Local J/sub C/ and microstructures of multilayer Bi-2212 composite tape

We investigated the local J/sub C/ and microstructures of Bi-2212 multilayer tapes. Multilayer tapes were prepared by wrapping four dip-coated sheets with silver foil. These tapes were fabricated with a melt-solidification method with a Pre-Annealing and Intermediate Rolling (PAIR) process. The local J/sub C/ distribution along the transverse direction of the tapes was determined in a nondestructive manner in which a magnetic field with a steep gradient was applied at 77 K, and the I/sub C/ was measured. The microstructures of the superconducting oxide layers were observed by using an optical micrograph and an SEM micrograph. Bi-2212 superconducting oxide layers existed on silver substrates homogeneously, and the silver/oxide interfaces were almost smooth along the silver substrates. From the J/sub C/-profile, J/sub C/ values at the middle region on the tape were low in comparison with the J/sub C/ values in the edge regions. The depression of the J/sub C/ values around the middle region was due to the overlapping of silver foil and, hence, the inferior microstructure.