Phase development and microstructure in Bi-based 2212 Ag-clad tapes processed at 880, 890, and 905°C: The Cu-free phase and (Sr,Ca)CuO2

Abstract The optimum temperature to melt-process thick 2212 BSCCO films on Ag and Ag-clad 2212 BSCCO tapes is reported to be between 885 and 890°C. In the present study, tapes processed at or below the optimum processing temperature contained small grains of a Cu-free phase, whereas tapes processed above the optimum processing temperature contained large grains of the Cu-free phase. These differences in morphology of the nonsuperconducting phases in tapes that were processed at different maximum processing temperatures were correlated with changes that occur in the phase equilibria in the melt state with varying temperature.