Effects of precursor powder calcination on critical current density and microstructure of Bi-2223/Ag tapes

The effects of precursor powder calcination conditions on the phase formation, microstructure evolution and critical current density of the Bi-2223/Ag tapes have been studied. The precursor powders and tapes were characterized by XRD and SEM with EDX analysis. It has been found that both the microstructure and critical current density depend strongly on the powder calcination condition. Different calcination conditions resulted in different phase assemblages in the precursors, which determined the reactivity of the precursor and the final properties of the Bi-2223 tape. Increasing the calcination temperature, extending the calcination time and applying intermediate grinding resulted in the decrease in the relative amounts of and CuO, and the increase of in the precursor powder. The presence of aids liquid phase formation, enhancing diffusion and healing of microcracks.