JPH01157451A - Production of oxide superconducting sintered body - Google Patents
Production of oxide superconducting sintered bodyInfo
- Publication number
- JPH01157451A JPH01157451A JP62314362A JP31436287A JPH01157451A JP H01157451 A JPH01157451 A JP H01157451A JP 62314362 A JP62314362 A JP 62314362A JP 31436287 A JP31436287 A JP 31436287A JP H01157451 A JPH01157451 A JP H01157451A
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- sintered body
- oxide superconductor
- oxide
- oxide superconducting
- 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.)
- Pending
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 19
- 239000002887 superconductor Substances 0.000 claims abstract description 38
- 238000010438 heat treatment Methods 0.000 claims abstract description 30
- 238000005245 sintering Methods 0.000 claims abstract description 30
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 20
- 239000001301 oxygen Substances 0.000 claims abstract description 20
- 239000000843 powder Substances 0.000 claims abstract description 15
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 9
- 230000002950 deficient Effects 0.000 claims abstract description 7
- 229910052788 barium Inorganic materials 0.000 claims abstract description 4
- 229910052802 copper Inorganic materials 0.000 claims abstract description 3
- 238000000034 method Methods 0.000 claims description 11
- 230000007547 defect Effects 0.000 claims description 7
- 239000011812 mixed powder Substances 0.000 claims description 4
- 239000013078 crystal Substances 0.000 abstract description 19
- 239000002245 particle Substances 0.000 abstract description 5
- 239000000203 mixture Substances 0.000 abstract description 4
- 229910052727 yttrium Inorganic materials 0.000 abstract description 4
- 238000000465 moulding Methods 0.000 abstract description 3
- 230000003028 elevating effect Effects 0.000 abstract 2
- 125000004430 oxygen atom Chemical group O* 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 3
- 238000010304 firing Methods 0.000 description 3
- 229910052746 lanthanum Inorganic materials 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 229910052706 scandium Inorganic materials 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910052692 Dysprosium Inorganic materials 0.000 description 2
- 229910052688 Gadolinium Inorganic materials 0.000 description 2
- 229910052689 Holmium Inorganic materials 0.000 description 2
- 229910052779 Neodymium Inorganic materials 0.000 description 2
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 229910020647 Co-O Inorganic materials 0.000 description 1
- 229910020704 Co—O Inorganic materials 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910052770 Uranium Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000003776 cleavage reaction Methods 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 230000007017 scission Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
Landscapes
- Compositions Of Oxide Ceramics (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
Abstract
Description
【発明の詳細な説明】
［発明の目的］
（産業上の利用分野）
本発明は、結晶の配向性に優れた酸化物超電導焼結体の
製造方法に関する。Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing an oxide superconducting sintered body with excellent crystal orientation.
（従来の技術）
近年、Ｂａ−Ｌａ−Ｃｕ−０系の層状ペロブスカイト型
の酸化物が高い臨界温度を有する可能性のあることが発
表されて以来、各所で酸化物超電導体の研究が行われテ
ィる（Ｚ、Ｐｈｙｓ、Ｂ Ｃｏｎｄｅｎｓｅｄ Ｍａｔ
ｔｅｒ６４、１８９−１９３（１９８６１）。その中で
も、ＬｎＢａ２Ｃｕ３Ｏ７−δ（δは酸素欠陥を表わし
通常１以下、ｔｎは、Ｙ 、 Ｌａ、 Ｓｃ、 Ｎｄ、
Ｓｎ＋１Ｅｕ、 Ｇｄ、 Ｄｙ、 Ｈｏ、 Ｅｒ、
Ｔｍ。(Prior Art) In recent years, it has been announced that layered perovskite-type oxides based on Ba-La-Cu-0 may have a high critical temperature, and since then, research on oxide superconductors has been carried out in various places. Tiru (Z, Phys, B Condensed Mat
ter64, 189-193 (19861). Among them, LnBa2Cu3O7-δ (δ represents oxygen defect and is usually 1 or less, tn is Y, La, Sc, Nd,
Sn+1Eu, Gd, Dy, Ho, Er,
Tm.
Ｙｂおよび［Ｕから選ばれた少なくとも１種の元素、Ｂ
ａの一部はＳｒなどで置換可能。）で示される酸素欠陥
を有する欠陥ペロブスカイト型の酸化物超電導体は、臨
界温度が９０に以上と液体窒素の沸点以上の高い温度を
示すため非常に有望な材料として注目されている（Ｐｈ
ｙｓ、Ｒｅｖ、Ｌｅｔｔ、 Ｖｏｌ、５８ Ｎｏ。９，
９０８−９１０）。At least one element selected from Yb and [U, B
A part of a can be replaced with Sr, etc. The defective perovskite-type oxide superconductor with oxygen vacancies shown in ) is attracting attention as a very promising material because it exhibits a critical temperature of 90 or higher, which is higher than the boiling point of liquid nitrogen (Ph
ys, Rev. Lett, Vol. 58 No. 9,
908-910).
このような酸化物角ｆｆｆ導体は、結晶性の酸化物であ
るため、これらを各種形状の超電導部材として利用する
場合には、次のような方法により製造することが考えら
れている。Since such oxide angle fff conductors are crystalline oxides, when they are used as superconducting members of various shapes, it is considered that they can be manufactured by the following method.
すなわち、まず目的とする酸化物超電導体の構成元素を
含有する各出発原料を所定の比率で混合し、この混合粉
末を−Ｕ仮焼して結晶化させる。That is, first, starting materials containing constituent elements of the desired oxide superconductor are mixed at a predetermined ratio, and this mixed powder is calcined by -U to crystallize it.
次いで、この仮焼物を粉砕した模にプレス成形などによ
り所要の形状とする。この後、所定の温度で焼成し、さ
らに必要に応じて十分に酸素の供給できる雰囲気中で７
ニーリングを行い超電導特性を向上させ、酸化物超電導
体を青る。Next, this calcined product is pressed into a desired shape by press molding or the like into a pulverized model. After that, it is fired at a predetermined temperature, and if necessary, it is heated for 7 days in an atmosphere where sufficient oxygen can be supplied.
Knealing is performed to improve the superconducting properties and turn the oxide superconductor blue.
（発明が解決しようとする問題点）
しかしながら、上述したような酸化物超電導体は、結晶
性の酸化物であって、その結晶の０面に沿って超電導電
流が流れるという性質を有しているため、上述したよう
に酸化物超電導体粉末を単に焼結させただけでは、結晶
の配列方向がランダムとなり、充分に実用的な電流密度
が得られないという問題があった。(Problems to be Solved by the Invention) However, the above-mentioned oxide superconductor is a crystalline oxide, and has the property that superconducting current flows along the zero plane of the crystal. Therefore, as described above, simply sintering the oxide superconductor powder has the problem that the orientation of the crystals becomes random and a sufficiently practical current density cannot be obtained.
本発明は、このような従来の問題点を解決するためにな
されたもので、結晶の０面を一定方向に配向させること
により、臨界電流密度などの超電導特性を向上させた酸
化物超電導焼結体を製造する方法を提供することを目的
とする。The present invention was made to solve these conventional problems, and it is an oxide superconducting sintered material that improves superconducting properties such as critical current density by orienting the zero plane of the crystal in a certain direction. The purpose is to provide a method for manufacturing the body.
［発明の構成］
（問題点を解決するための手段）
本発明の酸化物超電導焼結体の製造方法は、酸化物超電
導体粉末または加熱により酸化物超電導体となる混合粉
末を所要の形状に成形し、次いで得られた成形体を焼結
ｉ度まで昇温し、この焼結温度で所定時間保持して酸化
物超電導焼結体を製造するにあたり、前記焼結温度への
昇温過程で、温度勾配の緩かな予備加熱工程を行った後
、局部的な加熱を行うことにより所定方向の急激な温度
勾配をもたせて前記焼結温度まで昇温する局部加熱工程
を行うことを特徴としている。[Structure of the Invention] (Means for Solving the Problems) The method for producing an oxide superconducting sintered body of the present invention involves shaping an oxide superconductor powder or a mixed powder that becomes an oxide superconductor by heating into a desired shape. The molded body is then heated to sintering temperature and held at this sintering temperature for a predetermined period of time to produce an oxide superconducting sintered body. , after performing a preheating step with a gentle temperature gradient, a local heating step is performed in which the temperature is raised to the sintering temperature with a steep temperature gradient in a predetermined direction by performing local heating. .
酸化物超電導体としては多数のものが知られているが、
臨界温度の高い、希土類元素含有のペロブスカイト型の
酸化物超電導体を用いることが実用上好ましい。ここで
いう希土類元素を含有しペロブスカイト型構造を有する
酸化物超電導体は、超電導状態を実現できるものであれ
ばＪ：＜、ＬｎＢａ２Ｃｕ３Ｏ７−５ （ＬｎはＹ
、 Ｙｌ＋、 Ｔｍ５Ｅｒ、 Ｄｙ、 Ｈｏ、Ｌａ、
Ｓｃ、 Ｎｄ、 Ｓｍ、 Ｅｕ、 Ｇｄなどの希土類元
素から選ばれた少なくとも １種、δはＰａ素大欠陥表
し通常１以下の数を表し、Ｂａの一部はＳｒなどで置換
可能）などの酸素欠陥を有する欠陥ペロブスカイト型、
５ｒ−Ｌａ−Ｃｏ−Ｏ系などの層状ペロブスカイト型な
どの広義にペロブスカイト型を有する酸化物が例示され
る。また、希土類元素も広義の定義とし、Ｓｃ、Ｙおよ
びＬａ系を含むものとする。代表的な系としてはＹ−Ｂ
ａ−Ｃｕ−０系のほかに、ＹをＹｂｌＴｍ、 Ｅｒ、
Ｄｙ。Many oxide superconductors are known, but
It is practically preferable to use a rare earth element-containing perovskite-type oxide superconductor that has a high critical temperature. The oxide superconductor containing a rare earth element and having a perovskite structure is J:<, LnBa2Cu3O7-5 (Ln is Y
, Yl+, Tm5Er, Dy, Ho, La,
At least one element selected from rare earth elements such as Sc, Nd, Sm, Eu, and Gd, δ represents a Pa elemental large defect, and usually represents a number of 1 or less, and a part of Ba can be replaced with Sr, etc.). defective perovskite type with defects,
Examples include oxides having a perovskite type in a broad sense, such as a layered perovskite type such as 5r-La-Co-O type. Furthermore, rare earth elements are also broadly defined to include Sc, Y, and La-based elements. A typical system is Y-B
In addition to the a-Cu-0 series, Y is YblTm, Er,
Dy.
ｌｌｏ、 Ｅｕなどの希土類元素で置換した系、５ｃ−
Ｂａ−Ｃｕ−〇系、５ｒ−Ｌａ−Ｃｕ−０系、さらには
Ｓｒ＠ ＢａやＣａなとで置換した系などが挙げられる
。llo, system substituted with rare earth elements such as Eu, 5c-
Examples include Ba-Cu-○ system, 5r-La-Cu-0 system, and systems substituted with Sr@Ba or Ca.
本発明に使用される酸化物超電導体粉末は、たとえば以
下のようにしてＶＪ造される。The oxide superconductor powder used in the present invention is produced by VJ manufacturing, for example, as follows.
まず、Ｙ、 Ｂａ、 Ｃｕなどの構成元素を十分混合す
る。混合の際には、Ｙ２０３．ＢａＣＯ３、ＣｕＯなど
の酸化物や炭酸塩を原料として用いることができるほか
、他の焼成後酸化物に転化する硝酸塩、水酸化物などの
化合物を用いてもよい。さらには、共沈法などで（ｑた
シュウ酸塩などを用いてもよい。First, constituent elements such as Y, Ba, and Cu are thoroughly mixed. When mixing, use Y203. In addition to using oxides and carbonates such as BaCO3 and CuO as raw materials, other compounds such as nitrates and hydroxides that are converted into oxides after firing may also be used. Furthermore, oxalate or the like may be used in a coprecipitation method or the like.
Ｙ−Ｂａ−Ｃｕ−０系酸化物超電導体を構成する元素は
、基本的に化学ω論比の組成となるように混合するが、
多少製造条件などとの関係でずれていても差支えない。The elements constituting the Y-Ba-Cu-0 based oxide superconductor are basically mixed to have a composition in a stoichiometric ratio, but
There is no problem even if there is a slight deviation due to manufacturing conditions.
たとえば、’ｆ １ｍ０Ｉに対しＢａ ２１１１０＋
。For example, Ba 21110+ for 'f 1m0I
.
Ｃｕ ３ｍｏｌが標準組成であるが、実用上は１１ｍｏ
ｌに対して、Ｂａ ２±０．６ｍｏｌ 、Ｃｕ ａ±０
．４ｍｏｌ程度のずれは問題ない。The standard composition is 3 mol of Cu, but in practice it is 11 mol.
1, Ba 2±0.6 mol, Cu a±0
．． A deviation of about 4 mol is not a problem.
そして、前述の原料を充分に混合した後、８００℃〜９
８０℃程度の温度条件で仮焼して結晶化さぼる。この後
、必要に応じて酸素含有雰囲気中、好ましくは酸素雰囲
気中で熱処理するか、または同様な雰囲気中で３Ｏ０℃
程度まで徐冷することにより、酸素欠陥δに酸素を尋人
し超電導特性を向上させることができる。この熱処理は
、通常３Ｏ０℃〜７００℃程度で行う。After thoroughly mixing the above-mentioned raw materials,
It is calcined at a temperature of about 80°C to prevent crystallization. After this, heat treatment may be performed in an oxygen-containing atmosphere, preferably an oxygen atmosphere, or at 300°C in a similar atmosphere.
By slow cooling to a certain degree, oxygen can be added to the oxygen defects δ and the superconducting properties can be improved. This heat treatment is normally performed at about 300°C to 700°C.
次に、この仮焼物をボールミル、サンドグラインダ、そ
の他公知の手段により粉砕する。このとき、ペロブスカ
イト型の酸化物超電導体は、へき開面から分割されて微
粉末となる。この粉砕は、平均粒径（Ｃ面上の最大の軸
の長さ）が１〜５μ１１軸比（粒径対厚さの比）が３〜
５程度となるように行うことが好ましい。Next, this calcined product is pulverized using a ball mill, a sand grinder, or other known means. At this time, the perovskite-type oxide superconductor is split from the cleavage plane and becomes fine powder. This pulverization has an average particle size (the length of the largest axis on the C-plane) of 1 to 5μ, an axial ratio (ratio of particle size to thickness) of 3 to
It is preferable to perform this so that it becomes about 5.
このようにして得られた酸化物超電導体粉末は、酸素欠
陥δを有する酸素欠陥型ペロブスカイト構造を（ＬｎＢ
ａ Ｃｕ Ｏ（δは通常１以下の数）〉２３１−δ
となる。なお、・ＢａをｓｒやＣａなどで置換すること
も可能であり、ざらニＣＵの一部をＴｉ、 Ｖ 、 Ｃ
ｒ、ＨＯｌＦｅ、 Ｎｉ、 ｚｎなどで置換することも
できる。この置換ｍは、超電導特性を低下させない程度
で適宜設定可能であるが、あまり多量の置換は超電導特
性低下させてしまうので８０ｍｏ １％以下とする。The oxide superconductor powder obtained in this way has an oxygen-deficient perovskite structure having oxygen defects δ (LnB
a Cu O (δ is usually a number of 1 or less)>231−δ. In addition, it is also possible to replace Ba with sr, Ca, etc., and a part of the rough CU can be replaced with Ti, V, C
It can also be replaced with r, HOlFe, Ni, zn, etc. This substitution m can be set as appropriate to the extent that it does not deteriorate the superconducting properties, but too much substitution will deteriorate the superconducting properties, so it is set to 80 mo 1% or less.
本発明の酸化物超電導焼結体の製造方法についてさらに
詳述すると、まず上述したような方法により作製した酸
化物超電導体粉末、あるいは前述した酸化物超電導体の
原料となる混合粉末を用いて、プレス成形法、射出成形
法などの各種手段により、ブロック状、線状、管状なの
各種形状め成形体を作製する。To explain in more detail the method for producing the oxide superconducting sintered body of the present invention, first, using the oxide superconductor powder produced by the method described above or the mixed powder serving as the raw material for the oxide superconductor described above, Molded bodies in various shapes such as block, linear, and tubular shapes are produced by various means such as press molding and injection molding.
次いで、この成形体を焼結温度まで昇温し、焼成するが
、本発明においてはこの焼結温度への昇温過程において
、少なくとも下記の２工程を経て焼結温度まで昇温する
。Next, the temperature of this compact is raised to a sintering temperature and fired. In the process of raising the temperature to the sintering temperature in the present invention, the temperature is raised to the sintering temperature through at least the following two steps.
■ 温度勾配の緩かな予備加熱工程。■ Preheating process with gentle temperature gradient.
この予備加熱工程は、続いて行う局部加熱工程において
結晶粒が速やかに成長するように、酸化物超電導体を粒
成長を起こさない温度までほぼ均一に品温しておくため
の工程である。この予備加熱工程は、あまり低い温度か
ら行っても焼成時間が長くなるため、製造コストがｎく
なり、あまり高い温度まで行うと結晶粒の成長が起こっ
たり、焼結温度との差が小さくなるため、局部加熱工程
の効果が減少す詠ので、焼結温度より４００℃低い温度
から焼結温度より２００℃低い温度の範囲内程度で行う
ことが好ましい。また、この予備加熱工程における昇温
速度は、５℃／分以下が好ましく、より好ましくは２℃
／コ）〜０．０５℃／分の範囲である。昇温速度が５℃
／分を超えると成形体の形状や大きさにもよるが破壊の
原因となる。This preheating step is a step for keeping the oxide superconductor at a substantially uniform temperature to a temperature that does not cause grain growth so that crystal grains will grow rapidly in the subsequent local heating step. Even if this preheating process is performed at a temperature that is too low, the firing time will be longer, increasing manufacturing costs.If it is performed at a temperature that is too high, grain growth may occur or the difference from the sintering temperature may become small. Therefore, the effect of the local heating step is reduced, so it is preferable to carry out the heating at a temperature between 400° C. lower than the sintering temperature and 200° C. lower than the sintering temperature. Furthermore, the temperature increase rate in this preheating step is preferably 5°C/min or less, more preferably 2°C/min.
/c) to 0.05°C/min. Temperature increase rate is 5℃
If the heating time exceeds 1/min, it may cause destruction, although it depends on the shape and size of the molded product.
■ 局部的な加熱を行うことにより所定方向の急激な温
度勾配をもたせて焼結温度まで昇温する局部加熱工程。■ A local heating process in which the temperature is raised to the sintering temperature by heating locally to create a steep temperature gradient in a predetermined direction.
この局部加熱工程は、前述の予備加熱工程により結晶粒
の成長を起こさない所定温度までほぼ均一に昇温されて
いる酸化物超電導体を、局部的に加熱し、所定方向の急
激な温度勾配をもたせて昇温することににす、結晶粒の
成長に貸方性、すなわち一定方向に結晶の０面を配向さ
せつつ結晶粒の成長を行わせるものである。この局部加
熱工程における昇温速度は、５℃／分以上が好ましく、
より好ましくは１０℃／分〜２００℃／分の範囲である
。この昇温速度が２℃／分未満であると結晶粒の成長に
充分な異方性を持たせることができず、本発明の効果を
充分に得ることができない。In this local heating step, the oxide superconductor, which has been heated almost uniformly to a predetermined temperature that does not cause crystal grain growth in the preheating step described above, is locally heated to create a sharp temperature gradient in a predetermined direction. By increasing the temperature, the growth of the crystal grains is made to be oriented, that is, the crystal grains grow while orienting the zero plane of the crystal in a certain direction. The temperature increase rate in this local heating step is preferably 5°C/min or more,
More preferably, it is in the range of 10°C/min to 200°C/min. If the temperature increase rate is less than 2° C./min, sufficient anisotropy cannot be imparted to the growth of crystal grains, and the effects of the present invention cannot be sufficiently obtained.
このように所定方向の温度勾配をもたせて急激に焼結温
度まで昇温するためには、たとえば連続炉内において局
部加熱領域を設け、上述した昇温速度を満足するように
酸化物超電導体を移動させることにより、容易に行うこ
とが可能である。In order to rapidly raise the temperature to the sintering temperature with a temperature gradient in a predetermined direction, for example, a localized heating area is provided in a continuous furnace, and the oxide superconductor is heated so as to satisfy the temperature increase rate described above. This can be easily done by moving it.
この後、使用した酸化物超電導体に適した温度で所定時
間保持することにより、充分な密度となるように焼結さ
せる。この焼結条件は、使用する酸化物超［３体によっ
て異なるが、たとえばＬｌｌ−Ｂａ−Ｃｕ−０系の酸化
物超電導体であれば、９００℃〜１０５０℃の範囲が好
ましい。焼結温度が９００℃未満では、充分な焼結が起
こらず、焼結体密度が低下し、１０５０℃を超えると超
電導体相の分解が起こり、異相が生成されるためである
。Thereafter, the oxide superconductor used is held at a temperature suitable for a predetermined period of time to sinter it to a sufficient density. The sintering conditions vary depending on the oxide superconductor used, but for example, in the case of an Lll-Ba-Cu-0 based oxide superconductor, a range of 900°C to 1050°C is preferable. This is because if the sintering temperature is less than 900°C, sufficient sintering does not occur and the density of the sintered body decreases, and if it exceeds 1050°C, the superconductor phase decomposes and a different phase is generated.
なお、このようにして焼結を行った後に酸素を供給しな
がら室温近傍まで徐冷するか、あるいは酸素の十分に供
給可能な雰囲気中で３Ｏ０℃〜１００℃程度の温度でア
ニールを行うことが好ましい。After sintering in this way, it is possible to slowly cool the material to near room temperature while supplying oxygen, or to perform annealing at a temperature of about 300°C to 100°C in an atmosphere where oxygen can be sufficiently supplied. preferable.
これにより、酸素欠陥δへの酸素尋人が行え、超電導特
性が向上する。As a result, oxygen depletion can be performed on the oxygen defect δ, and the superconducting properties are improved.
（作 用）
本発明の酸化物超電導焼結体の製造方法においては、焼
結温度への昇温時に局部的な加熱を行い、一定方向の急
激な温度勾配をもたせて焼結温度まで昇温させているの
で、結晶粒の成長がこの昇温時の温度勾配の方向に沿っ
て起こる。このようにして結晶粒の成長に異方性をもた
せたものを焼結することにより、得られる酸化物超電導
焼結体は結晶がほぼ一定方向に配向されたものとなり、
この結晶のＣ面方向に電流を流すことによって、臨界電
流密度が大幅に向上する。(Function) In the method for producing an oxide superconducting sintered body of the present invention, local heating is performed when the temperature is raised to the sintering temperature, and the temperature is raised to the sintering temperature with a steep temperature gradient in a certain direction. As a result, crystal grain growth occurs along the direction of the temperature gradient during this temperature rise. By sintering the crystal grains that have grown anisotropically in this way, the resulting oxide superconducting sintered body has crystals oriented in a nearly constant direction.
By passing a current in the direction of the C-plane of this crystal, the critical current density is significantly improved.
（実施例） 次に、本発明の実施例について説明する。(Example) Next, examples of the present invention will be described.
実施例
粒径２〜５μｍのＢａＣ０，粉末２ｍ０１、Ｙ２Ｏ３粉
末０．５ｍｏｌ 、ＣｕＯ粉末３１０１を、充分混合し
て大気中９００℃で４８時間焼成して反応させた後、こ
の焼成物をさらに酸素中で８００℃で２４時間焼成して
反応させ、酸素空位に酸素を導入した後、ボールミルを
用いて粉砕し、分級して、平均粒径２μｍ、直径対厚さ
の比が３〜５の欠陥ペロブスカイト型構造を有するＹ−
Ｂａ−Ｃｕ−０系酸化物超電導体粉末を得た。Example 2 m01 of BaC0 powder with a particle size of 2 to 5 μm, 0.5 mol of Y2O3 powder, and 3101 CuO powder were thoroughly mixed and fired at 900°C in the atmosphere for 48 hours to react.The fired product was further heated in oxygen. After reacting by firing at 800°C for 24 hours to introduce oxygen into the oxygen vacancies, it was crushed using a ball mill and classified to produce defective perovskites with an average particle size of 2 μm and a diameter-to-thickness ratio of 3 to 5. Y- with type structure
A Ba-Cu-0 based oxide superconductor powder was obtained.
次に、この酸化物超電導体粉末をプレス成形により１０
ｍｍｘ １００ｍｍＸ厚さ２■の形状に成形し、次い
でこの成形体を白金補助ヒータが設けられ、下記の各加
熱領域を有する電気連続炉によって、大気中で焼成を行
った。Next, this oxide superconductor powder was press-molded to 10
The molded body was molded into a shape of 100 mm x 2 mm thick, and then fired in the air in an electric continuous furnace equipped with a platinum auxiliary heater and having the following heating regions.
■ 常温から６００℃まで５℃／分の昇温速度となるよ
うに設定された第１予備加熱領域。■ The first preheating area is set to have a heating rate of 5°C/min from room temperature to 600°C.
■ ６００℃から８００℃まで１℃／分の昇温速度とな
るように設定された第２予備加熱領域。■ A second preheating region set to have a heating rate of 1°C/min from 600°C to 800°C.
■ 局部的な加熱を行いつつ、８００℃から９５０℃ま
で所定方向の温度勾配を与え、かつ５０℃／分の昇温速
度となるように設定された局部加熱領域。(2) A local heating area that is set to provide a temperature gradient in a predetermined direction from 800°C to 950°C while heating locally, and to achieve a temperature increase rate of 50°C/min.
■ ９５０℃で４８時間保持するように設定された焼結
領域。■ Sintering zone set to hold at 950°C for 48 hours.
上記■〜■の各領域を順次通過させることにより焼結さ
せ、続いて１．５℃／分の冷却速度により徐冷して酸化
物超′Ｆｉ導焼結体を得た。Sintering was carried out by sequentially passing through each of the above regions ① to ②, followed by slow cooling at a cooling rate of 1.5° C./min to obtain an oxide super-Fi conductive sintered body.
このようにして得た酸化物超電導焼結体について、臨界
温度の測定を行ったところ、９１にと良好な値を示し、
また局部加熱領域における通過方向に、７７にで臨界電
流密度の測定を行ったところ、８０００Ａ／ｃ／と優れ
た値が得られた。When the critical temperature of the oxide superconducting sintered body thus obtained was measured, it showed a good value of 91.
Further, when the critical current density was measured at 77 in the passing direction in the local heating region, an excellent value of 8000 A/c/ was obtained.
また、この酸化物超電導焼結体の微細構造をＳＥＭＩＱ
察により調べたところ、局部加熱領域における通過方向
に長く成長した結晶粒を確認した。In addition, the microstructure of this oxide superconducting sintered body was determined by SEMIQ
Upon inspection, we found crystal grains that had grown long in the passing direction in the locally heated region.
さらに、Ｘ線回折からは結晶の０面が約８０％配向して
いることが明らかとなった。Furthermore, X-ray diffraction revealed that the zero plane of the crystal was approximately 80% oriented.
［発明の効果］
以上の実施例からも明らかなように、本発明の酸化物超
電導焼結体の製造方法によれば、焼結温度への昇温時に
局部的な加熱を行い、所定方向の急激な温度勾配をもた
せて昇温しているので、結晶粒の成長が温度勾配の方向
に配向しながら成長し、よって結晶粒がほぼ一定方向に
配向された焼結体となり、臨界電流密度のような超電導
特性が向上された酸化物超電導焼結体が１！１られる。[Effects of the Invention] As is clear from the above examples, according to the method for producing an oxide superconducting sintered body of the present invention, local heating is performed when the temperature is raised to the sintering temperature, and the heating is performed in a predetermined direction. Since the temperature is raised with a sharp temperature gradient, the crystal grains grow while being oriented in the direction of the temperature gradient, resulting in a sintered body in which the crystal grains are oriented in a nearly constant direction, and the critical current density increases. An oxide superconducting sintered body with such improved superconducting properties can be produced on a 1:1 scale.
出願人 株式会社 東芝 代理人 弁理士 須 山 佐 −Applicant: Toshiba Corporation Agent Patent Attorney Suyama Sa
Claims (7)
導体となる混合粉末を所要の形状に成形し、次いで得ら
れた成形体を焼結温度まで昇温し、この焼結温度で所定
時間保持して酸化物超電導焼結体を製造するにあたり、 前記焼結温度への昇温過程で、温度勾配の緩かな予備加
熱工程を行った後、局部的な加熱を行うことにより所定
方向の急激な温度勾配をもたせて前記焼結温度まで昇温
する局部加熱工程を行うことを特徴とする酸化物超電導
焼結体の製造方法。(1) Form the oxide superconductor powder or the mixed powder that becomes the oxide superconductor by heating into the desired shape, then raise the temperature of the obtained compact to the sintering temperature, and hold it at this sintering temperature for a predetermined period of time. In producing an oxide superconducting sintered body, in the process of raising the temperature to the sintering temperature, a preheating step with a gentle temperature gradient is performed, and then local heating is performed to produce a rapid rise in a predetermined direction. A method for manufacturing an oxide superconducting sintered body, comprising performing a local heating step of raising the temperature to the sintering temperature with a temperature gradient.
低い温度から２００℃低い温度までの範囲内で行い、か
つ昇温速度が５℃／分以下であることを特徴とする特許
請求の範囲第１項記載の酸化物超電導焼結体の製造方法
。(2) The preheating step is 400°C higher than the sintering temperature.
The method for manufacturing an oxide superconducting sintered body according to claim 1, characterized in that the manufacturing method is carried out at a temperature ranging from a low temperature to a temperature 200° C. lower, and at a heating rate of 5° C./min or less.
分以上であることを特徴とする特許請求の範囲第１項記
載の酸化物超電導焼結体の製造方法。(3) The temperature increase rate in the local heating step is 10°C/
2. The method for producing an oxide superconducting sintered body according to claim 1, wherein the manufacturing time is at least 1 minute.
ロブスカイト型の酸化物超電導体であることを特徴とす
る特許請求の範囲第１項記載の酸化物超電導焼結体の製
造方法。(4) The method for producing an oxide superconducting sintered body according to claim 1, wherein the oxide superconductor is a perovskite-type oxide superconductor containing a rare earth element.
Ｃｕを原子比で実質的に１：２：３の割合で含有するこ
とを特徴とする特許請求の範囲第１項記載の酸化物超電
導焼結体の製造方法。(5) The oxide superconductor according to claim 1, wherein the oxide superconductor contains rare earth elements, Ba and Cu in an atomic ratio of substantially 1:2:3. A method for producing a sintered body.
＿７＿−＿δ（Ｌｎは希土類元素から選ばれた少なくと
も１種を、δは酸素欠陥を表す。）で示される酸素欠陥
型ペロブスカイト構造の酸化物超電導体であることを特
徴とする特許請求の範囲第１項記載の酸化物超電導焼結
体の製造方法。(6) The oxide superconductor is LnBa_2Cu_3O
Claim 1, characterized in that it is an oxide superconductor with an oxygen-deficient perovskite structure represented by _7_-_δ (Ln represents at least one element selected from rare earth elements, and δ represents an oxygen defect). A method for producing an oxide superconducting sintered body according to item 1.
あることを特徴とする特許請求の範囲第１項記載の酸化
物超電導焼結体の製造方法。(7) The method for producing an oxide superconducting sintered body according to claim 1, wherein the sintering temperature is in a range of 900°C to 1050°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62314362A JPH01157451A (en) | 1987-12-11 | 1987-12-11 | Production of oxide superconducting sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62314362A JPH01157451A (en) | 1987-12-11 | 1987-12-11 | Production of oxide superconducting sintered body |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01157451A true JPH01157451A (en) | 1989-06-20 |
Family
ID=18052420
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62314362A Pending JPH01157451A (en) | 1987-12-11 | 1987-12-11 | Production of oxide superconducting sintered body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01157451A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5904506A (en) * | 1994-07-07 | 1999-05-18 | Fujitsu Limited | Semiconductor device suitable for testing |
-
1987
- 1987-12-11 JP JP62314362A patent/JPH01157451A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5904506A (en) * | 1994-07-07 | 1999-05-18 | Fujitsu Limited | Semiconductor device suitable for testing |
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