Electron diffraction effects in mixed layer compounds. I. Theoretical considerations

Abstract

Mixed layer compounds form a class of materials of which the electron diffraction patterns exhibit characteristic features. In part I of this paper the geometrical aspects of these diffraction patterns are discussed. The intensity distribution is derived on the basis of the kinematical diffraction theory. From the diffraction point of view, shear structures, long period anti‐phase boundary structures, polysynthetic twins, periodic inversion boundary structures, i.e. periodic interface modulated structures in general, can be considered as subsets of the set of mixed layer compounds, each having typical characteristics. Extinctions and quasi‐extinctions, similar to the extinctions associated with the presence of certain symmetry elements in space groups are also found in the periodic interface modulated structures. In part II these theoretical considerations will be illustrated with a number of observations. Copyright © 1987 WILEY‐VCH Verlag GmbH & Co. KGaA