STOICHIOMETRY VARIATION EFFECT ON THE SUPERCONDUCTING PROPERTIES OF POLYMER-PROCESSED (BI1-XPBX)2SR2CA2CU3O10 CERAMICS

Bismuth family high-temperature superconducting samples with varying i nitial Pb, Sr and Ca stoichiometries have been prepared using a polyme r solution synthesis method. These samples have been characterized by powder X-ray diffraction, scanning electron microscopy, energy-dispers ive spectroscopy and magnetic ac susceptibility. The samples which yie ld the highest percentage of 2223 phase have in common an excess amoun t of Pb and a deficiency in Sr. The sample with best intragranular pro perties has a stoichiometry represented by Bi1.8Pb0.35Sr1.87Ca2.1Cu3O1 0+delta. It is also shown that, in contrast with the intragranular pro perties, the intergranular properties are irreproducible in almost all the samples studied.