EFFECT OF SILVER ON PHASE-FORMATION AND SUPERCONDUCTING PROPERTIES OFBI-2223 AG TAPES/

The effect of Ag on the phase formation and superconducting properties of Ag-clad Bi-2223 tapes has been studied. TEM studies reveal that th e grains adjacent to the Ag-sheath are nearly single 2223 phase with t heir c-axis perpendicular to the Ag-sheath, but in the interior of the superconductor core, an intergrowth of the 2223/2212 polytypoids with in the grain and misalignment become evident. Ag addition in the Bi-22 23 tapes lowers the annealing temperature and accelerates the formatio n of 2223 phase. However, its undesirable shape and large size cause g rain misorientation and hence leads to a decrease of J(c). The improve ment in bend strain is attributable to the interfacial layer adjacent Ag sheath. The results of magnetoresistance of a well defined tape aft er correction for the parallel conduction through the Ag-sheath and th e core show that the effective activation energy for the flux creep is larger than those for the single crystals and thin films. But the dis sipative behaviour is similar to single crystals and the epitaxial thi n films.