MAGNETIC CHARACTERIZATION OF AG-SHEATHED BI(PB)2223 TAPES

Ag/BPSCCO (2223) tapes were characterized by SQUID magnetometry over a wide range of temperatures (4.2-95 K) and under a magnetic field H (u p to 5 T) applied either parallel or perpendicular to the c axis of th e tape. For the two different field orientations, taking into account (when required) the anisotropy of the currents and demagnetization eff ects, the values of the critical current density J(c) were evaluated a s a function of the applied magnetic field H and temperature. The magn etization decay for H perpendicular to the c axis exhibited a non-line ar dependence of the flux creep activation energy on the current J. Fr om J(c)(T) behaviour and from the relaxation data M(t) some conclusion s about dissipation mechanisms were drawn.