The influence of sintering conditions on the critical current density and the microstructure of Ag-sheathed Bi2Sr2CaCu2Oxsuperconducting tapes

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Abstract
Ag-sheathed Bi2Sr2CaCu2Ox tape was fabricated by a combination of partial melting, subsequent cooling, annealing and quenching. The partial-melting temperature TH affects the growth of the 2212 grains. The promotion of the growth at TH>or approximately=885 degrees C enhances the JC value at 77 K and 0 T, until the appearance of microcracks at TH>or approximately=895 degrees C. The annealing temperature TL also effects JC and yields a maximum between 840 degrees CLLLC. The optimum cooling period tS from TH to TL is around 10 h, which corresponds to a cooling rate of 3.8 degrees C h-1. The prolongation of the period tK during annealing at TL enhances JC by the improvement of the weak links and reaches the highest value of JC=6.5*103 A cm-2 at 77 K and 0 T for tK=150 h.