Electron microscope studies on Nd_2-xCe_xCuO₄

Abstract

The crystal structure of Nd 2-x Ce x CuO 4 , as determined from neutron powder diffraction and high resolution synchrotron radiation, has been reported in the literature. The space group was found to be Immm. The ratio of the tetragonal unit cell was reported to vary as a function of the compositions with two separate branches resulting in two different ratios for each composition. In addition, commensurate superlattices have been observed and related to ordering, of atoms or vacancies. The present work deals with electron diffraction data on the same samples used for the neutron diffraction work at Argonne National Laboratory. The samples were kindly supplied by Dr. Bogdan Dabrowski.