Том 81, № 5 (2017)

Huntite-like EuM₃(BO₃)₄ crystals (M = Al, Cr, Fe, or Ga) are synthesized by means of spontaneous crystallization from a solution in a melt. The infrared spectra of the compounds are measured. The experimental data and the results from ab initio DFT calculations are compared. The comparison shows that the compounds have a primarily noncentrosymmetric rhomboherdal structure with the R32 space group. This indicates these compounds could exhibit magnetoelectric and nonlinear optical properties.

Dependences of the decay of stimulated photon echoes excited in thin textured p- and n-type zinc oxide and silicon films characterized by different sizes of crystal fibers are studied. Two characters of recombination were revealed for localized excitons on crystal lattice defects, presented in the studied dependences in the form of fast and slow decay components.

The main problems of analyzing nanoscopic images and approaches to solving them that allow the processing of data in real time are discussed. Examples of performing individual steps of processing nanoscopic imaging and recommendations for ensuring the required performance of a computer system are presented.

The McCall–Hahn area theorem for a photon echo in an optically dense medium is generalized in light of an absorption line consisting of several spectrally unresolved optical transitions and characterized by symmetrical form. Certain theoretical results are compared to experimental data obtained for a photon echo in a Tm³⁺:Y₃Al₅O₁₂ crystal.

The stochastic behavior of the strain fields of coupled systems (a fractal layer, a nanotrap, and quantum dots in a fractal multilayer nanosystem) is studied theoretically and numerically. As the semiaxes of a quantum dot shorten, the amplitude of the primary peak falls, a bump emerges on it, and the region of stochastic behavior shrinks in size. As the semiaxes grow, a broadened peak with a stochastic base in the background (a halo-type signal) forms.

In situ Raman spectroscopy is used to study the layered mineral phengite K(Al, Mg)₂(Si, Al)₄O₁₀(OH)₂ in water under the high temperature and pressure conditions typical of cold subduction zones (T up to 373°C and P = 12.5 GPa). High pressure and temperature were created in a resistively heated diamond anvil cell. Raman spectra show the high P–T stability of phengite. No reversible polymorphic transitions (overhydration or notable amorphization) are observed.

A way of calculating the structural parameters of semiconductor epitaxial layers grown on miscut (0 0 1) substrates is developed. It is shown that the difference between the tensor of film elastic strains and the spherical tensor of strains translating the film’s crystal lattice into the substrate’s lattice is a tensor whose components are proportional to X-ray strains. The technique is used to analyze GaAs and Ge_0.2Si_0.8 films grown on (1 1 13) Si substrates. The anisotropy of the degree of plastic relaxation is established for lateral directions perpendicular and parallel to the interfacial steps in the GeSi film. It is proposed that noninteger Miller indices be used to denote the direction and value of the rotation of the film’s crystal lattice with respect to the substrate lattice.

Interfacial energies of chromium and α-iron at boundaries with nonpolar organic liquids are calculated within the modified variant of the statistical electron method. Calculations are performed with allowance for dispersion, oscillatory, polarization corrections and the contribution from temperature. The dependence of the interfacial energy on the orientation of metallic crystals, and on the macroscopic dielectric permeability of the organic liquid, is established. The profiles of the potential and electron density at the boundary of the phase separation are considered.

New relationships for the interfacial tension and composition at the boundary of phase precipitates of arbitrary (including nanometer) size and a matrix are derived as functions of the temperature in a binary system. The results from calculations for spherical nanoparticles with BCC and HCP structures in the liquid the phase, and with dispersal of a solid phase with HCP structure in a solid matrix having the BCC lattice in the Mo–Ru system are presented.

Procedures for analytically describing surface tension isotherms and calculating the adsorption of the components of a binary melt with stable compounds in the system were proposed. The considerable effect the emergence of complexes related to the formation of compounds of the system’s components has on the courses of the surface tension and adsorption isotherms is shown.

It is found that the kinetics of contact melting and the formation of contact layer structures depend on both the concentration of lead in the alloy and the direction of electric current during the process of contact melting. It is shown that direct current flowing through the zone of contact melting helps intensify this process and regulate the morphology of inclusions (their shapes, sizes, and direction of migration). The inversion of effective charge z_Bi*, compared to two-component systems with Bi participation, is observed.

Fluoro-substituted Ba₂CaNbO_{5.5 − 0.5x}F_x double perovskites and Ba₂In₂O_{5 − 0.5x}F_x brownmillerites are synthesized. It is confirmed by X-ray analysis that they are single-phase at 0 ≤ х ≤ 0.40 and 0 ≤ х ≤ 0.25, respectively. It is found that introducing fluoride ions into both double-perovskite and brownmillerite phases reduces the unit cell volume (due to shorter Nb/In–O bond lengths). The preferential positions for fluorine are those in niobium or indium tetrahedra. Energetically inequivalent ОН⁻ groups are the main form in which protons are found in hydrated compositions. Increasing the density of the dopant reduces the fraction of hydroxyl groups involved in strong hydrogen bonds.