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[en] A method for measuring the curvature of single crystals on a triple-crystal X-ray diffractometer has been developed for the Bragg geometry. The divergence of the X-ray radiation from the third crystal (a specimen) is determined by the angle formed by the tangents at the points of incidence of the end rays of the beam incident onto a bent crystal. A formula is obtained that relates the width of a diffraction maximum to the curvature radius of the crystal studied

[en] In the course of the investigation of phase equilibria in Zr-Co-In and Zr-Ni-In systems at 870 K, ternary compounds Zr₂M₂In (M = Ni, Co) were found at a section of 0.40 atomic fractions of Zr. The X-ray structure analysis was performed for a single crystal from the Zr-Ni-In system. A single crystal in the form of a parallelepiped was extracted from the Zr_0.40Ni_0.40In_0.20 alloy annealed at 870 K. The tetragonal system was determined by the Laue method, and the unit-cell dimensions were found from rotation photographs. The X-ray data were collected on an automated DARCH-1 diffractometer (MoKα radiation, graphite monochromator, 2θ_max = 75 degrees). The unit-cell constants were refined to a = 7.173(2) and c = 3.338(1) Angstrom. The structure was solved by direct methods in the sp. gr. P4/mbm, Z = 2. The CSD package for the IBM PC was used. Atomic parameters were refined to R = 0.0269 for 183 independent reflections with I > 4σ(I). 2 refs., 2 tabs

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[en] One of the channels of scattering of x rays in matter is Compton scattering. In a crystal the arising Compton radiation can be diffracted, forming in the frequency-angle spectrum of scattered x rays lines with a fine structure, similar to Kikuchi or Kossel lines. They were first discovered by Yoneda in LiF crystals, and recently it has been reported that the lines are observed in metallic alloys. In a number of articles they have been called interference Compton lines. Since interference lines have been observed in crystals with a low degree of perfection, i.e., with dislocation density n ≥ 10⁷ cm^-2, Bushuev et al. proposed a theory of interference lines with Compton and thermal diffuse scattering, based on the model of a mosaic crystal and the formation of secondary extinction. Experimental verification of the theory for angular and frequency spectra revealed fairly good agreement. However, calculation of the contrast of the interference Compton lines in the symmetrical geometry of Laue sharply disagreed with the observed value; the experimental value of the contrast, i.e., the ratio (I-I₀)/I₀, where I is the intensity of inelastic scattering with allowance for diffraction, I₀ is that without such allowance, exceeded the calculated value by a factor of 30. The authors saw the cause of the contrast in the diffraction redistribution of the intensity of radiation, due to the steep angular dependence of Compton scattering at small angles. The author argues that the contrast of the interference lines can be explained by the geometry of diffraction of diffuses scattering of a bounded beam of x rays in a mosiac crystal without allowance for the angular dependence of Compton scattering. 5 refs., 2 figs