Original scientific paper
Thermal influence on Jc-B-T surfaces of Ag-clad Bi-based superconducting tapes
Ivica Kušević
; Department of Physics, Faculty of Science, University of Zagreb, P.O. Box 162, HR-10001 Zagreb, Croatia
Emil Babić
; Department of Physics, Faculty of Science, University of Zagreb, P.O. Box 162, HR-10001 Zagreb, Croatia
Perica Šimundić
; Department of Physics, Faculty of Science, University of Zagreb, P.O. Box 162, HR-10001 Zagreb, Croatia
Jovica Ivkov
; Institute of Physics of the University, P.O. Box 304, HR-10001 Zagreb, Croatia
Željko Marohnić
; Institute of Physics of the University, P.O. Box 304, HR-10001 Zagreb, Croatia
Hua Kun Liu
; Centre of Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW2522, Australia
Shi Xue Dou
; Centre of Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW2522, Australia
Abstract
We have studied Jc-B-T surfaces for high-Jc Ag-clad Bi2Sr2CaCu2O8+x (Bi2212) and (Bi,Pb)2Sr2Ca2Cu3O10+y (Bi2223) tapes in the temperature range 4.5 - 100 K and magnetic field B Ł 1 T. In both types of tapes, for temperature T ł 0.5 Tc, Jc(T,B) and the pinning force density Fp = Jc B exhibit scaling behaviour analogous to that observed in high-Tc single crystals and epitaxial films. The parallel study of the pinning potentials U0 and of the irreversibility fields Birr (deduced from the resistive transitions in the applied field) for the same tapes, revealed that the activation barrier U = U0(1-T/Tc)/Bm determines both the magnitudes and temperature dependency of the scaling fields B* (defined by Fp = Fpmax) and Birr. Considerably larger U0 for Bi2223 tape, compared to that of Bi2212 tape, is probably due to both lower electronic anisotropy of this compound and higher content of defects. However, in both types of tapes, the pinning of vortices is insufficient for the high-B high-T applications.
Keywords
Hrčak ID:
299838
URI
Publication date:
1.3.1997.
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