。
また、本セラミックスの透明度は電子線励起した材料の発光効率と密接な関係があるため高いことが好ましい。この透明度は、光吸収係数で表すことができる。即ち、ランバート・ベールの法則、log(Io/I)=αd〔ここで、Io:入射光強度、I:透過光強度(試料を透過した光の強度)、α:光吸収係数、d:試料厚さ〕で算出される「α」の値で表される。電子線シンチレータは比較的薄い形状(厚さが薄い)で利用される。媒質内で発生した蛍光を通過させるだけで良いのでレーザー材料並みの高透過特性は必要ではなく、30%/cm以下(好ましくは20%/cm以下)の内部ロスであることが好ましい。
Furthermore, the ceramic is transparent. The term “transparent” means that the transmittance for at least a specific wavelength included in the visible light range is 65% or more. The wavelength range with high transmittance is not particularly limited, but is preferably in the range of 400 to 800 nm.
Further, the transparency of the present ceramic is preferably high because it has a close relationship with the luminous efficiency of the electron beam excited material. This transparency can be expressed by a light absorption coefficient. That is, Lambert-Beer's law, log (Io / I) = αd [where Io: incident light intensity, I: transmitted light intensity (intensity of light transmitted through the sample), α: light absorption coefficient, d: sample Thickness] is represented by the value of “α”. The electron beam scintillator is used in a relatively thin shape (thin thickness). Since it is only necessary to pass fluorescence generated in the medium, high transmission characteristics similar to those of laser materials are not necessary, and an internal loss of 30% / cm or less (preferably 20% / cm or less) is preferable.

更に、本セラミックスは上記透明特性に加えて、本セラミックス材料全体にわたる光学的均一性が高いことが好ましい。光学的均一性は、セラミックスの両面を平坦度λ/10且つ平行度10s以内に光学研磨し、マッハツエンダー又はトワイマン・グリーン干渉計を用いて、セラミックス内の屈折率変動を測定することで調べることが出来る。本セラミックスでは、単位測定面積当たり(1cm)の屈折率変動が5x10−3以下(好ましくは1x10−3以下)とすることが好ましい。この範囲では、均一であり、且つ画質特性に優れた電子線蛍光材料、特に電子線シンチレータを得ることができる。 Furthermore, it is preferable that the present ceramic has high optical uniformity over the entire ceramic material in addition to the above-mentioned transparency. The optical uniformity is examined by optically polishing both surfaces of the ceramic within a flatness of λ / 10 and a parallelism of 10 s, and measuring the refractive index fluctuation in the ceramic using a Mach-Zender or Twyman Green interferometer. I can do it. In this ceramic, it is preferable that the refractive index change per unit measurement area (1 cm 2) is to 5x10 -3 or less (preferably 1x10 -3 or less). Within this range, an electron beam fluorescent material, particularly an electron beam scintillator, which is uniform and excellent in image quality characteristics can be obtained.

上記の光学的均一性はマクロ領域におけるものであるが、本セラミックスでは、更に、ミクロ領域における蛍光元素の均一性(均一分散性)を非常に高くすることができる点において単結晶の電子線検出材料に比べて優れている。この均一性は、セラミックスを構成する結晶粒子の80%以上(個数における)において、各結晶粒子に含有される蛍光元素の濃度差が±15%の範囲(例えば、2原子%の蛍光元素を含むものは2±0.3%の範囲)とすることができる。この濃度分布は、セラミックスの結晶粒子の任意の10個以上の粒子に含まれる蛍光元素(ランタニド元素)の濃度分布を測定することで算出するものとする。計測にあたってはEDX(エネルギー分散型X線分光器)及び/又はIMA(イオンマイクロアナライザー)等の微小領域計測できる機器分析装置により測定できる。   The above optical uniformity is in the macro region, but with this ceramic, the single crystal electron beam detection can be further improved in that the uniformity (uniform dispersibility) of the fluorescent element in the micro region can be made extremely high. Excellent compared to materials. This uniformity is such that the concentration difference of the fluorescent elements contained in each crystal particle is within a range of ± 15% (including, for example, 2 atomic% of the fluorescent element) in 80% or more (in number) of the crystal particles constituting the ceramic. Can range from 2 ± 0.3%). This concentration distribution is calculated by measuring the concentration distribution of a fluorescent element (lanthanide element) contained in any 10 or more particles of ceramic crystal particles. In the measurement, it can be measured by an instrument analyzer capable of measuring a minute region such as EDX (energy dispersive X-ray spectrometer) and / or IMA (ion microanalyzer).

本セラミックスは、上記Y及びランタニド元素以外に他の元素を含有できる。他の元素としてはZr及び/又はCaが挙げられる。本セラミックスは、これらZr及びCaのうちの少なくとも一方を含有し、Zr及びCaの含有量は、Yとランタニド元素との酸化物換算(前記ランタニド元素の酸化物換算をそのまま適用する)合計量に対して、各々酸化物換算で1000質量ppm以下であることが好ましい。この含有量は、Zrのみを含有する場合はZrを1000質量ppm以下(この場合、好ましくは50〜800質量ppm)、Caのみを含有する場合はCaを1000質量ppm以下(この場合、好ましくは50〜800質量ppm)、ZrとCaとの両方を含有する場合はZrを1000質量ppm以下且つCaを1000質量ppm以下である。   The present ceramic can contain other elements in addition to the Y and lanthanide elements. Other elements include Zr and / or Ca. This ceramic contains at least one of these Zr and Ca, and the content of Zr and Ca is an oxide equivalent of Y and a lanthanide element (the oxide equivalent of the lanthanide element is applied as it is). On the other hand, it is preferable that it is 1000 mass ppm or less in each oxide conversion. In the case of containing only Zr, the content of Zr is 1000 mass ppm or less (in this case, preferably 50 to 800 ppm by mass), and in the case of containing only Ca, Ca is 1000 mass ppm or less (in this case, preferably 50 to 800 ppm by mass), when both Zr and Ca are contained, Zr is 1000 ppm by mass or less and Ca is 1000 ppm by mass or less.

Zr及び/又はCaを含有することで、特に優れた画質が得られる電子線蛍光用多結晶透明Yセラミックスを得ることができる。ZrとCaとは、いずれか一方をのみを含有するよりも、ZrとCaとの両方を含有することが好ましい。即ち、ZrとCaとの両方を各々1000質量ppm以下含有することが好ましい。Zr及びCaの両方を含有する場合、これらの含有割合は特に限定されないが、ZrとCaとのモル比Zr/Caにおいて、0.5〜2.0(より好ましくは0.8〜1.5)であることが好ましい。この範囲であれば、特に均質で優れた画質を得ることができる。 By containing Zr and / or Ca, it is possible to obtain a polycrystalline transparent Y 2 O 3 ceramic for electron beam fluorescence that can obtain particularly excellent image quality. It is preferable that Zr and Ca contain both Zr and Ca rather than containing only one of them. That is, it is preferable to contain both Zr and Ca at 1000 ppm by mass or less. When both Zr and Ca are contained, the content ratio thereof is not particularly limited, but the molar ratio Zr / Ca between Zr and Ca is 0.5 to 2.0 (more preferably 0.8 to 1.5). ) Is preferable. Within this range, a particularly uniform and excellent image quality can be obtained.

更に、本セラミックス内におけるZr及びCaの含有形態は特に限定されない。即ち、例えば、ZrO及びCaO等の各々酸化物として含有することができるが、ZrとCaとの両方を含む複酸化物として含有されることが好ましい。即ち、例えば、ZrCaO等の複酸化物が挙げられる。これらは1種のみが含有されてもよく2種以上が含有されてもよい。 Furthermore, the content of Zr and Ca in the ceramic is not particularly limited. That is, for example, it can be contained as an oxide such as ZrO 2 and CaO, but is preferably contained as a double oxide containing both Zr and Ca. That is, for example, a double oxide such as ZrCaO 3 can be mentioned. These may contain only 1 type and 2 or more types may contain them.

本セラミックスの形状及び大きさは特に限定されず、使用目的に適したものとすることができるが、特にその大きさは従来に比べて大きくすることができる。即ち、例えば、本セラミックスを用いた場合には、例えば、1〜50cm(好ましくは1〜5cm)の大面積の一体的な透明セラミックスとすることができる。 The shape and size of the ceramics are not particularly limited and can be suitable for the purpose of use, but in particular, the size can be increased as compared with the prior art. That is, for example, when this ceramic is used, it can be made into an integral transparent ceramic having a large area of, for example, 1 to 50 cm 2 (preferably 1 to 5 cm 2 ).

[2]製造方法
本セラミックスの得る方法は特に限定されないが、通常、セラミック原料を焼成して得る。このセラミック原料の調製方法(製造方法)は特に限定されない。即ち、例えば、Y粉末とその他の酸化物粉末(ランタニド酸化物粉末等)を混合する固相法、アルコキシド法、共沈法、及び均一沈澱法等を用いることができる。また、これらの方法は1種のみを用いてもよく2種以上を併用してもよい。
上記のうち固相法を用いる場合、Y粉末は粒径2μm以下(好ましくは1μm以下)且つ純度99.9質量%以上、ランタニド酸化物粉末は粒径10μm以下(好ましくは5μm以下)且つ純度99.9質量%以上、亜鉛酸化物粉末及びカルシウム酸化物粉末は、各々粒径5μm以下且つ純度99質量%以上、の各粉末を用いることが好ましい。
これらのうちのランタニド酸化物の添加は、その濃度によって適宜な手段とすることが好ましい。例えば、微量添加の場合は、アルコキシド法及び/又は硝酸塩等から熱分解により生じる酸化物を用いることが好ましい。
[2] Manufacturing Method The method for obtaining the present ceramic is not particularly limited, but it is usually obtained by firing a ceramic raw material. The preparation method (manufacturing method) of this ceramic raw material is not particularly limited. That is, for example, a solid phase method, an alkoxide method, a coprecipitation method, a uniform precipitation method, or the like in which Y 2 O 3 powder and other oxide powder (such as a lanthanide oxide powder) are mixed can be used. Moreover, these methods may use only 1 type and may use 2 or more types together.
Among the above, when using the solid phase method, the Y 2 O 3 powder has a particle size of 2 μm or less (preferably 1 μm or less) and a purity of 99.9% by mass or more, and the lanthanide oxide powder has a particle size of 10 μm or less (preferably 5 μm or less). In addition, it is preferable to use a powder having a purity of 99.9% by mass or more and a zinc oxide powder and a calcium oxide powder each having a particle size of 5 μm or less and a purity of 99% by mass or more.
Of these, the addition of the lanthanide oxide is preferably performed according to the concentration. For example, in the case of a slight addition, it is preferable to use an oxide generated by thermal decomposition from the alkoxide method and / or nitrate.

これら酸化物粉末(Y粉末、ランタニド酸化物粉末、Zr粉末及びCa粉末)は、目的の組成となるように秤量し、有機溶媒(エチルアルコール等)を加えてポットミル等の混合手段を用いて混合して混合粉末を得る(混合粉末調整工程)。 These oxide powders (Y 2 O 3 powder, lanthanide oxide powder, Zr powder and Ca powder) are weighed so as to have the desired composition, and an organic solvent (such as ethyl alcohol) is added to perform mixing means such as a pot mill. And mixed to obtain a mixed powder (mixed powder adjustment step).

その後、得られた混合粉末は乾燥した後に成形する(成形工程)。成形方法は特に限定されないが、一軸プレス又はCIP(コールド・アイソスタティック・プレス)が好ましい。成形工程により得られる圧粉体の相対密度は50〜70%が好ましい。この相対密度を得るために、CIPを用いる場合、CIP圧力は98〜490MPaが好ましい。   Thereafter, the obtained mixed powder is dried and then molded (molding process). Although a shaping | molding method is not specifically limited, A uniaxial press or CIP (cold isostatic press) is preferable. The relative density of the green compact obtained by the molding process is preferably 50 to 70%. In order to obtain this relative density, when CIP is used, the CIP pressure is preferably 98 to 490 MPa.

成形工程を経て得られた成形体(圧粉体)は、その後、焼成工程において焼成を行い本発明の電子線蛍光用多結晶透明Yセラミックスとなる。
この焼成工程における焼成の方法は特に限定されないが、例えば、真空焼成、雰囲気焼成(水素や酸素等の雰囲気)、及び、加圧焼成{HP(ホットプレス)、HIP(ホットアイソスタティックプレス)など}等の方法を用いることができる。これらの方法は、通常、1種のみを用いるが、2種以上を併用してもよい。
The molded body (green compact) obtained through the molding step is then fired in the firing step to be the polycrystalline transparent Y 2 O 3 ceramic for electron beam fluorescence of the present invention.
The firing method in this firing step is not particularly limited. For example, vacuum firing, atmosphere firing (hydrogen or oxygen atmosphere), and pressure firing {HP (hot press), HIP (hot isostatic press), etc.} Etc. can be used. These methods usually use only one type, but two or more types may be used in combination.

これらのなかでは、加圧焼成が好ましく、更には、温度1500〜1800℃の範囲且つ圧力49〜198MPaの範囲で加圧焼成することが好ましい。また、この加圧焼成前には、酸素雰囲気中において温度1500〜1700℃で一次焼結することが好ましい。即ち、本セラミックスを得るには、焼成工程において、一次焼成工程と、二次焼成工程と、を備え、一次焼成工程では酸素雰囲気中において温度1500〜1700℃で焼成することが好ましい。また、二次焼成工程では、温度1500〜1800℃の範囲且つ圧力49〜198MPaの範囲でHIP焼成することが好ましい。この一次焼成工程と二次焼成工程とを備えることで、焼結体を構成する結晶粒子が組成的及び組織的に均一化され、その結果、焼結体の透明度を向上させることができる。   Among these, pressure firing is preferable, and further, pressure firing is preferably performed at a temperature of 1500 to 1800 ° C. and a pressure of 49 to 198 MPa. Moreover, it is preferable to perform primary sintering at a temperature of 1500 to 1700 ° C. in an oxygen atmosphere before the pressure firing. That is, in order to obtain the present ceramic, it is preferable that the firing step includes a primary firing step and a secondary firing step, and in the primary firing step, firing is performed at a temperature of 1500 to 1700 ° C. in an oxygen atmosphere. In the secondary firing step, it is preferable to perform HIP firing at a temperature of 1500 to 1800 ° C. and a pressure of 49 to 198 MPa. By providing the primary firing step and the secondary firing step, the crystal particles constituting the sintered body are made uniform in terms of composition and organization, and as a result, the transparency of the sintered body can be improved.

即ち、本発明の製造方法は、Y粉末及びランタニド酸化物粉末を含有する成形体を、酸素雰囲気下1500〜1800℃で焼成して一次焼成体を得る一次焼成工程と、
該一次焼成体を更に温度1600〜1800℃且つ圧力49〜198MPaで焼成する二次焼成工程と、を備えることを特徴とする。
この方法における上記「酸素雰囲気」とは、酸素分圧が雰囲気全体に対して90%以上である雰囲気を意味する。また、上記一次焼成における焼成時間は1〜10時間であることが好ましい。更に、上記二次焼成における焼成時間は1〜3時間であることが好ましい。
That is, the production method of the present invention includes a primary firing step of obtaining a primary fired body by firing a molded body containing Y 2 O 3 powder and lanthanide oxide powder at 1500 to 1800 ° C. in an oxygen atmosphere,
A secondary firing step of firing the primary fired body at a temperature of 1600 to 1800 ° C. and a pressure of 49 to 198 MPa.
The “oxygen atmosphere” in this method means an atmosphere having an oxygen partial pressure of 90% or more with respect to the entire atmosphere. Moreover, it is preferable that the baking time in the said primary baking is 1 to 10 hours. Furthermore, the firing time in the secondary firing is preferably 1 to 3 hours.

尚、前記真空焼結及び水素雰囲気焼結を用いる場合の焼成温度は1700〜2270℃の範囲が好ましい。但し、常圧以下(減圧〜常圧)における環境下での焼成では残留気孔が大きくなりがちである。   The firing temperature in the case of using the vacuum sintering and the hydrogen atmosphere sintering is preferably in the range of 1700 to 2270 ° C. However, residual pores tend to be large when firing in an environment at or below normal pressure (reduced pressure to normal pressure).

本セラミックスに関して、SEMやTEM等の電子線検出は元来数k〜MVに加速された電子を材料表面から内部に照射し、高速の電子が媒質内部にある蛍光イオンを励起することで蛍光物質からの放射を発生させ、その蛍光の強度や分布をCCDカメラなでで画像化することで、電子線計測への応用がなされている。ここで、多結晶セラミックスのような粒界がある材料に電子線を照射して蛍光を得る場合、材料内部で励起→発光→蛍光の画像化により電子線検出がなされている。しかし、蛍光が粒界部で著しい損失(異相や結晶欠陥等に起因する減衰)を起こすこと、蛍光物質の不均一な分布により材料内部で均一な発光を生じにくいこと、さらには焼結体中に残存する気孔(非蛍光部)により正確な画像が取れないなどの懸念が考えられ、多結晶体から直接精密な電子線像を取り出することは非常に難しいと考えるのが一般的である。   With regard to this ceramic, electron beam detection such as SEM and TEM is originally performed by irradiating electrons accelerated to several k to MV from the surface of the material to the inside, and high-speed electrons excite fluorescent ions inside the medium. The intensity and distribution of the fluorescence is imaged with a CCD camera, and the application to electron beam measurement is made. Here, when fluorescence is obtained by irradiating an electron beam to a material having a grain boundary such as polycrystalline ceramic, electron beam detection is performed by imaging excitation → emission → fluorescence inside the material. However, fluorescence causes significant loss at the grain boundary (attenuation due to heterogeneous phase, crystal defects, etc.), non-uniform distribution of the fluorescent material makes it difficult to produce uniform light emission inside the material, and in the sintered body It is generally considered that it is very difficult to extract a precise electron beam image directly from a polycrystal because there is a concern that an accurate image cannot be taken due to pores (non-fluorescent part) remaining in the crystal.

また仮に電子線像を取り出したとしても、粒界部の光損失や結晶内部と粒界部の物性変動(例えば、例えば蛍光強度、蛍光寿命、アフターグローなど)が生じることも予測されることから電子線検出材料はすべて単結晶であるべきと考えられており、現状もその通りとなっている。多結晶体は溶融しないため、粒子内部の結晶欠陥(格子欠陥)のレベルは元来単結晶より低くなるはずであるが、焼結過程で理想に近い物質移動が起きにくいため粒子内部に組織的又は結晶構造的欠陥を残すこととなる。しかしこのような不都合を回避すれば、多結晶セラミックスの粒子内部の光学的特性は単結晶を上回り、材料性性能は高くなる。従って焼結性に優れたY粉末、更には、焼成により本セラミックスとなる原料を用いることが本セラミックスを製造する上でのキーテクノロジーとなる。この問題は特にZn及びCaを用いることが解決することができる。 Moreover, even if an electron beam image is taken out, it is predicted that light loss at the grain boundary part and physical property fluctuations (for example, fluorescence intensity, fluorescence lifetime, afterglow, etc.) between the inside of the crystal and the grain boundary part will occur. It is believed that all electron beam detection materials should be single crystals, and the current situation is also true. Since the polycrystalline body does not melt, the level of crystal defects (lattice defects) inside the particle should be lower than that of the single crystal originally. Alternatively, crystal structural defects are left. However, if such inconveniences are avoided, the optical characteristics inside the particles of the polycrystalline ceramics exceed that of the single crystal, and the material performance is enhanced. Therefore, using Y 2 O 3 powder excellent in sinterability, and further using a raw material that becomes the present ceramic by firing is a key technology for producing the present ceramic. This problem can be solved especially by using Zn and Ca.

更に、粒界部の光損失などの物性変動については否定できないが、プロセス技術により粒界部の物性を本目的に耐えうる性能にせしめることにより、実用に十分耐えうるものとなる。また、電子線検検出材料としての特性は散乱の大きさだけが全てでなく、発光元素の均一性、ホスト材料中の発光元素濃度、材料の歪みなど様々な因子があり、透明度を除くその他の要因については多結晶体の方が単結晶体よりも優れていることから、特性全体から考えれば同等または単結晶を凌駕するものが存在する。電子線検出材料として現在汎用されるYAG単結晶よりY系単結晶が優れた特性を示すことが予想できるが、現実的に良質のY単結晶は製造することが困難である。また、材料の歪みに関して、ベルヌイ法で作成された単結晶では結晶育成時及び育成された結晶が冷却される場合に、2280℃付近に存在する相転移(六方晶→立方晶)の影響で偏光板を通して観察したときにかなりの残留歪みや、場合によっては微小クラックが確認できるが、本セラミックスではこのようなものは殆ど検出できないなどの優れた特徴を得ることができる。 Furthermore, although physical property variations such as light loss at the grain boundary portion cannot be denied, by making the physical properties of the grain boundary portion to a performance that can withstand this purpose by the process technology, it becomes sufficiently practical. In addition, the characteristics of the electron beam detection material are not only the magnitude of the scattering, but there are various factors such as the uniformity of the luminescent element, the concentration of the luminescent element in the host material, and the distortion of the material. Regarding the factors, since the polycrystal is superior to the single crystal, there are some which are equivalent or exceed the single crystal in terms of the whole characteristics. Although Y 2 O 3 single crystals can be expected to exhibit superior characteristics than YAG single crystals that are currently widely used as electron beam detection materials, it is difficult to produce good quality Y 2 O 3 single crystals in practice. is there. In addition, regarding the distortion of the material, in the single crystal prepared by the Bernoulli method, it is polarized by the influence of the phase transition (hexagonal crystal → cubic crystal) existing at around 2280 ° C. when the crystal is grown and when the grown crystal is cooled. When observed through a plate, considerable residual strain and, in some cases, microcracks can be confirmed, but this ceramic can provide excellent characteristics such as being hardly detectable.

また、蛍光元素を含有した単結晶Yは、その濃度分布も電子線検出用結晶としては充分に均一とは言えず、またその濃度にも限度がある。しかし、焼結による本セラミックスでは蛍光元素の濃度は幅広く選択でき、しかもその分布も極めて均一とすることができる。このことから、超寿命・高画質等の特徴を有する電子線蛍光材料、特に電子線シンチレータを得ることができる。本セラミックスを用いた電子線シンチレータは、SEM及びTEM等の電子線シンチレータに用いることができる他、イメージインテンシファイア等の新型電子線検出器にも用いることができる。 Further, the single crystal Y 2 O 3 containing a fluorescent element cannot be said to have a sufficiently uniform concentration distribution as an electron beam detecting crystal, and its concentration is limited. However, in the present sintered ceramics, the concentration of the fluorescent element can be selected widely, and the distribution can be made extremely uniform. From this, it is possible to obtain an electron beam fluorescent material, particularly an electron beam scintillator having characteristics such as a long life and high image quality. An electron beam scintillator using this ceramic can be used for an electron beam scintillator such as an SEM and a TEM, and can also be used for a new electron beam detector such as an image intensifier.

尚、電子線検出分野以外の分野であるX線検出(特にX線CT)分野においては、(YGd)及びYOS等をホストとする検出材料が知られている。しかし、X線検出分野では、数百個以上の検出器から得られたシグナルを合成して画像を形成し、検出材料が発した蛍光を直接画像化するものではない。このため、材料内部に蛍光ムラ及び気孔等の欠陥を有しても画質低下の問題とはならない。これに対して、電子線検出分野では、1個の検出材料から得られる蛍光を直接画像化するため、検出材料に求められる要求精度(光学的均一性など)はX線検出分野に比べて著しく高いものである。従って、X線検出分野の検出材料を電子線検出分野へそのまま転用することは困難である。 In the field of X-ray detection (particularly X-ray CT), which is a field other than the electron beam detection field, detection materials using (YGd) 2 O 3 and Y 2 OS as hosts are known. However, in the field of X-ray detection, an image is formed by synthesizing signals obtained from several hundred or more detectors, and fluorescence emitted from the detection material is not directly imaged. For this reason, even if the material has defects such as uneven fluorescence and pores, it does not cause a problem of image quality deterioration. In contrast, in the electron beam detection field, the fluorescence obtained from a single detection material is directly imaged, so the required accuracy (such as optical uniformity) required for the detection material is significantly higher than in the X-ray detection field. It is expensive. Therefore, it is difficult to divert the detection material in the X-ray detection field directly to the electron beam detection field.

[1]電子線蛍光用多結晶透明Yセラミックスの製造(実施例1〜6)
(1)原料粉末の調製
純度99.9質量%且つ粒径0.1μmのY粉末と、純度99.9質量%且つ粒径0.5μm以下のランタニド酸化物粉末(表1に記載の各ランタニド元素の酸化物)と、を合量150gとなるように{表1に記載の各ランタニド元素種が、各々併記された原子%含有量(atm%)となるように}秤量した。
次いで、これらのY粉末と、ランタニド酸化物と、エチルアルコール300ccと、PVA系バインダー1質量%と、ジルコニアボールと、をポットミルへ投入して14時間湿式混合してスラリーを得た。得られたスラリーは、その後、熱風温度86℃且つアトマイザー回転数12000rpmの条件でスプレードライし、直径20〜40μmの粒度分布の顆粒を形成した。
[1] Production of polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence (Examples 1 to 6)
(1) Preparation of raw material powder Y 2 O 3 powder having a purity of 99.9% by mass and a particle size of 0.1 μm, and a lanthanide oxide powder having a purity of 99.9% by mass and a particle size of 0.5 μm or less (described in Table 1) The oxide of each lanthanide element) was weighed so that the total amount was 150 g {so that each lanthanide element species shown in Table 1 had the atomic% content (atm%) written together}.
Next, these Y 2 O 3 powder, lanthanide oxide, 300 cc of ethyl alcohol, 1% by mass of PVA binder, and zirconia balls were put into a pot mill and wet mixed for 14 hours to obtain a slurry. Thereafter, the obtained slurry was spray-dried under the conditions of a hot air temperature of 86 ° C. and an atomizer rotation speed of 12000 rpm to form granules having a particle size distribution of 20 to 40 μm in diameter.

(2)成形工程
その後、得られた顆粒粉末を、直径30mm且つ高さ15mmのタブレット形状に仮成形した後、更に、294MPaの圧力でCIP成形して成形体を得た。次いで、得られた成形体を電気炉に入れ、大気中600℃で3時間仮焼して脱脂した。
(2) Molding step Thereafter, the obtained granular powder was temporarily molded into a tablet shape having a diameter of 30 mm and a height of 15 mm, and then further CIP molded at a pressure of 294 MPa to obtain a molded body. Subsequently, the obtained molded body was put in an electric furnace and decalcified by calcining at 600 ° C. for 3 hours in the atmosphere.

(3)一次焼成工程
上記(2)で得られた成形体(圧粉体)を、酸素雰囲気中100°C/時間の昇温速度で昇温し、表1に記載の一次焼成温度(1600〜1790℃)で焼成した。その後、100°C/時間の降温速度で冷却して、一次焼成体を得た。
(3) Primary firing step The compact (compact) obtained in (2) above is heated at a rate of temperature increase of 100 ° C / hour in an oxygen atmosphere, and the primary firing temperature shown in Table 1 (1600). ˜1790 ° C.). Then, it cooled at the temperature decreasing rate of 100 degreeC / hour, and obtained the primary sintered body.

(4)二次焼工程
上記(3)で得られた一次焼成体を、更にHIP炉に入れ、表1に記載の二次焼成温度(1650〜1800℃)且つ加圧圧力(49〜198MPa、圧力媒体はAr)にてHIP焼成を行い、透明焼結体(電子線蛍光用多結晶透明Yセラミックス)を得た。
(4) Secondary firing step The primary fired body obtained in the above (3) is further put into a HIP furnace, and the secondary firing temperature (1650-1800 ° C.) and pressure (49-198 MPa) shown in Table 1 are applied. The pressure medium was HIP fired with Ar) to obtain a transparent sintered body (polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence).

(5)試験片調製
上記(4)までに得られた各電子線蛍光用多結晶透明Yセラミックスから直径12mm且つ厚さ2mmの試験片を作成し、両面の平坦度をλ/10且つ平行度を10s以内に研磨調製した。
(5) Test piece preparation A test piece having a diameter of 12 mm and a thickness of 2 mm was prepared from each of the polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence obtained up to the above (4), and the flatness of both surfaces was λ / 10 And the parallelism was polished and prepared within 10 s.

(6)シンチレータの形成及び蛍光特性の評価
上記(5)までに得られた各試験片11(電子線蛍光用多結晶透明Yセラミックス)の一面側にアルミニウムフィルム12(厚さ0.05μm、Al含量99質量%以上)を貼り付けてシンチレータ1を形成した。
次いで、図1に模式的に示す装置を構成した。即ち、減圧チャンバー2内に、上記各シンチレータ1を配置し、電子銃21と上記シンチレータ1に貼り付けたアルミニウムフィルム12との間に6kVの電圧を印加(チャンバー内圧力10−3Pa)した。そして、電子銃21から放出された電子線によってもたらされる蛍光を、減圧チャンバー2の窓22を通してCCDカメラ3で捉え、その映像をCRTモニタ4に投影し、下記蛍光画質の評価に供した。また、上記CCDカメラ3及び上記CRTモニタ4に換えて、蛍光スペクトル測定器(日本分光株式会社製)を用い、下記各種蛍光特性の評価に供した。
(6) Formation of scintillator and evaluation of fluorescence characteristics Aluminum film 12 (thickness 0. 5) is formed on one side of each test piece 11 (polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence) obtained up to (5) above. The scintillator 1 was formed by pasting a film having a thickness of 05 μm and an Al content of 99% by mass or more.
Next, an apparatus schematically shown in FIG. 1 was constructed. That is, each scintillator 1 was placed in the vacuum chamber 2, and a voltage of 6 kV was applied between the electron gun 21 and the aluminum film 12 attached to the scintillator 1 (chamber internal pressure 10 −3 Pa). Then, the fluorescence caused by the electron beam emitted from the electron gun 21 was captured by the CCD camera 3 through the window 22 of the decompression chamber 2, and the image was projected on the CRT monitor 4 for the following evaluation of the fluorescence image quality. Moreover, it replaced with the said CCD camera 3 and the said CRT monitor 4, and used for evaluation of the following various fluorescence characteristics using the fluorescence spectrum measuring device (made by JASCO Corporation).

表1に示した各項目は以下のようにして測定を行った。
「蛍光のピーク波長」;蛍光スペクトル測定器(日本分光株式会社製)を用いて測定した。
「相対蛍光強度」;比較例1のCe:YAG単結晶による最大蛍光強度を100%として、この蛍光強度に対する相対値を上記蛍光スペクトル測定器(日本分光株式会社製)を用いて測定した。
「蛍光時間」;励起状態の準位よりも下位の準位に移行するまでの時間{即ち、蛍光元素が励起準位(上準位)から基底準位(下準位)に達するまでの時間}を上記蛍光スペクトル測定器(日本分光株式会社製)を用いて測定した。
Each item shown in Table 1 was measured as follows.
“Fluorescence peak wavelength”: Measured using a fluorescence spectrum measuring instrument (manufactured by JASCO Corporation).
“Relative fluorescence intensity”: The maximum fluorescence intensity of the Ce: YAG single crystal of Comparative Example 1 was taken as 100%, and the relative value with respect to this fluorescence intensity was measured using the fluorescence spectrum measuring instrument (manufactured by JASCO Corporation).
“Fluorescence time”: time until a transition to a lower level than the level of the excited state {that is, time until the fluorescent element reaches the ground level (lower level) from the excited level (upper level) } Was measured using the above fluorescence spectrum measuring instrument (manufactured by JASCO Corporation).

「残光時間」;相対蛍光強度(最大強度)の0.1%以下になるまでの時間を上記蛍光スペクトル測定器(日本分光株式会社製)を用いて測定した。
「透過率」;実施例1〜6は厚さ2mmの試験片における波長633nm光の透過率を、比較例1〜4は厚さ0.5mmの試験片における波長633nm光の透過率をスペクトルフォトメーター(株式会社日立製作所製、型式「U350」)を用いて測定した。
「蛍光画質」;上記CRTモニタ4に投影された画像を目視し、「◎:全面にわたって均一であり、不均一性が認められない」、「○:3ヶ所以下の不均一ヶ所が散見される」、「△:10ヶ所を超える不均一ヶ所が認められる」、「×:全面にわたって不均一である」の4段階の評価を行った。
これらの結果を表1に示した。また、実施例1〜6は、ランタニド元素の種類、ランタニド元素の添加量、焼成時間並びに焼成温度を変化させることで変化させた焼結体の結晶平均粒子径、を各々併記している。
“Afterglow time”: The time until the relative fluorescence intensity (maximum intensity) became 0.1% or less was measured using the above fluorescence spectrum measuring instrument (manufactured by JASCO Corporation).
“Transmittance”: Examples 1 to 6 show the transmittance of light having a wavelength of 633 nm in a test piece having a thickness of 2 mm, and Comparative Examples 1 to 4 show the transmittance of light having a wavelength of 633 nm in a test piece having a thickness of 0.5 mm. Measurement was performed using a meter (manufactured by Hitachi, Ltd., model “U350”).
“Fluorescent image quality”: Visually observe the image projected on the CRT monitor 4 and “◎: Uniform over the entire surface and no non-uniformity is recognized”, “O: There are 3 or less non-uniform places. ”,“ Δ: more than 10 non-uniform places are recognized ”, and“ ×: non-uniform over the entire surface ”were evaluated in four stages.
These results are shown in Table 1. In Examples 1 to 6, the type of lanthanide element, the added amount of the lanthanide element, the firing time, and the crystal average particle diameter of the sintered body changed by changing the firing temperature are also shown.

[2]比較例1〜4
表2に示すように、比較例1〜4として、従来公知のシンチレータ材料として、比較例1にはCe:YAG(株式会社トーキン製)、比較例2にはTb:YAG単結晶、比較例3にはP46粉末{Ce:Y(AlGa)O12}、比較例4にはGdS系焼結体(Pr,Ce:GdS)を用いた。表2には、前記実施例1〜6における各測定と同様にして、各々の結晶構造、蛍光のピーク波長、相対蛍光強度、蛍光時間、残光時間、材料の透過率(厚さ0.5mm、測定波長633nm)、得られた蛍光画質について示した。
[2] Comparative Examples 1 to 4
As shown in Table 2, as Comparative Examples 1 to 4, as a conventionally known scintillator material, in Comparative Example 1, Ce: YAG (manufactured by Tokin Corporation), in Comparative Example 2, Tb: YAG single crystal, Comparative Example 3 P46 powder {Ce: Y 3 (Al 3 Ga 2 ) O 12 } was used for the sample 4, and a Gd 2 O 2 S-based sintered body (Pr, Ce: Gd 2 O 2 S) was used for the comparative example 4. Table 2 shows the crystal structure, fluorescence peak wavelength, relative fluorescence intensity, fluorescence time, afterglow time, and material transmittance (thickness 0.5 mm) in the same manner as in each measurement in Examples 1-6. , The measurement wavelength 633 nm), and the obtained fluorescence image quality is shown.

表1及び表2の結果より、比較例3及び4では安定した画像が選らないことが分かる。比較例2では、優れた画質が得られているものの残光時間が50msと長いという点において劣っていることが分かる。
これに対して、実施例1〜4は、いずれも○〜◎の優れた画質が得られている。これに加えて蛍光強度はいずれもCe:YAG単結晶(比較例1)に対して60%以上を達成している。また、蛍光寿命はいずれも1msと短い。更に、残光時間いずれも10ms以下である。即ち、実施例1〜6は、いずれも画質が優れていることに加えてその他のすべての特性にバランスよく優れていることが分かる。
尚、比較例1は、安定した画像は得られるものの量産性に劣る。即ち、前述のようにCeを蛍光元素とするYAG系単結晶材料であり、作製が極めて難しく、高い育成温度と長い育成時間とを要し、特に蛍光元素を均一分布及び高濃度添加が困難である。
From the results of Tables 1 and 2, it can be seen that in Comparative Examples 3 and 4, a stable image is not selected. It can be seen that Comparative Example 2 is inferior in that excellent image quality is obtained, but the afterglow time is as long as 50 ms.
On the other hand, in Examples 1 to 4, excellent image quality of ◯ to ◎ was obtained. In addition, the fluorescence intensity is 60% or higher with respect to Ce: YAG single crystal (Comparative Example 1). Further, the fluorescence lifetime is as short as 1 ms. Furthermore, all afterglow times are 10 ms or less. That is, it can be seen that Examples 1 to 6 are all in excellent balance with respect to all other characteristics in addition to excellent image quality.
In Comparative Example 1, although a stable image can be obtained, it is inferior in mass productivity. That is, as described above, it is a YAG-based single crystal material having Ce as a fluorescent element, which is extremely difficult to manufacture, requires a high growth temperature and a long growth time, and in particular, it is difficult to add a uniform distribution and high concentration of the fluorescent element. is there.

本発明の電子線蛍光用多結晶透明Yセラミックスは、電子線蛍光分野において広く用いられる。特に高精細な画像出力を要するモニタを備える各種器機に用いることができる。即ち、例えば、走査型電顕微鏡(SEM)のシンチレータ、透過型電子顕微鏡(TEM)のシンチレータ、イメージインテンシファイア(電子線を用いた撮像管)などとして利用される。 The polycrystalline transparent Y 2 O 3 ceramic for electron beam fluorescence of the present invention is widely used in the field of electron beam fluorescence. In particular, it can be used in various devices including a monitor that requires high-definition image output. That is, for example, it is used as a scintillator of a scanning electron microscope (SEM), a scintillator of a transmission electron microscope (TEM), an image intensifier (an imaging tube using an electron beam), or the like.

実施例で用いた評価方法を説明する模式的な説明図である。It is typical explanatory drawing explaining the evaluation method used in the Example.

符号の説明Explanation of symbols

1;シンチレータ、11;電子線蛍光用多結晶透明Yセラミックス、12;アルミニウムフィルム、2;減圧チャンバー、21;電子銃、22;減圧チャンバー窓、3;CCDカメラ、4;CRTモニタ。 1; scintillator, 11; electron beam fluorescent polycrystalline transparent Y 2 O 3 ceramic, 12; aluminum film, 2; decompression chamber, 21; electron gun, 22; vacuum chamber window, 3; CCD camera, 4; CRT monitor.

Claims (5)

を主成分とする多結晶焼結体からなる電子線蛍光用多結晶透明Yセラミックスであって、
該多結晶焼結体は、気孔率が0.1%以下であり、平均結晶粒子径が5〜300μmであり、且つ、ランタニド元素を含有することを特徴とする電子線蛍光用多結晶透明Yセラミックス。
A polycrystalline transparent Y 2 O 3 ceramic for electron beam fluorescence comprising a polycrystalline sintered body containing Y 2 O 3 as a main component,
The polycrystalline sintered body has a porosity of 0.1% or less, an average crystal particle diameter of 5 to 300 μm, and contains a lanthanide element. 2 O 3 ceramics.
Zr及びCaのうちの少なくとも一方を含有し、
Zr及びCaの含有量は、Yとランタニド元素との酸化物換算合計量に対して、各々酸化物換算で1000質量ppm以下である請求項1に記載の電子線蛍光用多結晶透明Yセラミックス。
Containing at least one of Zr and Ca,
2. The polycrystalline transparent Y 2 O for electron beam fluorescence according to claim 1, wherein the content of Zr and Ca is 1000 ppm by mass or less in terms of oxide with respect to the total amount in terms of oxide of Y and lanthanide element, respectively. 3 Ceramics.
Zr及びCaの両元素を含有し、且つZr及びCaの両方が含まれる複酸化物を含有する請求項1又は2に記載の電子線蛍光用多結晶透明Yセラミックス。 3. The polycrystalline transparent Y 2 O 3 ceramic for electron beam fluorescence according to claim 1, comprising a double oxide containing both elements of Zr and Ca and containing both of Zr and Ca. Zr及びCaの両元素を含有し、ZrとCaとのモル比Zr/Caは0.5〜2.0である請求項1乃至3のうちのいずれかに記載の電子線蛍光用多結晶透明Yセラミックス。 4. The polycrystalline transparent for electron beam fluorescence according to claim 1, comprising both elements of Zr and Ca, wherein the molar ratio Zr / Ca of Zr and Ca is 0.5 to 2.0. 5. Y 2 O 3 ceramics. 請求項1乃至4のうちのいずれかに記載の電子線蛍光用多結晶透明Yセラミックスの製造方法であって、
粉末及びランタニド酸化物粉末を含有する成形体を、酸素雰囲気下1500〜1800℃で焼成して一次焼成体を得る一次焼成工程と、
該一次焼成体を更に温度1600〜1800℃且つ圧力49〜198MPaで焼成する二次焼成工程と、を備えることを特徴とする電子線蛍光用多結晶透明Yセラミックスの製造方法。
A method of manufacturing an electron-ray fluorescence for polycrystalline transparent Y 2 O 3 ceramic according to any one of claims 1 to 4,
A primary firing step of obtaining a primary fired body by firing a molded body containing Y 2 O 3 powder and a lanthanide oxide powder at 1500 to 1800 ° C. in an oxygen atmosphere;
And a secondary firing step of further firing the primary fired body at a temperature of 1600 to 1800 ° C. and a pressure of 49 to 198 MPa. A method for producing polycrystalline transparent Y 2 O 3 ceramics for electron beam fluorescence.
JP2006329949A 2006-12-06 2006-12-06 Polycrystalline transparent y2o3 ceramics and its production method Pending JP2008143726A (en)

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