Kristallografiâ
A peer-reviewed journal that publishes original articles, short communications, and reviews on various aspects of crystallography: diffraction and scattering of X-rays, electrons, and neutrons, determination of crystal structure of inorganic and organic substances, including proteins and other biological substances; UV–Vis and IR spectroscopy; growth, imperfect structure and physical properties of crystals; thin films, liquid crystals, nanomaterials, partially disordered systems, and the methods of studies.
The journal was founded in 1956.
Media registration certificate: № 0110215 от 08.02.1993
Founders: Russian Academy of Sciences, Shubnikov Institute of Crystallography of RAS
Editor-in-Chief: Michail V. Kovalchuk, corresponding member RAS, Doctor of Sc., Full Professor
Frequency / Access: 6 issues per year / Subscription
Included in: White list (2nd level), Higher Attestation Commission list, RISC
Edição corrente



Volume 70, Nº 4 (2025)
- Ano: 2025
- Artigos: 22
- URL: https://cardiosomatics.orscience.ru/0023-4761/issue/view/13713
Edição completa



Articles
Editor-in-Chief's Column



ДИФРАКЦИЯ И РАССЕЯНИЕ ИОНИЗИРУЮЩИХ ИЗЛУЧЕНИЙ
X-ray diffraction tomography: image filtering by singular value decomposition and 1D smoothing Whittaker-Eilers methods
Resumo
Digital processing of the 2D noisy X-ray diffraction images (2D-XDI) of a single point defect in Si(111) crystal, registered at the level of dispersion of statistical Gaussian noise of the detector using filtering methods such as singular value decomposition and 1D-line-by-line smoothing of test 2D-XDIs, is carried out. The efficiency of digital filtering of 2D-XDI is evaluated and analyzed by means of control parameter FOM (figure-of-merit) value of reconstruction of the displacement field function of a point defect of Coulomb type fh(r–r0), (h – diffraction vector, r0 – radius-vector of the defect position in the sample). It is shown that the filtering technique using the singular value decomposition of 2D-XDI works significantly better than the 1D linear-by-line smoothing method of 2D-XDI, which, apparently, in relation to our problem requires further research on its improvement.



Computer diffraction tomography. Digital image processing and analysis based on the 1D-, 2D-sized guided and wavelet-function filter processing
Resumo
One presents and analyzes the results of computer processing for a plane-wave X-ray topography imaging of a point defect of the Coulomb-types in the Si(111) crystal recorded by an X-ray detector against a background of the Gaussian noise, and their subsequent filtering by using the 1D-, 2D-sized guided and a heuristic wavelet 4th-order Daubechie’s atomic function. The filtering efficiency of a topography image is determined by the parameter of the averaged over all pixels relative square deviations of the pixel intensities (RMS.) of the processed and reference (noise-free) 2D image. Practical methods for selecting filtration parameters are proposed, using which the considered methods work well enough to be used in practice for the noise processing of plane-wave X-ray topography images, meaning their use for the 3D digital recovering nanosized crystal defects.



ТЕОРИЯ КРИСТАЛЛИЧЕСКИХ СТРУКТУР
Crystallographic classification of special intercrystalline boundaries
Resumo
A classification of special intercrystalline boundaries in centrosymmetric crystals of all syngonies is constructed based on the symmetric properties of planar lattices. It is shown that the set of orientation parameters identifying special boundaries is determined by the orientation of the plane formed by the matching atoms of the contacting crystals. Unlike the general type of boundaries, the number of these parameters is either two or three. It is shown that the lattice of matching bicrystal nodes appears only in crystals with high-order axes of symmetry. Possible misorientations of the contacting crystals are found depending on the symmetry of the crystallographic plane for different crystallographic conditions.



REAL STRUCTURE OF CRYSTALS
X-ray topo-tomography of large HPHT synthetic diamonds
Resumo
Extended defects in large synthetic diamonds grown at high pressures and high temperatures (HPHT) using thermal gradient method were studied by X-ray topo-tomography with a laboratory setup. It is shown that temperature and growth rate are the principal factors influencing crystalline quality of the diamonds. Synthesis at high temperatures and low rate allows growth of single crystals with low density of dislocations, stacking faults and microtwin lamellae. Annihilation kinetics of the extended defects during annealing at high pressure implies important role of vacancies diffusion. The annihilation of such defects leads to formation of perfect dislocations.



Interaction of ferroelectric domain walls and shape of equilibrium repolarization nuclei
Resumo
The growth of a repolarization nucleus in an electric field is hindered by cohesive forces acting near its tips on the adjacent domain walls. They can reach large values when the distance between the domain walls becomes comparable to their thickness. It is shown that the cohesive forces are expressed in terms of the coefficients of the Ginzburg–Landau energy expansion, which includes a gradient contribution. For a uniaxial ferroelectric, an estimate of the maximum value of the internal field associated with the gradient interaction of the domain walls is obtained. Its relation to the internal coercive field Ec0 in the Ginzburg–Landau theory is E* max/Ec0 = 3√3/8 ≈ 0.65.



Kinetics of discrete kinks and domain walls
Resumo
The kinetics of kinks and domain walls in quasi-one-dimensional systems is described within the framework of a model intermediate between the sharp kink model and the continuum model of an elastic string. The effects resulting from the discrete structure of crystalline materials are considered, including the periodic inhomogeneity of the energy relief for kink migration. Within the framework of a transparent approximation using a minimum number of internal variables, the dependence of the Peierls barriers on the driving force is calculated and the transition between static and dynamic regimes is described. The theory is based on the universal Frenkel-Kontorova model and can be applied to extended systems of various natures.



СТРУКТУРА НЕОРГАНИЧЕСКИХ СОЕДИНЕНИЙ
Structural features and transport properties of lithiated fluorite-like molybdates Nd5MO3O16 in the temperature range 20–900°C
Resumo
The structure of lithiated fluorite-like molybdates of the Ln5Mo3O16+δ family was studied using accurate X-ray diffraction analysis in the temperature range 20–777°C (293–1050 K). Thermally activated redistribution of oxygen ions over basic and interstitial positions and reversible change in the position occupancies upon heating–cooling were established. Thermal stability, ionic oxygen conductivity and dielectric properties of ceramic samples of undoped and Li-containing Nd5Mo3O16+δ phases were studied in the temperature range 20–900°C. The results demonstrate the possibility of controlling the functional properties of materials for use in medium-temperature solid oxide fuel cells.



КРИСТАЛЛОГРАФИЯ В БИОЛОГИИ И МЕДИЦИНЕ
Crystallization of proteins using a temperature gradient
Resumo
The paper presents the results of many years of work on the development of a new method of temperature control and the apparatus developed on its basis for the automatic growth of protein crystals, in which the possibility of separate control of both the process of nucleation and growth of the formed crystals is realized.



X- ray diffraction analysis revealed the role of the L254 residue in the recognition of the substrate by carboxypeptidase T from Thermoactinomyces vulgaris
Resumo
Crystal structures of complexes of the mutant protein L254N carboxypeptidase T from Thermoactinomyces vulgaris with stable transition state analogues -N- sulfamoyl-L-glutamate, N-sulfamoyl-L-arginine, N-sulfamoyl-L-valine and N-sulfamoyl-L-leucine (resolution 2.05, 1.89, 2.30, 1.79 Å) were obtained. The dependence of the association constants of these inhibitors, as well as the efficiency of catalysis of the corresponding tripeptide substrates ZAAX, on the distances between the atoms of the ligand O15, O16, O20, T19 and the active center of the mutant protein N146, Y225 and E277 was found. This dependence differs significantly from the previously identified dependence for wild-type carboxypeptidase T. The results obtained indicate the involvement of leucine 254, which is part of the mobile loop of metallocarboxypeptidases, in the discrimination of substrates by carboxypeptidase T according to the induced fit mechanism.



ФИЗИЧЕСКИЕ СВОЙСТВА КРИСТАЛЛОВ
Memory effects in magnetoplasticity of NaCl crystals
Resumo
Memory effects in magnetoplasticity of NaCl crystals with different impurity content are studied. Dislocation paths and microhardness of crystals after their exposure to a constant magnetic field or to crossed ultralow magnetic fields are measured. In two crystals, noticeable relaxation displacements of dislocations, introduced after exposure, are found. In two other crystals with a lower impurity concentration, the paths remain at the background level, but in one of them, exposure causes an increase in the density of mobile dislocations. Similar magnetic exposure also leads to a decrease in the microhardness of crystals, but to different extent. Interpretation of observations is reduced to a spin-dependent transformation of impurity centers in a magnetic field, which plasticizes the crystal. Introduction of dislocations after magnetic exposure leads to their relaxation displacements from unstable positions, and at strongly weakened pinning centers, dislocations straight away take up positions close to equilibrium.



Surface acoustic waves in layer – substrate structures of arbitrary anisotropy
Resumo
The existence of surface acoustic waves in a semi-infinite substrate with a solid layer is theoretically investigated. The substrate and the layer are not piezoelectrics, but can belong to any class of crystallographic symmetry. By presenting the dispersion equation as a condition on the substrate and layer impedance matrices, it is possible to determine, using the properties of impedances, the maximum allowable number of surface waves depending on the type of contact and the ratio between the velocities of the bulk waves in the substrate and the layer materials. In addition, a dispersion equation is derived for the symmetrical orientation of an orthorhombic substrate with a deposited monoatomic layer and the possibility of a purely flexure surface acoustic wave in the case of a very hard surface layer, for example, a monolayer of graphene on a soft polymer substrate, is shown.



Temperature dependence of elastic moduli and period of magnetic spirals in cubic helimagnets with spins in non-equivalent positions
Resumo
Critical phenomena in cubic helimagnets with nonequivalent magnetic atoms are investigated within the framework of the Weiss mean-field theory. The reason for the appearance of temperature dependences of elastic moduli and the pitch of the magnetic helicoid is found and the form of these dependences, determining the change in the conditions for the appearance of magnetic skyrmions in type II multiferroic Cu2OSeO3, is predicted.



Evolution of the magnetic domain structure in iron borate FeBO3 single crystals in external fields, studied by X-ray diffraction and magneto-optical techniques
Resumo
An X-ray diffraction technique using a synchrotron radiation source has been developed and implemented to study the evolution processes of magnetic domain structure in external fields. High-quality single crystals of iron borate FeBO3 were chosen as model objects. A series of X-ray and magneto-optical experiments were performed to investigate the evolution of the magnetic domain structure in weak external magnetic fields. It has been established that the movement of domain walls leads to a stepwise broadening of the diffraction reflection curves of FeBO3 crystals. It is demonstrated that X-ray diffraction studies of the magnetic domain structure can be useful for characterizing magnetic materials in which direct observation of domains by magneto-optical and electron-microscopic methods is difficult.



Bulk photovoltaic effect in gyrotropic crystals
Resumo
The effect of optical activity on the linear and circular bulk photovoltaic effect in crystals without a center of symmetry is investigated. It is shown that there is a phase shift of the linear photovoltaic current JL, which is opposite for the right and left crystals, and a modulus change. The circular photovoltaic current JC does not change in phase depending on the amount of optical activity, but depends on absorption and circular dichroism. The dependences of the JL current on the polarization of incident light are calculated, taking into account the optical activity for the right and left crystals Bi12SiO20, Bi12GeO20 and Bi12TiO20 (class 23). Similar JL calculations were performed for the right crystals Pb5Ge3O11 (class 3), La3Ga5SiO14 with impurities of Pr, Fe, Cr and Mn, Ca3TaGa3Si2O14 (class 32), Er(HCOO)3·2H2O (class 222) when light propagates in the direction of the optical axis. Examples of the JC value for Pb5Ge3O11, La3Ga5SiO14 crystals with impurities of Co, Cr, and Fe, as well as α-HgS (class 32), are given. It is shown that consideration of optical activity is necessary when studying the photorefractive effect in crystals.



Irradiation creep in metals: multiscale modelling
Resumo
The irradiation creep in metals with cubic crystal lattices at low stresses (less than the yield strength) was studied within the framework of multiscale modelling. The modelling combines theoretical (dislocation theory of crystal plasticity, diffusion theory, anisotropic theory of elasticity, chemical kinetics) and computational (molecular statics, molecular dynamics, object kinetic Monte Carlo method) methods. The values of the rate and modulus of irradiation creep were determined in metals with bcc (Fe, V) and fcc (Cu) crystal lattices containing rectilinear dislocations with Burgers vectors 1/2 <111>, <100> (bcc) and 1/2 <110> (fcc), uniformly distributed over possible families of their slip systems. The obtained calculated and theoretical values of the rate and modulus of irradiation creep are in good agreement with the results of reactor experiments.



Recombination-enhanced of dislocation glide in 4H-SiC and GaN under electron beam irradiation
Resumo
The analysis of the investigations of recombination-enhanced dislocation transport in GaN and 4H-SiC is carried out. It is shown that in both crystals, when irradiated with a low-energy electron beam, dislocations can shift even at liquid nitrogen temperature. The activation energies of dislocation glide stimulated by electron beam irradiation are estimated. The results are presented demonstrating practically activation-free migration of double kinks along a 30° partial dislocation with a silicon core in 4H-SiC. It is shown that localized obstacles significantly affect the dislocation transport in GaN both under the action of shear stresses and under irradiation. Nonequilibrium charge carriers introduced into GaN by irradiation not only help to overcome the Peierls barrier, but also stimulate the detachment of dislocations from obstacles.



Dislocation structures and active deformable media
Resumo
The relationship between dislocation and autowave models of plastic flow is established. It is shown that the activity of the deformed medium required for generating autowave processes of plastic deformation is provided by the dislocation structure of the medium. The relationship between the dispersion of autowaves and the stages of plastic flow and the dislocation structures observed at each of them is analyzed and explained. A mechanism for excitation of low-frequency autooscillations in a deformed medium due to the elastic interaction of dislocation ensembles with moving dislocations is proposed. The mutual complementarity of the autowave and dislocation approaches to the description of plasticity is discussed.



Features of the influence of Guinier-Preston zones on inelastic processes under high-energy external loads
Resumo
A theoretical analysis of the motion of an ensemble of edge dislocations in an aged binary alloy under conditions of high-energy external influences has been performed. Within the framework of the theory of dynamic interaction of defects, an analytical expression is obtained for the dependence of the dynamic yield strength on the density of dislocations. It is shown that a high concentration of Guinier–Preston zones in an aged binary alloy leads to a minimum on the resulting dependence.



Magnetoresistance in superionic conductor
Resumo
The magnetoresistance effect has been revealed in a superionic conductor: a single crystal of Pb0.66Cd0.34F2. The effect is apparently related with the action of the Lorentz force on the system of mobile F– ions. The effect is approximately 1% at a magnetic field with induction of about 1 T.



МЕТАМАТЕРИАЛЫ И ФОТОННЫЕ КРИСТАЛЛЫ
Quasi-synchronous second harmonic generation in photonic crystal structures based on iodic acid
Resumo
The frequency conversion efficiency of the long-wavelength part of the optical spectrum is considered. The problem of generating the second harmonic in two-dimensional photonic crystals based on iodic acid is considered in order to convert long-wave radiation into the visible range for subsequent registration by traditional silicon detectors. The problems of synthesis of two-dimensional photonic crystal structures for practical problems of nonlinear optics and photonics are discussed.



ПОВЕРХНОСТЬ, ТОНКИЕ ПЛЕНКИ
Microstructural changes in magnesium alloy Mg-Zn-REE after irradiation with nanosecond laser pulses
Resumo
The article presents the results of studies of the structure and composition of the surface and near-surface layers of the Mg–Y–Zn–Nd–Yb–Zr alloy system with a long-period phase after irradiation with nanosecond laser pulses using electron microscopy and energy-dispersive X-ray microanalysis. It is shown that in a two-phase alloy, a layer of nanocrystalline MgO with a thickness from 5 nm to hundreds of nm is formed on the surface in the α-Mg matrix region. A recrystallized layer of columnar crystallites with a thickness of about 1 μm and a lateral size of 0.2–1 μm with inclusions of cubic MgO is formed under it. In the area of the intermetallic compound (phase Mg12YZn–REE type 18R), a three-layer amorphous-crystalline structure is formed: an amorphous layer 15–20 nm thick on the surface, under it a crystalline layer of columnar crystallites 0.1–0.3 μm thick and with lateral dimensions of 0.1–0.5 μm, then an amorphous layer of intermetallic compound about 1 μm thick.


