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  • Critical current density  (2)
  • Bi2223 tapes  (1)
  • Critical current  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 13 (2000), S. 441-446 
    ISSN: 1572-9605
    Keywords: Bi2223 tapes ; grain orientation ; critical current density ; microstructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract For polycrystalline Ag/Bi-2223 tapes, the preferential orientation of grains is a very important issue. The platelike grains in the tapes are generally believed in a high-order alignment. However, microstructural observation by SEM shows that the grain alignment is far from perfect. Theoretically, upper critical field, H c2, for H parallel to ab plane and c axis was calculated form the relation of M(H). However, the ratio of H c2 (H//ab) to H c2(H//c) depends on the angle (θ) between the ab plane of grains and the broad surface of the tapes. Based on the ratio, the orientation distribution of grains is obtained. The results show that grains in Ag/Bi-2223 tapes can grow with ab plans at any angle between 75° 〉 θ 〉 −75°, but no grain can grow with its ab plane perpendicular to the tape broad surface. The overall distribution is that: 〉90% grains orient in the angle range of |θ| 〈 ± 75°, about 5% grains at ±75° ≤|θ| ≤ ±85°, and no grains at |θ| 〉 ±85°.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-9605
    Keywords: Critical current density ; Ag addition ; grain alignment ; flux pinning ; defect structure ; YBCO ; melt-texturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Silver has been previously added to the melt-textured YBa2Cu3O7−x in order to increase the critical current density (J c ) of these materials. However, the effect of this addition on theJ c is presently unclear. The purpose of this study is to investigate the effect of silver on both critical current density and the microstructure of the melt-textured YBa2Cu3O7−x superconductors by means of X-ray diffraction, optical polarized microscopy, and transmission electron microscopy (TEM). TheJ c of the MTG YBCO/Ag samples is more than 104A/cm2 under the 5 kOe magnetic field. It has been shown that as the concentration of silver increases, the fraction of the 211 phase dispersed within the 123 matrix decreases. Therefore, theJ c slightly decreases. These results, together with the effect of the 211 phase, dislocations, and other structure defects on flux pinning, are described in this paper.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-9605
    Keywords: Critical current density ; coherence length ; penetration depth ; lower critical field H c2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The influence of Sn doping on superconductivity in the Bi-based 2212 phase is studied in this paper. For the samples R–T relations and magnetic hysteresis loops were measured. X-ray powder diffraction analysis was also performed. For Bi1.75Pb0.25Sr2CaCu2.3−x Sn x O y , the experimental results show that by adding the proper amount of Sn the superconductivity of the samples can be improved. As x = 0.15, the critical temperature T c, the critical current density J c, and the magnetic pinning force density F reach a maximum. At T = 11 K, the critical state parameters H c1, H c2, κ, λ, and ξ are calculated and compared with the results reported by other researchers. The experimental results also show that the Sn doping is able to speed up the growth of the 2223 phase. In brief, Sn doping is an effective way of improving the superconductivity in Bi-based superconductors.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 7 (1994), S. 809-812 
    ISSN: 1572-9605
    Keywords: Critical current ; Ag/Bi-2223 tape ; flux creep ; ac susceptibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract True zero-field critical current densityJ c of a well-characterized BPSCCO/Ag tape has been determined by means of high-resolution ac susceptibility in the temperature range 77–110 K. The resultant values (30,000 A/cm2 at 77 K) agree well with the transportJ c of the same tape. Because of a very thin BPSCCO, the coreJ c determined from the imaginary part of the ac susceptibility is nearly the same as the zero field one. AllJ c 's follow the same (1-T/T c )n withn=1.45 dependence.J c shows an approximateH −0.5 field dependence over the explored temperature range. Accordingly, the variations ofJ c withT andH seem to be determined by the flux creep.
    Type of Medium: Electronic Resource
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