ELECTRON CRYSTALLOGRAPHIC STUDY OF BI-4(SR0.75LA0.25)(8)CU5OY STRUCTURE

Structure of Bi-4(Sr0.75La0.25)(8)Cu5Oy was studied by a image-process ing technique based on the combination of high-resolution electron mic roscopy and electron diffraction. Positions of heavy atoms were obtain ed by image deconvolution and then positions of oxygen were obtained b y phase extension. Both image deconvolution and phase extension are ba sed on the direct method developed in X-ray crystallography The electr on diffraction intensity used in phase extension was corrected by a ki nd of empirical method to reduce the distortions caused by various eff ects including the Ewald sphere curvature, dynamic scattering, etc. Th e efficiency of the image-processing technique and the empirical metho d of electron diffraction intensity correction is discussed.