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  • Articles  (14)
  • critical current density  (14)
  • 2010-2014
  • 1990-1994  (11)
  • 1985-1989  (3)
  • 1950-1954
  • Electrical Engineering, Measurement and Control Technology  (14)
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  • Articles  (14)
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  • Electrical Engineering, Measurement and Control Technology  (14)
  • Physics  (14)
  • 1
    Electronic Resource
    Electronic Resource
    Effect of columnar defects on theJ c anisotropy of YBa2Cu3O7−δ thin films and YBa2Cu3O7−δ /PrBa2Cu3O7−δ multilayers (1994)
    Springer
    Journal of superconductivity 7 (1994), S. 205-207 
    Details
    ISSN: 1572-9605
    Keywords: HTSC thin films ; critical current density ; anisotropy ; columnar defects ; multilayers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Epitaxial YBa2Cu3O7−δ thin films (YBCO) and YBa2Cu3O7−δ /PrBa2Cu3O7−δ multilayers (Y/Pr) were irradiated with high-energy heavy ions (770 Mev208Pb) under various directionsφ relative to thec-axis. The irradiation resulted in columnar defects tilted byφ from thec-axis. The angular dependence of their pinning activity was studied by measuring the anisotropy of the critical current density. TheJ c (B, T,ϑ) behavior of the irradiated YBCO thin films showed an additional peak, which exceeds the intrinsic pinning peak, exactly at the irradiation direction. The Y/Pr multilayers, however, showed an isotropicT c -enhancement by a factor of 5, without any additional structure in theJ c(B, T,ϑ) curve.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00730395
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  • 2
    Electronic Resource
    Electronic Resource
    Superconducting behavior of high-T c YBa2Cu3O7 thin films with BaO impurity produced by pulsed laser deposition (1994)
    Springer
    Journal of superconductivity 7 (1994), S. 709-713 
    Details
    ISSN: 1572-9605
    Keywords: YBa2Cu3O7 thin films ; critical current density ; pulsed laser deposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We have investigated the superconducting behavior of high-T c YBa2Cu3O7 (YBCO) thin films containing BaO impure phase produced by pulsed laser deposition. The thin films were characterized by the standard four-probe method, X-ray diffraction (XRD), and scanning electron microscopy (SEM). XRD showed that all these thin films contained BaO impurity, with thec-axis normal to the surface of the substrates. The presence of impurity existed from substrate temperatureT s of 727 to 796°C. When these thin films with BaO impurity were measured under the magnetic fields, it was found that the critical current densityJ c increased slightly with increase in magnetic fieldB within the range ofB≤500 G, in the case ofB perpendicular to thec-axis of the film.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00721652
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  • 3
    Electronic Resource
    Electronic Resource
    The influence of columnar defects on the critical current density in (Bi, Pb)2Sr2Ca2Cu3O10 + δAg tapes (1994)
    Springer
    Journal of superconductivity 7 (1994), S. 783-786 
    Details
    ISSN: 1572-9605
    Keywords: Columnar defects ; critical current density ; tapes ; 2223 BPSCCO ; pinning energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract An excellent tool to enhance the critical current density in superconductors is the controlled introduction of defects by irradiation damage. Irradiation with 2.65 GeV Au ions provides the generation of amorphous line defects. Polycrystalline (Bi, Pb)2Sr2Ca2Cu3O10 + δ Ag tapes processed by the powder-in-tube technique were irradiated up to doses of 3.5× 1011 Au ions/cm2 at a temperature of 100 K. On the one hand, our irradiation experiments were performed to investigate the degree ofj c enhancement and, on the other hand, to examine the flux pinning mechanism in (Bi, Pb)2Sr2Ca2Cu3O10 + δ tapes. Characterization of the samples was performed by magnetization measurements using a vibrating sample magnetometer (VSM) up to 13 T in a temperature range between 5 and 100 K. Further, we have measured the relaxation of the magnetic moment before and after irradiation to determine the influence of columnar defects on the activation energyU. A comparison of the irradiation-induced effects with previous results obtained on Bi2Sr2CaCu2O8 + δ irradiation experiments is included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01320869
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  • 4
    Electronic Resource
    Electronic Resource
    Film thickness dependence of critical current density for YBa2Cu3O7 films post-annealed at a low oxygen partial pressure (1993)
    Springer
    Journal of superconductivity 6 (1993), S. 37-41 
    Details
    ISSN: 1572-9605
    Keywords: Superconducting films ; YBa2Cu3O7 ; critical current density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The variation of critical current density at 77 K as a function of film thickness was studied for YBa2Cu3O7 films on (100) LaAlO3 substrates. Film thicknesses were in the range 0.2–1.6μm. The films were deposited by co-evaporation and post-annealed under conditions which have previously resulted in high-quality films (750°C and an oxygen partial pressure of 29 Pa). The critical current density at 77 K exceeds 1 MA cm−2 for the thinner films, and decreases with increasing film thickness in excess of about 0.4μm. The decrease is in rough agreement with a switch fromc-axis toa-axis growth at about this critical thickness. A good anticorrelation was found between room temperature resistivity and critical current density at 77 K. The results are compared to those obtained before by post-annealing at 850°C in 1 atm of oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618503
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of processing history on the properties of Ag-based tapes (1993)
    Springer
    Journal of superconductivity 6 (1993), S. 59-62 
    Details
    ISSN: 1572-9605
    Keywords: Superconducting tapes ; critical current density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The Bi-system tapes and coils were prepared by the powder-in-tube method. The effect of processing and heat treatment on the properties of the tapes and coils was studied. It is found that the shearing stress produced by the rolling process may destroy the 2223 phase, and the destroyed 2223 phase cannot be recovered by heat treatment, whereas the pressing stress produced by the uniaxial pressing process only makes the 2223 phase grains break, and the broken 2223 phase can be closed by the heat treatment. TheJ c values of the rolling samples, pressing sample, and the coil with a diameter of 35 mm are over 1.3×104, 2.5×104, and 4×103 A/cm2 (77 K, 0 T), respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618507
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  • 6
    Electronic Resource
    Electronic Resource
    Magnetic and microwave properties of Sm1−xBa2Cu3+xO7−δ superconductors at 4.2 K prepared by an organic carbonate coprecipitation route (1992)
    Springer
    Journal of superconductivity 5 (1992), S. 245-250 
    Details
    ISSN: 1572-9605
    Keywords: Magnetic hysteresis ; pinning potentials ; critical current density ; flux creep ; weak links
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Samples of Sm1Ba2Cu3O7−δ and Sm0.95Ba2Cu3.05O7−δ are prepared by a coprecipitation technique using organic carbonates in the presence of stable polymers. The electrical, magnetic, and microwave measurements have been carried out to characterize the materials. Both normal (Sm1Ba2Cu3O7−δ ) and copper-rich (Sm0.95Ba2Cu3.05O7−δ ) samples showed sharp superconducting transitions at 94 K. Lower and upper critical fields of the samples are estimated from magnetization measurements. The critical magnetization current density (J mc ) and pinning force density (F p ) of the samples are obtained from the magnetization hysteresis loop at 4.2 K for fields up to 5T. Superconducting parameters (H c (O),K GL,λ,ξ) are obtained by using the values of lower and upper critical magnetic fields. Microwave-induced d.c. voltage measurements indicated a smaller number of weak links for copper-rich samples. The enhancement of critical current density and the reduction of total number of weak links for copper-rich samples may be due to the increase in hole concentration caused by the partial replacement of Sm by Cu.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617624
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of Ho addition on the properties of Y-system superconductors (1992)
    Springer
    Journal of superconductivity 5 (1992), S. 95-99 
    Details
    ISSN: 1572-9605
    Keywords: YBCO ; Ho addition ; critical current density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract (YHo)Ba2Cu3O7−y is prepared by the powder melting process and its properties are investigated. It is found that Ho addition can change the melting temperature of a Y-system superconductor. TheJ c values of YBCO can be improved by Ho substitution, which is due to the effect of Ho addition on the number and quality of grain boundaries and the size and distribution of 211 particles. The highestJ c value was found to be 50,000 A/cm2 (77 K, 1T,H⊥I) in Y0.8Ho0.2Ba2Cu3O7−y. Our results indicate that the number and quality of grain boundaries have a great influence on the superconducting properties. A discussion is given on the relationship betweenJ c and the size and phase proportion of 211 particles. There are a lot of dense twins in the sample, and many crystal defects exist around the 211 phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618051
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  • 8
    Electronic Resource
    Electronic Resource
    Critical current density and microstructure of YBa2Cu3O7 thin films post-annealed at a low oxygen partial pressure (1992)
    Springer
    Journal of superconductivity 5 (1992), S. 143-147 
    Details
    ISSN: 1572-9605
    Keywords: Superconducting films ; YBa2Cu3O7 ; critical current density ; microstructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Post-annealing of thin films of YBa2Cu3O7 (YBCO) has been performed at 29 Pa and 750°C. For films 0.6 μm thick, a critical current density 〉1 MA cm−2 is obtained at 77 K, with a sharp eddy current response at 25 MHz. Microstructural investigation of these films by crosssectional and planar transmission electron microscopy reveals that the YBCO film has thec-axis normal to the plane of the substrate in a continuous sheet of varying thickness, frequently covering the entire thickness of the film. Mutually perpendicular rods with thec-axis in the plane of the LaAlO3 substrate are also seen. The microstructure and critical current density of these films are compared with those of previously reported films post-annealed in atmosphericpressure oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618058
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  • 9
    Electronic Resource
    Electronic Resource
    Artificial in-plane ordering of textured YBa2Cu3O7−x films deposited on polycrystalline yttria-stabilized zirconia substrates (1992)
    Springer
    Journal of superconductivity 5 (1992), S. 533-537 
    Details
    ISSN: 1572-9605
    Keywords: YBCO films ; in-plane ordering ; critical current density ; surface texturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Anisotropie surface texturing of the polycrystalline yttria-stabilized zirconia substrates, prior to YBa2Cu3O7−x film deposition, is shown to promote in-plane (basal plane) ordering of the film growth in addition to thec-axis texturing. TheJ c 's of the films in the weak-link-dominated low-field regime are enhanced considerably, and this result is attributed to the reduction of weak links resulting from a reduction in the number of in-plane large-angle grain boundaries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618244
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  • 10
    Electronic Resource
    Electronic Resource
    On dislocation-induced reentrant-like behavior in deoxygenated high-T c superconductors (1991)
    Springer
    Journal of superconductivity 4 (1991), S. 431-435 
    Details
    ISSN: 1572-9605
    Keywords: Dislocation density ; twin boundary ; weak links ; critical current density ; oxygen deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A possible scenario for dislocation-induced intragrain weak-link generation is proposed. The theory predicts a reentrant-like behavior of the critical current density vs. magnetic field due to the sample deoxygenation. A qualitative agreement with high-T c single crystal anomalies is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00635861
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  • 11
    Electronic Resource
    Electronic Resource
    On the limiting factors of the critical current density in high-T c superconducting ceramics (1990)
    Springer
    Journal of superconductivity 3 (1990), S. 391-394 
    Details
    ISSN: 1572-9605
    Keywords: High-T c superconducting ceramics ; critical current density ; Josephson vortices ; pinning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The temperature dependence of the critical current density at high temperatures and in weak applied magnetic field for YBa2Cu3O7−y ceramic samples with a pronounced granular character is analyzed. The experimental results can be explained in terms of thermally activated motion of the intergrain Josephson vortices at grain boundaries, which may be an indication that the actual limiting factor for the critical current density in ceramic samples results from a weak pinning force density for the intergrain vortices rather than from the weak-link quenching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617464
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  • 12
    Electronic Resource
    Electronic Resource
    Magnetic field dependence of shielding current density in Y-Ba-Cu-O rings at 77 K (1989)
    Springer
    Journal of superconductivity 2 (1989), S. 219-233 
    Details
    ISSN: 1572-9605
    Keywords: Y-Ba-Cu-O ; shielding currents ; critical current density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A method for contactless measurement of the shielding critical current density and its dependence on the external magnetic field is described and analyzed. The obtained values are compared with those measured resistively on two different samples. It is shown that the shielding critical current densityJ cs and the intergranular transport current densityJ cr are identical if the measurement conditions are similar. A degradation ofJ cs measured in the external field with AC ripple has been observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617872
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  • 13
    Electronic Resource
    Electronic Resource
    Structure and superconductivity of Bi-(Pb)-Ca-Sr-Cu-O ceramics processed by arc melting (1989)
    Springer
    Journal of superconductivity 2 (1989), S. 501-511 
    Details
    ISSN: 1572-9605
    Keywords: superconductors ; Bi-(Pb)-Ca-Sr-Cu-O ; X-ray diffraction ; electrical resistivity ; critical current density ; SEM ; a.c. susceptibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The Bi-(Pb)-Ca-Sr-Cu-O ceramics of typical cation composition 2 (0.4) 223, presintered at 800°C, are formed by arc melting and rapidly cooling the 2021 superconducting phase, CaO, and Cu2O. The arc-melted samples sintered in air at 840°C exhibit a solid-state structural transformation of the components and a mixture of 2122 and 2223 superconducting phases, and small amounts of Ca2CuO3, Ca2PbO4, and CuO appear. When the arc melting is used as an intermediate stage in the preparation of the high-T c superconductors in this system, a significant increase in density (from 3.7 to 5.7 g/cm3) and in critical current density (from 28 to 60 A/cm2 in zero field and at liquid-nitrogen temperature) is observed, while the critical temperature remains practically unchanged (−104 K).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00627563
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  • 14
    Electronic Resource
    Electronic Resource
    Processing of single-phase ceramic 123 YBaCu-oxide superconductor by hot pressing (1988)
    Springer
    Journal of superconductivity 1 (1988), S. 45-52 
    Details
    ISSN: 1572-9605
    Keywords: YBa2Cu3O7 ; hot pressing ; electrical resistivity ; critical current density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract High-quality, single-phase, polycrystalline samples of high-temperature superconducting 123 YBaCu-oxide have been processed by hot pressing of specially prepared charge material at elevated temperatures. The samples are orthorhombic with unit cell dimensionsa = 3.824(1) Å,b = 3.888(1) Å, andc = 11.679(2) Å. They exhibit: (i) densities up to 82% of the theoretical value; (2) a sharp phase transition between the normal and superconducting states at 91.6 K; (3) a reduced dependence on thermal cycling effects and on excitation currents in resistivity measurements; and (4) a reduction in surface deterioration due to water, air, and acid attack. The hot-pressed samples supported current densities at least two orders of magnitude greater than those found in cold-pressed samples measured under similar conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617950
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