Electron crystallographic study of Bi 4(Sr 0.75La 0.25) 8Cu 5O y structure

Abstract

Structure of Bi 4(Sr 0.75La 0.25) 8Cu 5O y was studied by a image-processing technique based on the combination of high-resolution electron microscopy and electron diffraction. Positions of heavy atoms were obtained by image deconvolution and then positions of oxygen were obtained by phase extension. Both image deconvolution and phase extension are based on the direct method developed in X-ray crystallography. The electron diffraction intensity used in phase extension was corrected by a kind of empirical method to reduce the distortions caused by various effects including the Ewald sphere curvature, dynamic scattering, etc. The efficiency of the image-processing technique and the empirical method of electron diffraction intensity correction is discussed.