编号 3 (2024)

Quasi-two-dimensional systems play an important role in the manufacture of various devices for the needs of nanoelectronics. Obviously, the functional efficiency of such systems depends on their structure, which can change during phase transitions under the influence of external conditions (for example, temperature). Until now, the main attention has been focused on the search for signals of phase transitions in continuous two-dimensional systems. One of the central issues is the analysis of the conditions for the nucleation of the hexatic phase in such systems, which is accompanied by the appearance of defects in the Wigner crystalline phase at a certain temperature. However, both practical and fundamental questions arise about the critical number of electrons at which the symmetry of the crystal lattice in the system under consideration will begin to break and, consequently, the nucleation of defects will start. The dependences of the orientational order parameter and the correlation function, which characterize topological phase transitions, as functions of the number of particles at zero temperature have been studied. The calculation results allows us to establish the precursors of the phase transition from the hexagonal phase to the hexatic one for N = 92, 136, 187, considered as an example.

The anisotropic properties of a layer of carbon nanotubes upon electron reflection have been studied. Only a small part of the incident electrons is found to reflect from a target with a surface layer of oriented carbon nanotubes. Reflection occurs only from a layer of horizontally oriented nanotubes at an angle of incidence greater than 80° and vertically oriented nanotubes at an angle of incidence less than 10°. The effect is explained by peculiarities of the formation of an electron flux in the surface layers of the target.

Substrates with a layer of anodized aluminum oxide are obtained by one-stage and two-stage anodization. The samples had different porosity in volume and on the surface. Bismuth nanoparticles were obtained by thermal evaporation in argon by condensation onto substrates with a layer of anodized aluminum oxide. The distribution of sizes, shapes, and numbers of nano- and microparticles was studied using images obtained with a scanning electron microscope. The largest number of nanoparticles (21%) on the sample with a surface layer of aluminum oxide without pores had a diameter of 70 nm. It was assumed that the presence of pores on the surface affected the migration of deposited atoms and particles of bismuth melt until stable condensation centers were formed. The presence of pores with a diameter of 20–100 nm led to a decrease in the diameter of the most common bismuth nanoparticles from 80 to 40 nm. Nanoparticles with a diameter of 90 nm were predominant (25%) in the sample with pores with a diameter of 60–220 nm. The largest number of spherical crystallites on all substrates had a diameter of 110 nm. It was established that a uniform distribution of particles was obtained on a sample, the surface of which was not subjected to chemical polishing.

Implantation of heavy ions into metal matrices leads to the creation of a high concentration of radiation defects. X-ray diffraction studies of Mo and Ta foils implanted with ⁵⁷Fe ions have been carried out. It is shown that the implantation of Fe ions does not significantly affect the lattice parameters. It has been established that irradiation leads to broadening of diffraction lines and a decrease in the size of crystal grains. The Mo and Ta foils with {100} orientation are found to be highly textured. Irradiation with Fe ions has no noticeable effect on the texture. However, subsequent annealing at a temperature of 700°С weakens the texture on the irradiated side for Mo and Ta foils without affecting the texture of the nonirradiated side.

The features of the surface treatment of single crystals of potassium gadolinium tungstate doped with neodymium ions with low- and high-energy cluster argon ions are considered. Two radically different treatment modes were used: low-energy for more efficient surface smoothing and high-energy for more efficient target etching. Using atomic force microscopy, the topography of the target surface was analyzed before and after cluster ion treatment. Treatment in a low-energy mode was shown to smooth out irregularities on the target surface formed by chemical-mechanical polishing at an etching depth of less than 100 nm. The root-mean-square roughness and maximum height difference of the initial and treated surfaces of potassium gadolinium tungstate doped with neodymium ions were compared. Survey X-ray photoelectron spectra of the initial surface of a KGd(WO₄)₂:Nd single crystal and after the cluster ion treatment in different modes are presented. The intensities of the potassium and gadolinium peaks were shown to decrease after cluster ion treatment in both modes. A significant decrease in the concentration of potassium atoms in the subsurface layer of the target is explained by the predominant sputtering of potassium as a lighter chemical element. The mutual decrease in the concentrations of gadolinium and potassium atoms can be explained by the weak bonds of these atoms in the lattice of the KGd(WO₄)₂:Nd single crystal.

The features of formation of surface morphology of chlorinated polyvinyl chloride (pure and with the addition of the catalyst - ferrocene) under the influence of a high-power ion beam of nanosecond duration after the preliminary pulsed laser treatment of the polymer surface have been investigated. It was found that the morphology of the irradiated surface of chlorinated polyvinyl chloride after pulsed laser surface pretreatment differs significantly from the morphology of the irradiated surface of chlorinated polyvinyl chloride after a preliminary stationary heat treatment. For pure chlorinated polyvinyl chloride, pulsed laser pretreatment with increasing power leads to an increase in the porosity of the surface layer after high-power ion beam irradiation, whereas different surface morphologies, including fibers (including polymer fibers) of different diameters, can be obtained for the pre-stationary post-irradiation thermal treatment of this polymer. Pre-stationary thermal pretreatment of chlorinated polyvinyl chloride with the addition of ferrocene (Fe(C₅H₅)₂) leads to a decrease in the diameter of formed carbon nanofibers (with an increase in the treatment temperature). During the pulsed laser pretreatment, an increase in the porosity of the treated layer and a slight increase in the proportion of nanofibers of larger diameter are observed. To explain the obtained differences for pulsed laser and stationary thermal pretreatment, the effect of polymer heating rate on the features of chlorinated polyvinyl chloride decomposition was analyzed.

The morphology, topography and wetting with distilled water of Al–1.5 at. % Fe alloy films with a thickness 25–90 nm, formed on glass by ion-assisted deposition using a resonance ion source of vacuum electric arc plasma, have been studied. Using scanning probe microscopy, it is shown that, depending on the mode and the time of deposition, the modification of films is accompanied by changes in longitudinal and transverse roughness parameters, as well as parameters – dimensionless complexes, the measurement of which makes it possible to quantitatively describe the processes of coning in the Al–Fe alloy/glass system. Thus, the arithmetic mean roughness of the films increases with deposition time in the range 20–40 nm. Under self-irradiation conditions, a transition from island-like film growth to layer-by-layer film growth was detected. The influence of the substrate topography on the longitudinal step parameters of the film topography has been established. The size and surface density of the microdroplet fraction particles are studied by scanning electron microscopy. The frequency distributions of the microdroplet fraction by size are satisfactorily approximated by the lognormal distribution. It is found that in the mode of irradiation with intrinsic ions, 60–70% of the microparticles have a size of up to 0.8 μm. For the first time, a double Gaussian function was used to approximate the distribution histograms of local maxima and minima of the film relief, which made it possible to increase the accuracy of the description compared to the normal law. The effectiveness of this approach in analyzing the structure formation of nanometer films at various stages of growth has been demonstrated. Using the bi-Gaussian surface model, the role of topographic characteristics in controlling the wetting of modified coatings is revealed. The mechanism of heterogeneous wetting of hydrophilic films in the Cassie mode with contact angles ranging 50°–80° is discussed. It is found that in the potential mode, with an increase in the deposition duration to 10 h, the distribution of the film relief is close to the normal law, and the formation of a developed submicron conical morphology on the surface leads to blended wetting.