Superconductivity in the high-Tc Bi-Ca-Sr-Cu-O system: Phase identification

Abstract

Four phases are observed in superconducting Bi-Ca-Sr-Cu-O samples. The superconducting phase, with onset temperature near 120 K, is a 15.4-layered compound with composition near Bi2Ca1Sr2O9 and an A-centered orthorhombic unit subcell 5.41×5.44×30.78 3. X-ray diffraction and electron microscopy data are consistent with a structure of alternating perovskite and Bi2O2 layers. High-resolution transmission electron microscopy images reveal a b-axis superstructure of 27.2, numerous (001) stacking faults, and other defects. © 1988 The American Physical Society.