Preparation and Microstructural Investigation of the High?Tc Superconductor Pb2Sr2Y0.5Ca0.5Cu308

Simple conditions for the preparation of the high-Tc superconductor Pb2Sr2Yo-sCao·sCu308+o in single phase are given. High resolution electron microscope studies of this material confirm the basic orthorhombic structure having Cmmm symmetry. Overlaying this structure is a perturbation due to random displacements of Pb from the ideal square-symmetric Sites, attributed to a randomness in oxygen sub-stoichiometry. This and the absence of superstructure ordering appears to characterise the uperconducting form of this compound.