JP3195041B2 - Oxide superconductor and manufacturing method thereof - Google Patents
Oxide superconductor and manufacturing method thereofInfo
- Publication number
- JP3195041B2 JP3195041B2 JP08303792A JP8303792A JP3195041B2 JP 3195041 B2 JP3195041 B2 JP 3195041B2 JP 08303792 A JP08303792 A JP 08303792A JP 8303792 A JP8303792 A JP 8303792A JP 3195041 B2 JP3195041 B2 JP 3195041B2
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- composition
- phase
- molded body
- oxide superconductor
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Description
【0001】[0001]
【産業上の利用分野】本発明は、REBa2 Cu3 O
7-x 型の酸化物超電導体相を有するバルク超電導材料に
関するものである。BACKGROUND OF THE INVENTION This invention is, REBa 2 Cu 3 O
The present invention relates to a bulk superconducting material having a 7-x type oxide superconductor phase.
【0002】[0002]
【従来の技術】REBa2 Cu3 O7-x 型(123相
型)の超電導体は結晶の大型化が課題となっている。こ
のような結晶の大型化は多結晶組織では結晶粒界が弱結
合として作用して超電導特性を害するので単結晶にしな
ければならない。従来の技術は結晶成長させる前の成形
体を重ねクエンチ法やRE、Ba、Cuの複合酸化物の
混合粉末をRE組成を変えながら層状に成形することで
得ており、これを大気中で半溶融状態に加熱し種結晶
や、123相生成温度(Tf)のちがいを利用して結晶
の大型化を行っている[Advances in Su
perconductivity III (Spri
nger−Verlag.Tokyo,1990) p
733] 2. Description of the Related Art In the REBa 2 Cu 3 O 7-x type (123 phase type) superconductor, there is an issue of increasing the size of the crystal. Such an increase in the size of the crystal requires a single crystal since the crystal grain boundaries act as weak bonds in the polycrystalline structure and impair the superconducting characteristics. The conventional technique is obtained by stacking the compacts before crystal growth and forming the mixed powder of the composite oxide of RE, Ba, and Cu into layers while changing the RE composition. The size of the crystal is increased by heating to a molten state and utilizing the difference between the seed crystal and the 123 phase formation temperature (Tf) [Advences in Su]
perconductivity III (Spri
nger-Verlag. (Tokyo, 1990) p
733]
【0003】[0003]
【発明が解決しようとする課題】従来は、成形体を大気
中で加熱し半溶融状態にしていた。このため成形体中に
隙間があるものや、粉末を加圧したような密度の低いも
のは特に、気体が大量に閉じこめられたまま半溶融状態
になる。たとえば成形体を重ねクエンチ法により作製し
た場合、各層の隙間にわずかに気泡が残る。また粉末を
成形した場合は表面から5mm程度を除いた部分には、
多くの気泡が残ってしまうことになる[Advance
s in Superconductivity II
I (Springer−Verlag.Tokyo,
1990)]。Conventionally, a molded body has been heated to a semi-molten state in the atmosphere. For this reason, a molded article having a gap or a powder having a low density such as a pressed powder is in a semi-molten state while a large amount of gas is trapped. For example, when a molded article is produced by the overlap quench method, bubbles slightly remain in the gaps between the layers. Also, when powder is molded, the part except about 5 mm from the surface is
Many bubbles will remain [Advanced
s in Superconductivity II
I (Springer-Verlag. Tokyo,
1990)].
【0004】この気泡の問題は成形体を大きくしたとき
に特に深刻になる。粉末を加圧成形した大きな成形体を
半溶融状態にすると中心部分で気泡が集まり、すが入っ
た状態になる。このようなすは種結晶からの結晶成長を
妨げたり、超電導電流の流れを遮るため、超電導材料と
しての特性を損う結果をもたらす。そこで本発明では、
半溶融状態に加熱する際に、気泡を含まない加熱方法を
提供することによって、殆ど気泡を含まない大きな超電
導材料およびその製造方法を提供することを課題とす
る。[0004] The problem of air bubbles is particularly serious when the molded article is made large. When a large compact obtained by press-molding a powder is made into a semi-molten state, air bubbles are collected at a central portion, and a state is obtained in which a soot is contained. Such a barrier hinders the crystal growth from the seed crystal and interrupts the flow of the superconducting current, resulting in a loss of properties as a superconducting material. Therefore, in the present invention,
It is an object of the present invention to provide a large superconducting material containing almost no bubbles and a method for producing the same by providing a heating method containing no bubbles when heating to a semi-molten state.
【0005】[0005]
【課題を解決するための手段】本発明は上記課題を解決
するものであって、RE(Yを含む希土類元素およびそ
れらの組み合わせ)、BaおよびCuの複合酸化物であ
る酸化物超電導体において、RE2 BaCuO5 (21
1)相が単結晶状のREBa2 Cu3 O7-x (123)
相中に微細分散した組織を有し、かつ気孔率が体積率で
3%以下であることを特徴とする酸化物超電導体であ
る。SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems and provides an oxide superconductor which is a composite oxide of RE (a rare earth element including Y and a combination thereof), Ba and Cu, RE 2 BaCuO 5 (21
1) Single phase REBa 2 Cu 3 O 7-x (123)
An oxide superconductor having a structure finely dispersed in a phase and having a porosity of 3% or less by volume.
【0006】また、RE(Yを含む希土類元素およびそ
れらの組み合わせ)、Ba、Cuの酸化物または複合酸
化物の少くとも一方からなる成形体を酸素純度が90%
以上の雰囲気中で加熱し溶融状態にした後、そのままの
雰囲気中で徐冷するか、または雰囲気を大気もしくは酸
化性雰囲気に置換した後、徐冷することによって、単結
晶状に結晶成長させることを特徴とする酸化物超電導体
の製造方法である。Further, a molded body made of at least one of RE (a rare earth element containing Y and a combination thereof), Ba and Cu oxides or composite oxides has an oxygen purity of 90%.
After a molten state heated in above the atmosphere, after either slowly cooled in a neat atmosphere, or the atmosphere was replaced with air or an oxidizing atmosphere, by slow cooling, single binding
A method for producing an oxide superconductor, which comprises growing a crystal in a crystalline state.
【0007】また、RE(Yを含む希土類元素およびそ
れらの組み合わせ)、Ba、Cuの酸化物または複合酸
化物の少くとも一方からなる成形体を酸素純度が90%
以上の雰囲気中で加熱し溶融状態にした後、室温にまで
冷却し炉内から取りだした後、さらに大気もしくは酸化
性雰囲気中で加熱溶融した後、徐冷することによって、
単結晶状に結晶成長させることを特徴とする酸化物超電
導体の製造方法である。Further, a molded body made of at least one of RE (a rare earth element containing Y and a combination thereof), an oxide of Ba and Cu or a composite oxide has an oxygen purity of 90%.
After being heated and melted in the above atmosphere, cooled to room temperature and taken out of the furnace, and further heated and melted in the air or an oxidizing atmosphere, and then gradually cooled,
A method for producing an oxide superconductor, which comprises growing a crystal in a single crystal state.
【0008】また上記製造方法において、成形体が金属
元素のモル比(RE:Ba:Cu)が(30:33:3
7)、(15:38:37)、(15:30:55)、
(30:25:45)で結ばれる領域内の組成を有し、
かつ0.1から2.0重量%のPtまたは0.01から
1.0重量%のRhの少なくとも一方を含有しているこ
とも特徴とする。さらにこのとき高い123相生成温度
(Tf)を有するRE組成の層からより低いTfを有す
るRE組成の層へ順に層状に変化する成形体(M)を作
製し、この成形体(M)中の最も高いTfのRE組成よ
り高いTfを有するRE組成の成形体(H)と、成形体
(M)中の最も低いTfのRE組成より低いTfを有す
るRE組成の成形体(L)とをM−L−H−支持材の順
で配置し、成形体Mが211相と液相が共存する温度領
域(この温度領域の下限を以下Tgとする)に加熱し、
しかるのち種結晶のREの組成のTfよりも低くTgよ
りも高い温度にした後、Tgから成形体中の最も低いR
E組成のTfよりもさらに30℃低い温度まで20℃/
hr以下の冷却速度で徐冷し種結晶から結晶を成長させ
た後、一旦室温に戻すかまたは連続して800℃から2
00℃の温度領域を酸化性雰囲気中で酸素付加処理をし
て各REBa2 Cu3 O7-x 層のX値を0.2以下にし
て超電導材料を得ることも特徴とする。[0008] In the above-mentioned manufacturing method, the molded product may have a metal element molar ratio (RE: Ba: Cu) of (30: 33: 3).
7), (15:38:37), (15:30:55),
(30:25:45) having a composition in the region connected by
Further, it is characterized in that it contains at least one of Pt of 0.1 to 2.0% by weight and Rh of 0.01 to 1.0% by weight. At this time to produce a molded article which varies in layers in this order onto a layer of RE composition having a lower Tf from a layer of RE composition having a high 123-phase generation temperature (Tf) (M) In addition, in the adult form body (M) A molded article (H) having an RE composition having a higher Tf than the RE composition having the highest Tf, and a molded article (L) having an RE composition having a lower Tf than the RE composition having the lowest Tf in the molded article (M). The molded body M is arranged in the order of MLH-supporting material, and the molded body M is heated to a temperature region where the 211 phase and the liquid phase coexist (the lower limit of this temperature region is hereinafter referred to as Tg),
After the temperature higher than Tg lower than Tf the composition of RE in later seed crystal accordingly, the lowest R in the compact from Tg
20 ° C./30° C. lower than the Tf of E composition
After slowly growing the seed crystal by cooling at a cooling rate of not more than hr, the temperature is returned to room temperature once or continuously from 800 ° C. to 2 ° C.
It is also characterized in that a superconducting material is obtained by performing an oxygen addition treatment in a temperature range of 00 ° C. in an oxidizing atmosphere so that the X value of each REBa 2 Cu 3 O 7-x layer is 0.2 or less.
【0009】[0009]
【作用】本発明は上記課題を解決するために、成形体を
加熱溶融する際に、雰囲気の酸素割合を上げることによ
って、半溶融状態において気泡を減少せ得ることを見い
だした。すなわち、RE(Yを含む希土類元素およびそ
れらの組み合わせ)、Ba、Cuの酸化物またはおよび
複合酸化物からなる成形体を酸素純度が90%以上の雰
囲気中で加熱し溶融状態にした後、そのままの雰囲気中
で徐冷することによって超電導相を結晶成長をさせるか
または、上記成形体を上記雰囲気中で加熱し溶融状態に
した後、雰囲気を大気もしくは任意の酸化性雰囲気に置
換した後、徐冷することによって結晶成長させるかまた
は、上記成形体を上記酸素純度の雰囲気中で加熱し溶融
状態にした後、室温にまで冷却し炉内から取りだし、さ
らに酸化性雰囲気中で加熱溶融した後、徐冷することに
よって結晶成長させ、気泡を含まない酸化物超電導体を
製造するものである。In order to solve the above-mentioned problems, the present invention has found that bubbles can be reduced in a semi-molten state by increasing the oxygen ratio in the atmosphere when the molded body is heated and melted. That is, a molded body made of an oxide of RE (a rare earth element containing Y and a combination thereof), Ba, Cu or a composite oxide is heated in an atmosphere having an oxygen purity of 90% or more to be in a molten state, and is then left as it is. After the superconducting phase is crystal-grown by gradually cooling in an atmosphere of, or after the molded body is heated and melted in the above-described atmosphere, the atmosphere is replaced with air or any oxidizing atmosphere, and then gradually cooled. After crystal growth by cooling, or after heating the molded body in an atmosphere of the oxygen purity to a molten state, cooling to room temperature, taking out from the furnace, and further heating and melting in an oxidizing atmosphere, The crystal is grown by slow cooling to produce an oxide superconductor containing no bubbles.
【0010】本発明でいうところの単結晶とはマトリッ
クスの123相(超電導相)は内部に数10μm以下の
微細な211相(絶縁体相)、双晶界面、小傾角粒界、
直径数100μm程度の気泡やa−b面間のマイクロク
ラックを含むものの、数cm3 以上の大きさにわたっ
て、超電導電流の流れを大きく遮る大傾角粒界を含まな
い複合超電導材料を意味する。また実質的に上記複合超
電導体材料の集合体も含めるものとする。The term “single crystal” as used in the present invention means that the 123 phase (superconducting phase) of the matrix has a fine 211 phase (insulator phase) of several tens μm or less, a twin interface, a small angle grain boundary,
It means a composite superconducting material that contains bubbles having a diameter of about 100 μm and microcracks between a and b planes, but does not contain large-angle grain boundaries that greatly block the flow of superconducting current over a size of several cm 3 or more. In addition, an aggregate of the composite superconductor material is substantially included.
【0011】成形体を半溶融状態(211相と液状のB
aとCuの複合酸化物の混合状態)に加熱する場合、成
形体はおもに表面から半溶融状態になるため、溶融前の
雰囲気の成分が気泡として半溶融状態の成形体中に取り
込まれることになる。そのとき、成形体中の気体の成分
は雰囲気の成分と同じことになる。そのため、たとえば
大気中で半溶融状態にした場合、気泡中の成分は約80
%が窒素で約20%が酸素になる。しかしながら、酸素
は半溶融状態の液相成分を構成する元素であり、半溶融
状態の成形体中に吸収され気泡中の成分はほぼ窒素だけ
となることが判明した。この気泡は最終的に超電導材料
中に残ることになり、前記の問題を引きおこす。そこで
発明者は加熱溶融時の雰囲気の大部分を酸素にすること
で気泡をほとんど無くし、この問題を解決した。[0011] The compact is placed in a semi-molten state (211 phase and liquid B
When the mixture is heated to a mixed state of a and Cu), the molded body is mainly in a semi-molten state from the surface, so that components of the atmosphere before melting are taken into the semi-molten molded body as bubbles. Become. At that time, the components of the gas in the compact are the same as the components of the atmosphere. Therefore, for example, when it is made to be in a semi-molten state in the atmosphere, the components in the bubbles are about 80%.
% Is nitrogen and about 20% is oxygen. However, it has been found that oxygen is an element constituting the liquid phase component in the semi-molten state, and is absorbed in the semi-molten state molded body, and the component in the bubbles is almost only nitrogen. These bubbles will eventually remain in the superconducting material, causing the aforementioned problems. The inventor solved this problem by eliminating most of the bubbles by converting most of the atmosphere during heating and melting to oxygen.
【0012】気孔率は雰囲気中の酸素濃度のほかにも成
形体の大きさや半溶融状態に加熱するときの昇温速度に
よっても多少変化する。数10cm3 の成形体を大気中
で200℃/hr程度の昇温速度で半溶融状態にした場
合、超電導材料の数mmの表層を除く中心部では気孔率
は体積率で約10〜15%程度である。これを雰囲気中
の酸素割合を90%にすることで気孔率を3%以下に抑
え、超電導材料作製上問題とならなくなる程度に気孔率
を下げることができ、緻密な超電導材料を得ることがで
きる。また、99%以上の酸素雰囲気中で半溶融状態に
することによってより望ましい気孔率が1%以下の超電
導材料が得られる。The porosity slightly varies depending on the oxygen concentration in the atmosphere, the size of the compact, and the rate of temperature rise when the compact is heated to a semi-molten state. When a compact of several tens of cm 3 is made to be in a semi-molten state at a heating rate of about 200 ° C./hr in the air, the porosity is about 10 to 15% by volume in the central portion of the superconducting material excluding the surface layer of several mm. It is about. By setting the oxygen content in the atmosphere to 90%, the porosity can be suppressed to 3% or less, the porosity can be reduced to such an extent that no problem occurs in the production of the superconducting material, and a dense superconducting material can be obtained. . Further, a superconducting material having a more desirable porosity of 1% or less can be obtained by making the semi-molten state in an oxygen atmosphere of 99% or more.
【0013】大気中で半溶融処理を行った場合、成形体
の形によっても多少異なるが、ブロック状の成形体で
は、体積が約50cm3 程度を超える大きさから大きく
なればなるほど中心部に残留ガスが集まり、すが入った
状態になりやすくなる。300cm3 を超えるもので
は、ほとんどのものが内部にすが入った状態となる。こ
のようなすも気泡同様に雰囲気の酸素濃度上げることに
よって容易に解決できる。[0013] When performing the semi-molten treatment in the atmosphere, but slightly varies depending on the shape of the molded body, in the block-shaped molded article, remaining in the more central portion the larger the size of the volume is greater than about 50 cm 3 degree The gas collects and it becomes easier for the soot to enter. If the size exceeds 300 cm 3 , most of the material will be in a state of being soaked inside. Such a problem can be easily solved by increasing the oxygen concentration of the atmosphere similarly to the bubble.
【0014】上記説明からもわかるように、超電導材料
作製プロセスにおいて半溶融状態に加熱する時にのみ酸
素雰囲気にすればよく、結晶成長過程においては必ずし
も高酸素の雰囲気中で行う必要はない。そこで熱処理パ
ターンと雰囲気との3通りタイミングを図1のa、b、
cに示した。As can be seen from the above description, an oxygen atmosphere may be used only when heating to a semi-molten state in the superconducting material manufacturing process, and the crystal growth process does not necessarily need to be performed in a high oxygen atmosphere. Therefore, the three timings of the heat treatment pattern and the atmosphere are shown in FIGS.
c.
【0015】また、123中の211相は半溶融状態に
おいては成形体の形状を保つ働きをし、また最終的に得
られる超電導材料においては割れを防いだり臨界電流密
度を高める働きがある。そこで211相の超電導材料に
占める割合が0から50%になるように各元素の比(R
E:Ba:Cu)を(30:33:37)、(15:3
8:37)、(15:30:55)、(30:25:4
5)の範囲と限定した。半溶融状態において液相となる
Ba、Cuの比率を上記範囲以上にした場合は、液相成
分の成形体外への流出が多くなり、成形体が大きく収縮
したり、形状が保てなくなる傾向がある。逆に半溶融状
態において固相(211相)をつくるRE成分の割合が
上記範囲を超えると、123相の結晶成長時に液相が不
足して途中で結晶成長が止まりやすくなる。この様な観
点から、123相の結晶が安定に成長できたときの、単
結晶バルク体中に占める211相の体積割合の上限が約
50%であったため211相の体積率を50%以下とし
た。In the semi-molten state, the 211 phase in 123 functions to maintain the shape of the compact, and in the finally obtained superconducting material, functions to prevent cracking and increase the critical current density. Therefore, the ratio (R) of each element is set such that the ratio of the 211 phase to the superconducting material is 0 to 50%.
E: Ba: Cu) to (30:33:37), (15: 3
8:37), (15:30:55), (30: 25: 4)
It was limited to the range of 5). When the ratio of Ba and Cu in the liquid phase in the semi-molten state is set to the above range or more, the outflow of the liquid phase component to the outside of the molded body increases, and the molded body tends to largely shrink or lose its shape. is there. Conversely, if the proportion of the RE component that forms the solid phase (211 phase) in the semi-molten state exceeds the above range, the liquid phase becomes insufficient during the crystal growth of the 123 phase, and the crystal growth tends to stop halfway. From such a viewpoint, the upper limit of the volume ratio of the 211 phase in the bulk single crystal when the crystal of the 123 phase can be grown stably is about 50%, so that the volume ratio of the 211 phase is 50% or less. did.
【0016】添加元素のPt、Rhは211相とBaC
u複合酸化物の液相とからなる半溶融状態で211相の
粒成長を妨げる働きがあり、211相を微細化させ、特
に臨界温度近傍では主なピンニングセンターとなり高い
臨界電流密度をもたらす原因となる。添加量は効果を生
じ始める値を下限とし、Baとの複合酸化物が多く現れ
る値を上限とし、0.1〜2.0wt%のPtまたはお
よび0.01〜1.0wt%のRhとした。出発原料は
基本的にRE、Ba、Cuの酸化物またはおよび複合酸
化物であればよいが、211相を直接出発原料とする場
合、211相粉末を十分微細化しなければ最終的に21
1相が微細化した最終組織は得られない。The added elements Pt and Rh are 211 phases and BaC
In the semi-molten state consisting of the liquid phase of the u composite oxide, it has the function of hindering the grain growth of the 211 phase, making the 211 phase finer, and becoming a main pinning center especially near the critical temperature, causing a high critical current density. Become. The amount of addition is defined as a lower limit at which the effect starts to be produced, and as an upper limit at a value at which a complex oxide with Ba frequently appears, as 0.1 to 2.0 wt% of Pt or 0.01 to 1.0 wt% of Rh. . The starting material may basically be an oxide of RE, Ba, or Cu or a composite oxide. However, when the 211 phase is used directly as the starting material, the final 21
A final structure in which one phase is refined cannot be obtained.
【0017】上記の製造方法により、殆ど気泡を含まず
かつ211相の割合が体積率で全体の50%以下であり
211相の95個数%以上が20ミクロン以下にである
酸化物超電導体やさらに、211相の95個数%以上が
2ミクロン以下にであり、かつ0.1〜2.0wt%の
Ptまたはおよび0.01〜1.0wt%のRhを含有
している酸化物超電導体が作製される。According to the above-mentioned manufacturing method, an oxide superconductor containing almost no air bubbles and having a proportion of 211 phases by volume ratio of 50% or less and 95% or more of 211 phases by 20 μm or less can be obtained. The oxide superconductor in which 95% by number or more of the 211 phase is 2 μm or less and contains 0.1 to 2.0 wt% of Pt or 0.01 to 1.0 wt% of Rh. Is done.
【0018】成形体中のREの成分は単一元素のRE
(Y、La、Nb、Sm、Eu、Gd、Dy、Ho、E
r、Tm、Yb、Lu)または複数のRE元素から成っ
ていてもよい。123相生成温度(Tf)はイオン半径
が大きいREほど高いがYはDyとHoの間に位置す
る。例えば大気中では、ほぼSm:1060℃、Dy:
1010℃、Y:1000℃、Er:970℃、Yb:
900℃である。また複数のRE元素からなる場合はT
fは各RE元素のTfのモル平均にほぼ等しい。The component of RE in the compact is a single element of RE.
(Y, La, Nb, Sm, Eu, Gd, Dy, Ho, E
r, Tm, Yb, Lu) or a plurality of RE elements. The 123 phase formation temperature (Tf) is higher for RE having a larger ionic radius, but Y is located between Dy and Ho. For example, in the atmosphere, approximately Sm: 1060 ° C., Dy:
1010 ° C, Y: 1000 ° C, Er: 970 ° C, Yb:
900 ° C. In the case of a plurality of RE elements, T
f is approximately equal to the Tf molar average of each RE element.
【0019】また成形体は成形体中の最も高いTf以上
に加熱され成形体全体が211相と液相から成る半溶融
状態に加熱される。その後成形体中最も高いTfよりも
高いTfのRE組成を有する種結晶を成形体中で最も高
いTfの層に載置することにより種結晶植付けを行う。
その後成形体中の最も低いTfよりも30℃低い温度ま
で徐冷することによって結晶を成長させる。このような
Tfの違いを利用した技術によって、123相および2
11相中のRE元素の組成が123相生成温度の順に層
状に分布している酸化物超電導体を作製することができ
る。Further, the molded body is heated to the highest Tf or more in the molded body, and the whole molded body is heated to a semi-molten state composed of 211 phases and a liquid phase. Thereafter, a seed crystal having an RE composition having a higher Tf than the highest Tf in the molded body is placed on the layer having the highest Tf in the molded body to perform seed crystal planting .
Thereafter, the crystal is grown by gradually cooling to a temperature 30 ° C. lower than the lowest Tf in the molded body. By the technology using the difference of Tf, 123 phases and 2
An oxide superconductor in which the composition of the RE element in the 11 phases is distributed in a layered manner in the order of the 123 phase formation temperature can be manufactured.
【0020】また、成形体と支持台との成形体LとHは
支持台を通して液相が流れ出すのを防ぎかつ種結晶以外
から結晶が成長するのを防ぐ働きがある。すなわち、成
形体を熱処理する際、成形体はなんらかの物質で支持す
る必要があるが本発明においては支持材は123相自身
を用いることにした。即ち、前記したように成形体Mと
該成形体Mを支持する支持材との間に、前記成形体M中
の123相のRE組成より結晶生成温度が高いRE組成
を有する別の成形体Hと、前記成形体M中の123相の
RE組成より結晶生成温度が低いRE組成を有する別の
成形体Lとを成形体M−成形体L−成形体H−支持材の
順番で配置し、かかる成形体を支持材とのバリアーに利
用するのである。成形体Hは成形体Mの液相部分が支持
材へ流れ出すのを防ぐバリアーとして、また成形体Lは
成形体Hでできた123相の結晶が成長して成形体Mの
結晶成長を防げることを防ぐバリアーとして用いられ
る。なお、前記成形体Mの最下層の123相が、成形体
Lと同様な作用をなすものであれば、成形体Lを省略し
ても差支えない。かかるバリアーを配置することによ
り、より効率よく結晶を成長させることができるのであ
る。The compacts L and H of the compact and the support have a function of preventing the liquid phase from flowing out through the support and preventing the growth of crystals other than seed crystals. That is, when heat-treating the compact, it is necessary to support the compact with some substance, but in the present invention, the support material uses the 123 phase itself. That is, as described above, another formed body H having an RE composition having a higher crystal formation temperature than the RE composition of the 123 phase in the formed body M between the formed body M and the supporting material supporting the formed body M. And another formed body L having an RE composition whose crystal formation temperature is lower than the RE composition of the 123 phase in the formed body M, in the order of formed body M-formed body L-formed body H-supporting material, Such a molded article is used as a barrier with the support material. The molded body H serves as a barrier to prevent the liquid phase portion of the molded body M from flowing out to the support material, and the molded body L prevents the crystal growth of the molded body M by growing crystals of the 123 phase formed of the molded body H. Used as a barrier to prevent Note that the molded body L may be omitted if the lowermost 123 phase of the molded body M has the same function as the molded body L. By arranging such a barrier, crystals can be grown more efficiently.
【0021】またさらに、成長させた直後の123相は
正方晶であり、これを800℃から200℃まで酸化性
雰囲気中で徐冷し酸素を吸収させることにより、斜方晶
に転移させ、超電導材料を得る。Further, immediately after the growth, the 123 phase is tetragonal, which is gradually cooled in an oxidizing atmosphere from 800 ° C. to 200 ° C. to absorb oxygen, thereby transforming the phase into orthorhombic and superconducting. Get the material.
【0022】[0022]
実施例1 Y2 O3 、BaO2 とCuOの各粉末を各金属元素のモ
ル比(Y:Ba:Cu)が(11:19:28)になる
ように混合し、さらにこの混合粉に0.5wt%の白金
粉末を添加し、原料粉末を作製した。この原料粉末から
2種類の大きさの成形体(直径40mm厚さ15mmと
直径60mm厚さ30mm)を作製した。そして図1に
示す3通りの熱処理方法により試料を作製した。熱処理
温度等はそれぞれ次に示す。Example 1 Each powder of Y 2 O 3 , BaO 2 and CuO was mixed so that the molar ratio of each metal element (Y: Ba: Cu) became (11:19:28), and 0 was added to this mixed powder. A raw material powder was prepared by adding 0.5 wt% of platinum powder. From this raw material powder, molded bodies of two sizes (diameter 40 mm, thickness 15 mm and diameter 60 mm, thickness 30 mm) were produced. Then, samples were prepared by the three heat treatment methods shown in FIG. The heat treatment temperature and the like are shown below.
【0023】(a)室温から1100℃まで200℃/
hrで昇温し、1時間保持した後1030℃まで30分
で降温し、続いて960℃まで1℃/hrで徐冷するこ
とによって超電導になる123相を成長させ、さらに6
00℃から200℃まで3℃/hrで徐冷し酸素付加処
理を行った。そして、本発明材として全熱処理を99%
酸素の濃度の雰囲気で行ったときと、比較例として酸素
付加処理以外を大気中で行ったときについて試料内部の
様子を調べた。(A) From room temperature to 1100 ° C., 200 ° C. /
The temperature was increased for 1 hour, maintained for 1 hour, then decreased to 1030 ° C. in 30 minutes, and then gradually cooled to 960 ° C. at 1 ° C./hr to grow a 123 phase which became superconducting.
It was gradually cooled at a rate of 3 ° C./hr from 00 ° C. to 200 ° C. to perform an oxygen addition treatment. And as the material of the present invention, the total heat treatment is 99%
The inside state of the sample was examined when it was performed in an atmosphere having an oxygen concentration, and as a comparative example, when it was performed in the air except for the oxygen addition treatment.
【0024】(b)室温から1100℃まで200℃/
hrで昇温し、1時間保持した後雰囲気を大気に置換
し、続いて1030℃まで30分で降温し、続いて96
0℃まで1℃/hrで徐冷することによって超電導にな
る123相を成長させ、さらに600℃から200℃ま
で3℃/hrで徐冷し酸素付加処理を行った。また、本
発明材として1100℃で1時間保持する過程を99%
酸素の濃度の雰囲気で行ったときと、比較例として11
00℃で1時間保持する過程を大気中で行ったときにつ
いて試料内部の様子を調べた。(B) From room temperature to 1100 ° C., 200 ° C. /
The temperature was raised for 1 hour, maintained for 1 hour, and the atmosphere was replaced with the atmosphere. Subsequently, the temperature was lowered to 1030 ° C. in 30 minutes, and then 96 ° C.
By gradually cooling to 0 ° C. at 1 ° C./hr, a 123 phase to become superconducting was grown, and further gradually cooling from 600 ° C. to 200 ° C. at 3 ° C./hr to perform an oxygen addition treatment. The process of holding at 1100 ° C. for 1 hour as the material of the present invention is 99%
When the test was performed in an atmosphere having an oxygen concentration, and as a comparative example,
The state inside the sample was examined when the process of holding at 00 ° C. for 1 hour was performed in the air.
【0025】(c)室温から1100℃まで200℃/
hrで昇温し、1時間保持した後室温まで2時間で冷却
した。つぎにまた室温から1100℃まで200℃/h
rで昇温し、1時間保持した後1030℃まで30分で
降温し、続いて960℃まで1℃/hrで徐冷すること
によって超電導になる123相を成長させ、さらに60
0℃から200℃まで3℃/hrで徐冷し酸素付加処理
を行った。また、本発明材として1100℃で1時間保
持した後、室温まで冷却する過程を99%酸素の濃度の
雰囲気で行ったときと、比較例として1100℃で1時
間保持し、室温まで冷却する過程を大気中で行ったとき
について試料内部の様子と気孔率を調べた。(C) From room temperature to 1100 ° C., 200 ° C. /
The temperature was raised for hr, maintained for 1 hour, and then cooled to room temperature in 2 hours. Next, 200 ℃ / h from room temperature to 1100 ℃
After heating for 1 hour, the temperature was lowered to 1030 ° C. in 30 minutes, and then gradually cooled to 960 ° C. at 1 ° C./hr to grow a 123 phase which became superconducting.
The mixture was gradually cooled from 0 ° C. to 200 ° C. at 3 ° C./hr to perform an oxygen addition treatment. In addition, the process of cooling to room temperature after holding at 1100 ° C. for 1 hour as the material of the present invention was performed in an atmosphere of 99% oxygen concentration, and the process of holding at 1100 ° C. for 1 hour and cooling to room temperature as a comparative example The state inside the sample and the porosity were examined when the test was performed in the atmosphere.
【0026】酸素付加処理は、すべて純酸素中で行っ
た。また、これらの得られた試料は3cm3 程度の単結
晶状の超電導体集合体であった。その結果をまとめると
表1のようになった。以上の結果から高酸素濃度中での
半溶融加熱処理により、試料中の気孔率を大幅に低減で
きることがわかった。All the oxygen addition treatments were performed in pure oxygen. In addition, these obtained samples were single-crystal superconductor aggregates of about 3 cm 3 . Table 1 summarizes the results. From the above results, it was found that the porosity in the sample could be significantly reduced by the semi-melting heat treatment in a high oxygen concentration.
【0027】[0027]
【表1】 [Table 1]
【0028】実施例2 Ho2 O3 、Dy2 O3 、BaCuO2 とCuOの各粉
末を各金属元素のモル比(Ho:Dy:Ba:Cu)が
(7:6:17:24)になるように混合し、さらにこ
の混合粉に0.05wt%のRh粉末を添加し、原料粉
末を作製した。この原料粉末から直径50mm厚さ20
mmの成形体(M)を作製した。ハンマークエンチ法で
作製したSmおよびYb組成の成形体を成形体(M)と
白金の支持台との間に配置した後、熱処理温度等はそれ
ぞれ実施例1記載のa、b、c3種類の方法で行った。
ただし、図2にa、b、cに示すように、1045℃1
0分間保持しこの温度でSm系の123相の種結晶を用
い種結晶植付けを行った。Example 2 Each powder of Ho 2 O 3 , Dy 2 O 3 , BaCuO 2 and CuO was adjusted to have a molar ratio of each metal element (Ho: Dy: Ba: Cu) of (7: 6: 17: 24). , And 0.05 wt% of Rh powder was added to the mixed powder to prepare a raw material powder. From this raw material powder, diameter 50 mm thickness 20
mm of a molded product (M) was produced. After the compact having the composition of Sm and Yb produced by the hammer ench method is disposed between the compact (M) and the support of platinum, the heat treatment temperature and the like are set to three kinds of methods a, b and c described in Example 1, respectively. I went in.
However, as shown by a, b, and c in FIG.
After holding for 0 minutes, seed crystals were seeded at this temperature using Sm-based 123 phase seed crystals.
【0029】成形体を半溶融状態に加熱したときの雰囲
気は、酸素と窒素の比(O2 :N2)を変えて4種類
[(20:80)、(50:50)、(90:10)、
(99:1)]で行った。その後、酸素付加処理を行う
ため800℃に降温した後200℃まで150時間かけ
て酸素気流中で徐冷した。このようにして実質的に試料
全体が単結晶状の超電導材料が得られた。The atmosphere when the molded body is heated to a semi-molten state can be changed into four types [(20:80), (50:50), (90:80) by changing the ratio of oxygen to nitrogen (O 2 : N 2 ). 10),
(99: 1)]. Thereafter, the temperature was lowered to 800 ° C. in order to perform an oxygen addition treatment, and then gradually cooled to 200 ° C. in an oxygen stream over 150 hours. Thus, a superconducting material in which the entire sample was substantially a single crystal was obtained.
【0030】成形体を半溶融状態に加熱したときの雰囲
気は、酸素と窒素の比(O2 :N2)を変えて4種類
[(20:80)、(50:50)、(90:10)、
(99:1)]で行った。上記熱処理によって得られた
12種類の試料の中心部の状態と気孔率は表2のようで
あった。以上の結果から高酸素濃度中での半溶融加熱処
理により、試料中の気孔率を大幅に低減できることがわ
かった。The atmosphere when the molded body is heated to a semi-molten state is changed into four types [(20:80), (50:50), (90:80) by changing the ratio of oxygen to nitrogen (O 2 : N 2 ). 10),
(99: 1)]. Table 2 shows the state and porosity at the center of the twelve samples obtained by the heat treatment. From the above results, it was found that the porosity in the sample could be significantly reduced by the semi-melting heat treatment in a high oxygen concentration.
【0031】[0031]
【表2】 [Table 2]
【0032】実施例3 RE2 BaCuO5 (REの組成はY:Ybが(10
0:0)、(90:10)、(80:20)になるよう
に3種類作製した)、BaCuO2 とCuOを各元素比
(RE:Ba:Cu)が(13:18:26)になるよ
うに配合し、0.4wt%のPtを添加した後、混練し
3種類の混合粉末を作製した。この時REBaCuOは
平均粒径が1.5μmまで粉砕した。Example 3 RE 2 BaCuO 5 (RE has a composition of Y: Yb (10
(0: 0), (90:10), and (80:20) were prepared), and BaCuO 2 and CuO were converted to elemental ratios (RE: Ba: Cu) of (13:18:26). Then, after adding 0.4 wt% of Pt, the mixture was kneaded to prepare three types of mixed powder. At this time, REBaCuO was pulverized to an average particle size of 1.5 μm.
【0033】はじめにY100%のREを含む粉末を直
径20mmの金型により一軸成形し、次にこの成形体1
を直径40mmの金型に入れ周囲をYb10%含む粉末
を入れ同様に一軸成形し(成形体1+2)さらにYb2
0%を含む粉末に関しても直径55mmの金型を用い同
様の操作を繰り返し(成形体1+2+3)、図2に示す
成形体(M)を作製した。First, a powder containing 100% RE of Y is uniaxially molded by a mold having a diameter of 20 mm.
Was put into a mold having a diameter of 40 mm, and a powder containing 10% of Yb in the periphery was put therein, and similarly uniaxially molded (molded product 1 + 2), and further Yb2
With respect to the powder containing 0%, the same operation was repeated using a mold having a diameter of 55 mm (compact 1 + 2 + 3) to produce a compact (M) shown in FIG.
【0034】ハンマークエンチ法で作製したSmおよび
Yb組成の成形体を成形体(M)と白金の支持台との間
に配置した後、この成形体は99.9%以上の酸素気流
中で1150℃に室温から2時間で昇温し30分間保定
した。その後雰囲気を大気に置換した。しかるのち10
30℃に降温し、この温度でSm系に123相の種結晶
4(図2)を用い種結晶植付けを行った。After the compact having the composition of Sm and Yb produced by the hammer ench method is arranged between the compact (M) and the platinum support, the compact is subjected to 1150% or more in an oxygen gas stream of 99.9% or more. The temperature was raised from room temperature to 2 ° C. over 2 hours and kept for 30 minutes. Thereafter, the atmosphere was replaced with air. 10
Was cooled to 30 ° C., was crystallized planting seed using Sm system 123 phase seed crystal 4 at this temperature (Fig. 2).
【0035】次に1020℃から940℃まで平均0.
5℃/hrで降温し結晶を成長させた。その後、酸素付
加処理を行うため800℃に降温した後200℃まで1
50時間かけて酸素気流中で徐冷した。このようにして
実質的に試料全体が単結晶状の超電導材料が得られた。
そして、試料内部の気孔率は約0.1%であった。Next, on average from 1020 ° C. to 940 ° C.
The temperature was lowered at 5 ° C./hr to grow crystals. Thereafter, the temperature is lowered to 800 ° C. in order to perform an oxygen addition treatment,
The mixture was gradually cooled in an oxygen stream for 50 hours. Thus, a superconducting material in which the entire sample was substantially a single crystal was obtained.
The porosity inside the sample was about 0.1%.
【0036】[0036]
【発明の効果】以上詳述したごとく本発明により、気孔
率の極めて少ない緻密な単結晶状の酸化物超電導材料が
より容易に得られるようになった。このような材料は各
分野での応用が可能であり大きな工業的効果が期待でき
る。As described in detail above, according to the present invention, a dense single-crystal oxide superconducting material having extremely low porosity can be obtained more easily. Such a material can be applied in various fields and a great industrial effect can be expected.
【図1】(a)、(b)、(c)はそれぞれ、熱処理の
ヒートパターンと雰囲気とのタイミングを示すグラフFIGS. 1A, 1B, and 1C are graphs showing heat patterns of heat treatment and timings of atmospheres, respectively.
【図2】(a)、(b)、(c)は、実施例2で種結晶
植付けを行ったときの熱処理のヒートパターンと雰囲気
とのタイミングを示すグラフ2 (a), 2 (b) and 2 (c) are seed crystals in Example 2. FIG.
Graph showing the timing of the heat pattern and atmosphere of heat treatment when planting is performed
【図3】実施例3において作製した成形体のRE組成の
構成を示す断面図FIG. 3 is a cross-sectional view showing a configuration of an RE composition of a molded body produced in Example 3.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7,DB名) C01G 1/00,3/00 C30B 29/22 ──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. 7 , DB name) C01G 1/00, 3/00 C30B 29/22
Claims (8)
の組み合わせ)、BaおよびCuの複合酸化物である酸
化物超電導体において、RE2 BaCuO5(211)
相が単結晶状のREBa2 Cu3 O7-x (123)相中
に微細分散した組織を有し、かつ気孔率が体積率で3%
以下であることを特徴とする酸化物超電導体。1. An oxide superconductor which is a composite oxide of RE (a rare earth element containing Y and a combination thereof), Ba and Cu, wherein RE 2 BaCuO 5 (211)
It has a structure in which the phase is finely dispersed in a single crystal REBa 2 Cu 3 O 7-x (123) phase, and has a porosity of 3% by volume.
An oxide superconductor characterized by the following.
であることを特徴とする請求項1記載の酸化物超電導
体。2. The oxide superconductor according to claim 1, wherein the volume of one superconductor is 50 cm 3 or more.
の組み合わせ)、Ba、Cuの酸化物または複合酸化物
の少くとも一方からなる成形体を酸素純度が90%以上
の雰囲気中で加熱し溶融状態にした後、そのままの雰囲
気中で徐冷することによって、単結晶状に結晶成長させ
ることを特徴とする酸化物超電導体の製造方法。3. A molded body comprising at least one of RE (a rare earth element containing Y and a combination thereof), Ba and Cu oxides or composite oxides is heated and melted in an atmosphere having an oxygen purity of 90% or more. A method for producing an oxide superconductor , wherein a crystal is grown into a single crystal by gradually cooling in an atmosphere as it is.
の組み合わせ)、Ba、Cuの酸化物または複合酸化物
の少くとも一方からなる成形体を酸素純度が90%以上
の雰囲気中で加熱し溶融状態にした後、雰囲気を大気も
しくは酸化性雰囲気に置換した後、徐冷することによっ
て、単結晶状に結晶成長させることを特徴とする酸化物
超電導体の製造方法。4. A molded body composed of at least one of RE (a rare earth element including Y and a combination thereof), Ba and Cu oxides or composite oxides is heated and melted in an atmosphere having an oxygen purity of 90% or more. A method for producing an oxide superconductor , wherein a crystal is grown in a single crystal state by changing the atmosphere to an atmosphere or an oxidizing atmosphere after cooling, and then slowly cooling the atmosphere.
の組み合わせ)、Ba、Cuの酸化物または複合酸化物
の少くとも一方からなる成形体を酸素純度が90%以上
の雰囲気中で加熱し溶融状態にした後、室温にまで冷却
し炉内から取りだした後、さらに大気もしくは酸化性雰
囲気中で加熱溶融した後、徐冷することによって、単結
晶状に結晶成長させることを特徴とする酸化物超電導体
の製造方法。5. A molded body comprising at least one of RE (a rare earth element containing Y and a combination thereof), Ba and Cu oxides or composite oxides is heated and melted in an atmosphere having an oxygen purity of 90% or more. after the state, after taken out from the cooled furnace to room temperature, it was further heated and melted in air or an oxidizing atmosphere, by slow cooling, single binding
A method for producing an oxide superconductor, which comprises growing a crystal in a crystalline state.
ことを特徴とする請求項3ないし5記載の酸化物超電導
体の製造方法。6. The method for producing an oxide superconductor according to claim 3 , wherein the size of the molded body is 50 cm 3 or more.
a:Cu)が(30:33:37)、(15:38:3
7)、(15:30:55)、(30:25:45)で
結ばれる領域内の組成を有し、かつ0.1から2.0重
量%のPtまたは0.01から1.0重量%のRhの少
なくとも一方を含有していることを特徴とする請求項3
ないし6記載の酸化物超電導体の製造方法。7. The molded body has a molar ratio of a metal element (RE: B).
a: Cu) is (30:33:37), (15: 38: 3)
7) having a composition in the region bounded by (15:30:55), (30:25:45), and 0.1 to 2.0 wt% Pt or 0.01 to 1.0 wt% % Of at least one of Rh.
7. The method for producing an oxide superconductor according to any one of items 6 to 6.
RE組成の層からより低いTfを有するRE組成の層へ
順に層状に変化する成形体(M)を作製し、この成形体
(M)中の最も高いTfのRE組成より高いTfを有す
るRE組成の成形体(H)と、成形体(M)中の最も低
いTfのRE組成より低いTfを有するRE組成の成形
体(L)とをM−L−H−支持材の順で配置し、成形体
Mが211相と液相が共存する温度領域(この温度領域
の下限を以下Tgとする)に加熱し、しかるのち種結晶
のREの組成のTfよりも低くTgよりも高い温度にし
た後、Tgから成形体中の最も低いRE組成のTfより
もさらに30℃低い温度まで20℃/hr以下の冷却速
度で徐冷し種結晶から結晶を成長させた後、一旦室温に
戻すかまたは連続して800℃から200℃の温度領域
を酸化性雰囲気中で酸素付加処理をして各REBa2 C
u3 O7-x 層のX値を0.2以下にして超電導材料を得
ることを特徴とする請求項7記載の酸化物超電導材料の
製造方法。8. to prepare a molded body that changes in layers in this order onto a layer of RE composition having a lower Tf from a layer of RE composition having a high 123-phase generation temperature (Tf) (M), the adult form body (M )), A molded product (H) having an RE composition having a higher Tf than the RE composition having the highest Tf, and a molded product (L) having an RE composition having a lower Tf than the RE composition having the lowest Tf in the molded product (M). Are arranged in the order of M-L-H-supporting material, and the compact M is heated to a temperature region where the 211 phase and the liquid phase coexist (the lower limit of this temperature region is hereinafter referred to as Tg), and then the seed crystal is formed. to a temperature higher than Tg lower than Tf the composition of RE
Was then, after the lowest RE to a temperature below further 30 ° C. than Tf the composition 20 ° C. / hr or less of the cooling rate in the compact from gradually cooled seed crystal from Tg to grow crystals, or once returned to room temperature Alternatively, each REBa 2 C is continuously subjected to an oxygen addition treatment in a temperature range of 800 ° C. to 200 ° C. in an oxidizing atmosphere.
method of manufacturing an oxide superconducting material according to claim 7, wherein the X value of u 3 O 7-x layer is 0.2 or less; and obtaining superconducting material.
Priority Applications (1)
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JP08303792A JP3195041B2 (en) | 1992-03-06 | 1992-03-06 | Oxide superconductor and manufacturing method thereof |
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JP08303792A JP3195041B2 (en) | 1992-03-06 | 1992-03-06 | Oxide superconductor and manufacturing method thereof |
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JPH05254834A JPH05254834A (en) | 1993-10-05 |
JP3195041B2 true JP3195041B2 (en) | 2001-08-06 |
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