Structure Analysis of High-Tc Superconductor Bi-Ca-Sr-Cu-O by Processing of High-Resolution Electron Microscope Images

Abstract
A modulated structure in Bi-Ca-Sr-Cu-O was analyzed by image processing of high-resolution electron micrographs. The contrast of the modulated structure along the [010] direction with about 5a period was strongly enhanced by the processing. The structural modulation, mainly caused by the displacements of Bi atoms due to oxygen vacancies in the Bi4Ti3O12 derivative structure was clearly revealed. By combining the above result with processed images in other orientations, a realistic model of the modulated structure is proposed. It is demonstrated that the processing of high resolution images is useful in analyzing the complicated modulated structures such as observed in the new high-T c superconductor Bi-Ca-Sr-Cu-O.