HIGH CRITICAL-CURRENT DENSITY IN THE HEAVILY PB-DOPED BI2SR2CACU2O8- GENERATION OF EFFICIENT PINNING CENTERS(DELTA SUPERCONDUCTOR )

Critical-current density (J(c)) is a parameter of primary importance f or potential applications of high-temperature copper oxide superconduc tors. It is limited principally by the breakdown of zero-resistive cur rent due to thermally activated flux flow at high temperatures and hig h magnetic fields. One promising method to overcome this limitation is to introduce efficient pinning centers into crystals that can suppres s the flux flow, A marked increase in J(c) was observed in B(2)iSr(2)C aCu(2)O(8+delta) (Bi-2212) single crystals doped with a large amount o f Pb. By electron microscopy, characteristic microstructures were reve aled that probably underlie the observed enhancement in J(c): thin (10 to 50 nanometers), platelike domains having a modulation-free structu re appeared with spacings of 50 to 100 nanometers along the b axis.