The spatial intensity profile of an X-ray beam reflected by a crystal with microdefects in the Bragg case is considered. A practically pure diffuse component was measured at the tail of the intensity distribution. From these data, static Debye-Waller factors of nearly perfect silicon crystals were obtained.

Bragg and diffuse scattering contributions to a reflection can be separated using the intensity dependence on the amplitude of transverse ultrasound excited in the crystal. The method is based on the fact that a weak ultrasound with wavelength equal to the extinction length suppresses almost completely the anomalous transmission of the coherent (Bragg) beam in a sufficiently thick absorbing crystal and does not affect diffuse scattering. Both parameters characterizing diffraction in a slightly imperfect crystal, the static Debye-Waller factor and the coefficient of additional absorption due to diffuse scattering, have been determined for a silicon crystal containing oxide precipitates after heat treatment.

The effect of high temperature (up to 1120°C)-high pressure (up to 1.1 GPa) treatment mr tle resulting defect structure of preannealed (450-725°C, up to 96 hours) Czochralski grown Si crystals was studied by X-ray diffraction. The values of the Debye-Waller static factor and of the root-mean-square atomic dispalacement due to defects were determined for various Laue reflections. Well-defined development of the cłuster like defect structure after high temperatnre pressurization depending to a substantial extent mi the preannealing conditions was observed.

The amplitude dependences of the integral reflectivity (IR) Ri(W) of perfect silicon crystals distorted by shear short wave ultrasonic vibrations are investigated for high order reflections of AgKβ, AgKα1 radiations. Transition to the kinematical regime of diffraction is obtained for high ultrasound amplitudes both, in the Laue and in the Bragg case of diffraction. The ratios of the integral reflectivities measured in the initial and distorted state of a crystal are in agreement with the theory developed formerly. The influence of structural defects on the transition of the IR to the kinematical regime is studied, too.