GAMMA-RAY DIFFRACTION IN DISLOCATION-CONTAINING QUARTZ SINGLE CRYSTALS. Alexei Sokolov, Alexander Kurbakov, Department of Condensed Matter, Petersburg Nuclear Physics Institute, 188350, Gatchina, Russia

At present ideal method for the dislocation density determination does not exist. Actual techniques are destructive or require a long time. The aim of our works is development of the express non-destructive method allowing to determine the dislocation density with high accuracy. Another purpose is experimental testing of different modern theories of diffraction in real single crystals.

Gamma-ray diffractometry method has been applied for investigations of the quartz single crystals, containing dislocations with wide range of their density. Strictly mathematically the problem of the dynamical scattering in dislocation-containing single crystals is not solved yet. The method based on the statistical dynamical theory of diffraction seems to be fruitful. Unfortunately primary theory proposed by Kato can lead to inaccurate results in certain cases. Modifications of this theory so far have been applied to rather perfect dislocationless silicon single crystals. In present work they are propagated to dislocation-containing, more imperfect quartz crystals, which permits to carry out experimental testing of the different versions of the statistical dynamical theory of diffraction.

Data obtained by means of this technique have been compared with those obtained by other methods (X-ray topography, etching channel counting). Developed technique allows to determine very low dislocation density with high accuracy (a few dislocations / c.cm).

This work is supported by Russian Foundation of Basic Research, grant 94-02-03771.