The effect of lead-rich phases on the microstructure and properties of (Bi, Pb)-2223/Ag tapes

The effect of lead-rich phases on the microstructure and properties of (Bi, Pb)-2223/Ag tapes has been studied. Powders containing different types of lead-rich phases were prepared by controlling the processing parameters, including temperature, time and oxygen partial pressure. Then, monofilament (Bi, Pb)-2223/Ag tapes were fabricated using these powders. The phase compositions of the powders and tapes were analysed by x-ray diffraction and the microstructure of these tapes was observed using scanning electron microscopy. Experimental results show that the lead-rich phases in powders played an important role in the formation of the (Bi, Pb)-2223 phase, and the microstructure and the superconducting properties of (Bi, Pb)-2223/Ag tapes. The formation process of (Bi,Pb)2Sr2CaCu2Ox in tape fabricated using the powder containing Ca2PbO4 is different from a tape fabricated using the powder containing Pb3Sr2.5Bi0.5Ca2CuOy, which differs in the formation process and grain sizes of the (Bi, Pb)-2223 phase. Therefore, the critical currents of (Bi, Pb)-2223/Ag tapes containing various lead-rich phases are different. The highest critical current is obtained for tape fabricated using powder containing both Ca2PbO4 and 3321 phases