PREPARATION AND PROPERTIES OF PB-DOPED AND V-DOPED BI-BASED SUPERCONDUCTORS

The effect of the stochiometric replacement of Pb and Pi by V in the B i-Sr-Ca-Cu-O system has been studied. The content of Pi, Pb and V in t he BiaPbbVcSr4Ca5 Cu7Ox was altered according to the formula: a + b c = 4 (a = 2.6-3.6, b = 0-0.8, c = 0-0.6). The influence of the dopant on the properties of the samples was detected by XRD analysis, by the measurement of the electrical resistivity, critical current density a nd magnetic susceptibility. The increasing amount of V on account of P b led to the decreasing content of the 2223 phase and to the deteriora tion of the superconducting properties. On the other hand, the samples with V substituting Pi in material with a constant concentration of P b (b = 0.8) reveal improved intergrain boundaries and a large content of the 2223 phase. The XRD analysis confirmed a decrease of the lattic e parameter c of the 2223 phase from 37.173 nm to 37.079 nm for increa sing amount of V in these samples. An unknown phase detected on x-ray diffraction patterns (Cu K-alpha) was attributed to the presence of V.