Effect of the precursor composition on the structure and superconducting properties of the Bi1.8Pb0.4Sr2Ca2.2Cu3Ox (2223) ceramics in Ag-sheathed monofilamentary composite tapes

X-ray diffraction, transmission and scanning electron microscopy. electron microprobe analysis, and measurements of superconducting properties were us ed to study tape composites based on the 222.3 phase. It is shown that afte r four cycles of thermomechanical treatment (cold pressing + annealing) in the composites fabricated from the precursor (oxides + 50% 2212), the criti cal current density reaches 4 x 10(4) A/cm(2). This corresponds to the sing le-phase state of the ceramics (2223), the occurrence of the doping additio n of Ph in solid solution in the 222.3 phase, and the presence of Ag, which penetrates into the ceramics during the thermomechanical treatment, in the form of particles 100-500 Angstrom located along the boundaries of planar crystallites.