Microstructure characterisation of Ag-clad 2223 superconducting tapes

The evolution of the microstructure of the ceramic core of the Ag-clad (Bi, Pb) - 2223 tapes during the obtaining process has been investigated using scanning electron microscopy and X-ray microanalysis (EDAX). The superconducting tapes were prepared by the PIT process, according to two routes, with a slight difference regarding the environment during the heat treatment. One of the routes produced 2223 plate-like crystals, completely aligned parallel to the rolling direction. The superconducting characteristics were Tc = 106.3 K and Jc = 12.2 kA/cm2. The other route produced a ceramic core with (Ca,Sr)2 Cu O3, (Ca,Sr)Cu2 O3 and (Ca,Sr)2 Pb O4 type crystals in a matrix of 2223 crystals oriented parallel to the rolling direction. A 5μm depth diffusion of Ag from the clad to the ceramic core has been observed. The superconducting characteristics have been affected by the presence of the residual oxide phases identified: Tc = 106 K and Jc = 7 kA/cm2. (authors)