Preparation and magnetic properties of (Bi,Pb)-1212

Polycrystalline samples of (Bi,Pb)Sr-2(Y,Ca)Cu2O7-z[(Bi,Pb)-1212] were prepared to study the influence of one missing BiO-layer in the BSCCO system [Bi-2212, (Bi,Pb)-2223] on its physical properties, In a structural analysis, the high percentage of the (Bi,Pb)-1212 phase(approximate to 80%) was proven by XRD and EDX, and the structure of the 1212 phase as well as the incorporation of the 2212 phase in the 1212 matrix were evidenced by a HRTEM analysis, The best samples exhibit T-c,T-R=0=92 K and T-c,T-onset=110 K. The pinning properties were investigated by means of SQUID-magnetometry. The critical current density J(c) shows a strong decrease with temperature, similar to that of Bi-2212 and Bi-2223. Furthermore, regimes of pinning of individual flux lines and pinning of small and large flux bundles were identified by measurements of the magnetic relaxation rate. The transition temperatures separating these regimes lie in the same range as for Bi-2212, indicating a comparable anisotropy of the two compounds.