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WO1999003159A1 - Supraconducteurs a temperature 'elevee' a structures microjumelles secondaires provoquant un fort pinning - Google Patents

Supraconducteurs a temperature 'elevee' a structures microjumelles secondaires provoquant un fort pinning Download PDF

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Publication number
WO1999003159A1
WO1999003159A1 PCT/US1997/011899 US9711899W WO9903159A1 WO 1999003159 A1 WO1999003159 A1 WO 1999003159A1 US 9711899 W US9711899 W US 9711899W WO 9903159 A1 WO9903159 A1 WO 9903159A1
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bacuo
particles
superconductor
yba
twin
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PCT/US1997/011899
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English (en)
Inventor
Manoj Chopra
Siu-Wai Chan
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Columbia University in the City of New York
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Columbia University in the City of New York
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Priority to PCT/US1997/011899 priority Critical patent/WO1999003159A1/fr
Priority to CA002295848A priority patent/CA2295848A1/fr
Publication of WO1999003159A1 publication Critical patent/WO1999003159A1/fr
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/80—Constructional details
    • H10N60/85—Superconducting active materials
    • H10N60/855—Ceramic superconductors
    • H10N60/857—Ceramic superconductors comprising copper oxide

Definitions

  • the present invention relates to high temperature cuprate-compound superconductor devices, and more specifically, to superconductor devices which maintain a large critical current even in the presence of an applied magnetic field.
  • Microscope images of the superconductor reveal that when a twin layer intersects and goes through a twin layer of differing oriention, "secondary" microtwins are created in the vicinity of the area of intersection of the principal twins.
  • twin boundaries in the crystal act as pinning barriers which disrupt magnetic flux penetration of the superconductor, i.e., vortices of flux cannot easily pass through the boundaries and pile up on one side of the superconductor.
  • An object of the present invention is to provide a superconductor device which is able to maintain a large critical current density in the presence of an applied magnetic field.
  • Another object of the present invention is to provide a technique for inducing secondary microtwin structures in a cuprate-compound superconductor.
  • a further object of the present invention is to provide a YBa 2 Cu 3 O 7 . d superconductor which has an optimum pattern of secondary microtwin structures that serve to effectively pin magnetic flux penetration of the superconductor.
  • the present invention is a high- temperature superconductor device capable of maintaining a large critical current density in the presence of an applied magnetic field.
  • the device advantageously comprises crystalline YBa 2 Cu 3 O 7 _ d and a plurality of non- reactive particles which make up at least 10% of the initial volume of the device, where the particles are less deformable than the YBa 2 Cu 3 O 7 . d .
  • twinning and secondary microtwinning of at least a portion of the crystalline YBa 2 Cu 3 O 7 . d is induced by the inclusion of the particles.
  • the non-reactive particles advantageously are Y 2 BaCuO 5 particles that comprise at least 20% of the initial volume of the device, and preferably comprise from 30% to 50% of the initial volume of the device.
  • the particles have an average diameter of approximately 0.5 ⁇ m.
  • a different aspect of the present invention beneficially provides for the inclusion of a doping material which acts to refine the distribution of the non- reactive particles, so that the average size of the non-reactive particles is kept from coarsening during processing.
  • the doping material is PtO 2 in amount equal to approximately 0.5% of the total weight of the superconductor.
  • the non-reactive particles are profitably chosen to be Y 2 BaCuO 5 particles which comprise at least 20% of the initial volume of the device, the PtO 2 doping reduces the average size of the Y 2 BaCuO 5 particles to thus increase the inducement of twinning and secondary microtwinning in the crystalline YBa 2 Cu 3 O 7 . d .
  • the doping material is CeO 2 in amount equal to approximately 1% of the total weight of the superconductor device.
  • the non-reactive particles are profitably chosen to be Y 2 BaCuO 5 particles which comprise at least 20% of the initial volume of the superconductor material of the device, the CeO 2 doping reduces the average size of the Y 2 BaCuO 5 particles to thereby increase the inducement of twinning and secondary microtwinning in the crystalline YBa 2 Cu 3 O 7 . d .
  • Fig. 1 is a diagram representing a 2-dimensional flux-line structure showing the three close-packed slip directions of flux line movement in a type-II superconductor;
  • Fig. 2 is a diagram representing two twin variants that are 90° misoriented with respect to each other;
  • Fig. 3 is a diagram representing a different twin variant boundary separating two twin varients where twinning has occurred
  • Fig. 4 is a transmission electron micrograph showing a twin boundary where two twin variants penetrate one another and form multiple secondary microtwin structures
  • Fig. 5 is a diagram representing a portion of a YBa 2 Cu 3 O 7 . d superconductor where perpendicular twin regions have intersected and penetrated one another to form multiple secondary microtwin structures;
  • Fig. 6 is a graph plotting the area fraction of twin intersections against the maximum magnetic field that may be applied to a superconductor before its superconducting current decreases as the Lorentz force has increased beyond the volume pinning force;
  • Fig. 7 is a three-dimensional graphical representation of a typical stress distribution around a rigid particle having a diameter of 0.5 ⁇ m that is subjected to a sheer stress;
  • Fig. 8 is a transmission electron micrograph illustrating two neighboring Y 2 BaCuO 5 particles and the resulting twin structure which formed between the particles;
  • Fig. 9 is a graph plotting twin spacing against the square root of local interparticle spacing showing finer twins as interparticle spacing decreases
  • Fig. 10 is a schematic representation of twin spacing in the vicinity of a Y 2 BaCuO 5 /YBa 2 Cu 3 O 7 . d interface;
  • Fig 11 is a graph plotting the ratio of the product of twin spacing (Tw) and local particle curvature (a) over the square root of Y 2 BaCuO 5 interparticle spacing (S 2U ) against effective distance (R);
  • Fig. 12 is a graph plotting the pinning force of the superconductor twin structures against the applied magnetic field withstood by several superconductor devices fabricated in accordance with the present invention;
  • Fig. 13 is a graph plotting the number of Y 2 BaCuO 5 particles against particle size for undoped and PtO 2 doped samples of a superconductor devices fabricated in accordance with one aspect of the present invention
  • Fig. 14 is a graph plotting the number of Y 2 BaCuO 5 particles against particle size for undoped and CeO 2 doped samples of a superconductor devices fabricated in accordance with another aspect of the present invention.
  • Fig. 15 is a graph plotting local twin spacing against the square root of interparticle spacing for undoped, PtO 2 doped and CeO 2 doped samples of a superconductor devices fabricated in accordance with still another aspect of the present invention.
  • the present invention provides a technique for effectively utilizing twinning and microtwinning in certain cuprate compounds, e.g., YBa 2 Cu 3 O 7 . d , in order to provide a superconducting device which is able to maintain a large critical current even in the presence of an applied magnetic field.
  • the present invention provides a technique for obstructing or "pinning" lines of magnetic flux in a crystalline superconductor material in order to prevent the above-mentioned Lorentz force from limiting the superconducting critical current density of the device.
  • FIG. 1 illustrates a so-called Abrikosov lattice 100 with the three closed-packed directions of a flux line movement 110, 120, 130 inherent in any type II superconductor where no twinning has occurred.
  • lines of magnetic flux are free to slip in any of the three illustrated directions, thereby causing energy dissipation and degrading the critical current density.
  • cuprate-compound superconductor one of the three close-pack directions of the magnetic flux-line structure will align itself with the parallel twin boundaries. Thus particular close-packed direction will remain as an easy slip direction, while the other two will not.
  • a boundary 220 separates two twin variant 200, 210 of a cuprate superconductor where twinning has occurred.
  • Variant 210 is perpendicular to varient 220, so none of the three close-packed directions of variant 210 are parallel with any one ofthe three close-packed directions ofthe flux-line lattice in variant 200.
  • Fig. 3 Another arrangement is illustrated in Fig. 3, where two touching variants 300 and 310 have been twinned in perpendicular planes so as to form a 45° angle along twin variant boundary 320.
  • any left to right flux flow that is pinned in twin variant 300 will have to jump to a different pin position in twin variant 310, and hence the flow of magnetic flux through a superconductor having the structure shown in Fig. 3 will also be limited.
  • twin variant boundary is a good barrier for flux line motion as flux-lines are moving towards the variant boundary instead of away from it.
  • the importance is to have a high density of twin variant boundaries for effective obstruction of flux-line motions.
  • Fig. 4 a transmission electron micrograph showing an structure where two twin variants not only border but penetrate one another will now be described.
  • the secondary twins 400 are microscopic or nanoscopic in size, and are formed spontaneously in order to relieve stress when YBa 2 Cu 3 O 7 . d material undergoes a tetragonal to orthombic phase transition.
  • Fig. 5 illustrates a portion of a YBa 2 Cu 3 O 7 .
  • d superconductor where perpendicular twin variants have intersected and penetrated one another, thereby forming multiple secondary microtwin structures 530 of lenticular shape.
  • twin planes 510, 520 separate the two orthogonal twin variants.
  • Dotted line 540 represents the boundary between the twinned region 550 and the region which includes the microtwin structure 530, where a two degree misorientation occurs across 540.
  • points 560 are areas of potential high flux pinning, as they represent areas where a closed-packed direction of possible flux line flow runs into effective flux traps.
  • the higher concentration of potential flux pinning centers enabled by the microtwin structure permits the superconductor to withstand a greater applied magnetic field before the superconducting current sustainable by the superconductor is subjected to degradation.
  • This behavior is illustrated in Fig. 6, where the total area fraction of twin intersections, i.e., the area where microtwinning occurs, is plotted against the forth power ofthe maximum magnetic field that may be applied to the superconductor before the superconducting current is degraded. Accordingly, by inducing microtwinning in YBa 2 Cu 3 O 7 . d superconductors, one may fabricate a superconducting device which is able to maintain a large critical current in the presence of high magnetic fields.
  • a technique for inducing microtwin structures in a YBa 2 Cu 3 O 7 . d superconductor will now be described.
  • twins form in YBa 2 Cu 3 O 7 . d in order to reduce transformation stress in the crystal during cooling.
  • twinning may be induced in the vicinity of such localized stress points.
  • a non-deformable particle shall mean a particle which is not necessary rigid, but is less deformable that the superconductor material itself.
  • Fig. 7 illustrates a typical stress distribution around a non-deformable particle having a diameter of 0.5 ⁇ m that is subjected to a sheer stress. If particles are added to YBa 2 Cu 3 O 7 . d material prior to cooling and crystal formation, the transforming crystal will be subjected to numerous points of localized stress which may potentially act as centers for inducing the formation of finer twins, finer twin variants, and secondary twins.
  • Any insulating non-deformable particle which is non-reactive with YBa 2 Cu 3 O 7.d is a suitable potential candidate for such non-deformable particle inclusion.
  • Y 2 BaCuO 5 particles are especially adapted to inclusion into YBa 2 Cu 3 O 7 .
  • d material for the purpose of altering the stress patterns in that material.
  • One suitable method of preparing a sample of YBa 2 Cu 3 O 7 . d material with included Y 2 BaCuO 5 particles is to place a pellet of a correct mixture of compacted powder YBa 2 Cu 3 O 7 . d and Y 2 BaCuO 5 , and add a SmBa 2 Cu 3 O 7 .
  • Both SmBa 2 Cu 3 O 7 . d and NbBa 2 Cu 3 O 7 . d have a higher peritectic temperature than YBa 2 Cu 3 O 7 . d .
  • Y 2 BaCuO 5 particles should be added to the YBa 2 Cu 3 O 7 .
  • d sample such that a fairly uniform dispersion of a homogenous array of closely spaced Y 2 BaCuO 5 particles is achieved.
  • Neighboring Y 2 BaCuO 5 particles should be close enough to induce twins and rotations in twinning, to be more fully described below, while not so close so as to choke off the superconducting current J flowing in the device.
  • Fig. 8 illustrates an exemplary structure of two neighboring Y 2 BaCuO 5 particles and the resulting twin structure which formed between the particles.
  • Y 2 BaCuO 5 particles In order to determine the preferable concentration of Y 2 BaCuO 5 particles, large grained YBa 2 Cu 3 O 7 . d samples containing an initial Y 2 BaCuO 5 volume of 10, 20, 30, 40 and 50 percent were analyzed. Transmission electron microscope samples were prepared using conventional polishing and dimpling to approximately 50 ⁇ m. These dimpled samples were then ion-milled at 5kV to perforation and later polished at 3kV to minimize artifacts due to ion-milling. The samples were observed under a JEOL (JEM 100C) transmission electron microscope. The variation ofthe twin spacing and its dependence on the local interparticle spacing (S 2] ] ) were both studied.
  • the local twin spacing and the corresponding local Y 2 BaCuO 5 interparticle spacing were measured for the 40% Y 2 BaCuO 5 sample and for a sample containing 30% Y 2 BaCuO 5 with 0.5wt% PtO 2 doping. As further discussed below, PtO 2 was added to the mixture in order to refine the Y 2 BaCuO 5 particles and produce a more homogeneous range of sized of Y 2 BaCuO 5 particles.
  • the results, illustrated in Fig. 9, show that local mean twin spacing varies linearly with the square root ofthe local interparticle spacing in both 40% Y 2 BaCuO 5 and the 30% Y 2 BaCuO 5 samples. Theoretically, it can be shown that the average local twin spacing is dependant on the Y 2 BaCuO 5 interparticle spacing in accordance with equation (1):
  • twin spacing is the distance between two consecutive twin boundaries in the same plane
  • twin boundary energy is denoted by ⁇ tw the shortest local distance between two YBa 2 Cu 3 O 7 . d /Y 2 BaCuO 5 interfaces is S 21 !
  • ⁇ is the shear modulus (59GPa for YBa 2 Cu 3 O 7 . d )
  • e is the shear strain due to twinning and is given by (b/a -1), where 'b' and 'a' refer to the basal plane lattice parameters of YBa 2 Cu 3 O 7 . d .
  • the best fit lines for the data shown in Fig. 9 is shown as lines 900, 910.
  • the line 900 for the 40% Y 2 BaCuO 5 sample yields a slope of 4.664 nm" 2 .
  • the mean twin boundary energy is computed to be approximately 28.9 ⁇ 0.6 mJ/m 2 .
  • twin spacing in the vicinity of a Y 2 BaCuO 5 / YBa 2 Cu 3 O 7 . d interface is illustrated.
  • the change of twin spacing is a highly localized phenomenon about the Y 2 BaCuO 5 particles.
  • R is the effective distance between the twin and the Y 2 BaCuO 5 particle 1000, i.e., the sum ofthe radius of curvature ofthe Y 2 BaCuO 5 particle (a) and the distance from the Y 2 BaCuO 5 /YBa 2 Cu 3 O 7 . d interface (r).
  • Twins near a YBa 2 Cu 3 O 7 . d /Y 2 BaCuO 5 interface 1010 were observed to be finer than those 1020 in the matrix.
  • twin structures evolve, e.g., twin intersections and variations in the twin density at the YBa 2 Cu 3 O 7 .
  • d /Y 2 BaCuO 5 interface various types of twin structures evolve, e.g., twin intersections and variations in the twin density at the YBa 2 Cu 3 O 7 .
  • d /Y 2 BaCuO 5 interface various types of twin structures evolve, e.g., twin intersections and variations in the twin density at the YBa 2 Cu 3 O 7 .
  • the stress at the YBa 2 Cu 3 O 7 . d /Y 2 BaCuO 5 interface originates from a combination of coherency strain between the YBa 2 Cu 3 O 7 . d /Y 2 BaCuO 5 interface, difference in thermal expansion coefficients and the result ofthe tetragonal to orthorhombic (t ⁇ o) transformation. If we assume that the stress at the YBa 2 Cu 3 O 7 . d /Y 2 BaCuO 5 interface is entirely due to the t-o transformation, a higher strain energy density at the YBa 2 Cu 3 O 7 . d /Y 2 BaCuO 5 interface is expected around particles with a smaller radius of curvature.
  • the magnitude ofthe stress at a distance R from a Y 2 BaCuO 5 particle varies as R 2 where R is the effective distance ofthe YBa 2 Cu 3 O 7 . d /Y 2 BaCuO 5 interface.
  • R is the effective distance ofthe YBa 2 Cu 3 O 7 . d /Y 2 BaCuO 5 interface.
  • the stress continues to decrease with increasing R until the interfacial stress approaches the average bulk stress.
  • a consequence ofthe stress variation at the interface is the creation of a gradient in the strain energy density along the interface.
  • One manifestation of this strain energy gradient is the variation in the twin spacing at the interface.
  • the twin density would be higher at the interface to compensate for a locally higher strain energy density. This implies that the twin density at a smaller or alternatively sharper Y 2 BaCuO 5 /YBa 2 Cu 3 O 7 . d interface would lead to a higher twin density at the interface or to the nucleation of an additional twin variant.
  • the true pinning force for the 40% Y 2 BaCuO 5 sample shows a point of inflection at a magnetic field of 2.2T while the 50% Y 2 BaCuO 5 sample shows a inflection point at 3T indicating that the flux pinning at higher field for the latter sample has actually improved.
  • This can be substantiated by the fact that for the 50% Y 2 BaCuO 5 sample, the true pinning force is practically unaltered for the magnetic field range from 0.8T to 3.5T for the 50% Y 2 BaCuO 5 sample.
  • the magnetic field at maximum true pinning force increases as the amount of Y 2 BaCuO 5 included in the sample increases.
  • the effective flux pinning efficiency ofthe YBa 2 Cu 3 O 7 . d matrix tends to improve with an increasing Y 2 BaCuO 5 addition, although the electrical connectivity is substantially reduced when the actual volume of YBa 2 Cu 3 O 7 . d falls below 20%.
  • the electrical characteristics ofthe superconductor are impacted by the increasing quantity of insulating material in the superconductor.
  • the amount of Y 2 BaCuO 5 included in the superconducting device should be selected depending on the both the strength of the applied magnetic field and the desired electrical characteristics ofthe device. For potentially large magnetic fields, 40, 50 or even 80% Y 2 BaCuO 5 inclusion may be appropriate. For smaller magnetic fields, adding Y 2 BaCuO 5 so that 20% ofthe initial sample comprises that compound may be sufficient while yielding maximum electrical benefits.
  • YBa 2 Cu 3 O 7 YBa 2 Cu 3 O 7 .
  • d material with Y 2 BaCuO 5 inclusions may be doped or loaded with certain materials which can refine the Y 2 BaCuO 5 particles and thereby enhance the impact of the Y 2 BaCuO 5 particles on inducing twinning and secondary microtwinning.
  • Y 2 BaCuO 5 particles having a smaller radius of curvature lead to a higher strain energy density at the YBa 2 Cu 3 O 7 .
  • d /Y 2 BaCuO 5 interface than do Y 2 BaCuO 5 particles having a larger radius of curvature.
  • the Y 2 BaCuO 5 material will congeal into particles of a wide range of sizes. It is therefore desirable to employ a technique which produces a more homogeneous distribution of Y 2 BaCuO 5 particles which are small in size, e.g., within the range of 0.05 - 2 ⁇ , and accordingly have a smaller radius of curvature.
  • a technique to fabricate a YBa 2 Cu 3 O 7 . d superconductor with a more homogeneous distribution of small sized Y 2 BaCuO 5 particles is by doping the material with a small quantity of PtO 2 .
  • the data points in Fig. 13 represented by squares indicate the number of particles that were observed at different sizes when Y 2 BaCuO 5 is added to YBa 2 Cu 3 O 7 . d to initially form 30%) ofthe material.
  • Data points represented by circles indicate the same 30%) Y 2 BaCuO 5 sample but with the addition of PtO 2 , in an amount totaling 0.5% ofthe sample by weight.
  • the inclusion of PtO 2 in the sample substantially reduces the mean Y 2 BaCuO 5 particle size, and appears to prevent large Y 2 BaCuO 5 particles having a radius of lO ⁇ m or greater from forming in the sample.
  • a superconductor with an improved distribution of small sized Y 2 BaCuO 5 particles requires doping the material with a small quantity of CeO 2 .
  • the data represented by circles indicate the number of particles that were observed at different sizes when Y 2 BaCuO 5 is added to YBa 2 Cu 3 O 7 .
  • d to initially form 40% of the material while the data represented by squares indicate the same sample but with the addition of CeO 2 , in an amount totaling 1% ofthe sample by weight. With the addition of CeO 2 , the average Y 2 BaCuO 5 particle size is also reduced.
  • Figs. 13 and 14 indicate a considerable refinement ofthe Y 2 BaCuO 5 particles and twin spacing in YBa 2 Cu 3 0 7 . d with PtO 2 or CeO 2 addition.
  • the localized spacing of twins observed in the samples is plotted against the square root ofthe local interparticle spacing S 2I 1 .
  • the sample containing 30% Y 2 BaCuO 5 with 0.5wt% PtO 2 shows a much shallower slope, approximately 2.92 nm" 2 , when compared to the sample containing 40% Y 2 BaCuO 5 with no doping.
  • the sample which included CeO 2 doping showed improvement over the undoped sample.
  • twin spacing in structures changes with a smaller and relatively homogeneous distribution of Y 2 BaCuO 5 particles. Intersections of twin spacings appear particularly in the 30% Y 2 BaCuO 5 with PtO 2 sample and in 40% and 50% Y 2 BaCuO 5 samples without any PtO 2 . It was observed that twin intersections begin to form when the Y 2 BaCuO 5 interparticle spacing is about 740nm for the samples without PtO 2 , and 300nm for the case when PtO 2 is added. Twin morphologies such as intersecting twins begin to appear because ofthe stress fields associated with adjacent YBa 2 Cu 3 O 7 . d /Y 2 BaCuO 5 interfaces. They can also form because ofthe presence of submicron Y 2 BaCuO 5 particles which have a locally high strain energy density as compared to larger particles (>l ⁇ m) leading to the nucleation of both twin variants.
  • the major factors affecting the inducement of twin intersections and, accordingly, the formation of secondary twin spacings are the proximity of a Y 2 BaCuO 5 particle to its neighbors and the radius of curvature of the Y 2 BaCuO 5 /YBa 2 Cu 3 O 7 . d interface.
  • Ba 2 ZrO 3 or SrZTiO 3 are suitable non-deformable particles for inclusion in YNa 2 Cu 3 O 7 . d .
  • YBa 2 Cu 3 O 7 . d other cuprate compounds which generally follow the chemical formula XBa 2 Cu 3 O 7 . d where "X" is a rare earth metal, e.g., Yb, Sm, Nd or La, may be used to form the high temperature superconductor device.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Superconductor Devices And Manufacturing Methods Thereof (AREA)

Abstract

L'invention porte sur des supraconducteurs à température 'élevée' capables de conserver une importante densité de courant en présence d'un champ magnétique faits de YBa2CuO7-d cristallin et de nombreuses petites particules non réactives et non déformables, telles que du Y2BaCuO5 représentant jusqu'à au moins 10 % du volume initial du matériau supraconducteur. Les particules non réactives et non déformables ont un rayon de courbure suffisamment faible pour accroître les contraintes localisées dans le supraconducteur et entraîner la formation de structures intersécantes jumelles et microjumelles secondaires agissant comme centres de pinning du flux magnétique dans le YBa2CuO7-d cristallin.
PCT/US1997/011899 1997-07-10 1997-07-10 Supraconducteurs a temperature 'elevee' a structures microjumelles secondaires provoquant un fort pinning Ceased WO1999003159A1 (fr)

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PCT/US1997/011899 WO1999003159A1 (fr) 1997-07-10 1997-07-10 Supraconducteurs a temperature 'elevee' a structures microjumelles secondaires provoquant un fort pinning
CA002295848A CA2295848A1 (fr) 1997-07-10 1997-07-10 Supraconducteurs a temperature "elevee" a structures microjumelles secondaires provoquant un fort pinning

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7820596B2 (en) * 2000-10-23 2010-10-26 The Trustees Of Columbia University In The City Of New York Thick film high temperature superconducting device supporting high critical currents and method for fabricating same

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US5240903A (en) * 1990-05-10 1993-08-31 Asahi Glass Company Ltd. Oxide superconductor comprising babo3 dispersions (where b is zr, sn, ce or ti)
US5278137A (en) * 1988-06-06 1994-01-11 Nippon Steel Corporation YBa2 Cu3 O7-y type oxide superconductive material containing dispersed Y2 BaCuO5 phase and having high critical current density
US5292716A (en) * 1991-01-18 1994-03-08 Ngk Insulators, Ltd. Oxide superconducting material and process for producing the same
US5430008A (en) * 1988-10-28 1995-07-04 The Regents Of The University Of California Method and composition for improving flux pinning and critical current in superconductors
US5434125A (en) * 1990-12-20 1995-07-18 International Superconductivity Technology Center Rare earth oxide superconducting material and process for producing the same
US5496799A (en) * 1992-08-25 1996-03-05 Ngk Insulators, Ltd. Method for making rare earth superconductive composite

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Publication number Priority date Publication date Assignee Title
US5278137A (en) * 1988-06-06 1994-01-11 Nippon Steel Corporation YBa2 Cu3 O7-y type oxide superconductive material containing dispersed Y2 BaCuO5 phase and having high critical current density
US5430008A (en) * 1988-10-28 1995-07-04 The Regents Of The University Of California Method and composition for improving flux pinning and critical current in superconductors
US5240903A (en) * 1990-05-10 1993-08-31 Asahi Glass Company Ltd. Oxide superconductor comprising babo3 dispersions (where b is zr, sn, ce or ti)
US5434125A (en) * 1990-12-20 1995-07-18 International Superconductivity Technology Center Rare earth oxide superconducting material and process for producing the same
US5292716A (en) * 1991-01-18 1994-03-08 Ngk Insulators, Ltd. Oxide superconducting material and process for producing the same
US5496799A (en) * 1992-08-25 1996-03-05 Ngk Insulators, Ltd. Method for making rare earth superconductive composite

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7820596B2 (en) * 2000-10-23 2010-10-26 The Trustees Of Columbia University In The City Of New York Thick film high temperature superconducting device supporting high critical currents and method for fabricating same

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