Identification of the Superconducting Phase in the Bi-Ca-Sr-Cu-O System

In order to identify the superconducting phase in the Bi-Ca-Sr-Cu-O system, phase search experiments were performed. The results of power X-ray study, EPMA study, specific gravity measurements and oxygen analysis revealed that the compound having the composition Bi2(Ca, Sr)3Cu2O9 or Bi2(Ca, Sr)3-Δ x Cu2O9-Δ y is responsible for the high-T c superconductivity. Two possible structure models, which are closely related to the structure of the bismuth titanate Bi4Ti3O12, are proposed for this compound.