The growth process of the (2223) phase in Bi-Sr-Ca-Cu-O has been studied for oxides with nominal composition Bi2Pb0.6Sr2Ca2Cu3O x prepared by sintering at 835∼855°C for 5∼160 h in air. The partial melting which starts to occur at T pm≃842°C enhances the growth rate of the (2223) phase and produces a nearly single phase within 40 h. However, it causes a disturbance in current paths and suppresses the value of T c(ρ=0) below 100 K. The sample which has the highest T c(ρ=0) and the nearly single (2223) phase is obtained by sintering at a temperature just below T pm for a long period of time.

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The powder-in-tube method using an Ag sheath is applied to achieve high current capacity in the tapes of Bi-Pb-Sr-Ca-Cu-O (BPSCCO) with the high-Tc phase (Tc=110 K), by a combination process of cold working and sintering. Two kinds of the BPSCCO powder with and without Ag doping are used as the materials for tape fabrication. The morphology, structure, and critical current density Jc are investigated on the tapes by x-ray diffraction, differential thermal analysis, scanning electron microscope, magnetic susceptibility, and I-V curves. The optimum sintering conditions to obtain a maximum in the value of Jc at 77 K and 0 T are presented in the Ag-doped tapes and the nondoped ones. An improvement in the Jc vs B properties up to 1 T at 77 K is presented in the BPSCCO tape by Ag doping. The Ag doping causes neither change in the value of Tc (=110 K) nor decomposition of the high-Tc phase.

The powder-in-tube method using an Ag sheath is applied to achieve high current-capacity in the tapes of Bi-Pb-Sr-Ca-Cu-0 (BPSCCO) with the high-Tc phase, by a combination of cold working and sintering. Two kinds of the BPSCCO powders with and Magnetic Susceptibility and I-V characteristics at 77K obtained for above powders are presented and discussed: An improvement in Jc vs B properties of the BPSCCO tapes by Ag doping is presented.

Studies of DTA, XRD, resistivity and susceptibility are made for oxides with the nominal composition of Bi2Pb0.6Sr2Ca2Cu3O x . The (2223) phase has been singled out, to our knowledge, in the shortest sintering time reported so far in air from the partially melted phase by introducing the re-press process, but the value of T c(ρ=0) is lowered to ∼73 K by a disturbance in current paths at the grain boundaries. A prolonged sintering improves this and enhances T c(ρ=0) to above 100 K. Taken together, we can see the efficacy of the re-press process and the slowness of the intergrain reaction to open up the current paths.