THE EFFECT OF AG DIFFUSION ON THE CRYSTAL-STRUCTURE AND ELECTRICAL-PROPERTIES OF BI(PB)SRCACUO SUPERCONDUCTORS

X-ray diffraction of Bi(Pb)SrCaCuO compounds, prepared by a convention al solid-state technique, were measured from 20 degrees C to 500 degre es C. It was found that diffusion of Ag (600-825 degrees C) in Bi cera mics stimulates a high degree of grain orientation along the c-axis. I n Ag-doped samples the lattice parameters a and c are decreased (in co mparison with the undoped samples) and their dependences on temperatur e reveal a non-linear character. The critical temperature, determined from the resistivity measurements, for Ag-doped samples increased to 1 18 K. Ag diffusion at 790 degrees C increases the critical current den sity more than twice. The influence of low annealing temperature for A g-doped samples on critical current density was also investigated. The se results are discussed on the basis of precipitation of Ag solid sol ution in Bi(Pb)SrCaCuO superconductors.