JP4011130B2

JP4011130B2 - Manufacturing method of oxide superconducting wire

Info

Publication number: JP4011130B2
Application number: JP23698695A
Authority: JP
Inventors: 哲幸兼子; 謙一佐藤
Original assignee: Japan Science and Technology Agency; Sumitomo Electric Industries Ltd; National Institute of Japan Science and Technology Agency
Current assignee: Japan Science and Technology Agency; Sumitomo Electric Industries Ltd; National Institute of Japan Science and Technology Agency
Priority date: 1995-09-14
Filing date: 1995-09-14
Publication date: 2007-11-21
Anticipated expiration: 2015-09-14
Also published as: JPH0982153A

Description

【０００１】
【発明の属する技術分野】
本発明は、酸化物超電導線材の製造方法に関し、より具体的には、高い臨界電流密度を有する酸化物超電導線材の製造方法に関するものである。
【０００２】
【従来の技術】
従来、酸化物超電導線材は、銀などの金属パイプに酸化物粉末を充填し伸線、圧延加工を施し、それを熱処理するような工程をとって製造されている。超電導線材の最も重要な特性である臨界電流密度（以下、Ｊｃと称する）は、Ｂｉ−２２２３超電導相を主相とする線材において液体窒素温度で約６０，０００Ａ／ｃｍ² 程度であった（参考文献：M. Satou et al., Appl. Phys. Lett., Vol. 64, No.5,（1994） p.640）。しかし、実用上要求されるＪｃはさらに高いものであり、その向上が望まれている。
【０００３】
一般的に酸化物超電導線材のＪｃに強く影響しているのは、線材中の酸化物部分の状態であると考えられており、この酸化物部分の形成に大きく関与するのが、金属パイプに充填される粉末の性質である。従来の製造方法では、図２に示すように、必要とされる元素の原料（Ａ〜Ｎ）をすべて混合し、その粉末を単一の方法で作製（ステップ１０１）した後、この粉末が金属管に充填されていた（ステップ１０３）。
【０００４】
（参考文献：Boston MA, A. Otto et al., Proceedings in Applied Superconductivity Conference, 16-20 October, 1994 、L. N. Wang et al., Supercond. Sci. Technol., Vol.7, （1995） p.94 、Yi-Bing Huang et al., Solid State Ionics, Vol. 63-65, （1993） p.889、Y. E. High et al., Physica C, 220,（1994) p.81 ）
また２種類の化合物を似通った方法（たとえば２種類の成分を固相反応法で生成する）で作製し、それらを混合し使用する方法をとっていた（参考文献：S. E. Dorris et al., Physica C, 223,（1994) p.163）。
【０００５】
【発明が解決しようとする課題】
これらの単一方法で作製された場合（図２）、粉末中には目的とする超電導相の生成（あるいは分解）エネルギーと近い生成（あるいは分解）エネルギー値を持つ種々の化合物が混在することになる。このため、すべての化合物が目的とする超電導相に移行する確率が低くなり、最終的に線材を焼成する過程において、未反応の化合物が不純物として大きく析出したり、目的とする超電導相の結晶粒のサイズが小さくなる。これらが線材のＪｃ値を律速している原因であった。
【０００６】
それゆえ、本発明の目的は、高いＪｃ値を有する酸化物超電導線材の製造方法を提供することである。
【０００７】
【課題を解決するための手段】
酸化物超電導線材のＪｃ値を向上させるためには、不純物相が析出せず、目的とする超電導相の結晶粒が大きく成長する粉末を開発することが必要である。このため、超電導相への移行の確率の高い、言い換えれば反応がスムーズに進行する粉末形態を見出す必要がある。超電導相への反応の確率を高くするためには、金属パイプに充填される粉末中に含まれる種々の化合物の生成（あるいは分解）エネルギーに差をつける必要がある。
【０００８】
本願発明者らは、同一の元素比率を持つ粉末においてもその作製法が異なると、大きく反応（あるいは分解）エネルギーが異なることを見出し、これら製法の異なる粉末を混合することで、高いＪｃ値を有する酸化物超電導線材が得られることを見出した。
【０００９】
それゆえ、本発明の酸化物超電導線材の製造方法は、図１に示すように互いに異なる製法（ステップ１ａ，１ｂ）を経て作製された複数の種類の粉末を混合して（ステップ２）、金属管に充填する（ステップ３）ことを特徴としている。
【００１０】
作製法の異なる複数の種類の粉末を混ぜ合わせることにより、粉末内の化合物間の反応エネルギー差を大きくし、超電導相への反応確率を高くして、不純物の少ない、かつサイズの大きい超電導結晶粒を含む酸化物部分を金属被覆内に形成することができ、それによって超電導線材の臨界電流密度が向上する。
【００１１】
なお、ここで言う粉末作製法とは、以下の１〜６の方法を有する。
１．混合された原料をそれらの融点以下の温度に保持し、固体間の原子の拡散によって反応させる固相反応法を行なった後、粉末化させる方法。
【００１２】
２．混合された原料をそれらの包晶反応温度以上に保持し、溶融した液相を介して反応させる溶融法を行なった後、粉末化させる方法。
【００１３】
３．混合された原料を酸などの溶媒に溶かし、それらから化合物を析出させた後、粉末化させる方法。
【００１４】
４．混合された原料を溶媒に溶かし、それらを加熱しながら噴霧して反応させる熱分解噴霧法により粉末を得る方法。
【００１５】
５．混合された原料を完全融解点以上の温度に保持し、そこから急冷（クエンチ）し、結晶性を持たない物質を得るアモルファス法を行なった後、粉末化させる方法。
【００１６】
６．粉末を酸化物ではなく金属の形態で構成する合金法。
これらの製法において別々に作られた粉末を混合することによって、不純物量が少なく、かつ生成した超電導結晶粒の大きい超電導部分が作製され得る。
【００１７】
ここで異なる製法の定義としては、上記の１つの方法中で保持温度や保持時間を変えただけのものは含まない。たとえば固相反応法で保持温度を変えた異なる成分を持つ２種類の粉末を使用する方法は、本発明の酸化物超電導線材の製造方法の範疇には入らない。
【００１８】
また本願発明者らは、これら各製法の組合せに特定の制限がないことも見出した。なぜならば、各製法が単独で用いられた場合においても、参考文献からもわかるようにある程度のＪｃは得られている。つまり各製法単独でも超電導相の生成は可能である。よって、各製法で作製された粉末の反応を促進させるために異なる製法で作られた、つまり反応エネルギーの異なる粉末を触媒のような効果として用いる本発明では、どの製法の組合せでも常に単独の製法で粉末を作製する場合よりも高いＪｃが得られる。よって、その組合せに特定の制限はない。
【００１９】
さらに付け加えるならば、異なる製法で作製された粉末の構成元素比が同じ場合でもよいが、それら粉末の構成元素比が異なる場合はより顕著に効果が現われる。これは構成元素比が異なれば、粉末内に含まれる化合物間により反応（あるいは分解）エネルギーの差がつきやすいからである。
【００２０】
【実施例】
実施例１
Ｂｉ₂ Ｏ₃ 、ＰｂＯ、ＳｒＣＯ₃ 、ＣａＣＯ₃ 、ＣｕＯ原料粉末を、元素比がＢｉ：Ｐｂ：Ｓｒ：Ｃａ：Ｃｕ＝１．８：０．３：１．９：２．０：３．０となるように混合した。その混合粉末を５等分した。さらにＢｉ、Ｐｂ、Ｓｒ、Ｃａ、Ｃｕの金属粉を同じ元素比になるように混合した。用意された粉末を以下の６通りの手法で処理した。
【００２１】
［１］酸化物および炭酸塩が混合された粉末を８００〜８５０℃で１０時間程度焼成し、それを粉砕した。この工程を３回繰り返した。
【００２２】
［２］酸化物および炭酸塩が混合された粉末を１１００℃で２時間熱処理した。この温度で粉末は溶解しており、その後、１００℃／ｈの速度で室温まで冷却し、それを粉砕し粉末を得た。
【００２３】
［３］酸化物および炭酸塩が混合された粉末を硝酸液中に溶解させた。その後、溶媒を蒸発させた。すると青色の粘土状のものが得られた。この粘土状のものを乾燥させるため、７００〜８００℃の温度で熱処理し、冷却後、粉砕し粉末を得た。
【００２４】
［４］酸化物および炭酸塩が混合された粉末をアルコール液中に溶かし、７００〜８５０℃の温度に保持された炉中にその液体を噴霧した。炉を冷却後、乾燥した粉末を回収した。
【００２５】
［５］酸化物および炭酸塩が混合された粉末を１２００℃の温度で１時間保持した。この温度で粉末は液相になっており、この高温の液体を液体窒素中で急冷（クエンチ）した。得られた固体を粉砕し粉末を得た。得られた粉末は結晶性を持たないガラス状のものであった。
【００２６】
［６］金属粉で混合された粉末を真空中（〜１０^-2Ｔｏｒｒ程度）、１０００℃の温度で２時間熱処理し、その後３００℃／ｈの速度で冷却した。得られた固体は金属的な光沢を有していた。この固体を粉砕して粉末を得た。
【００２７】
以上作製された６種類の粉末のうち、２種類を取出し混合した。組合せは１５通りできる。混ぜ合わされた粉末を銀パイプに充填し、伸線、圧延加工を施してテープ状の試料を得た。そのテープ状試料を８４０〜８５０℃の温度で５０時間大気中で熱処理し、冷却後さらに圧延加工を施し、再度８４０〜８５０℃の温度で５０時間大気中で熱処理した。冷却後、得られたテープ状試料の臨界電流密度を液体窒素中で測定した。比較のために単一の製法で作製された粉末を銀パイプに充填し、同様の工程を経てテープ状試料を得た。
【００２８】
以下の表１に粉末の各組合せで作られたテープ試料の液体窒素温度での臨界電流密度、および比較例の臨界電流密度を示す。
【００２９】
【表１】

【００３０】
表１からわかるように、本発明のとおり２種類の作製法で作られた粉末を混合した試料はいずれも、単独の製法で作られた粉末を用いた線材より高い臨界電流密度を有している。
【００３１】
実施例２
実施例１と同様に、酸化物および炭酸塩をＢｉ：Ｐｂ：Ｓｒ：Ｃａ：Ｃｕ＝１．８：０．３：１．９：１．０：２．０となるように混合し、５等分して実施例１中の［１］〜［５］の作製法を施し５種類の粉末を得た。また元素の金属粉末をＢｉ：Ｐｂ：Ｓｒ：Ｃａ：Ｃｕ＝１．８：０．３：１．９：１．０：２．０になるよう混合し、実施例１中の［６］の作製法を施し粉末を得た。
【００３２】
これらＢｉ：Ｐｂ：Ｓｒ：Ｃａ：Ｃｕ＝１．８：０．３：１．９：１．０：２．０の元素比を持つ６種類の粉末をＡ群とする。
【００３３】
またＢ群として次の６種類の粉末を作製した。ＣａＣＯ₃ およびＣｕＯの粉末をＣａ：Ｃｕ＝１．０：１．０の元素比となるよう混合し、５等分として実施例１中の［１］〜［５］の作製法を施し５種類の粉末を得た。またＣａおよびＣｕの金属粉をＣａ：Ｃｕ＝１．０：１．０の元素比となるよう混合し、実施例１中の［６］の作製法を施し粉末を得た。
【００３４】
これらＡ群から１種類、Ｂ群から異なる製法の１種類の粉末をとり、全元素比がＢｉ：Ｐｂ：Ｓｒ：Ｃａ：Ｃｕ＝１．８：０．３：１．９：２．０：３．０になるよう混合し、実施例１と同様、銀パイプに充填し、塑性加工、熱処理を繰り返してテープ状試料を得た。
【００３５】
これにより３０通りの組合せの試料ができる。また比較例としてＡ群、Ｂ群とも同じ製法で作られた６種類の試料も用意した。以下の表２にこれらの試料の液体窒素温度での臨界電流密度を示す。
【００３６】
【表２】

【００３７】
表２に示されるように、異なる組成を持つ粉末を混ぜ合わせた場合でも、それらの製法が異なる組合せの試料が高い臨界電流密度を有する。また表１の数値と比較して、異なる組成を持つ粉末を混ぜ合わせた場合の方が全体的に高い臨界電流密度を持つこともわかる。
【００３８】
以下の表３に、混ぜ合わせる粉末の１つを製法［１］に固定したとき、同じ組成をもつ粉末を混合した場合と異なる組成を持つ粉末を混合した場合の比較を示す。
【００３９】
【表３】

【００４０】
実施例３
実施例２におけるＡ群中（１）で作られた粉末（Ｂｉ：Ｐｂ：Ｓｒ：Ｃａ：Ｃｕ＝１．８：０．３：１．９：１．０：２．０の元素比を持つ）とＢ群の６種類の粉末（すべてＣａ：Ｃｕ＝１．０：１．０の元素比を持つ）を用意し、さらにＣ群としてＣａ：Ｐｂ＝２．０：１．０の比率を持つ化合物を実施例１の［１］〜［６］の製法において作製した。これらＡ群［１］の粉末とＢ群中の１種類の粉末とＣ群中１種類の粉末とを全体の元素比がＢｉ：Ｐｂ：Ｓｒ：Ｃａ：Ｃｕ＝１．８：０．４：１．９：２．２：３．０となるよう混合し、実施例１と同様の工程にてテープ状試料を作製した。粉末の組合せは全部で３６通りとなる。以下の表４にそれら作製されたテープ状試料の液体窒素温度の臨界電流密度を示す。
【００４１】
【表４】

【００４２】
表４に示されるように３種類の異なる組成を持つ粉末を混合した場合でも、製法が同じ粉末を混ぜ合わせた場合（表４中△試料）より高い臨界電流密度を持つことがわかる。またすべての粉末の製法が異ならなくても、たとえば表４中、［２］と［２］、［３］と［３］の組合せなど１種類でも異なる製法の粉末を用いる限りその効果が見られていることもわかる。
【００４３】
今回開示された実施例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上述した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。
【００４４】
【発明の効果】
以上説明したように、本発明によれば、酸化物超電導体を金属で被覆した線材において高い臨界電流密度を実現できるようになった。
【図面の簡単な説明】
【図１】本発明の酸化物超電導線材の製造方法を示すブロック図である。
【図２】従来の酸化物超電導線材の製造方法を示すブロック図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an oxide superconducting wire, and more specifically to a method for manufacturing an oxide superconducting wire having a high critical current density.
[0002]
[Prior art]
Conventionally, an oxide superconducting wire is manufactured by filling a metal pipe such as silver with an oxide powder, drawing and rolling, and heat-treating it. The critical current density (hereinafter referred to as Jc), which is the most important characteristic of a superconducting wire, was about 60,000 A / cm ² at a liquid nitrogen temperature in a wire having a Bi-2223 superconducting phase as a main phase (reference). Literature: M. Satou et al., Appl. Phys. Lett., Vol. 64, No. 5, (1994) p.640). However, Jc required for practical use is still higher and its improvement is desired.
[0003]
In general, it is considered that the oxide part in the wire has a strong influence on the Jc of the oxide superconducting wire, and it is considered that the metal pipe is greatly involved in the formation of the oxide part. The nature of the powder to be filled. In the conventional manufacturing method, as shown in FIG. 2, all the raw materials (A to N) of required elements are mixed, and the powder is produced by a single method (step 101). The tube was filled (step 103).
[0004]
(Reference: Boston MA, A. Otto et al., Proceedings in Applied Superconductivity Conference, 16-20 October, 1994, LN Wang et al., Supercond. Sci. Technol., Vol. 7, (1995) p.94. Yi-Bing Huang et al., Solid State Ionics, Vol. 63-65, (1993) p.889, YE High et al., Physica C, 220, (1994) p.81)
In addition, two kinds of compounds were prepared by a similar method (for example, two kinds of components were produced by a solid phase reaction method), and they were mixed and used (reference: SE Dorris et al., Physica C, 223, (1994) p.163).
[0005]
[Problems to be solved by the invention]
When produced by these single methods (FIG. 2), various compounds having a generation (or decomposition) energy value close to the generation (or decomposition) energy of the target superconducting phase are mixed in the powder. Become. For this reason, the probability that all the compounds will shift to the target superconducting phase is reduced, and in the process of finally firing the wire, unreacted compounds are largely precipitated as impurities, or crystal grains of the target superconducting phase. The size of becomes smaller. These were the reasons for determining the Jc value of the wire.
[0006]
Therefore, an object of the present invention is to provide a method for producing an oxide superconducting wire having a high Jc value.
[0007]
[Means for Solving the Problems]
In order to improve the Jc value of the oxide superconducting wire, it is necessary to develop a powder in which the impurity phase does not precipitate and the crystal grains of the target superconducting phase grow greatly. For this reason, it is necessary to find a powder form having a high probability of transition to the superconducting phase, in other words, the reaction proceeds smoothly. In order to increase the probability of reaction to the superconducting phase, it is necessary to make a difference in the generation (or decomposition) energy of various compounds contained in the powder filled in the metal pipe.
[0008]
The inventors of the present application have found that, even in powders having the same element ratio, if the production method is different, the reaction (or decomposition) energy is greatly different. By mixing these different powders, a high Jc value can be obtained. It has been found that an oxide superconducting wire can be obtained.
[0009]
Therefore, the oxide superconducting wire manufacturing method of the present invention mixes a plurality of types of powders manufactured through different manufacturing methods (

steps

1a and 1b) as shown in FIG. The tube is filled (step 3).
[0010]
By mixing multiple types of powders with different preparation methods, the reaction energy difference between the compounds in the powder is increased, the reaction probability to the superconducting phase is increased, and there are few impurities and large size superconducting crystal grains. An oxide portion containing can be formed in the metal coating, thereby improving the critical current density of the superconducting wire.
[0011]
In addition, the powder preparation method said here has the following methods 1-6.
1. A method in which the mixed raw materials are held at a temperature below their melting point and subjected to a solid phase reaction method of reacting by diffusion of atoms between solids and then pulverized.
[0012]
2. A method in which the mixed raw materials are held at a temperature higher than their peritectic reaction temperature and subjected to a melting method of reacting via a molten liquid phase and then pulverized.
[0013]
3. A method in which a mixed raw material is dissolved in a solvent such as an acid, a compound is precipitated therefrom, and then pulverized.
[0014]
4). A method of obtaining powder by a pyrolysis spray method in which mixed raw materials are dissolved in a solvent and sprayed to react while heating.
[0015]
5). A method in which a mixed raw material is held at a temperature equal to or higher than the complete melting point, and then rapidly cooled (quenched) to obtain a substance having no crystallinity, followed by pulverization.
[0016]
6). An alloy method in which the powder is made up of metal instead of oxide.
By mixing powders produced separately in these manufacturing methods, a superconducting portion with a small amount of impurities and a large superconducting crystal grain can be produced.
[0017]
Here, the definition of the different production methods does not include the one in which the holding temperature and the holding time are changed in the above one method. For example, the method of using two kinds of powders having different components with different holding temperatures in the solid phase reaction method does not fall within the category of the method for producing an oxide superconducting wire of the present invention.
[0018]
The inventors of the present application have also found that there is no specific limitation on the combination of these production methods. This is because even when each manufacturing method is used alone, a certain amount of Jc is obtained as can be seen from the reference literature. In other words, the superconducting phase can be generated by each manufacturing method alone. Therefore, in the present invention using powders produced by different production methods in order to promote the reaction of the powders produced by each production method, that is, powders having different reaction energies as an effect such as a catalyst, any production method combination is always a single production method. Thus, a higher Jc can be obtained than in the case of producing a powder. Therefore, there is no specific limitation on the combination.
[0019]
In addition, although the constituent element ratios of powders produced by different production methods may be the same, the effect is more remarkable when the constituent element ratios of the powders are different. This is because if the constituent element ratio is different, a difference in reaction (or decomposition) energy tends to occur between the compounds contained in the powder.
[0020]
【Example】
Example 1
Bi ₂ O ₃ , PbO, SrCO ₃ , CaCO ₃ , CuO raw material powder, the element ratio of Bi: Pb: Sr: Ca: Cu = 1.8: 0.3: 1.9: 2.0: 3.0 It mixed so that it might become. The mixed powder was divided into 5 equal parts. Further, Bi, Pb, Sr, Ca, Cu metal powders were mixed so as to have the same element ratio. The prepared powder was processed by the following six methods.
[0021]
[1] The powder in which the oxide and carbonate were mixed was baked at 800 to 850 ° C. for about 10 hours and pulverized. This process was repeated three times.
[0022]
[2] Powder mixed with oxide and carbonate was heat-treated at 1100 ° C. for 2 hours. The powder was dissolved at this temperature, and then cooled to room temperature at a rate of 100 ° C./h and pulverized to obtain a powder.
[0023]
[3] Powder mixed with oxide and carbonate was dissolved in nitric acid solution. Thereafter, the solvent was evaporated. A blue clay-like product was obtained. In order to dry this clay-like thing, it heat-processed at the temperature of 700-800 degreeC, after cooling, it grind | pulverized and obtained the powder.
[0024]
[4] Powder mixed with oxide and carbonate was dissolved in an alcohol liquid, and the liquid was sprayed into a furnace maintained at a temperature of 700 to 850 ° C. After the furnace was cooled, the dried powder was recovered.
[0025]
[5] The powder mixed with oxide and carbonate was held at a temperature of 1200 ° C. for 1 hour. At this temperature, the powder was in a liquid phase, and this hot liquid was quenched in liquid nitrogen. The obtained solid was pulverized to obtain a powder. The obtained powder was glassy without crystallinity.
[0026]
[6] The powder mixed with the metal powder was heat-treated in a vacuum (about −10 ⁻² Torr) at a temperature of 1000 ° C. for 2 hours, and then cooled at a rate of 300 ° C./h. The resulting solid had a metallic luster. This solid was pulverized to obtain a powder.
[0027]
Of the 6 types of powders prepared above, 2 types were taken out and mixed. There are 15 combinations. The mixed powder was filled into a silver pipe, drawn and rolled to obtain a tape-like sample. The tape-like sample was heat-treated in the atmosphere at a temperature of 840 to 850 ° C. for 50 hours, cooled and further subjected to rolling, and again heat-treated in the atmosphere at a temperature of 840 to 850 ° C. for 50 hours. After cooling, the critical current density of the obtained tape-like sample was measured in liquid nitrogen. For comparison, a powder produced by a single production method was filled in a silver pipe, and a tape-like sample was obtained through the same process.
[0028]
Table 1 below shows the critical current density at the liquid nitrogen temperature of the tape sample made from each combination of powders and the critical current density of the comparative example.
[0029]
[Table 1]

[0030]
As can be seen from Table 1, both of the samples prepared by mixing the powders produced by two kinds of production methods as in the present invention have a higher critical current density than the wire using the powder produced by a single production method. Yes.
[0031]
Example 2
In the same manner as in Example 1, the oxide and carbonate were mixed so that Bi: Pb: Sr: Ca: Cu = 1.8: 0.3: 1.9: 1.0: 2.0. Equally divided, the production methods [1] to [5] in Example 1 were applied to obtain 5 types of powders. The elemental metal powder was mixed so that Bi: Pb: Sr: Ca: Cu = 1.8: 0.3: 1.9: 1.0: 2.0, and [6] in Example 1 was mixed. The preparation method was applied to obtain a powder.
[0032]
These six types of powder having an element ratio of Bi: Pb: Sr: Ca: Cu = 1.8: 0.3: 1.9: 1.0: 2.0 are defined as Group A.
[0033]
Moreover, the following 6 types of powder were produced as B group. CaCO ₃ and CuO powders were mixed so as to have an element ratio of Ca: Cu = 1.0: 1.0, and were divided into five equal parts, and the production methods [1] to [5] in Example 1 were applied, and five types were applied. Of powder was obtained. Further, Ca and Cu metal powders were mixed so as to have an element ratio of Ca: Cu = 1.0: 1.0, and the production method [6] in Example 1 was applied to obtain a powder.
[0034]
One kind of powder from the A group and one kind of production method different from the B group are taken, and the total element ratio is Bi: Pb: Sr: Ca: Cu = 1.8: 0.3: 1.9: 2.0: It mixed so that it might become 3.0, It filled with the silver pipe similarly to Example 1, and plastic processing and heat processing were repeated, and the tape-shaped sample was obtained.
[0035]
As a result, 30 combinations of samples can be obtained. In addition, as a comparative example, six types of samples made by the same manufacturing method were prepared for both the A group and the B group. Table 2 below shows the critical current densities of these samples at the liquid nitrogen temperature.
[0036]
[Table 2]

[0037]
As shown in Table 2, even when powders having different compositions are mixed, samples of combinations having different production methods have a high critical current density. It can also be seen that, compared with the values in Table 1, the mixture of powders having different compositions has a higher critical current density overall.
[0038]
Table 3 below shows a comparison when one of the powders to be mixed is fixed in the production method [1], and a powder having a different composition is mixed with a powder having the same composition.
[0039]
[Table 3]

[0040]
Example 3
Powder (Bi: Pb: Sr: Ca: Cu = 1.8: 0.3: 1.9: 1.0: 2.0) made in Group A of Example 2 in Example 2 ) And six types of powders of Group B (all having an element ratio of Ca: Cu = 1.0: 1.0), and the ratio of Ca: Pb = 2.0: 1.0 as Group C. The compound having the above was prepared in the production method of [1] to [6] of Example 1. The total element ratio of these Group A [1] powder, one type of powder in Group B, and one type of powder in Group C is Bi: Pb: Sr: Ca: Cu = 1.8: 0.4: Mixing was performed so that 1.9: 2.2: 3.0 was obtained, and a tape-like sample was produced in the same process as in Example 1. There are 36 powder combinations in total. Table 4 below shows the critical current density at the liquid nitrogen temperature of the tape-shaped samples prepared.
[0041]
[Table 4]

[0042]
As shown in Table 4, it can be seen that even when three types of powders having different compositions are mixed, the critical current density is higher than when the same powder is mixed (Δ sample in Table 4). Even if all the powders are manufactured in different ways, for example, in Table 4, the effect can be seen as long as powders of different types such as combinations of [2] and [2], [3] and [3] are used. You can see that
[0043]
It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0044]
【The invention's effect】
As described above, according to the present invention, a high critical current density can be realized in a wire in which an oxide superconductor is coated with a metal.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a method for producing an oxide superconducting wire according to the present invention.
FIG. 2 is a block diagram showing a conventional method for producing an oxide superconducting wire.

Claims

Mixing various types of powders produced through different manufacturing methods, filling them into metal tubes,
One of said process, characterized in that after performing the method of precipitating crystals from the solvent which is a method for powdering method for producing oxides superconducting wire.

Mixing various types of powders produced through different manufacturing methods, filling them into metal tubes,
One of said process, characterized in that it is a method for obtaining a powder by thermal decomposition spraying method of oxides superconducting wire.

Mixing various types of powders produced through different manufacturing methods, filling them into metal tubes,
One of said process, characterized in that it is a method for powdering after is alloyed method of oxides superconducting wire.

Mixing various types of powders produced through different manufacturing methods, filling them into metal tubes,
A plurality of kinds of the powder produced by different method is characterized by having the same cation element ratio, method for producing oxides superconducting wire.

The cationic element ratio of the powder is

The method for producing an oxide superconducting wire according to claim 4 , wherein X is 0.05 or more and 0.2 or less.

Mixing various types of powders produced through different manufacturing methods, filling them into metal tubes,
Each of a plurality of types of the powders produced by different manufacturing methods has different cation element ratios,
One cation element ratio of the powder is

, And the wherein the X is 0.05 to 0.2, the production method of the oxides superconducting wire.