Contrast of Dislocation Images in X-Ray Transmission Topography

Abstract

A brief review of the different topographic methods is given in order to attempt a classification of the various types of contrast observed. Depending on whether the image is obtained by a reflection or transmission method, is simple or integrated, dynamic, direct, or intermediary, the contrast and image width vary greatly. A detailed analysis is given in the case of transmission section topographs.

Applications of dynamical diffraction under locally plane wave conditions: defects in nearly perfect crystals and X-ray refractometry

“…It can be noted that the black part of the image of the core of the defect is always in the direction of the exact Bragg position (Figs. 6a and 6c), as expected (Authier, 1967).…”

“…We can also consider such deviation induced inside the crystal. The displacement ®eld u r associated with a crystal defect leads to an effective local disorientation of the re¯ecting planes, representing a local variation of the Bragg condition, that can be expressed as (Authier, 1967)…”

X-ray diffraction moiré topography as a means to reconstruct relative displacement fields in weakly deformed bicrystals

“…On`usual' topographs of locally perfect single crystals, the diffracted intensity Ir jj is then given by the local shift of the Bragg angle, the effective misorientation Âr jj (Authier, 1967). For a given re¯ection, up to six of the nine components of the deformation tensor may contribute to this quantity.…”

Application of the `lamellar crystal' approach to study X-ray interbranch scattering by a bent crystal

“…As is well known, the process of interbranch scattering is activated considerably in the case of X-ray dynamical diffraction by a strongly deformed crystal. Such an idea was ®rst given by Penning (1966) and was used by Authier (1967) to explain empirically some features of dislocation images on X-ray section topographs. This phenomenon contradicts the ray theory and occurs when the eikonal approximation (Kato, 1964) becomes invalid.…”