JP3536290B2 - Method for producing columnar rare earth silicate single crystal - Google Patents
Method for producing columnar rare earth silicate single crystalInfo
- Publication number
- JP3536290B2 JP3536290B2 JP05967294A JP5967294A JP3536290B2 JP 3536290 B2 JP3536290 B2 JP 3536290B2 JP 05967294 A JP05967294 A JP 05967294A JP 5967294 A JP5967294 A JP 5967294A JP 3536290 B2 JP3536290 B2 JP 3536290B2
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- single crystal
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- 239000013078 crystal Substances 0.000 title claims description 103
- 229910052761 rare earth metal Inorganic materials 0.000 title claims description 21
- -1 rare earth silicate Chemical class 0.000 title claims description 20
- 238000004519 manufacturing process Methods 0.000 title claims description 3
- 238000005498 polishing Methods 0.000 claims description 11
- 239000000155 melt Substances 0.000 claims description 10
- 239000002994 raw material Substances 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 2
- 238000000034 method Methods 0.000 description 14
- 238000003776 cleavage reaction Methods 0.000 description 12
- 230000007017 scission Effects 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 8
- 238000005336 cracking Methods 0.000 description 8
- 238000001816 cooling Methods 0.000 description 7
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 6
- 229910052688 Gadolinium Inorganic materials 0.000 description 5
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 5
- 238000005520 cutting process Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 229910052684 Cerium Inorganic materials 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 150000000921 Gadolinium Chemical class 0.000 description 1
- 229910052689 Holmium Inorganic materials 0.000 description 1
- 229910052765 Lutetium Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 101100386054 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) CYS3 gene Proteins 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 229910052771 Terbium Inorganic materials 0.000 description 1
- 229910052775 Thulium Inorganic materials 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 101150035983 str1 gene Proteins 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
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- Crystals, And After-Treatments Of Crystals (AREA)
Description
【発明の詳細な説明】
【０００１】
【産業上の利用分野】本発明は、希土類珪酸塩単結晶の
育成方法に関する。
【０００２】
【従来の技術】珪酸ガドリニウム単結晶等の希土類珪酸
塩単結晶は、シンチレータ、蛍光体等として広く用いら
れている。この単結晶系に属する珪酸ガドリニウム単結
晶等は、原料融液からチョクラルスキー法によって作る
ことができる。すなわち、原料を入れたるつぼを加熱し
て融液とし、るつぼ内の融液に種結晶を接触させ、種結
晶を引き上げることにより、種結晶に更に単結晶を成長
させることにより製造された。また、シンチレータ等と
して用いられる場合には、一般に円柱あるいは直方体の
形状に加工して使用される。実際には更に、１面〜全面
を鏡面研磨し、鏡面研磨を施した１面を除いて反射材を
塗布あるいは巻き付けた状態で、反射材の無い面を光電
子増倍管に密着させて使用される。しかしながら、この
単斜晶系に属する珪酸ガドリニウム単結晶等は、ａ面
（（１００）面）にへき開性があり、またｂ軸（［０１
０］軸）方向の熱膨張係数が他の方向に比べ方向に比べ
大きいという異方性があるために、結晶育成冷却中に
（１００）面及び（０１０）面に沿って割れ易く、加工
中にも新たな割れが発生し易い。割れのない希土類珪酸
塩単結晶を育成する方法として、引上軸を単結晶のｂ軸
（［０１０］軸）またはその近傍（ｂ軸からの傾きの角
度が０〜３０°）とする方法（特開平３−８０１８３号
公報）、及び引上軸を（１００）面に平行でかつ、ｃ軸
（［００１］軸）からの傾きの角度が０°〜２５°の方
向とする方法（特開平４−１７５２９７号公報）が提案
されている。
【０００３】
【発明が解決しようとする課題】しかし、これら従来法
では、希土類珪酸塩単結晶の育成冷却中あるいは加工時
に依然割れが発生する問題がある。すなわち、引上軸を
［０１０］軸またはその近傍とした場合には、育成冷却
中に種結晶や育成結晶の途中に割れが発生し、結晶が落
下してしまう。更に、この方向に育成した結晶から長い
円柱形試料を採取する場合には、育成結晶の長さ方向に
（円柱の軸方向を引上軸方向にして）試料を採取する
が、この場合側面の円筒研削時に割れが発生し易く、歩
留りが低下する問題がある。一方、引上軸を［００１］
軸またはその近傍とした場合には、育成結晶から試料を
採取、加工する際に、引上方向に垂直な面を研磨する時
にへき開割れが発生してしまう。この試料面の割れを防
止するためには、引上軸方向に対し試料の中心軸を十分
傾けて試料を採取する必要があり、試料採取の歩留りが
低下し作業も面倒になるという問題がある。本発明は、
引上軸方向を選択することにより、育成中に割れが発生
することがなく、かつ育成結晶の側面及び断面（引上方
向に垂直な面）の加工時に割れが発生しにくいため、結
晶育成及び試料採取が容易な単結晶が得られる希土類珪
酸塩単結晶の育成方法を提供するものである。
【０００４】
【課題を解決するための手段】上記目的を達成するため
に、本発明者らは、原料を入れたるつぼを加熱して融液
とし、その融液に種結晶の下端を接触させ、種結晶を引
き上げながら単結晶を育成する希土類珪酸塩単結晶の育
成において、引上軸の方位による育成中及び加工時の割
れの発生し易さについて検討した。その結果、引上軸を
単結晶のｂ軸（［０１０］軸）とｃ軸（［００１］軸）
の間のある範囲（ｂ軸からの傾きの角度が３０°以上、
かつｃ軸からの角度が２５°以上）で、かつ（１００）
面との傾きの角度が０〜２５°の方向にすることによ
り、育成中及び加工時の割れを防止することができるこ
とを見いだすことによって、本発明は成されたものであ
る。
【０００５】即ち本発明は、原料を入れたるつぼを加熱
して融液とし、その融液に種結晶の下端を接触させ、種
結晶を引き上げながら単結晶を育成する際に、引上軸
を、単結晶のｂ軸（［０１０］軸）からの傾きの角度が
３０°以上、ｃ軸（［００１］軸）からの傾きの角度が
２５°以上、かつ（１００）面との傾きの角度が０〜２
５°の方向（但し、（１００）面に平行な方向を除く）
として希土類珪酸塩単結晶を育成し、該希土類珪酸塩単
結晶に対して、側面の円筒研削を行った後、更に側面及
び両端面の鏡面研磨を行うことを特徴とする、円柱状希
土類珪酸塩単結晶の製造方法を提供する。
【０００６】
【作用】原料を入れたるつぼを加熱して融液とし、その
融液に種結晶の下端を接触させ、種結晶を引き上げなが
ら単結晶を育成する希土類珪酸塩単結晶の育成におい
て、引上軸を単結晶のｂ軸（［０１０］軸）とｃ軸
（［００１］軸）の間のある範囲で、かつ（１００）面
との傾きの角度が０〜２５°の方向にすることにより、
育成中及び加工時の割れを防止することができる原因は
次のように考えられる。希土類珪酸塩単結晶の材料力学
特性を調べた結果、［００１］軸方向の熱膨張係数が他
の方向よりも大きいことがわかっている。そのため、引
上軸を［０１０］軸またはその近傍とした場合には、こ
の［０１０］軸方向が温度勾配の大きい方向になるため
に、熱応力により育成中に種結晶や育成結晶の途中に割
れが発生し、結晶が落下してしまうと考えられる。そこ
で、結晶の落下を防止するためには、引上軸の［０１
０］軸からの傾きをある角度以上にすればよい。また、
希土類珪酸塩単結晶には、へき開面（（１００）面）に
垂直方向から荷重し、［００１］軸方向に引っ張りの応
力が作用する場合に塑性変形が発生すること。そして、
へき開割れ方向の破壊靱性値は（０１０）面よりも（０
０１）−１７°面（［００１］軸を法線方向とする面）
の方が約１桁小さく、へき開割れは（０１０）面側から
よりも（００１）−１７°面側から非常に発生し易いこ
とが今回新たにわかった。これらのへき開面に関する異
方性のある特性から、［０１０］軸近傍を引上軸とした
結晶から長さ方向に長い円柱状試料を採取する場合に
は、（００１）−１７°面に近い面（傾きの小さい面）
が側面になるために、へき開割れ及びへき開面の剥がれ
が発生し易い。そこで、円筒研削時の側面の割れ及び剥
がれを防止するためには、引上軸の［０１０］軸からの
傾きをある角度以上にすればよい。
【０００７】一方、同じくへき開割れの破壊靱性値の異
方性により、引上軸を［００１］軸近傍とした場合に
は、（００１）−１７°面に近い面（傾きの小さい面）
が引上方向に垂直になるために、加工に便利なこの面で
切断し試料を採取すると、この面を研磨する時にへき開
割れが発生してしまう。そこで、引上軸に垂直な面で試
料を採取しても、研磨する際に割れが入らないようにす
るためには、すなわち、試料採取に便利な（歩留りも良
い）結晶方向の育成結晶を得るためには、引上軸の［０
０１］軸からの傾きをある角度以上にすればよい。へき
開性のある（１００）面と引上軸の関係については、引
上軸を［００１］−１７°軸（（１００）面の法線方
向）近傍とすると、［０１０］軸近傍とした場合と同様
に、引上軸にほぼ垂直な面の割れによる結晶落下の問題
が発生し、（０１０）面割れよりも発生し易いために、
引上軸（１００）面に平行にした方向が最も結晶育成が
し易い。しかし、引上軸との傾きの角度か０〜２５°ま
では結晶の育成が可能であり、結晶の加工にも支障の無
い方向であるので、引上軸の方向として選択することが
できる。以上が、引上軸をｂ軸（［０１０］軸）からの
傾きの角度が３０°以上、ｃ軸（［００１］軸）からの
角度が２５°以上、かつ（１００）面との傾きの角度が
０〜２５°の方向にすることにより、育成中及び加工時
の割れを安定して防止できることの理由と考えられる。
【０００８】珪酸ガドリニウム単結晶以外の、化１の一
般式
【化１】Ｒ2 ＳｉＯ５
（但し、ＲはＬａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅ
ｕ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ、Ｙ、
Ｓｃから選ばれる１種以上の希土類元素）で示される希
土類珪酸塩単結晶についても、結晶の力学特性は同様で
あり、同様の結果となる。更に、これらの希土類珪酸塩
単結晶にＣｅ等の希土類元素やＣｒ等の鉄属遷移金属を
ドープした場合も、効果は同様である。以上の希土類珪
酸塩単結晶は、珪酸ガドリニウム単結晶の結晶構造と同
じ結晶構造を持ち、その構造は空間群Ｐ２／ｃに属す
る。
【０００９】
【実施例】
比較例１
セリウム付活珪酸ガドリニウム単結晶（Ｃｅ：Ｇｄ２
ＳｉＯ5 ）の場合の例を説明する。原料として、Ｇｄ2
Ｏ3 約３２６０ｇ、ＳｉＯ2 約５４０ｇ、ＣｅＯ2 約１
０ｇをφ１００のＩｒるつぼ中に採り、φ５０×１８０
ｍｍ3 の結晶をチョクラルスキー法で育成した。種結晶
の引上軸は［０１０］軸とし、引上速度は１〜３ｍｍ／
ｈ、回転速度は３０〜５０ｒｐｍとした。育成の切り離
し後、２０〜６０時間かけて室温まで結晶を冷却した。
しかし、その途中で、結晶直胴部の上部で引上軸にほぼ
垂直に割れが発生し、割れ発生位置から下の結晶部分が
落下してしまった。（図２）。このような結晶の落下は
９０％以上の確率で発生した。直胴部とは、融液に種結
晶の下端を接触させ種結晶を引き上げながら単結晶を育
成する場合、種結晶から目的径まで結晶径を広げ目的径
になった後育成される部分である。更に、育成結晶の割
れのない部分から、φ４０×１２０ｍｍ3 の試料の採取
を試みた。育成結晶を引上軸に約１２０ｍｍの長さに切
断した。その後、円筒研削機により側面の円筒研削を行
いφ４０の円柱に加工したが、側面にへき開面（（１０
０）面）方向の割れ及び剥がれが発生してしまった（図
３）。
【００１０】比較例２
比較例１と同様にＧＳＯ単結晶をチョクラルスキー法で
育成した。種結晶の引上軸は［００１］軸とし、引上速
度は１〜３ｍｍ／ｈ、回転速度は３０〜５０ｒｐｍとし
た。育成の切り離し後、２０〜５０時間かけて室温まで
結晶を冷却した。約５０％の確率で冷却途中に割れは発
生せず、直胴部がφ５０×１８０ｍｍ3 の単結晶が得ら
れた。育成結晶から、φ４０×１３０ｍｍ3 の試料の採
取するために切断加工を行った。育成結晶を引上軸に垂
直に約１３０ｍｍの長さに切断した。その後、円筒研削
機により側面の円筒研削を行いφ４０の円柱に加工し、
割れの無い側面を得ることができた。次に、鏡面研磨を
行ったところ、側面は割れが発生すること無く研磨する
ことができたが、両端面（底面）の研磨時には、へき開
面（（１００）面）方向の割れが発生してしまった（図
４）。
【００１１】参考例１
比較例１と同様にＧＳＯ単結晶をチョクラルスキー法で
育成した。種結晶の引上軸は、［０１０］軸からの傾き
が６０°で［００１］軸からの傾きが３０°、かつ（１
００）面に平行な方向とした。引上速度は１〜３ｍｍ／
ｈ、回転速度は３０〜５０ｒｐｍとした。育成の切り離
し後、２０〜６０時間かけて室温まで結晶を冷却した。
約８０％の確率で冷却途中に割れは発生せず、直胴部が
φ５０×１８０ｍｍ３の単結晶が得られた。育成結晶か
ら、φ４０×１３０ｍｍ３の試料の採取するために切断
加工を行った。育成結晶を引上軸に垂直に約１３０ｍｍ
の長さに切断した。その後、円筒研削機により側面の円
筒研削を行いφ４０の円柱に加工し、割れの無い側面を
得ることができた。次に、鏡面研磨を行ったところ、側
面及び両端面（底面）とも割れが発生すること無く研磨
することができた（図１）。
【００１２】実施例１
比較例１と同様にＧＳＯ単結晶をチョクラルスキー法で
育成した。種結晶の引上軸は、［０１０］軸からの傾き
が６０°で［００１］軸からの傾きが３０°、かつ（１
００）面との傾きの角度が２５°の方向とした。引上速
度は１〜３ｍｍ／ｈ、回転速度は３０〜５０ｒｐｍとし
た。育成の切り離し後、２０〜６０時間かけて室温まで
結晶を冷却した。約６０％の確率で冷却途中に割れは発
生せず、直胴部がφ５０×１８０ｍｍ３の単結晶が得ら
れた。育成結晶から、φ４０×１３０ｍｍ３の試料の採
取するために切断加工を行った。育成結晶を引上軸に垂
直に約１３０ｍｍの長さに切断した。その後、円筒研削
機により側面の円筒研削を行いφ４０の円柱に加工し、
割れの無い側面を得ることができた。次に鏡面研磨を行
ったところ、側面及び両端面（底面）とも割れが発生す
ること無く研磨することができた。
【００１３】
【発明の効果】本発明の育成方法により、結晶の育成・
冷却中に割れの発生しない、かつ加工の円筒研削時や研
磨時に割れが発生しない、育成及び加工が容易な希土類
珪酸塩単結晶を得ることができる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for growing rare earth silicate single crystals. [0002] Rare earth silicate single crystals such as gadolinium silicate single crystals are widely used as scintillators, phosphors and the like. The gadolinium silicate single crystal belonging to this single crystal system can be produced from the raw material melt by the Czochralski method. That is, it was manufactured by heating a crucible in which the raw materials were put into a melt, bringing a seed crystal into contact with the melt in the crucible, pulling up the seed crystal, and further growing a single crystal on the seed crystal. When used as a scintillator or the like, it is generally used after being processed into a cylindrical or rectangular parallelepiped shape. In practice, one surface to the entire surface is mirror-polished, and the surface without the reflection material is used in close contact with the photomultiplier tube in a state where the reflection material is applied or wound except for one surface which has been subjected to the mirror polishing. You. However, gadolinium silicate single crystals belonging to this monoclinic system have a cleaving property on the a-plane ((100) plane) and have a b-axis ([01
Since the crystal has anisotropy in which the coefficient of thermal expansion in the [0] axis) direction is larger than the other directions as compared with the other directions, it is easily cracked along the (100) plane and the (010) plane during crystal growth cooling, and during processing. New cracks are likely to occur. As a method for growing a rare-earth silicate single crystal without cracks, a method in which the pulling axis is set to the b-axis ([010] axis) of the single crystal or in the vicinity thereof (the angle of inclination from the b-axis is 0 to 30 °) ( JP-A-3-80183) and a method in which the pulling axis is parallel to the (100) plane and the angle of inclination from the c-axis ([001] axis) is 0 ° to 25 ° (JP-A-Hei. No. 4-175297) has been proposed. However, in these conventional methods, there is a problem that cracks still occur during growth and cooling of the rare earth silicate single crystal or during processing. That is, when the pulling axis is the [010] axis or in the vicinity thereof, cracks occur in the seed crystal or the grown crystal during the growth and cooling, and the crystal falls. Further, when collecting a long cylindrical sample from the crystal grown in this direction, the sample is collected in the length direction of the grown crystal (with the axial direction of the cylinder being the pull-up axis direction). There is a problem that cracks are easily generated during cylindrical grinding, and the yield is reduced. On the other hand, the lifting axis is set to [001]
If the axis is set at or near the axis, when a sample is taken from the grown crystal and processed, cleavage cracks occur when polishing a surface perpendicular to the pulling direction. In order to prevent the crack on the sample surface, it is necessary to collect the sample by sufficiently tilting the center axis of the sample with respect to the pulling-up axis direction, and there is a problem that the yield of the sample collection is reduced and the operation is troublesome. . The present invention
By selecting the pulling axis direction, cracks do not occur during growth, and cracks are less likely to occur during processing of the side and cross-section (plane perpendicular to the pulling direction) of the grown crystal. It is an object of the present invention to provide a method for growing a rare earth silicate single crystal from which a single crystal can be easily obtained. [0004] In order to achieve the above object, the present inventors heated a crucible containing raw materials into a melt and brought the lower end of a seed crystal into contact with the melt. In addition, in growing rare earth silicate single crystals in which a single crystal is grown while pulling a seed crystal, the possibility of occurrence of cracks during growth and processing according to the orientation of the pulling axis was examined. As a result, the pulling axis is set to the b-axis ([010] axis) and the c-axis ([001] axis) of the single crystal.
Within a certain range (the angle of inclination from the b-axis is 30 ° or more,
And the angle from the c-axis is 25 ° or more), and (100)
The present invention has been made by finding that cracks during growth and during processing can be prevented by setting the angle of inclination with respect to the surface to 0 to 25 °. That is, according to the present invention, when a crucible containing raw materials is heated to form a melt, the lower end of a seed crystal is brought into contact with the melt, and a single crystal is grown while pulling the seed crystal, the pulling shaft is raised. The angle of inclination of the single crystal from the b-axis ([010] axis) is 30 ° or more , the angle of inclination from the c- axis ([001] axis) is 25 ° or more , and the angle of inclination with the (100) plane Is 0-2
5 ° direction (excluding direction parallel to (100) plane)
Growing a rare-earth silicate single crystal as described above, performing cylindrical grinding of the side surface of the rare-earth silicate single crystal, and further performing mirror polishing of the side surface and both end surfaces, thereby forming a columnar rare-earth silicate. Provided is a method for producing a single crystal. The crucible containing the raw materials is heated to form a melt, and the lower end of the seed crystal is brought into contact with the melt to grow a single crystal while pulling up the seed crystal. The pulling axis is in a certain range between the b-axis ([010] axis) and the c-axis ([001] axis) of the single crystal, and the angle of inclination with respect to the (100) plane is 0 to 25 °. By
The causes that can prevent cracking during growing and processing are considered as follows. As a result of examining the material mechanical properties of the rare earth silicate single crystal, it has been found that the coefficient of thermal expansion in the [001] axis direction is larger than that in other directions. Therefore, when the pulling axis is the [010] axis or in the vicinity thereof, the [010] axis direction becomes a direction with a large temperature gradient. It is considered that cracks occur and crystals fall. Therefore, in order to prevent the crystal from falling, [01]
[0] The inclination from the axis may be set to a certain angle or more. Also,
The rare earth silicate single crystal undergoes plastic deformation when a load is applied from the direction perpendicular to the cleavage plane ((100) plane) and a tensile stress acts in the [001] axis direction. And
The fracture toughness value in the cleavage crack direction is (0) more than the (010) plane.
01) -17 ° plane (plane with [001] axis as the normal direction)
Is about one order of magnitude smaller, and it has been newly found that cleavage cleavage is much more likely to occur from the (001) -17 ° plane side than from the (010) plane side. Due to the anisotropic properties of these cleavage planes, when collecting a columnar sample long in the length direction from a crystal with the pull-up axis near the [010] axis, it is close to the (001) -17 ° plane. Surface (surface with small inclination)
Is a side surface, so that cleavage cleavage and peeling of the cleavage surface are liable to occur. Therefore, in order to prevent cracking and peeling of the side surface during cylindrical grinding, the inclination of the pulling shaft from the [010] axis may be set to a certain angle or more. On the other hand, when the pulling axis is set near the [001] axis due to the anisotropy of the fracture toughness value of the cleavage crack, a plane close to the (001) -17 ° plane (a plane with a small inclination)
Since this is perpendicular to the pulling-up direction, cutting and sampling on this surface, which is convenient for processing, causes cleavage cracks when polishing this surface. Therefore, in order to prevent cracks during polishing even when a sample is taken on a plane perpendicular to the pulling axis, a crystal grown in a crystal direction that is convenient for sample collection (good in yield) is used. In order to obtain it, [0
[01] The inclination from the axis may be set to a certain angle or more. Regarding the relationship between the cleaving (100) plane and the pulling axis, assuming that the pulling axis is near the [001] -17 ° axis (the normal direction of the (100) plane), it is near the [010] axis. In the same manner as described above, a problem of crystal falling due to cracks in a plane substantially perpendicular to the pulling axis occurs, and it is more likely to occur than (010) plane cracking.
Crystal growth is most easily performed in the direction parallel to the pulling axis (100) plane. However, the crystal can be grown up to an angle of inclination of 0 to 25 ° with respect to the pulling axis, and it is a direction that does not hinder the crystal processing. Therefore, the direction can be selected as the direction of the pulling axis. As described above, the angle of inclination of the pull-up axis from the b-axis ([010] axis) is 30 ° or more, the angle from the c-axis ([001] axis) is 25 ° or more, and the inclination with respect to the (100) plane. It is considered that setting the angle to a direction of 0 to 25 ° can stably prevent cracking during growth and during processing. [0008] other than gadolinium silicate single crystal, of formula ## STR1 ## in 1 R 2 SiO 5 (where, R represents La, Ce, Pr, Nd, Pm, Sm, E
u, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y,
The mechanical properties of the rare earth silicate single crystal represented by one or more rare earth elements selected from Sc) are the same, and the same result is obtained. The same effect is obtained when these rare earth silicate single crystals are doped with a rare earth element such as Ce or an iron-based transition metal such as Cr. The above rare earth silicate single crystal has the same crystal structure as the gadolinium silicate single crystal, and the structure belongs to the space group P2 / c. EXAMPLES Comparative Example 1 Cerium-activated gadolinium silicate single crystal (Ce: Gd 2
An example in the case of SiO 5 ) will be described. Gd 2 as raw material
O 3 about 3260 g, SiO 2 about 540 g, CeO 2 about 1
0 g is taken in an Ir crucible of φ100, and φ50 × 180
Crystals of mm 3 were grown by the Czochralski method. The pulling axis of the seed crystal is the [010] axis, and the pulling speed is 1 to 3 mm /
h, the rotation speed was 30 to 50 rpm. After separating the growth, the crystals were cooled to room temperature over a period of 20 to 60 hours.
However, on the way, a crack was generated almost vertically to the pulling axis at the upper part of the crystal straight body, and the lower crystal part dropped from the position where the crack occurred. (FIG. 2). Such a crystal drop occurred with a probability of 90% or more. When growing a single crystal while bringing the seed crystal into contact with the lower end of the seed crystal and pulling up the seed crystal, the straight body portion is a portion grown after the crystal diameter is expanded from the seed crystal to the target diameter and reaches the target diameter. . Further, a sample of φ40 × 120 mm 3 was attempted to be sampled from a portion where the grown crystal had no crack. The grown crystal was cut into a length of about 120 mm around a pulling shaft. Thereafter, the side surface was cylindrically ground by a cylindrical grinder and processed into a φ40 cylinder, but the cleaved surface ((10
Cracking and peeling occurred in the 0) plane) direction (FIG. 3). Comparative Example 2 As in Comparative Example 1, a GSO single crystal was grown by the Czochralski method. The pulling axis of the seed crystal was the [001] axis, the pulling speed was 1 to 3 mm / h, and the rotation speed was 30 to 50 rpm. After the growth was separated, the crystals were cooled to room temperature over 20 to 50 hours. About a 50% chance cracks during cooling is not generated, the straight body portion is a single crystal of ø50 × 180 mm 3 was obtained. A cutting process was performed to collect a sample of φ40 × 130 mm 3 from the grown crystal. The grown crystal was cut to a length of about 130 mm perpendicular to the pulling axis. After that, cylindrical grinding of the side is performed by a cylindrical grinding machine to process into a φ40 cylinder,
A crack-free side was obtained. Next, when mirror polishing was performed, the side surfaces could be polished without cracking. However, when polishing both end surfaces (bottom surface), cracks were generated in the cleavage plane ((100) plane) direction. (Fig. 4). Reference Example 1 In the same manner as in Comparative Example 1, a GSO single crystal was grown by the Czochralski method. The pulling axis of the seed crystal has a tilt of 60 ° from the [010] axis, a tilt of 30 ° from the [001] axis, and (1).
(00) plane. Lifting speed is 1-3mm /
h, the rotation speed was 30 to 50 rpm. After separating the growth, the crystals were cooled to room temperature over a period of 20 to 60 hours.
About 80% of the time cracks during cooling is not generated, the straight body portion is a single crystal of ø50 × 180 mm 3 was obtained. A cutting process was performed to collect a sample of φ40 × 130 mm 3 from the grown crystal. Approximately 130mm perpendicular to the pulling axis
Cut to length. Thereafter, the side surface was cylindrically ground by a cylindrical grinder and processed into a φ40 cylinder, whereby a crack-free side surface could be obtained. Next, when mirror polishing was performed, the side and both end faces (bottom face) could be polished without cracking (FIG. 1). Example 1 As in Comparative Example 1, a GSO single crystal was grown by the Czochralski method. The pulling axis of the seed crystal has a tilt of 60 ° from the [010] axis, a tilt of 30 ° from the [001] axis, and (1).
00) The direction of the inclination with respect to the plane was 25 °. The pulling speed was 1 to 3 mm / h, and the rotation speed was 30 to 50 rpm. After separating the growth, the crystals were cooled to room temperature over a period of 20 to 60 hours. With a probability of about 60%, cracks did not occur during cooling, and a single crystal having a straight body portion of φ50 × 180 mm 3 was obtained. A cutting process was performed to collect a sample of φ40 × 130 mm 3 from the grown crystal. The grown crystal was cut to a length of about 130 mm perpendicular to the pulling axis. After that, cylindrical grinding of the side is performed by a cylindrical grinding machine to process into a φ40 cylinder,
A crack-free side was obtained. Next, when mirror polishing was performed, the side and both end faces (bottom face) could be polished without cracking. According to the growth method of the present invention, it is possible to grow and grow crystals.
It is possible to obtain a rare earth silicate single crystal that does not generate cracks during cooling, does not generate cracks during cylindrical grinding or polishing, and is easy to grow and process.
【図面の簡単な説明】
【図１】実施例１の育成において得られた育成結晶の斜
視図。
【図２】比較例１の育成において得られた育成結晶の斜
視図。
【図３】比較例１において加工した結晶の斜視図。
【図４】比較例１において加工した結晶の斜視図。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a grown crystal obtained in growing Example 1. FIG. 2 is a perspective view of a grown crystal obtained in the growing of Comparative Example 1. FIG. 3 is a perspective view of a crystal processed in Comparative Example 1. FIG. 4 is a perspective view of a crystal processed in Comparative Example 1.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平４−175297（ＪＰ，Ａ) 特開 平３−80183（ＪＰ，Ａ) 特開 平６−169128（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C30B 1/00 - 35/00 ────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-4-175297 (JP, A) JP-A-3-80183 (JP, A) JP-A-6-169128 (JP, A) (58) Field (Int.Cl. 7 , DB name) C30B 1/00-35/00
Claims (1)
し、その融液に種結晶の下端を接触させ、種結晶を引き
上げながら単結晶を育成する際に、引上軸を、単結晶の
ｂ軸（［０１０］軸）からの傾きの角度が３０°以上、
ｃ軸（［００１］軸）からの傾きの角度が２５°以上、
かつ（１００）面との傾きの角度が０〜２５°の方向
（但し、（１００）面に平行な方向を除く）として希土
類珪酸塩単結晶を育成し、該希土類珪酸塩単結晶に対し
て、側面の円筒研削を行った後、更に側面及び両端面の
鏡面研磨を行うことを特徴とする、円柱状希土類珪酸塩
単結晶の製造方法。(57) [Claims 1] When growing a single crystal while heating a crucible containing raw materials to form a melt, contacting the lower end of the seed crystal with the melt and pulling up the seed crystal In addition, the angle of inclination of the pulling axis from the b axis ([010] axis) of the single crystal is 30 ° or more ,
the angle of inclination from the c- axis ([001] axis) is 25 ° or more ;
And a direction in which the angle of inclination with respect to the (100) plane is 0 to 25 °
(However, except for a direction parallel to the (100) plane) , a rare-earth silicate single crystal is grown, and the rare-earth silicate single crystal is subjected to cylindrical grinding on a side surface, and then to a mirror surface on the side surface and both end surfaces. A method for producing a columnar rare earth silicate single crystal, comprising polishing.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05967294A JP3536290B2 (en) | 1994-03-30 | 1994-03-30 | Method for producing columnar rare earth silicate single crystal |
| US08/413,287 US5667583A (en) | 1994-03-30 | 1995-03-30 | Method of producing a single crystal of a rare-earth silicate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05967294A JP3536290B2 (en) | 1994-03-30 | 1994-03-30 | Method for producing columnar rare earth silicate single crystal |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2003315659A Division JP3587262B2 (en) | 2003-09-08 | 2003-09-08 | Method for producing columnar rare earth silicate single crystal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07267782A JPH07267782A (en) | 1995-10-17 |
| JP3536290B2 true JP3536290B2 (en) | 2004-06-07 |
Family
ID=13119924
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP05967294A Expired - Fee Related JP3536290B2 (en) | 1994-03-30 | 1994-03-30 | Method for producing columnar rare earth silicate single crystal |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3536290B2 (en) |
-
1994
- 1994-03-30 JP JP05967294A patent/JP3536290B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07267782A (en) | 1995-10-17 |
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