FLUX-PINNING IN HIGH-J(C) BI2212 AG TAPE

The resistivity and critical current density J(c) of a well-characteri sed Ag-clad Bi2Sr2CaCu2O8+x (hereafter Bi2212) tape has been studied i n the temperature range 4.5-110K and magnetic fields B up to 1T. The f ield and temperature variations of the pinning potential U-0 and J(c) of the tape are qualitatively the same as those reported for the epita xial Bi2212 films and therefore indicate the same flux pinning mechani sm. However, whereas Uo of the tape is nearly the same as in Bi2212 fi lms, its J(c) is about ten times lower than that in the best Bi2212 fi lms. This shows that J(c) of the present-day tapes is limited by the l ow fraction of well connected grains along the length of the tape and not with the intergranular weak-links (as inferred from the magnetizat ion experiments). Accordingly, considerable enhancement of J(c) should result from the improvement in the fabrication and processing of Bi22 12/Ag tapes.