The comparative analysis of experimental and theoretically predicted values of helical dislocation densities for CdTe:Cl and MoOx/CdTe:Cl crystals with perfect and mosaic structures were carried out. Two-fold increase in the dislocation concentration was found for MoOx/CdTe:Cl heterostructures as a result of compression deformations of the CdTe:Cl crystal lattice. The transitional deformed layer at the boundary between MoOx film and CdTe:Cl single crystal with a thickness of about 0.1 μm significantly affects the electrical and spectroscopic properties of the obtained systems as materials for γ-radiation detection. Typical square-root type of the reverse branch of current-voltage characteristics were measured for a heterostructures based on a perfect CdTe:Cl, when for MoOx/CdTe:Cl heterostructures based on a mosaic substrate, an atypical quasi-linear type of I(V) dependence is observed. The characteristics of the detectors are affected not only by the quality of the initial crystals, but also by the technology of their post-treatment.
Chlorine doped CdTe single crystals (CdTe:Cl) were grown by the travelling heater method. The defect structure of the obtained single crystals was investigated using high-resolution X-ray diffractometry. The optimized models of dislocation systems based on the Thompson tetrahedron were constructed for CdTe:Cl single crystals. The analysis of the intensity distribution of diffracted X-rays as a function of reciprocal space coordinates and rocking curves was carried out using the kinematic theory of X-ray scattering in real crystals. The comparative analysis of experimental and theoretically predicted values of helical dislocation densities for CdTe:Cl crystals with perfect and mosaic structures were carried out. The dynamics of changes in concentrations and sizes of several types of interconnected dominant defects (spherical and disc-shaped clusters, dislocation loops) were studied with total integral reflectivity method. The generalized dynamic theory of X-ray diffraction in real crystals with randomly distributed microdefects of various types and a disturbed near-surface layer was used to interpret the experimental data.
The paper presents an improved approach for the analysis of Kikuchi patterns. Calculation of the deformation state in different crystallographic directions are performed in terms of developed model. It is proposed to determine the deformation of local regions of synthetic diamond crystals based on the normalized intensity profiles of the Kikuchi band (εP) and the normalized parameters of the Fourier energy spectrum (εT) without using a reference image.
Values of average deformations in local regions of synthesized diamonds are determined using the power Fourier spectrum in the analysis of Kikuchi pattern. The degree of bands blurring on image is related with the deformation, which are quantitatively described through the changes of average radial period of the energy spectrum. The planar distribution of deformations is allowed to determine anisotropy by the magnitude and direction in the crystal.
Аn analysis of the structure formation of concrete composites, compressive strength of which exceeds 120 MPa and a quantitative analysis of their qualitative composition and hydration products by X-ray diffraction, x-ray spectral analysis and electron microscopy. The main factors affecting the physicomechanical parameters of the complex of various nanofillers and the formation of a denser cement stone structure, which mainly includes calcium hydrosilicates, calcium silicate hydroaluminates and hydroaluminates of various basicity, are studied.
The defect structure of p-CdTe:Cl single crystals and MoOx/p-CdTe/MoOx heterostructures based on them were investigated by high-resolution X-ray diffractometry methods. Different models of dislocation systems were applied, according to which the densities of dislocations were estimated from the Wilson-Hall plot. It is shown that the application of the MoOx layer significantly affects the density of dislocations and their influence on the electrical and spectroscopic properties of heterostructures is estimated
Crystal and magnetic domain structures of iron garnet films with different thicknesses are studied by means of atomic and magnetic force scanning microscopies as well as by means of high-resolution Х-ray diffraction. The model of the garnet films as a set of vertical columns with certain lateral sizes is proposed and substantiated. Within this model, X-ray intensity distributions in the vicinity of the reciprocal lattice points are calculated using the Monte Carlo approach to determine densities of two dislocation types with different Burgers vectors.
A new approach for determining the distribution of mean-square deformations in the local regions of single crystals and polycrystals based on the analysis of electron backscatter diffraction images is proposed. The degree of bands blurring in Kikuchi pattern is related with the deformation values, which are quantitatively described through the changes of average radial period and the radial distribution area for the energy spectrum of the image. It is shown that the complex use of the power Fourier spectrum method in addition to the two-dimensional Fourier transform method create additional opportunities for determination of the influence of technological parameters on the structural homogeneity and the degree of perfection of studied crystals.
The degree of structural perfection of CdTe:Cl single crystals was estimated by methods of high-resolution Xray diffractometry. Two possible systems of dislocations that consists of two sets of complete 60-degree dislocations and Frank partial dislocations were investigated with the use of Krivoglaz kinematic theory and Monte Carlo method. The density of dislocations that provides correspondence between experimental and simulated reciprocal space maps is determined.
This work presents the results of investigation of crystal structure of yttrium iron garnet films of different thickness using high-resolution X-ray diffractometry data and simulation of X-ray intensity distributions in the vicinity of the reciprocal lattice points by the Monte Carlo approach. The parameters of films column microstructure are determined and substantiated, and the model of their defective structure as systems of two types of dislocations with different directions of the Burgers vector is proposed.
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