Title :
Pinning activation energies and the effect of cold deformation on critical currents in Bi(Pb)2223
Author :
Marti, F. ; Daumling, M. ; Flukiger, R.
Author_Institution :
Dept. de Phys. de la Matiere Condensee, Geneva Univ., Switzerland
fDate :
6/1/1995 12:00:00 AM
Abstract :
We have measured magnetic hysteresis loops on silver sheathed Bi(Pb)2223 tapes. In these specially prepared tapes the grains are completely decoupled, thus allowing a determination of the intra-grain properties of Bi(Pb)2223. Mechanical deformation at room temperature causes fracture of the grains, but raises the critical current density by a factor of two. The irreversibility line appears not to be affected by the deformation. Using the generalized inversion scheme of Schnack et al. (1993) we have determined the flux pinning energies U(j,T), as well as the true (non-decayed) critical current density. Best fits are obtained in the local 2D single flux pancake pinning limit, and U(j/j/sub c/=0.1,T=0) is about 70 meV in a magnetic field of 0.2T perpendicular to the tape.<>
Keywords :
bismuth compounds; calcium compounds; critical current density (superconductivity); deformation; flux pinning; high-temperature superconductors; lead compounds; magnetic hysteresis; silver; strontium compounds; superconducting tapes; (BiPb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O-Ag; 0.2 T; Ag sheathed tapes; cold deformation; critical current density; critical currents; decoupled grains; flux pinning; high temperature superconductor; irreversibility line; local 2D single flux pancake pinning limit; magnetic hysteresis loops; pinning activation energies; Critical current; Critical current density; Current density; Current measurement; Flux pinning; High temperature superconductors; Magnetic field measurement; Magnetic flux; Magnetic hysteresis; Magnetic materials;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
