JP3910483B2 - Method for producing oxide superconductor needle crystal - Google Patents
Method for producing oxide superconductor needle crystal Download PDFInfo
- Publication number
- JP3910483B2 JP3910483B2 JP2002133493A JP2002133493A JP3910483B2 JP 3910483 B2 JP3910483 B2 JP 3910483B2 JP 2002133493 A JP2002133493 A JP 2002133493A JP 2002133493 A JP2002133493 A JP 2002133493A JP 3910483 B2 JP3910483 B2 JP 3910483B2
- Authority
- JP
- Japan
- Prior art keywords
- crystal
- needle
- oxide superconductor
- crystals
- mol
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Inorganic Compounds Of Heavy Metals (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、酸化物超伝導体針状結晶の製造方法に関し、特に、超伝導エレクトロニクス素子を実現するために不可欠である、酸化物超伝導体の欠陥がほとんど存在しない針状の単結晶、すなわち完全結晶に極めて近似した、酸化物超伝導体針状結晶の製造方法に関するものである。
【０００２】
【従来の技術】
酸化物超伝導体の単結晶は、導電層と非導電層が交互に積層した結晶構造を有し、各層間は固有ジョセフソン結合して成っている。
近年、かかる固有ジョセフソン効果を用いた単結晶スイッチング素子デバイスが提案されている。この新しい単結晶スイッチング素子は、従来のジョセフソン接合を用いたものよりほぼ１／１００に小型化することができ、スイッチング速度も１００倍程度速く、作動周波数はＴＨｚ（テラヘルツ）の高周波が期待されている。
【０００３】
また現在、酸化物超伝導体の針状結晶を用いて作製したサブミクロン結晶素子においては、電子対が１個づつ通過する超伝導単電子トンネル現象が発生することが明らかとなっている。
かかる超伝導単電子トンネル現象を発生させるには、液体ヘリウム温度（４．２Ｋ）で作動させる必要があるが、結晶のユニットセルの積層数を１０００層程度にすると、液体窒素温度（７７Ｋ）で作動する超伝導単電子対素子が実現できるものと予想されている。
これらの素子の実現には、無欠陥もしくは欠陥の極めて少ない単結晶が要求される。
【０００４】
実用観点からの酸化物超伝導体には、超伝導臨界温度が約１１０Ｋの（ＢｉＰｂ）２Ｓｒ２Ｃａ２Ｃｕ３Ｏ１０、約８０ＫのＢｉ２Ｓｒ２Ｃａ１Ｃｕ２Ｏ８、および約９０ＫのＲ１Ｂａ２Ｃｕ３Ｏ７（Ｒは希土類元素を表す）の結晶構造物が知られている。
【０００５】
本発明者らは、（ＢｉＰｂ）２Ｓｒ２Ｃａ２Ｃｕ３Ｏ１０、Ｂｉ２Ｓｒ２Ｃａ１Ｃｕ２Ｏ８組成に、その融点を低減させる元素を含有する圧縮成形体から、急冷による工程や、非晶質化工程を経ることなく、極めて結晶性の良好な（ＢｉＰｂ）２Ｓｒ２Ｃａ２Ｃｕ３Ｏ１０およびＢｉ２Ｓｒ２Ｃａ１Ｃｕ２Ｏ８の針状結晶を育成できることに成功し、既に特許出願を行った。（特願２００１−３８１７０号及び特願２００１−２２４７４１号）。
【０００６】
一方、Ｒ１Ｂａ２Ｃｕ３Ｏ７（Ｒは、Ｙ、Ｌａ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ及びＬｕからなる群より選ばれる）は、（ＢｉＰｂ）２Ｓｒ２Ｃａ２Ｃｕ３０１０、Ｂｉ２Ｓｒ２Ｃａ１Ｃｕ２Ｏ８と比較して、磁束量子のピン止めが強く、高温、磁界中での臨界電流特性が良好であるため、高品位針状結晶の育成が切望されている。
【０００７】
しかし、これまで、かかる酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７（Ｒは、Ｙ、Ｌａ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ及びＬｕからなる群より選ばれる）系の針状結晶の育成は、出発材料の組成決定の困難性が伴うため未だ実現されていない。
【０００８】
【発明が解決しようとする課題】
従って、本発明の目的は、Ｒ１Ｂａ２Ｃｕ３Ｏ７の針状結晶の製造方法を確立し、極めて欠陥の少ない高品位針状結晶を製造して、未だ実現していない超伝導エレクトロニクス素子実用化への道を拓くことである。
具体的には、本発明は、超伝導デバイス素子の実現に不可欠である欠陥が極めて少ない酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７の針状結晶を提供することを目的とする。
【０００９】
また、本発明の他の目的は、上記酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７の針状結晶を、容易にかつ効率的に製造することができる経済的な酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７の針状結晶の製造方法を提供することである。
【００１０】
【課題を解決するための手段】
本発明者らは、上記目的を達成するため、Ｒ１Ｂａ２Ｃｕ３Ｏ７（但し、Ｒは希土類元素を示す）で表される原子比組成を有する酸化物に、ＴｅＯ２とＣａＯを一定の割合で複合含有した酸化物を、即ち、酸化物超伝導体を構成する各元素にＴｅとＣａを複合含有させたＲ１Ｂａ２Ｃｕ３Ｔｅ０．２〜０．８Ｃａ０．４〜２．４Ｏｘ（Ｒ：希土類元素）原子比組成の酸化物を、出発材料とすることにより、当該酸化物から直接、極めて欠陥の少ないＲ１Ｂａ２Ｃｕ３Ｏ７の酸化物超伝導体針状結晶を製造できることを見出し、本発明に到達するに至った。
【００１１】
本発明による酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶は、
下記の式；
Ｒ１Ｂａ２Ｃｕ３Ｔｅ０．２〜０．８Ｃａ０．４〜２．４Ｏｘ
（但し、Ｒは希土類元素を示す）
で表される原子比組成を有する酸化物から針状形態で得られる。
【００１２】
好適には、上記酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶において、前記（１）式で表される酸化物の粉末の圧縮成形体を、５〜１００％酸素雰囲気中、９００〜９９０℃で熱処理することにより、前記成形体からＲ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶形態が得られる。
【００１３】
本発明の酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶の製造方法は、
下記の式（１）；
Ｒ１Ｂａ２Ｃｕ３Ｏ７（１）
（但し、Ｒは希土類元素を示す）
で表される原子比組成を有する酸化物１モルに、ＴｅＯ２を０．２〜０．８モルとＣａＯを０．４〜２．４モルの割合で複合含有させた圧縮成形体を、５〜１００％酸素雰囲気中、９００〜９９０℃で熱処理することにより、前記成形体からＲ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶に育成されて形成されることを特徴とする。
【００１４】
【発明の実施の形態】
本発明を、好適例を挙げて以下に詳細に説明するが、これらに限定されるものではない。
本発明による酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶は、下記の
化学式；
Ｒ１Ｂａ２Ｃｕ３Ｔｅ０．２〜０．８Ｃａ０．４〜２．４Ｏｘ
（但し、Ｒは希土類元素を示す）
で表される原子比組成を有する酸化物から針状形態で得られるものである。
【００１５】
上記化学式で表される酸化物は、下記の式（１）；
Ｒ１Ｂａ２Ｃｕ３Ｏ７（１）
（但し、Ｒは希土類元素を示す）
で表される原子比組成を有する酸化物１モルに、ＴｅＯ２を０．２〜０．８モルとＣａＯを０．４〜２．４モルの割合で複合含有させた圧縮成形体である。
【００１６】
本発明の酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶を製造する際に、上記式（１）で表される原子比組成を有する酸化物に、ＴｅとＣａを複合含有させることが、当該針状結晶を有効に育成する点から最も重要なことである。
【００１７】
針状結晶は、酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７と圧縮成形体Ｒ１Ｂａ２Ｃｕ３Ｔｅ０．２〜０．８Ｃａ０．４〜２．４Ｏｘとの融点の差が大きいほど成長が促進される。
そこで、成形体の融点を低くするＴｅＯ２を、酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７の仕込み組成に含有させることが極めて有効であり、Ｒ１Ｂａ２Ｃｕ３Ｏ７１モルに対して、ＴｅＯ２を０．２〜０．８モル含有させることにより針状結晶が成長し、特に０．５モル含有近傍でその効果が最も大きい。
【００１８】
しかし、かかるＴｅＯ２を含有させた場合に育成された針状結晶には、Ｔｅが含まれていない。
この育成針状結晶は、超伝導を示さず、これは、針状結晶の成長過程で、成形体中にＢａ３Ｔｅ１Ｏ６が生成し、その結果Ｂａが欠乏してＲ２Ｃｕ３Ｏ６結晶構造の針状結晶が成長するためである。
【００１９】
一方、本発明者においては、上記成形体へＴｅとＣａとを複合含有させることにより、ＲｌＢａ２Ｃｕ３Ｏ７結晶構造の針状結晶を育成した。
すなわち、Ｔｅの他に、Ｃａをも含有させることによって、成形体中に（ＢａＣａ）３Ｔｅ１Ｏ６が生成するようになるとともに、Ｂａサイトの一部をＣａが置換して、Ｂａの欠乏を補うことができるのである。
【００２０】
かかるＣａの含有量は、Ｔｅの含有量の２〜３倍程度が最も効果的であり、Ｒ１Ｂａ２Ｃｕ３Ｏ７１モルに対して、ＣａＯを０．４〜２．４モル含有させることが望ましい。
このように、当該ＴｅとＣａとの複合含有によって、酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶を効果的に成長させることができる。
【００２１】
また、本発明により酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶を製造する際には、熱処理の温度と雰囲気の最適化が必要とされる。
具体的には、Ｒ１Ｂａ２Ｃｕ３Ｏ７の針状結晶は、熱処理の温度９００〜９９０℃、雰囲気の酸素割合５〜１００％において好適に成長することができる。特に好ましい最適条件は、熱処理の温度が９６５℃で、雰囲気の酸素割合が２０％の場合である。
【００２２】
【実施例】
［実施例１〜５、比較例１〜６］
［ＴｅとＣａの複合含有の効果］
酸化物超伝導体Ｙ１Ｂａ２Ｃｕ３Ｏ７結晶構造を構成する元素の酸化物Ｙ２Ｏ３、ＣｕＯ及び炭酸塩ＢａＣＯ３の各粉末に、更に酸化物ＴｅＯ２と炭酸塩ＣａＣＯ３粉末を、表１に示す割合で複合含有させたＹ１Ｂａ２Ｃｕ３Ｔｅ０．２〜０．８Ｃａ０．４〜２．４Ｏｘ原子比組成の混合粉末を、８２０℃で１０時間仮焼した後、直径φ１５ｍｍ、厚さ２ｍｍの圧縮成形体を作製した。
【００２３】
ここで、アルカリ土類元素に関して炭酸塩を用いたのは、酸化物より取り扱いが容易なためであり、ＢａＣＯ３、ＣａＣＯ３粉末のかわりに、ＢａＯ、ＣａＯ粉末を用いてもよい。
【００２４】
この圧縮成形体を２０％酸素雰囲気中、９６５℃で５時間熱処理した後、室温まで１２時間をかけて冷却し、成形体から針状結晶を育成した。
育成された針状結晶の構造および長さを表１に示す。
【００２５】
【表１】
Ｔｅの含有量が０．２〜０．８モルにおいて針状結晶が成長し、０．５モル近傍で最も成長がよいことがわかる。
【００２７】
しかし、比較例１〜６で得られた針状結晶はＢａを含有しない非超伝導のＹ２Ｃｕ３Ｏ６構造を有するものである。
これは、上記したように、針状結晶の成長過程で成形体にＢａ３Ｔｅ１Ｏ６が生成し、Ｂａが欠乏するためである。
【００２８】
一方、実施例１〜５で得られた針状結晶は、成形体にＴｅとＣａを複合含有させることによって、Ｙ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶が成長したことがわかる。
【００２９】
即ち、ＴｅとＣａとを複合含有することによって、成形体中に（ＢａＣａ）３Ｔｅ１Ｏ６が生成するとともに、Ｂａサイトの一部がＣａで置換されてＢａの欠乏を補うからである。
【００３０】
従って、Ｃａの含有量は、Ｔｅ量の２〜３倍程度の０．４〜２．４モルが好適である。
最も成長が良好で結晶性のよいＹ１Ｂａ２Ｃｕ３Ｏ７の針状結晶は、Ｔｅの含有量が０．５、Ｃａの含有量が１．０の複合含有における場合である。
【００３１】
ここで、図１に、Ｙ２Ｃｕ３Ｏ６結晶構造の針状結晶とＹ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶の電気抵抗と温度の関係を示す。かかる測定は、直流４端子法で測定した値である。
Ｙ１Ｂａ２Ｃｕ３Ｏ７針状結晶は、９０Ｋ近傍で超伝導遷移が発現し、超伝導体であるが、Ｙ２Ｃｕ３Ｏ６針状結晶は、超伝導遷移が現れず、常伝導体であることが明らかである。
【００３２】
［実施例６〜９］
［希土類元素の置換］
酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７結晶構造においては、希土類元素Ｒを相互に置換することが可能である。上記実施例１〜５におけるＲがＹの場合に代えて、表２で示す希土類元素を用いて、上記実施例１〜５と同様の方法で針状結晶を育成した。
その結果を表２に示す。
【００３３】
【表２】
表２から、希土類元素を置換しても、針状結晶の構造および成長に影響のないことが明らかとなった。
【００３５】
［実施例１０〜１４、比較例７〜９］
［熱処理の温度と雰囲気の効果］
Ｙ１Ｂａ２Ｃｕ３Ｔｅ０．５Ｃａ１．０Ｏｘ原子比組成の混合粉末を、８２０℃で１０時間仮焼した後、圧縮成形体を作製した。
かかる圧縮成形体を、表３に示す温度と雰囲気の酸素割合を変えて、５時間熱処した後、室温まで１２時間かけて冷却し、成形体から針状結晶を育成した。
表３には、熱処理の温度と雰囲気の酸素割合を変化させた際に育成した針状結晶の長さを示す。
【００３６】
【表３】
表３より、針状結晶は、熱処理温度９００〜９９０℃において成長し、９６５℃のとき最も成長が良好である。また、針状結晶は、雰囲気の酸素割合５〜１００％において成長し、２０％のときが最も成長が良好である。
更に、熱処理の最適条件は、温度９６５℃、雰囲気の酸索割合２０％の場合が最適であることもわかる。
【００３８】
上記実施例１〜１４で得られた、本発明の針状結晶は、Ｘ線回折装置（理学電機ＲＩＮＴ１２００）、電子線マイクロアナライザー（島津製作所ＥＰＭＡ８７０５）、エネルギー分散スペクトロメータ（ＰＨＩＬＩＰＳ ＥＤＡＸ ＰＶ９８００）で調べたところ、これらの針状結晶は、酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７結晶構造の単結晶構造であり、かかる単結晶構造中には、母相の融点を低くする元素Ｔｅが含有されていないことが明らかとなった。
【００３９】
【発明の効果】
本発明により得られた酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７の針状結晶は、極めて欠陥の少ない高品位針状結晶であり、当該針状結晶を提供することによって、現在理論的に提案されているが未だ実現していない超伝導エレクトロニクス素子の開発に貢献することができることとなる。すなわち、従来不可能な領域であった高周波・高速スイッチング素子を実現することができ、特に情報関連技術にブレークスルーをもたらすことが可能となる。
【００４０】
また、本発明の酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７の針状結晶の製造方法は、上記本発明の酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７の針状結晶を効率よく育成することができるものであり、超伝導エレクトロニクス分野に貢献することができる。
【００４１】
【図面の簡単な説明】
【図１】本発明のＹ１Ｂａ２Ｃｕ３Ｏ７針状結晶と、Ｙ２Ｃｕ３Ｏ６針状結晶の超伝導性を示した、温度と電気抵抗との関係の線図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an oxide superconductor acicular crystal, and in particular, an acicular single crystal that is indispensable for realizing a superconducting electronic device and has few defects of an oxide superconductor, ie, The present invention relates to a method for producing an oxide superconductor needle crystal that is very close to a perfect crystal.
[0002]
[Prior art]
A single crystal of an oxide superconductor has a crystal structure in which conductive layers and non-conductive layers are alternately stacked, and each layer is formed by intrinsic Josephson coupling.
In recent years, single crystal switching element devices using such intrinsic Josephson effect have been proposed. This new single-crystal switching element can be reduced in size to about 1/100 of the conventional one using a Josephson junction, the switching speed is about 100 times faster, and the operating frequency is expected to be THz (terahertz). ing.
[0003]
In addition, it is now clear that a superconducting single-electron tunneling phenomenon in which electron pairs pass one by one occurs in a submicron crystal device manufactured using an acicular crystal of an oxide superconductor.
In order to generate such a superconducting single electron tunnel phenomenon, it is necessary to operate at a liquid helium temperature (4.2 K). However, if the number of crystal unit cells is about 1000, the liquid nitrogen temperature (77 K) is used. It is expected that a working superconducting single-pair device can be realized.
In order to realize these elements, single crystals having no defects or very few defects are required.
[0004]
The oxide superconductor from a practical viewpoint includes (BiPb) 2 Sr 2 Ca 2 Cu 3 O 10 with a superconducting critical temperature of about 110 K, Bi 2 Sr 2 Ca 1 Cu 2 O 8 with about 80 K, and about 90 K. A crystal structure of R 1 Ba 2 Cu 3 O 7 (R represents a rare earth element) is known.
[0005]
The inventors have (BiPb) 2 Sr 2 Ca 2 Cu 3 O 10 , Bi 2 Sr 2 Ca 1 Cu 2 O 8 composition, a compression molded body containing an element that reduces its melting point, a step by rapid cooling, And succeeded in growing acicular crystals of (BiPb) 2 Sr 2 Ca 2 Cu 3 O 10 and Bi 2 Sr 2 Ca 1 Cu 2 O 8 with extremely good crystallinity without going through an amorphization step. Have already filed a patent application. (Japanese Patent Application Nos. 2001-38170 and 2001-224741).
[0006]
On the other hand, R 1 Ba 2 Cu 3 O 7 (R is selected from the group consisting of Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu) is (BiPb) 2. Compared with Sr 2 Ca 2 Cu 3 0 10 and Bi 2 Sr 2 Ca 1 Cu 2 O 8 , the pinning of the magnetic flux quantum is strong, and the critical current characteristics in a high temperature and magnetic field are good. There is a strong demand for the growth of crystal-like crystals.
[0007]
However, until now, such oxide superconductors R 1 Ba 2 Cu 3 O 7 (R is from the group consisting of Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu. The growth of the needle-like crystals of the selected system has not been realized yet because of the difficulty in determining the composition of the starting material.
[0008]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to establish a method for producing a needle crystal of R 1 Ba 2 Cu 3 O 7 , to produce a high-quality needle crystal with very few defects, and has not yet been realized. It is to open the way to practical use.
Specifically, the present invention is directed to purpose thereof is to provide a needle-like crystals of superconducting defect is essential to the realization of the device element is very small oxide superconductor R 1 Ba 2 Cu 3 O 7 .
[0009]
Another object of the present invention is to provide an economical oxide superconductor R that can easily and efficiently produce needle crystals of the oxide superconductor R 1 Ba 2 Cu 3 O 7. it is to provide a method for producing 1 Ba 2 Cu 3 needle crystal O 7.
[0010]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present inventors have made TeO 2 and CaO constant in an oxide having an atomic ratio composition represented by R 1 Ba 2 Cu 3 O 7 (where R represents a rare earth element). the oxide containing composite in a ratio of, i.e., oxide superconductors to each element constituting the and the Te and Ca are contained complex R 1 Ba 2 Cu 3 Te 0.2~0.8 Ca 0.4~ 2.4 O x (R: rare earth element) An oxide superconductor of R 1 Ba 2 Cu 3 O 7 having few defects directly from the oxide by using an oxide having an atomic ratio composition as a starting material. The inventors have found that acicular crystals can be produced, and have reached the present invention.
[0011]
The acicular crystals of the oxide superconductor R 1 Ba 2 Cu 3 O 7 crystal structure according to the present invention are:
The following formula:
R 1 Ba 2 Cu 3 Te 0.2~0.8 Ca 0.4~2.4 O x
(However, R represents a rare earth element)
In Ru obtained in acicular form an oxide having an atomic ratio composition represented.
[0012]
Preferably, in the needle-like crystal having the oxide superconductor R 1 Ba 2 Cu 3 O 7 crystal structure, the oxide powder compression-molded body represented by the formula (1) is 5 to 100% oxygen. atmosphere, by heat treatment at nine hundred to nine hundred ninety ° C., Ru acicular crystal form of R 1 Ba 2 Cu 3 O 7 crystal structure is obtained from the green body.
[0013]
The manufacturing method of the acicular crystal of the oxide superconductor R 1 Ba 2 Cu 3 O 7 crystal structure of the present invention is as follows:
The following formula ( 1 );
R 1 Ba 2 Cu 3 O 7 ( 1 )
(However, R represents a rare earth element)
A compression molded body in which 0.2 mol of TeO 2 and 0.4 mol of CaO are combined in a ratio of 0.4 to 2.4 mol in 1 mol of an oxide having an atomic ratio composition represented by 5 It is characterized in that it is grown and formed into a needle-like crystal having an R 1 Ba 2 Cu 3 O 7 crystal structure from the molded body by heat treatment at 900 to 990 ° C. in an atmosphere of ˜100% oxygen.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below with reference to preferred examples, but is not limited thereto.
The acicular crystal of the oxide superconductor R 1 Ba 2 Cu 3 O 7 crystal structure according to the present invention has the following chemical formula:
R 1 Ba 2 Cu 3 Te 0.2~0.8 Ca 0.4~2.4 O x
(However, R represents a rare earth element)
It is obtained in an acicular form from an oxide having an atomic ratio composition represented by:
[0015]
The oxide represented by the chemical formula is represented by the following formula ( 1 );
R 1 Ba 2 Cu 3 O 7 ( 1 )
(However, R represents a rare earth element)
This is a compression-molded product in which 1 mol of the oxide having an atomic ratio composition represented by the formula is combined with 0.2 to 0.8 mol of TeO 2 and 0.4 to 2.4 mol of CaO.
[0016]
When manufacturing the needle crystal of the oxide superconductor R 1 Ba 2 Cu 3 O 7 crystal structure of the present invention, Te and Ca are added to the oxide having the atomic ratio composition represented by the above formula ( 1 ). It is the most important to make it contain together from the point which grows the said acicular crystal | crystallization effectively.
[0017]
The acicular crystal has a melting point of the oxide superconductor R 1 Ba 2 Cu 3 O 7 and the compression molded body R 1 Ba 2 Cu 3 Te 0.2 to 0.8 Ca 0.4 to 2.4 O x . The larger the difference, the more growth is promoted.
Therefore, it is extremely effective to contain TeO 2 that lowers the melting point of the molded body in the preparation composition of the oxide superconductor R 1 Ba 2 Cu 3 O 7 , and 1 mol of R 1 Ba 2 Cu 3 O 7 On the other hand, acicular crystals grow by containing 0.2 to 0.8 mol of TeO 2 , and the effect is greatest particularly in the vicinity of containing 0.5 mol.
[0018]
However, Te is not contained in the acicular crystal grown when such TeO 2 is contained.
This grown acicular crystal does not show superconductivity, and this is because Ba 3 Te 1 O 6 is formed in the compact during the growth of the acicular crystal, and as a result, Ba is deficient and R 2 Cu 3 O This is because acicular crystals having a six- crystal structure grow.
[0019]
On the other hand, in the present inventor, needle-like crystals having an R 1 Ba 2 Cu 3 O 7 crystal structure were grown by compounding Te and Ca into the molded body.
That is, by containing Ca in addition to Te, (BaCa) 3 Te 1 O 6 comes to be formed in the molded body, and at the same time, a part of the Ba site is replaced by Ca, resulting in a deficiency of Ba. Can be supplemented.
[0020]
The Ca content is most effective about 2 to 3 times the Te content, and 0.4 to 2.4 mol of CaO is contained with respect to 1 mol of R 1 Ba 2 Cu 3 O 7 . It is desirable.
Thus, the combined content of the Te and Ca, it is possible to effectively grow the acicular crystals of the oxide superconductor R 1 Ba 2 Cu 3 O 7 crystal structure.
[0021]
Also, when manufacturing the needle-like crystals of the oxide superconductor R 1 Ba 2 Cu 3 O 7 crystal structure according to the present invention is required to optimize the temperature and atmosphere of the heat treatment.
Specifically, the needle crystal of R 1 Ba 2 Cu 3 O 7 can be suitably grown at a heat treatment temperature of 900 to 990 ° C. and an oxygen ratio of the atmosphere of 5 to 100%. Particularly preferable optimum conditions are when the heat treatment temperature is 965 ° C. and the oxygen ratio of the atmosphere is 20%.
[0022]
【Example】
[Examples 1-5, Comparative Examples 1-6]
[Effects of containing Te and Ca in combination]
Oxide superconductor Y 1 Ba 2 Cu 3 O 7 Oxide TeO 2 and carbonate CaCO 3 powder are further added to each powder of oxide Y 2 O 3 , CuO and carbonate BaCO 3 of the elements constituting the crystal structure. The mixed powder of Y 1 Ba 2 Cu 3 Te 0.2 to 0.8 Ca 0.4 to 2.4 O x atomic ratio composition mixedly contained in the ratio shown in Table 1 is calcined at 820 ° C. for 10 hours. After that, a compression molded body having a diameter of 15 mm and a thickness of 2 mm was produced.
[0023]
Here, the reason why carbonates are used for alkaline earth elements is that they are easier to handle than oxides, and BaO 3 and CaO 3 powders may be used instead of BaCO 3 and CaCO 3 powders.
[0024]
This compression-molded body was heat-treated at 965 ° C. for 5 hours in a 20% oxygen atmosphere and then cooled to room temperature over 12 hours to grow acicular crystals from the molded body.
Table 1 shows the structure and length of the grown needle crystal.
[0025]
[Table 1]
It can be seen that needle-like crystals grow when the Te content is 0.2 to 0.8 mol, and the growth is best near 0.5 mol.
[0027]
However, the acicular crystals obtained in Comparative Examples 1 to 6 have a non-superconducting Y 2 Cu 3 O 6 structure that does not contain Ba.
This is because, as described above, Ba 3 Te 1 O 6 is generated in the compact during the growth of the needle-like crystals, and Ba is deficient.
[0028]
On the other hand, it can be seen that the needle crystals obtained in Examples 1 to 5 were obtained by growing a needle crystal having a Y 1 Ba 2 Cu 3 O 7 crystal structure by incorporating Te and Ca into the compact.
[0029]
That is, by containing Te and Ca in combination, (BaCa) 3 Te 1 O 6 is generated in the molded body, and part of the Ba site is replaced with Ca to compensate for the deficiency of Ba.
[0030]
Therefore, the content of Ca is preferably 0.4 to 2.4 mol, which is about 2 to 3 times the amount of Te.
The needle-like crystal of Y 1 Ba 2 Cu 3 O 7 having the best growth and good crystallinity is in the case of a composite content in which the Te content is 0.5 and the Ca content is 1.0.
[0031]
Here, FIG. 1 shows the relationship between the electrical resistance and temperature of a needle crystal having a Y 2 Cu 3 O 6 crystal structure and a needle crystal having a Y 1 Ba 2 Cu 3 O 7 crystal structure. This measurement is a value measured by the direct current four-terminal method.
The Y 1 Ba 2 Cu 3 O 7 needle crystal has a superconducting transition in the vicinity of 90K and is a superconductor. However, the Y 2 Cu 3 O 6 needle crystal does not exhibit a superconducting transition and is normal. It is clear that it is a body.
[0032]
[Examples 6 to 9]
[Replacement of rare earth elements]
In the oxide superconductor R 1 Ba 2 Cu 3 O 7 crystal structure, the rare earth elements R can be substituted for each other. Instead of the case where R in Examples 1 to 5 is Y, needle crystals were grown in the same manner as in Examples 1 to 5 using rare earth elements shown in Table 2.
The results are shown in Table 2.
[0033]
[Table 2]
From Table 2, it has become clear that substitution of rare earth elements has no effect on the structure and growth of needle crystals.
[0035]
[Examples 10-14, Comparative Examples 7-9]
[Effects of heat treatment temperature and atmosphere]
A mixed powder having a Y 1 Ba 2 Cu 3 Te 0.5 Ca 1.0 O x atomic ratio composition was calcined at 820 ° C. for 10 hours, and then a compression molded body was produced.
The compression molded body was heat-treated for 5 hours while changing the temperature and the oxygen ratio in the atmosphere shown in Table 3, and then cooled to room temperature over 12 hours to grow acicular crystals from the molded body.
Table 3 shows the lengths of the needle crystals grown when the temperature of the heat treatment and the oxygen ratio in the atmosphere are changed.
[0036]
[Table 3]
From Table 3, the acicular crystal grows at a heat treatment temperature of 900 to 990 ° C. and grows best at 965 ° C. Further, the needle-like crystal grows at an oxygen ratio of 5 to 100% in the atmosphere, and the growth is best when it is 20%.
It can also be seen that the optimum conditions for the heat treatment are optimum when the temperature is 965 ° C. and the acid cord ratio in the atmosphere is 20%.
[0038]
The acicular crystals of the present invention obtained in Examples 1 to 14 above were examined with an X-ray diffractometer (Rigaku Denki RINT1200), an electron beam microanalyzer (Shimadzu Corporation EPMA 8705), and an energy dispersive spectrometer (PHILIPS EDAX PV9800). As a result, these acicular crystals have a single crystal structure of the oxide superconductor R 1 Ba 2 Cu 3 O 7 crystal structure, and in this single crystal structure, the element Te that lowers the melting point of the parent phase is contained. It became clear that it was not contained.
[0039]
【The invention's effect】
The acicular crystals of the oxide superconductor R 1 Ba 2 Cu 3 O 7 obtained according to the present invention are high-quality acicular crystals with extremely few defects. Therefore, it is possible to contribute to the development of superconducting electronics devices that have been proposed but not yet realized. That is, it is possible to realize a high-frequency / high-speed switching element that has been impossible in the past, and it is possible to bring a breakthrough particularly to information-related technologies.
[0040]
A method of manufacturing a needle-like crystals of the oxide superconductor R 1 Ba 2 Cu 3 O 7 of the present invention, the efficiency needle-like crystals of the oxide superconductor R 1 Ba 2 Cu 3 O 7 of the present invention It can be cultivated well and can contribute to the superconducting electronics field.
[0041]
[Brief description of the drawings]
FIG. 1 is a diagram of the relationship between temperature and electrical resistance, showing the superconductivity of Y 1 Ba 2 Cu 3 O 7 needle crystals and Y 2 Cu 3 O 6 needle crystals of the present invention.
Claims (1)
Ｒ１Ｂａ２Ｃｕ３Ｏ７（１）
（但し、Ｒは希土類元素を示す）
で表される原子比組成を有する酸化物１モルに、ＴｅＯ２を０．２〜０．８モルとＣａＯを０．４〜２．４モルの割合で複合含有させた圧縮成形体を、５〜１００％酸素雰囲気中、９００〜９９０℃で熱処理することにより、前記成形体からＲ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶に育成されて形成されることを特徴とする酸化物超伝導体Ｒ１Ｂａ２Ｃｕ３Ｏ７結晶構造の針状結晶の製造方法。The following formula ( 1 );
R 1 Ba 2 Cu 3 O 7 ( 1 )
(However, R represents a rare earth element)
A compression molded body in which 0.2 mol of TeO 2 and 0.4 mol to 2.4 mol of CaO are mixedly contained in 1 mol of an oxide having an atomic ratio composition represented by 5 An oxide superstructure characterized by being formed by growing into a needle-like crystal having an R 1 Ba 2 Cu 3 O 7 crystal structure from the molded body by heat treatment at 900 to 990 ° C. in an atmosphere of 100% oxygen. method for producing a needle-like crystals of the conductor R 1 Ba 2 Cu 3 O 7 crystal structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002133493A JP3910483B2 (en) | 2002-05-09 | 2002-05-09 | Method for producing oxide superconductor needle crystal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002133493A JP3910483B2 (en) | 2002-05-09 | 2002-05-09 | Method for producing oxide superconductor needle crystal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2003327498A JP2003327498A (en) | 2003-11-19 |
| JP3910483B2 true JP3910483B2 (en) | 2007-04-25 |
Family
ID=29696458
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2002133493A Expired - Fee Related JP3910483B2 (en) | 2002-05-09 | 2002-05-09 | Method for producing oxide superconductor needle crystal |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3910483B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4650721B2 (en) * | 2005-02-16 | 2011-03-16 | 日産自動車株式会社 | Whisker forming body and electrochemical capacitor using the same |
| JP5196368B2 (en) * | 2008-02-21 | 2013-05-15 | 独立行政法人物質・材料研究機構 | Oxide superconductor and manufacturing method thereof |
| CN109943890B (en) * | 2019-03-21 | 2021-02-12 | 上海交通大学 | Method for growing REBCO high-temperature superconducting crystal by using precursor component |
-
2002
- 2002-05-09 JP JP2002133493A patent/JP3910483B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2003327498A (en) | 2003-11-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4921834A (en) | Flux method of growing oxide superconductors | |
| JP3910483B2 (en) | Method for producing oxide superconductor needle crystal | |
| JPH04500196A (en) | Superconducting metal oxide composition | |
| JP2950422B2 (en) | Metal oxide material | |
| JP5196368B2 (en) | Oxide superconductor and manufacturing method thereof | |
| US5108986A (en) | Substituted YiBa2 Cu3 oxide superconductor | |
| JP2006045028A (en) | Needle-like crystal of oxide superconductor and method of producing the same | |
| JP3217905B2 (en) | Metal oxide material and method for producing the same | |
| JP2558695B2 (en) | Method for manufacturing oxide superconducting wire | |
| US6599862B2 (en) | Method for preparing bismuth-based high temperature superconductors | |
| JP3681768B2 (en) | Layered copper oxide and method for producing the same | |
| JP4141666B2 (en) | Method for producing oxide high temperature superconductor needle crystal | |
| JP3889139B2 (en) | Oxide superconductor containing silver and method for producing the same | |
| US5399312A (en) | Method for fabricating high-jc thallium-based superconducting tape | |
| JP4094238B2 (en) | Method for producing acicular crystals of high-temperature superconducting oxide | |
| JP2656531B2 (en) | Oxide superconductor | |
| JPH0769626A (en) | Metal oxide and production thereof | |
| JP2761727B2 (en) | Manufacturing method of oxide superconductor | |
| JPH01145364A (en) | Production of high-temperature superconducting ceramics | |
| JP2709000B2 (en) | Superconductor and method of manufacturing the same | |
| JPH0725639B2 (en) | Superconducting fibrous crystal, single crystal and method for producing the same | |
| JPH0446015A (en) | Oxide superconducting material and its production | |
| JPH01111715A (en) | Production of superconductor member | |
| JPH04501407A (en) | Superconducting metal oxide composition and method for producing and using the same | |
| JPH06157041A (en) | Lead complex copper oxide material |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| RD03 | Notification of appointment of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7423 Effective date: 20040210 |
|
| RD02 | Notification of acceptance of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7422 Effective date: 20040628 |
|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20040629 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20060502 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20060920 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20061120 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20070117 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20070124 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110202 Year of fee payment: 4 |
|
| LAPS | Cancellation because of no payment of annual fees |