The diffraction of X-rays by close-packed polytypic crystals containing single stacking faults. III. Measurements of diffraction effects caused by stacking faults in plate or film form samples

Abstract

A theory that describes the diffraction effects from stacking faults in close-packed polytypic crystal structures was developed in two previous papers of this series [Michalski (1988). Acta Cryst. A44, 640-649; Michalski, Kaczmarek & Demianiuk (1988). Acta Cryst. A44, 650-657]. In this paper, attention is paid to the measurement of these diffraction effects for the cases where needle-shaped or rod-like specimens cannot be made from the given sample (e.g. thin films) or when single-crystal samples should not be destroyed for preparing such specimens. For this purpose, methods of measurement based on standard X-ray diffraction equipment such as oscillation or Weissenberg cameras and a powder diffraction diffractometer have been developed A complete description of the limitation of the area of the reciprocal lattice that can intersect the Ewald sphere has been provided. Examples of the results obtained by these methods are given. The diffractometer two-dimensional scanning method, which allows an undistorted reciprocal lattice to be recorded and higher precision and results more convenient for mathematical treatment than in photographic methods to be obtained, seems to be especially interesting.