Preparation of Single 110 K Phase of the Bi-Pb-Sr-Ca-Cu-O Superconductor

A pure 110 K phase of the Bi-Pb-Sr-Ca-Cu-O superconductor was obtained by co-decomposition of metal nitrates and a solid reaction under low oxygen pressure. The best starting compositions were in the region close to Bi1.84Pb0.34Sr2Ca2Cu3O y with a little excess of Ca and Cu. In this region, the samples showed the absence of the 80 K and semiconducting phase, and there was no indication of impurities at all. The 110 K phase without stacking faults is stabilized by the addition of Pb, so that the nominal composition close to the ideal one is required at the start. A little excess of Ca and Cu, however, effectively decreases the 80 K phase.