110K phase and oxygen balance in BSCCO system

Abstract Bi 2 Sr 2 Ca 2 Cu 3 O y (2223) specimens added with 5 wt% and 7.5 wt% of PbO have been prepared. 110K phase is formed in specimens with 5 wt% PbO addition when annealed in vacuum (10 −1 torr) at 500°C for short period (2–3 hr). On the other hand, the formation of 110K phase needs oxygen annealing (500°C × 2 hr) for specimens with 7.5 wt% PbO addition. These results indicate that the annealing condition (vacuum or oxygen) is closely related to the Pb contents - both balancing the oxygen stoichiometry and the hole concentration to the optimum level for the 110K phase. The presence of the residual 80K phase indicates that the addition of PbO, to the master (2223) specimen already containing 80K phase, requires a long sintering time as the 110K phase grows around 80K phase through a slow kinetic diffusion.