RELATION OF STARTING PRECURSORS TO THE RESULTING HIGH-T-C PHASES IN THE PB AND SB DOPED BI-SR-CA-CU-O SYSTEM

The introduction of more reactive precursors for Pb and Sr (oxalates), as well as Ca (citrate) and the use of a Bi nitrate decomposition rou te, has increased the percentage of the high-T-c (2223) phase in the B i-Sr-Ca-Cu-O (BSCCO) system. Partial substitution of Bi(Pb) with Sb gi ves an almost single (2223) phase sample. In addition, a single (2212) phase sample is obtained when high purity Bi2O3 is used as a precurso r, whereas Bi acetate leads to semiconducting behavior. The morphology of the samples is studied with a scanning electron microscope (SEM), the stoichiometry with energy-dispersive x-ray analysis (EDAX), and th e structure with x-ray diffraction (XRD), while the superconducting pr operties are investigated by de-resistivity, ac-susceptibility, and SQ UID magnetometry techniques.