High-Resolution Transmission Electron Microscopy of Long-Period Structures of Various Phases in a Bi-Sr-Cu-O System

Abstract

Three nonsuperconducting phases ( B to D ) in a Bi-Sr-Cu-O system have long-period structures closely related to that of the superconducting phase A , Bi 2 Sr 2 CuO y . In phase B , the long periodicity is caused by the displacements of the (BiO) 2 planes along the c axis. In both phases C and D , it is due to the formations of thin vertical planes of different local structures and compositions. These planes are straight and repeat regularly to form a commensurate long-period structure in phase C , while they repeat irregularly to form an incommensurate structure with wavy lattice planes in phase D .