JPH013053A - Method for manufacturing superconducting materials - Google Patents
Method for manufacturing superconducting materialsInfo
- Publication number
- JPH013053A JPH013053A JP63-67651A JP6765188A JPH013053A JP H013053 A JPH013053 A JP H013053A JP 6765188 A JP6765188 A JP 6765188A JP H013053 A JPH013053 A JP H013053A
- Authority
- JP
- Japan
- Prior art keywords
- critical temperature
- high critical
- producing
- superconducting material
- temperature according
- 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
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- 238000004519 manufacturing process Methods 0.000 title claims description 36
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- 239000000843 powder Substances 0.000 claims description 40
- 239000002245 particle Substances 0.000 claims description 25
- 239000013078 crystal Substances 0.000 claims description 19
- 239000002887 superconductor Substances 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 13
- 238000000465 moulding Methods 0.000 claims description 13
- 238000010298 pulverizing process Methods 0.000 claims description 13
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- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 6
- 229910002651 NO3 Inorganic materials 0.000 claims description 6
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 6
- 229910052802 copper Inorganic materials 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 6
- 229910052721 tungsten Inorganic materials 0.000 claims description 6
- DOIRQSBPFJWKBE-UHFFFAOYSA-N dibutyl phthalate Chemical compound CCCCOC(=O)C1=CC=CC=C1C(=O)OCCCC DOIRQSBPFJWKBE-UHFFFAOYSA-N 0.000 claims description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims description 5
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- 239000002904 solvent Substances 0.000 claims description 5
- 229910052720 vanadium Inorganic materials 0.000 claims description 5
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 4
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims description 4
- 229910052733 gallium Inorganic materials 0.000 claims description 4
- 229910052738 indium Inorganic materials 0.000 claims description 4
- 229910052748 manganese Inorganic materials 0.000 claims description 4
- 150000002823 nitrates Chemical class 0.000 claims description 4
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 4
- 150000003467 sulfuric acid derivatives Chemical class 0.000 claims description 4
- 229910052715 tantalum Inorganic materials 0.000 claims description 4
- 238000007606 doctor blade method Methods 0.000 claims description 3
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- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 claims description 3
- 229910052718 tin Inorganic materials 0.000 claims description 3
- 229910052725 zinc Inorganic materials 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 229910052793 cadmium Inorganic materials 0.000 claims 2
- 229910052745 lead Inorganic materials 0.000 claims 2
- 229910052716 thallium Inorganic materials 0.000 claims 2
- 229910052688 Gadolinium Inorganic materials 0.000 claims 1
- 230000000694 effects Effects 0.000 description 13
- 230000005291 magnetic effect Effects 0.000 description 11
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 10
- 239000001301 oxygen Substances 0.000 description 10
- 229910052760 oxygen Inorganic materials 0.000 description 10
- 239000000919 ceramic Substances 0.000 description 8
- 239000007788 liquid Substances 0.000 description 8
- 239000011812 mixed powder Substances 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 239000001307 helium Substances 0.000 description 5
- 229910052734 helium Inorganic materials 0.000 description 5
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 239000002826 coolant Substances 0.000 description 4
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- 238000005259 measurement Methods 0.000 description 4
- 239000000523 sample Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000010931 gold Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
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- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 230000005668 Josephson effect Effects 0.000 description 2
- BYFGZMCJNACEKR-UHFFFAOYSA-N aluminium(i) oxide Chemical compound [Al]O[Al] BYFGZMCJNACEKR-UHFFFAOYSA-N 0.000 description 2
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
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- 238000010561 standard procedure Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
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- 229910000750 Niobium-germanium Inorganic materials 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
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- 229920001971 elastomer Polymers 0.000 description 1
- CMIHHWBVHJVIGI-UHFFFAOYSA-N gadolinium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Gd+3].[Gd+3] CMIHHWBVHJVIGI-UHFFFAOYSA-N 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
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- 239000012535 impurity Substances 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 238000005339 levitation Methods 0.000 description 1
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- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- XNGIFLGASWRNHJ-UHFFFAOYSA-L phthalate(2-) Chemical compound [O-]C(=O)C1=CC=CC=C1C([O-])=O XNGIFLGASWRNHJ-UHFFFAOYSA-L 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
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Abstract
(57)【要約】本公報は電子出願前の出願データであるた
め要約のデータは記録されません。(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.
Description
【発明の詳細な説明】
産業上の利用分野
本発明は超電導材料の製造方法に関する。より詳細には
、高い超電導臨界温度を有する新規な超電導材料の製造
方法に関する。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing superconducting materials. More specifically, the present invention relates to a method for producing a novel superconducting material having a high superconducting critical temperature.
従来の技術
超電導現象は、物体が特定の条件下で完全な反磁性を示
し、その内部で有限な定常電流が流れているにも関わら
ず電位差が現れな(なる現象である。このような状態に
ある物質を超電導体と呼び、電力損失の全くない伝送媒
体としての各種の応用が提案されている。Conventional technology The superconducting phenomenon is a phenomenon in which an object exhibits complete diamagnetic properties under certain conditions, and no potential difference appears despite a finite steady current flowing inside it. Such a state The materials found in superconductors are called superconductors, and various applications have been proposed for them as transmission media with no power loss.
例えば、超電導技術を電力送電に応用すれば、現在送電
に伴って生じている約7%の送電損失を大幅に減少でき
る。また、電力貯蔵方法としても、超電導電力貯蔵は今
日知られている電力貯蔵方法として最も効率の高いもの
であると言われている。For example, if superconducting technology is applied to power transmission, it will be possible to significantly reduce the approximately 7% transmission loss that currently occurs with power transmission. Furthermore, superconducting power storage is said to be the most efficient power storage method known today.
また、高磁場発生用電磁石への応用は、最も早くから実
現され、また利用分野も極めて広い。発電技術の分野で
はMHD発電、電動機等と共に、開発に発電N以上の電
力を消費するともいわれる核融合反応の実現を有利に促
進する技術として期待されている。また輸送機器の分野
では磁気浮上列車、電磁気推進船舶等の動力として、更
に、計測・医療の分野でもNMR1π中間子治療、高エ
ネルギー物理実験装置などへの利用が期待されている。Furthermore, its application to electromagnets for generating high magnetic fields was realized at the earliest, and the field of use is extremely wide. In the field of power generation technology, along with MHD power generation and electric motors, it is expected to be a technology that advantageously promotes the realization of nuclear fusion reactions, which are said to consume more power than N to be generated. Furthermore, in the field of transportation equipment, it is expected to be used as a power source for magnetic levitation trains, electromagnetic propulsion ships, etc., and in the field of measurement and medicine, it is expected to be used in NMR 1π meson therapy, high-energy physical experiment equipment, etc.
また、複数の超電導体を弱く接合すると、量子効果の巨
視的な具現であるジョセフソン効果が観測される。この
効果を利用したトンネル接合型ジョセフソン素子は、超
電導体のエネルギーギャップが小さいことから、極めて
高速且つ低電力消費のスイッチング素子として期待され
ている。更に、電磁波や磁場に対するジョセフソン効果
が鋭敏な量子現象として現れるこよから、この素子を磁
場、マイクロ波、放射線等の超高感度センサとして利用
することも提案されている。Furthermore, when multiple superconductors are weakly bonded, the Josephson effect, which is a macroscopic manifestation of a quantum effect, can be observed. A tunnel junction type Josephson device that utilizes this effect is expected to be an extremely high-speed and low-power switching device because the energy gap of the superconductor is small. Furthermore, since the Josephson effect on electromagnetic waves and magnetic fields appears as a sensitive quantum phenomenon, it has also been proposed to use this element as an ultra-sensitive sensor for magnetic fields, microwaves, radiation, etc.
このようにあらゆる分野において電力効率を向上すると
いう社会的ニーズに答える技術として、超電導技術は核
融合の実用化と並ぶ重要な技術であると言われている。In this way, superconducting technology is said to be an important technology, along with the practical application of nuclear fusion, as a technology that responds to the social need to improve power efficiency in all fields.
ところで、従来の技術においては超電導現象は超低温下
においてのみ観測されていた。即ち、従来開発された超
電導材料としては、A−15型の結晶構造を有する一群
の物質が比較的高いT。(超電導臨界温度)を示すこと
が確認されているが、Toが最も高いといわれる1li
b3GeにおいてもTcは依然として23.2 Kに止
まっている。By the way, in conventional technology, superconducting phenomena have been observed only at extremely low temperatures. That is, among conventionally developed superconducting materials, a group of materials having an A-15 type crystal structure have a relatively high T. (superconducting critical temperature), but 1li is said to have the highest To.
Even in b3Ge, Tc still remains at 23.2 K.
そこで、従来は、超電導現象を実施するために、沸点が
4.2にの液体ヘリウムを用いて超電導材料をTc以下
まで冷却している。尚、23..2にのTcに対しては
、沸点が20にの液体水素の使用等も考えられるが、臨
界温度Tcとは、一般に超電導現象の開始温度であり、
物質の相転移が終了して電気抵抗が零となる温度TCP
は臨界温度Tcよりも更に低い。従って、液体水素を冷
却媒体として材料を20Kまで冷却しても超電導体は得
られない。Therefore, conventionally, in order to implement the superconducting phenomenon, superconducting materials are cooled to below Tc using liquid helium with a boiling point of 4.2. Furthermore, 23. .. For Tc in 2, it is possible to use liquid hydrogen with a boiling point of 20, but the critical temperature Tc is generally the temperature at which the superconducting phenomenon starts,
TCP is the temperature at which the phase transition of a substance ends and the electrical resistance becomes zero.
is even lower than the critical temperature Tc. Therefore, even if the material is cooled down to 20K using liquid hydrogen as a cooling medium, a superconductor cannot be obtained.
ところが、液体ヘリウムを用いた場合、液化設備も含め
た冷却設備による技術的負担並びにコスト的負担は極め
て大きく、超電導技術による省エネルギ効果を虚しくし
てしまう。また、ヘリウムは元来存在量の少ない物質で
あり、1990年代後半には枯渇するとの試算もある。However, when liquid helium is used, the technical burden and cost burden due to cooling equipment including liquefaction equipment is extremely large, which negates the energy-saving effect of superconducting technology. Additionally, helium is a substance that is naturally present in small amounts, and some estimates suggest that it will be depleted in the late 1990s.
特に、わが国では液体ヘリウムの生産は行われておらず
、現状では全量を輸入に頼っている。従って、ヘリウム
の使用からの脱却は、超電導技術の実用化における極め
て重要な課題のひとつである。In particular, Japan does not produce liquid helium, and currently relies entirely on imports. Therefore, moving away from the use of helium is one of the extremely important issues in the practical application of superconducting technology.
また、超電導現象は、超電導材料の置かれた空間の磁場
の影響を受けることが知られており、第1種超電導体は
かなり低い下部臨界磁場HClにおいて容易に超電導効
果を失う。また、第2種超電導体にあっても特定のHc
2において超電導現象が消失する。従って、前述した高
磁場発生用電磁石への応用等を考えると、臨界磁場の高
い超電導材料が求約られる。現状では経験則に過ぎない
が、高い臨界磁場を得るためには、その材料が高い臨界
温度を有することが好ましいことが知られており、この
点からも超電導材料のTcの向上が望まれている。Furthermore, it is known that the superconducting phenomenon is affected by the magnetic field in the space in which the superconducting material is placed, and type 1 superconductors easily lose their superconducting effect in a considerably low lower critical magnetic field HCl. In addition, even in type 2 superconductors, certain Hc
2, the superconducting phenomenon disappears. Therefore, considering the application to the electromagnet for generating a high magnetic field mentioned above, a superconducting material with a high critical magnetic field is required. Although it is currently only a rule of thumb, it is known that in order to obtain a high critical magnetic field, it is preferable for the material to have a high critical temperature, and from this point of view as well, it is desired to improve the Tc of superconducting materials. There is.
発明が解決しようとする問題点
一方、長期間に亘る様々な努力にもかかわらず超電導材
料のT c l′!Nb3Geの23Kを越えることが
できなかったが、近年に到って、[a族元素あるいは1
lJa族元素の酸化物を含む焼結体が高いT。をもつ超
電導体となり得ることが報告され、非低温超電導体実現
の可能性が俄かに高まっている。Problems to be Solved by the Invention On the other hand, despite various efforts over a long period of time, the T c l' of superconducting materials! It was not possible to exceed 23K of Nb3Ge, but in recent years, [group a elements or
A sintered body containing an oxide of a lJa group element has a high T. It has been reported that this superconductor can be made into a superconductor with the following properties, and the possibility of realizing a non-low-temperature superconductor has suddenly increased.
既に報告されている例では、[La、 Ba] 2Cu
(14またはCLa、 Sr〕2Cu(14等のに2N
iF、型酸化物が挙げられ、これらはペロブスカイト型
超電導酸化物と類似した結晶構造を有するものと考えら
れている。これらの物質では、30乃至50にという従
来に比べて飛曜的に高いTcが観測され、更に、70に
以上のT。が観測された例もある。In already reported examples, [La, Ba] 2Cu
(14 or CLa, Sr) 2Cu (2N for 14 etc.
iF type oxides, which are considered to have a crystal structure similar to perovskite type superconducting oxides. In these materials, a significantly higher Tc of 30 to 50 than that of conventional materials has been observed, and a Tc of 70 or more. There are also cases where it has been observed.
しかしながら、前述のように、液体窒素等の1価で入手
の容易な冷却媒体を用いるためには依然として不充分で
あると言わざるを得ない。However, as mentioned above, it must be said that this is still insufficient to use a monovalent and easily available cooling medium such as liquid nitrogen.
また、超電導材料の実際の使用においては、これを所定
の形状に成形する技術が必要がある。Furthermore, in actual use of superconducting materials, a technique for molding them into a predetermined shape is required.
そこで、本発明の目的は、上記従来技術の問題点を解決
し、冷却媒体として液体窒素が利用可能な、高い臨界温
度Teを有する新規な超電導材料の製造方法を提供する
ことにある。SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above and to provide a method for manufacturing a novel superconducting material having a high critical temperature Te, in which liquid nitrogen can be used as a cooling medium.
さらに本発明の目的は、高いTc並びにT。Fを有する
と共に、その特性が長期間に亘って安定した新規な超電
導材料の製造方法を提供することにある。A further object of the invention is to obtain high Tc as well as T. It is an object of the present invention to provide a method for manufacturing a novel superconducting material which has F and whose properties are stable over a long period of time.
尚、本明細書において、超電導材料の超電導開始温度あ
るいは臨界温度をTc、材料の電気抵抗が完全に零とな
る相転移終了温度をT。2、T、とTCPとの差をΔT
と表す。In this specification, the superconductivity starting temperature or critical temperature of a superconducting material is Tc, and the phase transition end temperature at which the electrical resistance of the material becomes completely zero is T. 2. The difference between T and TCP is ΔT
Expressed as
問題点を解決するための手段
本発明者等は、Ba−Gd −Cu−0系の超電導材料
において超電導は主に結晶粒界の物質によって生起する
との推定に基づき超電導特性を改善するため種々の実験
、検討を繰り返した結果、粒径の小さい結晶とすること
によって高い超電導臨界温度を有する材料を製造するこ
とに成功したものである。Means for Solving the Problems The present inventors have devised various methods to improve superconducting properties based on the assumption that superconductivity in Ba-Gd-Cu-0 based superconducting materials is mainly caused by substances at grain boundaries. As a result of repeated experiments and studies, they succeeded in producing a material with a high superconducting critical temperature by forming crystals with small grain sizes.
すなわち、本発明に従うと、それぞれの平均粒1蚤が2
0μm以下、好ましくは10μm以下、さらに好ましく
は5μm以下のBa、 Gd、 Cuの酸化物、炭酸塩
、硫酸塩または硝酸塩の粉末を混合し、予備焼結後の焼
成体を平均粒径5μm以下、好ましくは3μm以下に粉
砕し、これを成形した後、(上記焼成体粉末の融点)〜
(上記焼成体粉末の融点−100℃)の範囲の温度で本
焼結して平均結晶粒径10μm以下のペロブスカイト型
または擬似ペロブスカイト型の酸化物を形成することを
特徴とする高臨界温度を有する超電導材料の製造方法が
提供される。本焼結に供する焼成体粉末は、平均粒径が
1μm以下となるように粉砕するのが好ましい。That is, according to the present invention, each average grain has 2 fleas.
Powders of Ba, Gd, Cu oxides, carbonates, sulfates, or nitrates of 0 μm or less, preferably 10 μm or less, more preferably 5 μm or less are mixed, and the sintered body after preliminary sintering has an average particle size of 5 μm or less, Preferably, after pulverizing to 3 μm or less and molding it, (melting point of the above-mentioned sintered body powder) ~
(melting point of the above-mentioned sintered body powder - 100°C) to form a perovskite-type or pseudo-perovskite-type oxide with an average crystal grain size of 10 μm or less, and has a high critical temperature. A method of manufacturing a superconducting material is provided. The fired body powder to be subjected to main sintering is preferably pulverized to have an average particle size of 1 μm or less.
さらに本発明の好ましい態様に従うと、得られる焼結体
超電導材料が下記の一般式で示され、(Bat−M G
dX)CuyOz
(ただし、x、yは0〜1の実数、2は0〜4の実数で
ある)
x、yがそれぞれ0.1〜0.9.0.4〜1.0 と
なるように、Ba5GdSCuの酸化物、炭酸塩、硫酸
塩または硝酸塩の粉末を混合し、この混合粉末を焼結す
ることによって超電導材料を製造する。Furthermore, according to a preferred embodiment of the present invention, the obtained sintered superconducting material is represented by the following general formula, (Bat-M G
D , Ba5GdSCu oxide, carbonate, sulfate, or nitrate powder and sintering the mixed powder to produce a superconducting material.
さらに本発明の好ましい態様に従うと、V、Nb、Ta
、 Mo、W、 Ti、 Cr、 i、in、 Ga5
In5CdXSnSTl、pb、 lnからなる群から
選択した少なくとも1種の元素の酸化物、炭酸塩、硫酸
塩または硝酸塩の粉末を上記混合粉末に添加してさらに
焼結体の結晶粒度を小さくして臨界温度を高める。これ
らのV、Nb、 Ta、 Mo、 W、 Ti、 Cr
、 Mn、 Ga、 In、 Cc、、 Sn。Furthermore, according to a preferred embodiment of the present invention, V, Nb, Ta
, Mo, W, Ti, Cr, i, in, Ga5
A powder of an oxide, carbonate, sulfate, or nitrate of at least one element selected from the group consisting of In5CdXSnSTl, pb, and ln is added to the above mixed powder to further reduce the crystal grain size of the sintered body and bring it to the critical temperature. Increase. These V, Nb, Ta, Mo, W, Ti, Cr
, Mn, Ga, In, Cc, Sn.
T1、PbSZnからなる群から選択した少なくとも1
種の元素とCuとの原子比をA4とすることが好ましい
。At least one selected from the group consisting of T1, PbSZn
It is preferable that the atomic ratio between the seed element and Cu is A4.
さらに本発明の好ましい態様に従うと、予備焼結を、7
00〜1000℃の範囲で実施し、また、予備焼結、粉
砕および成形の工程を少なくとも3回繰り返して得られ
る焼結体の結晶粒度を小さくする。Furthermore, according to a preferred embodiment of the present invention, the preliminary sintering is performed at 7
The crystal grain size of the obtained sintered body is reduced by carrying out the process at a temperature of 00 to 1000°C and repeating the steps of preliminary sintering, pulverization, and molding at least three times.
さらに、最終の予備焼結後の焼成体、すなわち、本焼結
に供する焼成体を平均粒径3μm、特に好ましくは1μ
m以下に粉砕するのが好ましい。この粉砕は、例えばA
I 203のボールを用いるボールミルによって行う
か、或いは空気、ArまたはN2を媒体とし、Al2O
3のターゲットにジェット流を衝突させるジェットミル
によって行うことができる。このようにして粉砕した焼
成体を60〜80%の相対密度で成形し、本焼結するの
が好ましい。Furthermore, the fired body after the final preliminary sintering, that is, the fired body to be subjected to main sintering, has an average particle size of 3 μm, particularly preferably 1 μm.
It is preferable to crush the powder to a size of less than m. This pulverization is carried out, for example, by A.
It is carried out by a ball mill using I 203 balls, or by using air, Ar or N2 as a medium and Al2O
This can be carried out by a jet mill that impinges a jet stream on the target of No. 3. It is preferable that the thus pulverized sintered body is molded to a relative density of 60 to 80% and then subjected to main sintering.
さらに本発明の好ましい態様に従うと、粉砕した焼成体
を、中心から表面までの距離が1mm以下、好ましくは
Q、 5mm以下の形状、例えば厚さ1.2mm以下の
テープ状または直径1.2mm以下の線材に成形し、本
焼結する。テープ状に成形するにはドクターブレード法
を用いてもよく、線材に成形するには押出し法を用いて
もよい。また、成形に際してポリビニルブチラール(P
VB)をバインダとして、ジブチルフタレート (DB
P)を可塑剤として用いることが好ましい。或いは水を
溶剤とし、ポリビニルアルコール(PVA)をバインダ
として用いて成形してもよい。これらの成形体を本焼結
する前に、大気中で400℃乃至800℃の範囲の温度
に加熱して上記溶剤およびバインダを除去することが好
ましい。Furthermore, according to a preferred embodiment of the present invention, the pulverized fired body is shaped into a shape with a distance from the center to the surface of 1 mm or less, preferably Q, and 5 mm or less, such as a tape shape with a thickness of 1.2 mm or less or a diameter of 1.2 mm or less. It is formed into a wire rod and sintered. A doctor blade method may be used to form a tape, and an extrusion method may be used to form a wire. Also, during molding, polyvinyl butyral (P
VB) as a binder, dibutyl phthalate (DB
Preference is given to using P) as a plasticizer. Alternatively, molding may be performed using water as a solvent and polyvinyl alcohol (PVA) as a binder. Before main sintering these molded bodies, it is preferable to heat them in the air to a temperature in the range of 400°C to 800°C to remove the solvent and binder.
さらに本発明の好ましい態様に従うと、本焼結を02分
圧が5〜2500気圧の酸素=囲気下で予備焼結および
/または本焼結を行って超電導臨界温度T。を著しく改
善することができる。Further, according to a preferred embodiment of the present invention, the preliminary sintering and/or main sintering is performed under an oxygen atmosphere with a partial pressure of 5 to 2,500 atmospheres to reach the superconducting critical temperature T. can be significantly improved.
さらに本発明の好ましい態様に従うと、本焼結後の焼結
体を500〜800℃の範囲で熱処理する。Furthermore, according to a preferred embodiment of the present invention, the sintered body after main sintering is heat-treated in the range of 500 to 800°C.
02分圧が10−1Torr以下の雲囲気て熱処理して
もよい。The heat treatment may be performed in a cloudy atmosphere with a partial pressure of 10-1 Torr or less.
さらに本焼結の別の態様に従うと、焼結後直ちに、また
は焼結後500乃至800℃の範囲に再加熱し、急冷し
てより微細な結晶構造として超電導臨界温度を高めるこ
とができる。Furthermore, according to another embodiment of the main sintering, the superconducting critical temperature can be increased by reheating immediately after sintering or after sintering to a temperature in the range of 500 to 800° C., and rapidly cooling it to create a finer crystal structure.
作用
本発明は、ペロブスカイトまたは擬似ペロブスカイト酸
化物からなる超電導体においては、結晶粒界すなわち結
晶粒間の境界面で超電導臨界温度の高い物質が形成され
易いとの知見に基づくものである。The present invention is based on the knowledge that in superconductors made of perovskite or pseudo-perovskite oxides, substances with high superconducting critical temperatures are likely to be formed at grain boundaries, that is, at interfaces between grains.
即ち、本発明者等は、上記知見に基づき、ペロブスカイ
トまたは擬似ペロブスカイト酸化物からなる焼結体を微
細組織化することによって極めて高い臨界温度を有する
超電導材料を形成することに成功した。That is, based on the above findings, the present inventors succeeded in forming a superconducting material having an extremely high critical temperature by microstructuring a sintered body made of perovskite or pseudo-perovskite oxide.
このような微細組織のペロブスカイトまたは擬似ペロブ
スカイト酸化物焼結体を得るには、次のような点につい
て厳重な管理が必要である。In order to obtain a perovskite or pseudo-perovskite oxide sintered body with such a fine structure, the following points must be strictly controlled.
■予備焼結前の材料粉末、の粒径
■予備焼結並びに粉砕後の粉末の粒径
■予備焼結温度
■本焼結温度
尚、後述するように、上記の管理項目の内、特に■、■
並びに■が重要である。■ Particle size of the material powder before preliminary sintering ■ Particle size of the powder after preliminary sintering and pulverization ■ Preliminary sintering temperature ■ Main sintering temperature As described later, among the above control items, especially ,■
Also, ■ is important.
即ち、予備焼結前の原料粉末の平均粒径が、20μmを
越えると、予備焼結後の粉砕工程によっても結晶粒を充
分に微細化ができず、成品焼結体が6μm以上の粗粒と
なってしまう。従って、焼結体の結晶粒の微細化を図る
ためには、原料粉末の粒径が20μm以下であることが
必須である。また原料粉末の粒径が10μm以下である
ことが好ましく、さらに5μm以下であることがさらに
好ましい。原料粉末の粒径が10μmのときには薄層に
成形しやすくなり、5μm以下のときには特にT。が高
くなり、T’cpとの差ΔTも小さくなる。特に、ΔT
は粒径の2乗に比例して改善される。That is, if the average particle size of the raw material powder before pre-sintering exceeds 20 μm, the grains cannot be sufficiently refined even in the pulverization process after pre-sintering, and the finished sintered body will have coarse grains of 6 μm or more. It becomes. Therefore, in order to refine the crystal grains of the sintered body, it is essential that the particle size of the raw material powder is 20 μm or less. Further, the particle size of the raw material powder is preferably 10 μm or less, and even more preferably 5 μm or less. When the particle size of the raw material powder is 10 μm, it is easy to form into a thin layer, and when the particle size is 5 μm or less, T. becomes higher, and the difference ΔT from T'cp also becomes smaller. In particular, ΔT
is improved in proportion to the square of the particle size.
また、予備焼結後の粉砕工程は、後の本焼結後の結晶粒
径に直接的な影響があり、粉砕後の粉末の粒度が5μm
を越えると、本焼結後の焼結体の結晶粒径が大きくなり
結晶粒界量が減少する。前述のように、結晶粒界の減少
は高いTcの達成に好ましくない。従って、予備焼結後
の粉砕により5μm以下、好ましくは3μm以下にする
。さらに1μm以下に粉砕すると焼結体の結晶粒径が小
さくなり、超電導臨界温度が上昇する。ただし、焼成体
を1μm未満に粉砕することは長時間の処理を要し、不
純物の混入等の可能性が増すので、留意する必要がある
。In addition, the crushing process after preliminary sintering has a direct effect on the crystal grain size after main sintering, and the particle size of the powder after crushing is 5 μm.
If it exceeds this, the grain size of the sintered body after main sintering will increase and the amount of grain boundaries will decrease. As mentioned above, grain boundary reduction is unfavorable for achieving high Tc. Therefore, the particle size is reduced to 5 μm or less, preferably 3 μm or less, by pulverization after preliminary sintering. Furthermore, if the powder is pulverized to 1 μm or less, the crystal grain size of the sintered body becomes smaller and the superconducting critical temperature increases. However, pulverizing the fired body to less than 1 μm requires a long processing time and increases the possibility of contamination with impurities, so care must be taken.
こうした〔予備焼結→粉砕→成形〕の工程を複数回繰り
返すことによって、原料粉末あるいは焼成体の固溶反応
を促進し、また、本焼結に供する粉末の結晶粒径を微細
化しておくことが好ましい。By repeating this process of [preliminary sintering → crushing → molding] multiple times, the solid solution reaction of the raw material powder or fired body is promoted, and the crystal grain size of the powder to be subjected to main sintering is refined. is preferred.
これらの観点から、上記〔予備焼結→粉砕→成形〕の一
連の工程は、少なくとも3回以上繰り返すことが好まし
い。From these viewpoints, it is preferable that the series of steps described above [preliminary sintering → crushing → molding] be repeated at least three times.
また、本焼結温度は、本発明による方法における極めて
重要な制御因子であり、本焼結中に材料の溶融が生ずる
ことなく面相反応のみで焼結が進行すること、並びに、
焼結されたペロブスカイト型または擬似ペロブスカイト
型酸化物の結晶成長が過大とならないように制御する必
要がある。これらの知見に基づいて実験を繰り返した結
果、本焼結温度が低い場合は、最終的な焼結体に十分な
強度が得られず、一方、焼成体の融点を越えて加熱され
ると焼結体に溶融相が生じ、あるいは粗大化した結晶粒
が生成する。従って、本発明においては、本焼結温度を
(上記焼成体粉末の融点)〜(上記焼成体粉末の融点−
100℃)の範囲内に制限した。Further, the main sintering temperature is an extremely important control factor in the method according to the present invention, and the sintering proceeds only by phase reaction without melting of the material during the main sintering, and
It is necessary to control the crystal growth of the sintered perovskite-type or pseudo-perovskite-type oxide so that it does not become excessive. As a result of repeated experiments based on these findings, we found that if the main sintering temperature is low, the final sintered body will not have sufficient strength, whereas if it is heated beyond the melting point of the sintered body, sintering will occur. A molten phase is formed in the solid, or coarse crystal grains are formed. Therefore, in the present invention, the main sintering temperature is (melting point of the above-mentioned sintered body powder) - (melting point of the above-mentioned sintered body powder -
100°C).
更に、上述の本焼結の制御と同様の理由で、予備焼結温
度も厳重に管理さるべきものである。即ち、予備焼結温
度が700℃未満の場合は、固溶反応が十分に進行せず
、超電導臨界温度を高めるのに有効なペロブスカイト型
または擬似ペロブスカイト型酸化物が得られない。一方
、予備焼結温度が1000℃を越えると、本焼結の場合
と同様に、焼成体に溶融相が生じ、あるいは結晶粒の粗
大化が生じ、以後の工程における粉砕による微細化が困
難になる。尚、ここでいう予備焼結とは、セラミックス
の分野で焼成とも呼ばれる操作を指している。Furthermore, for the same reason as the control of the main sintering described above, the preliminary sintering temperature should also be strictly controlled. That is, when the preliminary sintering temperature is less than 700° C., the solid solution reaction does not proceed sufficiently, and a perovskite or pseudo-perovskite oxide that is effective in increasing the superconducting critical temperature cannot be obtained. On the other hand, if the preliminary sintering temperature exceeds 1000°C, as in the case of main sintering, a molten phase will occur in the fired body or the crystal grains will become coarser, making it difficult to refine them by pulverization in the subsequent process. Become. Note that the pre-sintering here refers to an operation also called firing in the ceramics field.
また更に、本焼結前の焼成体の成形に際し、成形体の相
対密度を60乃至80%とすることが好ましい。本発明
者等の知見によれば、ペロブスカイト型または擬似ペロ
ブスカイト型酸化物による超電導体は、特に焼結体の表
面近傍において優れた特性を発揮する。これは、材料の
厚さが薄いため、焼結時または熱処理時に雰囲気との反
応が超電導特性に好ましく進行し、また、セラミックス
の表面に近い相が歪み効果を受けるために優れた超電導
特性が現出したものと考えられる。Furthermore, when molding the fired body before main sintering, it is preferable that the relative density of the molded body is 60 to 80%. According to the findings of the present inventors, a superconductor made of a perovskite or pseudo-perovskite oxide exhibits excellent properties, particularly near the surface of a sintered body. This is because the material is thin, so the reaction with the atmosphere during sintering or heat treatment favors superconducting properties, and the phase near the surface of the ceramic is subject to strain effects, resulting in excellent superconducting properties. It is thought that it was released.
従って、本発明の方法においては、成形体の相対密度を
60乃至80%と比較的低い状態として、本焼結時に表
面近傍と同じ効果がより深い領域まで浸透するように操
作する。また、同様の理由に基づき、ドクターブレード
法あるいは押出し成形法によって、成形体の厚さを2m
m以下、好ましくは1.2mm以下のテープ状、あるい
は直径l、 2mm以下の線材状とすることにより、焼
結体全体が特性の良好な超電導体となるようにすること
も本発明の範囲内にある。Therefore, in the method of the present invention, the relative density of the molded body is kept relatively low at 60 to 80%, and operations are performed so that the same effect as near the surface penetrates into a deeper region during main sintering. In addition, based on the same reason, the thickness of the molded body was reduced to 2 m by the doctor blade method or extrusion molding method.
It is also within the scope of the present invention to make the entire sintered body a superconductor with good characteristics by forming the sintered body into a tape shape with a diameter of 1.2 mm or less, preferably 1.2 mm or less, or a wire shape with a diameter of 1.2 mm or less. It is in.
尚、テープ状あるいは線材状の成形体の厚さまたは直径
を2mm以下としたのは、前述のよ子な表面効果が主に
表面から2mmの範囲の領域で生じることから、焼結時
の収縮を考慮して2mm以下に決定したものである。The reason why the thickness or diameter of the tape-shaped or wire-shaped compact is set to 2 mm or less is because the above-mentioned fine surface effect mainly occurs in an area within 2 mm from the surface, so shrinkage during sintering is avoided. The thickness was determined to be 2 mm or less in consideration of the following.
さらに本発明の好ましい方法では、得られる焼結体超電
導材料が下記の一般式で示され、(Bal−X GdX
)CUyOf
(ただし、x、yはO〜1の実数、2は0〜4の実数で
ある)
xSyがそれぞれ0.1〜0.9.0.4〜1.0 と
なるように、Ba、 Gcl、 Cuの酸化物、炭酸塩
、硫酸塩または硝酸塩の粉末を混合する。Ba:Gcl
:[uの原子比が上記範囲を外れて原料粉末が混合され
ると、所望のペロブスカイト型または擬似ペロブスカイ
ト型酸化物かえられない。さらにこの混合粉末にVSN
bSTa、 Mo、 W、 Ti、 Cr、 Mn、
Ga5In、 Cd。Further, in a preferred method of the present invention, the obtained sintered superconducting material is represented by the following general formula, (Bal-X GdX
) CUyOf (However, x and y are real numbers from O to 1, and 2 is a real number from 0 to 4.) Ba, Mix powders of Gcl, Cu oxide, carbonate, sulfate or nitrate. Ba:Gcl
: [If the raw material powder is mixed with an atomic ratio of u outside the above range, the desired perovskite or pseudo-perovskite oxide cannot be obtained. Furthermore, this mixed powder has VSN
bSTa, Mo, W, Ti, Cr, Mn,
Ga5In, Cd.
Sn、 TI、pbまたはZnの1種または2種以上の
元素の酸化物、炭酸塩、硫酸塩または硝酸塩の粉末を添
加して焼結体の結晶粒度を小さくすることが好ましいが
、これらの元素とCuとの原子比が0.01〜0.15
の範囲より低いときには添加効果が得られず、一方0.
01〜0.15の範囲より高いときには添加効果が飽和
し、或いは所望のペロブスカイト型または擬似ペロブス
カイト型酸化物が得られない。これらのV、 Nb、
Ta、 Mo、WSTi、CrSMn、 Ga、 In
。It is preferable to reduce the crystal grain size of the sintered body by adding powder of oxide, carbonate, sulfate or nitrate of one or more elements such as Sn, TI, PB or Zn, but these elements The atomic ratio between Cu and Cu is 0.01 to 0.15
When the amount is lower than the range of 0.0, no addition effect can be obtained;
If it is higher than the range of 0.01 to 0.15, the effect of addition is saturated or the desired perovskite type or pseudo-perovskite type oxide cannot be obtained. These V, Nb,
Ta, Mo, WSTi, CrSMn, Ga, In
.
Cd5Sn、 TI、pbまたはZnの1種または2種
以上の元素を添加することにより焼結体超電導材料の電
流値が大きくなる。これは添加によりエレクトロン・ホ
ールが形成されたためと考える。By adding one or more elements of Cd5Sn, TI, pb, or Zn, the current value of the sintered superconducting material increases. This is thought to be due to the formation of electron holes due to the addition.
また更に本発明の好ましい態様に従うと、得られた焼結
体をさらに熱処理して実質的に均一な擬似ペロブスカイ
ト型酸化物とする。この熱処理により電気抵抗が完全に
零となる超電導臨界温度が著しく上昇する。この熱処理
は、500〜800℃の範囲の温度で実施することが好
ましく、減圧下の酸素雰囲気で実施するのがさらに好ま
しい。すなわち、この低酸素分圧下での熱処理によって
焼結体から酸素原子が剥奪され、酸素欠陥が発生する。Furthermore, according to a preferred embodiment of the present invention, the obtained sintered body is further heat-treated to form a substantially uniform pseudo-perovskite oxide. This heat treatment significantly increases the superconducting critical temperature at which electrical resistance becomes completely zero. This heat treatment is preferably carried out at a temperature in the range of 500 to 800°C, more preferably in an oxygen atmosphere under reduced pressure. That is, by this heat treatment under a low oxygen partial pressure, oxygen atoms are stripped from the sintered body and oxygen defects are generated.
この欠陥により生ずるキャリヤによって電子のクーパ一
対ができる確率が高くなり、抵抗が完全に零となる超電
導臨界温度が著しく上昇するものと推定される。It is estimated that the carriers generated by this defect increase the probability of forming a Cooper pair of electrons, and the superconducting critical temperature at which the resistance becomes completely zero increases significantly.
尚、加熱温度が500℃未満の場合は、所望の熱処理効
果が得られないか、あるいは、長時間の熱処理が必要と
なる。一方、800℃を超える処理温度では超電導効果
を有するペロブスカイト型または擬似ペロブスカイト型
酸化物の結晶構造が消滅して臨界温度は著しく低下する
。Note that if the heating temperature is less than 500° C., the desired heat treatment effect may not be obtained or a long time heat treatment will be required. On the other hand, at a treatment temperature exceeding 800° C., the crystal structure of the perovskite-type or pseudo-perovskite-type oxide having a superconducting effect disappears, and the critical temperature decreases significantly.
これらの焼結後のセラミックスに対する熱処理により、
△Tは更に3〜5℃向上するので、より高いT。Fが得
られる。熱処理の条件は、10−’torr以下の酸素
減圧下で行うことが好ましい。この理由は、これ以上の
酸素分圧下では酸素欠陥の形成に長時間を要し、工業的
でないこと、および500℃未満あるいは800℃を越
える温度では、やはり酸素欠陥の形成が過小又は過大と
なり、十分に高いT’cpが得難いためである。By heat treatment of these ceramics after sintering,
ΔT is further improved by 3-5°C, so higher T. F is obtained. The heat treatment is preferably performed under reduced oxygen pressure of 10-'torr or less. The reason for this is that at higher oxygen partial pressures, it takes a long time to form oxygen vacancies, which is not industrially practical, and at temperatures below 500°C or above 800°C, the formation of oxygen vacancies becomes too small or too large. This is because it is difficult to obtain a sufficiently high T'cp.
更に本発明の好ましい態様に従うと、上記焼結後、直ち
に急冷する、または焼結後、500〜800℃の範囲に
再加熱し、急冷して、さらに超電導臨界温度を上昇させ
ることができる。この急冷処理により本発明の方法によ
り製造される焼結体は、より優れた超電導特性を有する
擬似ペロブスカイト構造となる。Furthermore, according to a preferred embodiment of the present invention, the superconducting critical temperature can be further increased by quenching immediately after the sintering, or by reheating to a temperature in the range of 500 to 800°C and quenching after sintering. Through this rapid cooling treatment, the sintered body produced by the method of the present invention has a pseudo-perovskite structure having superior superconducting properties.
また、これらの本発明の好ましい態様に従うことによっ
て、超電導材料の組成が均一化されると共に安定し、具
体的に後述するように、特性の経時劣化が少ないことも
認められた。Furthermore, it has been found that by following these preferred embodiments of the present invention, the composition of the superconducting material is made uniform and stable, and as will be specifically described later, there is little deterioration of the characteristics over time.
さらに本発明者等は、表面から中心迄の厚さが1mm以
下、好ましくは9.5mmのとき、セラミックス全体が
超電導特性に優れた、すなわち超電導臨界温度の低い組
織からなることを発見した。これは、厚さが薄いため、
焼結時または熱処理時に雰囲気との反応が超電導特性に
好ましく進行し、また、セラミックスの表面部分は酸素
欠陥および/または歪み効果を受けるため超電導特性に
優れるものと考えられる。Furthermore, the present inventors have discovered that when the thickness from the surface to the center is 1 mm or less, preferably 9.5 mm, the entire ceramic has excellent superconducting properties, that is, it consists of a structure with a low superconducting critical temperature. This is because the thickness is thin.
It is thought that the reaction with the atmosphere during sintering or heat treatment progresses favorably to improve superconducting properties, and the surface portion of the ceramic is subject to oxygen defects and/or strain effects, resulting in excellent superconducting properties.
また、焼結は1回に限定されるものではなく、−旦焼結
した材料を粉砕し、再び焼結することによって材料の一
層の均質化が達成できることが確認されている。すなわ
ち、粉末材料を仮焼した後得られた焼結体を粉砕する予
備焼結工程と、該予備焼結後に得られた粉末を成形、焼
結する本焼結工程の少なくとも3段階で実施することを
か好ましい。Furthermore, sintering is not limited to one time, and it has been confirmed that further homogenization of the material can be achieved by crushing the previously sintered material and sintering it again. That is, the process is carried out in at least three stages: a preliminary sintering process in which the sintered body obtained after calcining the powder material is crushed, and a main sintering process in which the powder obtained after the preliminary sintering is shaped and sintered. That is preferable.
実施例
以下に本発明を実施例により具体的に説明するが、以下
の開示によって本発明の技術的範囲は何等制限されるも
のではない。EXAMPLES The present invention will be specifically explained by examples below, but the technical scope of the present invention is not limited in any way by the following disclosure.
実施例1
純度3N以上、BaC0:+ 、Gd2O3、CuOの
各々の粉末を、0.6 :0.4 :1.OのBa
:Gd:Cuの原子比を有するように混合した。Example 1 Each powder of BaC0:+, Gd2O3, and CuO with a purity of 3N or higher was mixed in a ratio of 0.6:0.4:1. Ba of O
:Gd:Cu.
これらの混合粉末を、それぞれ粉砕し、それぞれ第1表
に示す平均粒径の粉末を得た。各々の混合粉末を大気中
で890℃/12時間焼成し、ケーキ状に固化した粉末
をボールミルでさらに粉砕して第1表に示す平均粒径に
なるまで粉砕した。以下、この工程を3回繰り返して、
はぼ完全に固溶し、最終の焼成前の粉砕工程では第1表
に示す平均粒径の粉末を得た。上述のようにして得た粉
末を各々ゴムモールドに充填し、l ton/’ant
の圧力で静圧成形を行い30φX5Qn+mのバルク状
成形体を得た。These mixed powders were each pulverized to obtain powders having the average particle diameters shown in Table 1. Each of the mixed powders was fired in the atmosphere at 890° C. for 12 hours, and the powder solidified into a cake was further ground in a ball mill until it had the average particle size shown in Table 1. Repeat this process three times,
The solid solution was almost completely dissolved, and in the final pulverization step before firing, a powder having the average particle size shown in Table 1 was obtained. Each of the powders obtained as described above was filled into a rubber mold, and 1 ton/'ant
Static pressure molding was performed at a pressure of 30φX5Qn+m to obtain a bulk molded product.
この成形体から機械加工により、第1表に示す寸法の成
形体を削り出した。A molded body having the dimensions shown in Table 1 was cut out from this molded body by machining.
続いて、成形体を大気中、920℃にて10時間保持し
て焼結してセラミックス焼結体を得た。Subsequently, the molded body was held in the atmosphere at 920° C. for 10 hours and sintered to obtain a ceramic sintered body.
得られた各々の焼結体の破面に金を蒸着し、走査型顕微
鏡によって観察した。こうして測定した焼結体の平均粒
径を第1表に併せて示す。Gold was deposited on the fractured surface of each of the obtained sintered bodies and observed using a scanning microscope. The average particle diameter of the sintered body thus measured is also shown in Table 1.
尚、臨界温度Tc並びにTCPの測定は、定法に従って
試料の両端にAg導電ペーストにて電極を付け、タラビ
オスタット中で直流4点プローブ法で行った。温度はキ
ャリブレーション済みのAu (Fe)−Ag熱電対を
用いて行った。温度を少しづつ上昇させながら抵抗の変
化を観察した。尚、第1表には、TcとT。Fとの差Δ
Tも併せて記載した。The critical temperature Tc and TCP were measured by attaching electrodes with Ag conductive paste to both ends of the sample according to a standard method, and using a DC four-point probe method in a Taraviostat. Temperature was measured using a calibrated Au (Fe)-Ag thermocouple. Changes in resistance were observed while increasing the temperature little by little. Furthermore, Table 1 shows Tc and T. Difference Δ from F
T is also listed.
また、これらの超電導材料を作製した3週間後に各材料
を同一条件で測定したところ、本発明にしたがって作成
した焼結体はいずれもTcの変化は±IKの範囲であり
有意な変化は認められなかった。このことはLメータを
用いて測定したAC帯磁率の測定結果でも確認された。Furthermore, when each material was measured under the same conditions three weeks after producing these superconducting materials, the change in Tc of the sintered bodies produced according to the present invention was within the range of ±IK, and no significant change was observed. There wasn't. This was also confirmed by the measurement results of AC magnetic susceptibility measured using an L meter.
実施例2
純度3N以上、平均粒径6μm以下のBaCO3、Gd
2O3、CuO1V205またはTa205の各々の粉
末を、焼成後のBa、 Gd、 Cu5VまたはTaの
原子比が0.6 :0.4 :1.0 :0.0
5または0.6 :0.4 :0.6:0,1 と
なるように混合した。この混合粉末を空気を媒体とじA
1゜03のターゲットに噴射、衝突させて3μmの平均
粒径とした。得られた混合粉末を、02分圧が1気圧の
N2O2混合ガス雲囲気で、880℃/12時間焼成し
た。ケーキ状に固化した粉末をさらに上記と同様のジェ
ットミルで粉砕して2μmとした。以下、この工程を3
回繰り返した。成形に際して、この粉末をトルエンを主
体とする溶媒を用いたPVE (ポリビニルブチエール
)をバインダーとして混練し、DBP(ゴブチルフタレ
ート)を可塑材として加えてドクターブレード成形の後
4 n+n+幅に切断して600℃、大気中にてバイン
ダーを除去した。Example 2 BaCO3, Gd with purity of 3N or more and average particle size of 6μm or less
Each powder of 2O3, CuO1V205 or Ta205 was fired so that the atomic ratio of Ba, Gd, Cu5V or Ta was 0.6:0.4:1.0:0.0
5 or 0.6:0.4:0.6:0.1. This mixed powder is blown with air A
The particles were injected and collided with a 1°03 target to obtain an average particle size of 3 μm. The obtained mixed powder was fired at 880° C. for 12 hours in a N2O2 mixed gas cloud atmosphere with a partial pressure of 1 atm. The cake-like solidified powder was further ground to 2 μm using a jet mill similar to the above. Below, this process is explained in 3
Repeated times. During molding, this powder was kneaded with PVE (polyvinyl butiere) using a toluene-based solvent as a binder, DBP (gobutyl phthalate) was added as a plasticizer, and after doctor blade molding, the powder was cut into 4 n+n+ widths. The binder was removed at 600° C. in the air.
上記の各々の成形体を100気圧の02雲囲気で、91
0℃にて5時間保持により焼結して焼結体を得た。Each of the above-mentioned molded bodies was heated to 91 m
It was sintered by holding at 0° C. for 5 hours to obtain a sintered body.
尚、臨界温度T。並びにT。、の測定は、定法に従って
試料の両端にAg導電ペーストにて電極を付け、タラビ
オスタット中で直流4点プローブ法で行った。温度はキ
ャリブレーション済みのAu (Fe)−Ag熱電対を
用いて行った。温度を少しづつ上昇させながら抵抗の変
化を観察した。In addition, the critical temperature T. and T. The measurements were carried out in a Tarabiostat using a DC four-point probe method, with electrodes made of Ag conductive paste attached to both ends of the sample according to a standard method. Temperature was measured using a calibrated Au (Fe)-Ag thermocouple. Changes in resistance were observed while increasing the temperature little by little.
■を含有する焼結体のTc は133 K、 TcFは
130にであり、一方、Taを含有する焼結体のTc
は131KXTopは127にであった。The Tc of the sintered body containing ■ is 133 K and TcF is 130, while the Tc of the sintered body containing Ta is 133 K and TcF of 130.
was 131KXTop was 127.
また、3週間後に同一材料を同一条件で測定したところ
、Tcの変化は±1°にの範囲であり、有意な変化は認
められなかった。Further, when the same material was measured under the same conditions after 3 weeks, the change in Tc was within ±1°, and no significant change was observed.
このことはLメータを用いて測定したAC帯磁率の測定
結果でも確認された。This was also confirmed by the measurement results of AC magnetic susceptibility measured using an L meter.
発明の詳細
な説明したように、本発明の方法により製造した超電導
性焼結体は、微細な結晶構造を示し、高く且つ安定した
T。を示す。As described in detail, the superconducting sintered body produced by the method of the present invention exhibits a fine crystal structure and a high and stable T. shows.
さらに、V、 NbSTaSMo、W、 Ti、 Cr
、 Ga、 In。Furthermore, V, NbSTaSMo, W, Ti, Cr
, Ga., In.
Cd、 5nSTISPbまたはZnを添加することに
よってさらに微細な結晶構造となり、より高いTcが得
られる。また、5乃至2500気圧の02雰囲気で焼結
することによりTcを大幅に向上させることができる。By adding Cd, 5nSTISPb, or Zn, a finer crystal structure can be obtained, and a higher Tc can be obtained. Further, Tc can be significantly improved by sintering in an O2 atmosphere of 5 to 2500 atmospheres.
さらに、本発明の好ましい態様に従い表面から中心迄の
厚さを1mm以下、好ましくは0.5n+m以下として
製造することにより、酸素欠陥濃度の均一性が達成され
、小さいΔTとなり、高いT。Fが得られる。Further, by manufacturing according to a preferred embodiment of the present invention with a thickness from the surface to the center of 1 mm or less, preferably 0.5 n+m or less, uniformity of the oxygen defect concentration is achieved, resulting in a small ΔT and a high T. F is obtained.
この様に高く安定したTcが得られるため、安価で経時
的な液体窒素を冷却剤として用いられる超電導性セラミ
ックスが得られる。Since such a high and stable Tc can be obtained, it is possible to obtain superconducting ceramics that are inexpensive and use liquid nitrogen as a coolant over time.
この超電導セラミックスセラミックスは、薄板材、細線
材あるいは小部品として、また、この線材をスパッタリ
ング等により薄膜化し、ジョセフソン素子、5QUID
(磁束計)、超電導マグネット、赤外センサ素子、モー
ター等への広範な応用分野に適用できる。These superconducting ceramics can be used as thin plates, thin wires, or small parts, or can be made into thin films by sputtering, etc., and can be used as Josephson elements, 5QUIDs, etc.
It can be applied to a wide range of fields such as (magnetometers), superconducting magnets, infrared sensor elements, and motors.
特許出願人 住友電気工業株式会社Patent applicant: Sumitomo Electric Industries, Ltd.
Claims (29)
、Cuの酸化物、炭酸塩、硫酸塩または硝酸塩の粉末を
混合し、予備焼結後の焼成体を平均粒径5μm以下に粉
砕し、これを成形した後、(上記焼成体粉末の融点)〜
(上記焼成体粉末の融点−100℃)の範囲の温度で本
焼結して平均結晶粒径10μm以下のペロブスカイト型
または擬似ペロブスカイト型の酸化物を形成することを
特徴とする高臨界温度を有する超電導材料の製造方法。(1) Ba and Gd each having an average particle size of 20 μm or less
, Cu oxide, carbonate, sulfate or nitrate powder is mixed, the pre-sintered sintered body is pulverized to an average particle size of 5 μm or less, and after molding, (melting point of the above sintered body powder) ~
(melting point of the above-mentioned sintered body powder - 100°C) to form a perovskite-type or pseudo-perovskite-type oxide with an average crystal grain size of 10 μm or less, and has a high critical temperature. A method for producing superconducting materials.
は硝酸塩の粉末の各々の平均粒径が10μm以下である
ことを特徴とする特許請求の範囲第1項に記載の高臨界
温度を有する超電導材料の製造方法。(2) The high critical temperature according to claim 1, characterized in that each of the powders of oxides, carbonates, sulfates, or nitrates of Ba, Gd, and Cu has an average particle size of 10 μm or less. A method for producing a superconducting material having
は硝酸塩の粉末の各々の平均粒径が5μm以下であるこ
とを特徴とする特許請求の範囲第1項に記載の高臨界温
度を有する超電導材料の製造方法。(3) The high critical temperature according to claim 1, wherein the average particle size of each of the powders of oxides, carbonates, sulfates, or nitrates of Ba, Gd, and Cu is 5 μm or less. A method for producing a superconducting material having
れ、 (Ba_1_−_xGd_x)Cu_yO_z(ただし
、x、yは0〜1の実数、zは0〜4の実数である) x、yがそれぞれ0.1〜0.9、0.4〜1.0とな
るように、Ba、Gd、Cuの酸化物、炭酸塩、硫酸塩
または硝酸塩の粉末を混合することを特徴とする特許請
求の範囲第1項乃至第3項のいずれか1項に記載の高臨
界温度を有する超電導材料の製造方法。(4) The obtained sintered superconducting material is represented by the following general formula, (Ba_1_-_xGd_x)Cu_yO_z (where x and y are real numbers from 0 to 1, and z is a real number from 0 to 4) x, A patent characterized in that powders of oxides, carbonates, sulfates, or nitrates of Ba, Gd, and Cu are mixed so that y is 0.1 to 0.9 and 0.4 to 1.0, respectively. A method for producing a superconducting material having a high critical temperature according to any one of claims 1 to 3.
、Mn、Ga、In、Cd、Sn、Tl、Pb、Znか
らなる群から選択した少なくとも1種の元素の酸化物、
炭酸塩、硫酸塩または硝酸塩の粉末を混合することを特
徴とする特許請求の範囲第1項乃至第4項のいずれか1
項に記載の高臨界温度を有する超電導材料の製造方法。(5) Furthermore, V, Nb, Ta, Mo, W, Ti, Cr
, an oxide of at least one element selected from the group consisting of Mn, Ga, In, Cd, Sn, Tl, Pb, and Zn;
Any one of claims 1 to 4, characterized in that powders of carbonate, sulfate or nitrate are mixed.
A method for producing a superconducting material having a high critical temperature as described in 2.
Ga、In、Cd、Sn、Tl、Pb,Znからなる群
から選択した少なくとも1種の元素とCuとの原子比を
0.01〜0.15とすることを特徴とする特許請求の
範囲第5項に記載の高臨界温度を有する超電導材料の製
造方法。(6) V, Nb, Ta, Mo, W, Ti, Cr, Mn,
Claim 1, characterized in that the atomic ratio of Cu to at least one element selected from the group consisting of Ga, In, Cd, Sn, Tl, Pb, and Zn is 0.01 to 0.15. A method for producing a superconducting material having a high critical temperature according to item 5.
ことを特徴とする特許請求の範囲第1項乃至第4項のい
ずれか1項に記載の高臨界温度を有する超電導材料の製
造方法。(7) A method for producing a superconducting material having a high critical temperature according to any one of claims 1 to 4, characterized in that preliminary sintering is carried out at a temperature in the range of 700 to 1000°C. .
回繰り返すことを特徴とする特許請求の範囲第1項乃至
第7項のいずれか1項に記載の高臨界温度を有する超電
導材料の製造方法。(8) At least 3 steps of pre-sintering, crushing and molding
A method for producing a superconducting material having a high critical temperature according to any one of claims 1 to 7, wherein the method is repeated several times.
供する焼成体を平均粒径3μm以下に粉砕することを特
徴とする特許請求の範囲第1項乃至第8項のいずれか1
項に記載の高臨界温度を有する超電導材料の製造方法。(9) Among the fired bodies after preliminary sintering, at least the fired bodies to be subjected to main sintering are pulverized to an average particle size of 3 μm or less.
A method for producing a superconducting material having a high critical temperature as described in 2.
とする特許請求の範囲第9項に記載の高臨界温度を有す
る超電導材料の製造方法。(10) The method for producing a superconducting material having a high critical temperature according to claim 9, wherein the pulverization is performed using a ball mill.
時間粉砕を行うことを特徴とする特許請求の範囲第10
項に記載の高臨界温度を有する超電導材料の製造方法。(11) At least 5 using Al_2O_3 balls
Claim 10, characterized in that time pulverization is performed.
A method for producing a superconducting material having a high critical temperature as described in 2.
徴とする特許請求の範囲第9項に記載の超電導材料の製
造方法。(12) The method for producing a superconducting material according to claim 9, wherein the pulverization is performed using a jet mill.
O_3のターゲットにジェット流を衝突させることによ
って上記粉砕を行うことを特徴とする特許請求の範囲第
12項に記載の高臨界温度を有する超電導材料の製造方
法。(13) Using air, Ar or N_2 as a medium, Al_2
13. The method for producing a superconducting material having a high critical temperature according to claim 12, wherein the pulverization is performed by impinging a jet stream on an O_3 target.
形し、本焼結することを特徴とする特許請求の範囲第1
項乃至第13項のいずれか1項に記載の高臨界温度を有
する超電導材料の製造方法。(14) Claim 1, characterized in that the pulverized fired body is molded to a relative density of 60 to 80% and subjected to main sintering.
A method for producing a superconducting material having a high critical temperature according to any one of Items 1 to 13.
1mm以下の形状に成形し、本焼結することを特徴とす
る特許請求の範囲第1項乃至第14項のいずれか1項に
記載の高臨界温度を有する超電導材料の製造方法。(15) The pulverized fired body is formed into a shape with a distance from the center to the surface of 1 mm or less, and is then sintered. A method for producing a superconducting material having a high critical temperature as described above.
0.6mm以下の形状に成形し、本焼結することを特徴
とする特許請求の範囲第15項に記載の高臨界温度を有
する超電導材料の製造方法。(16) The pulverized fired body is formed into a shape with a distance from the center to the surface of 0.6 mm or less, and is sintered, which has a high critical temperature as set forth in claim 15. A method for producing superconducting materials.
くは1.2mm以下のテープ状に成形することを特徴と
する特許請求の範囲第15項に記載の高臨界温度を有す
る超電導材料の製造方法。(17) Production of a superconducting material having a high critical temperature according to claim 15, characterized in that the pulverized fired body is formed into a tape shape with a thickness of 2 mm or less, preferably 1.2 mm or less. Method.
り成形することを特徴とする特許請求の範囲第17項に
記載の高臨界温度を有する超電導材料の製造方法。(18) A method for producing a superconducting material having a high critical temperature according to claim 17, characterized in that the pulverized fired body is molded by a doctor blade method.
くは1.2mm以下の線材に成形することを特徴とする
特許請求の範囲第15項に記載の高臨界温度を有する超
電導材料の製造方法。(19) A method for producing a superconducting material having a high critical temperature according to claim 15, characterized in that the pulverized fired body is formed into a wire rod having a diameter of 2 mm or less, preferably 1.2 mm or less.
ことを特徴とする特許請求の範囲第19項に記載の高臨
界温度を有する超電導材料の製造方法。(20) A method for producing a superconducting material having a high critical temperature according to claim 19, characterized in that the pulverized fired body is molded by an extrusion method.
PVB)をバインダとして用いて成形することを特徴と
する特許請求の範囲第1項乃至第20項に記載の高臨界
温度を有する超電導材料の製造方法。(21) The above pulverized fired body was treated with polyvinyl butyral (
21. A method for producing a superconducting material having a high critical temperature according to claims 1 to 20, characterized in that the superconducting material is molded using PVB) as a binder.
BP)を可塑剤として用いて成形することを特徴とする
特許請求の範囲第1項乃至第21項に記載の高臨界温度
を有する超電導材料の製造方法。(22) Dibutyl phthalate (D
22. A method for producing a superconducting material having a high critical temperature according to claims 1 to 21, characterized in that the superconducting material is molded using BP) as a plasticizer.
ルアルコール(PVA)をバインダとして用いて成形す
ることを特徴とする特許請求の範囲第1項乃至第22項
に記載の高臨界温度を有する超電導材料の製造方法。(23) The pulverized fired body is molded using water as a solvent and polyvinyl alcohol (PVA) as a binder, and has a high critical temperature according to claims 1 to 22. A method for producing superconducting materials.
加熱して上記溶剤およびバインダを除去することを特徴
とする特許請求の範囲第23項に記載の高臨界温度を有
する超電導材料の製造方法。(24) Production of a superconducting material having a high critical temperature according to claim 23, characterized in that the solvent and binder are removed by heating to a temperature in the range of 400°C to 700°C in the atmosphere. Method.
焼結を行うことを特徴とする特許請求の範囲第1項乃至
第24項のいずれか1項に記載の高臨界温度を有する超
電導材料の製造方法。(25) A superconductor having a high critical temperature according to any one of claims 1 to 24, wherein the main sintering is performed in an atmosphere with an O_2 partial pressure of 5 to 2,500 atmospheres. Method of manufacturing the material.
備焼結を行うことを特徴とする特許請求の範囲第1項乃
至第25項のいずれか1項に記載の高臨界温度を有する
超電導材料の製造方法。(26) A superconductor having a high critical temperature according to any one of claims 1 to 25, characterized in that preliminary sintering is performed in an atmosphere with an O_2 partial pressure of 5 to 2,500 atmospheres. Method of manufacturing the material.
熱処理することを特徴とする特許請求の範囲第1項乃至
第26項に記載の高臨界温度を有する超電導材料の製造
方法。(27) A method for manufacturing a superconducting material having a high critical temperature according to any one of claims 1 to 26, characterized in that the sintered body after main sintering is heat-treated in a range of 500 to 800°C. .
以下であることを特徴とする特許請求の範囲第27項に
記載の高臨界温度を有する超電導材料の製造方法。(28) O_2 partial pressure during heat treatment is 10^-^1Torr
A method for producing a superconducting material having a high critical temperature according to claim 27, characterized in that:
至800℃の範囲に再加熱し、急冷することを特徴とす
る特許請求の範囲第1項乃至第28項の何れか1項に記
載の高臨界温度を有する超電導材料の製造方法。(29) Immediately after the main sintering, or after the main sintering, the process is reheated to a temperature in the range of 500 to 800°C and then rapidly cooled. A method for producing a superconducting material having a high critical temperature as described above.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP63-67651A JPH013053A (en) | 1987-03-22 | 1988-03-22 | Method for manufacturing superconducting materials |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62-66201 | 1987-03-22 | ||
JP6620187 | 1987-03-22 | ||
JP63-67651A JPH013053A (en) | 1987-03-22 | 1988-03-22 | Method for manufacturing superconducting materials |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS643053A JPS643053A (en) | 1989-01-06 |
JPH013053A true JPH013053A (en) | 1989-01-06 |
Family
ID=
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