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FIZIKA A 6 (1997) 1, 23-32
 
THERMAL INFLUENCE ON Jc-B-T SURFACES OF Ag-CLAD Bi-BASED
SUPERCONDUCTING TAPES
IVICA KUŠEVIĆa, EMIL BABIĆa, PERICA ŠIMUNDIĆa,
JOVICA IVKOVb, ŽELJKO MAROHNIĆb, HUA KUN LIUc and SHI
XUE DOUc
aDepartment of Physics, Faculty of Science, University of
Zagreb, P.O. Box 162, HR-10001 Zagreb, Croatia
bInstitute of Physics of the University, P.O. Box 304, HR-10001 Zagreb, Croatia
cCentre of Superconducting and Electronic Materials, University of Wollongong,
Wollongong, NSW2522, Australia
Received 24 December 1996
Revised manuscript received 13 March 1997
This paper is dedicated to Professor A. Bonefačić on the occasion
of his 70th birthday
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.
UDC 538.945
PACS 74.60.Ge, 74.60.Jg, 74.72.H
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