QUANTITATIVE ANALYSIS OF WEAK DEFORMATION FIELDS IN CRYSTALS BY X-RAY PLANE WAVE TOPOGRAPHY A.E.Voloshin, I.L.Smolsky, S.S.Sorokin Shubnikov Institute of Crystallography of RAS, Moscow, Russia.

Plane wave X-ray topography has been successfully used for studies and measurements of a weak, spread both elastic and quasiplastic strains in nearly perfect crystalline plates due to high sensitivity to lattice distortions. Such a technique is particularly useful at studying of various inhomogeneities in distribution of impurities. It combines a wide observation area (up to 10 cm²) with a relatively good locality (1-10 um) and rather high sensitivity to crystal lattice distortions (up to 10^-7-10^-8). Quantitative estimation of a distortion field provided by the effective applying of computer image processing tools.

The surface elastic strain measurements by plane wave X-ray topography require only a series of the object images under different diffraction conditions. Number of topographs depends on the dimension of the existing distortion field. These topographs serve also as initial data for the calculations of quasi-plastic strains. A one-dimensional case of the inverse problem of the theory of elasticity was solved providing a direct calculation of quasi-plastic strains in a crystal with weak zonal striations. In two- and three-dimensional cases only the direct problem was solved so the computer simulation of the total deformation state of a body is necessary.

Described technique being illustrated by examples of the analysis of one-dimensionally distributed striations in silicon plate and vicinal sectoriality in (101)-plate of KDP crystal.