Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques最新文献

Electron exchange during grazing scattering of hydrogen ions on thin metal films is considered. The main characteristic being studied is the yield fraction, that is, the probability of the formation of a certain charge state of a scattered particle (in the case under consideration, H^–) as a function of the velocity component parallel to the surface of the sample. Based on an analysis of the electron distribution in the space of wave vectors and the application of the generally accepted model of displacement of Fermi spheres, it was shown that the dependence of the probability of the formation of a negative hydrogen ion on the parallel velocity component should decrease monotonically.

The influence of plastic deformation on the formation of nanocrystals in the Al₈₇Ni₆Nd₇ amorphous alloy was studied using X-ray diffraction analysis. It has been shown that the preliminary deformation of the amorphous alloy accelerates the crystallization of the amorphous phase and can lead to the formation of smaller nanocrystals compared to heat treatment. The size of nanocrystals and their number depend on the treatment conditions of the amorphous phase: when preliminary deformation is used, the size of nanocrystals formed during annealing is smaller than that in an undeformed sample and the proportion of nanocrystals is slightly higher. In samples subjected to preliminary deformation by rolling, a gradient structure is formed: the proportion of nanocrystals decreases with distance from the surface into the depth of the sample. The size of nanocrystals changes slightly with changing distance from the sample surface. The results show that preliminary plastic deformation can be an effective method to obtain a nanocrystalline structure with different proportion and sizes of nanocrystals in the amorphous phase. This is important for creating highly functional materials with outstanding physicochemical properties. The results obtained significantly expand the existing understanding of the mechanisms of formation of nanocrystals in the amorphous phase under external influences.

In cobalt-based thin-film nanostructures with chromium-group metal buffer layers, formed by magnetron sputtering, features of the conductivity of buffer layers of varying thicknesses and magneto-optical response of cobalt films on tungsten are identified. Analysis of electron-microscopy data, X-ray phase analysis, and magneto-optical measurements reveals specific structure and properties of tungsten films. The resistance of these films depends on their thickness and is determined by charge transfer between crystallites. The tungsten/cobalt layer nanostructures do not exhibit magnetic anisotropy.

An overview of the use of electron spectroscopy for the study of the physicochemical properties of solids is carried out. It is noted that the main source of information about the electronic states of atoms is the energy distribution of electrons excited by ions, X-ray quanta, and laser beams. The paper briefly discusses the problems that exist in registering the spectra of secondary electrons obtained by exciting the surface of samples with electrons of medium (1–20 keV) energies and ways to solve these problems in order to increase the information content and accuracy of research results. A method for recording secondary electron spectra in an integral form using an Auger spectrometer is proposed, which allows one to increase the energy resolution of the method. The possibilities of the method are demonstrated by the example of experimental studies of zirconium carbide and steel X17AG18.

Anodic oxidation is widely employed in industry to impart high mechanical properties and improve the corrosion resistance of Al–Si alloys. However, compared to pure Al, the high content of Si prevents the growth of a uniform anodic layer, leading to the formation of cracks and porosities within the oxide. In the present work, low-energy high-current electron beam is used as pretreatment of a hypoeutectic Al–Si alloy to enhance the properties of the anodic oxide. Electron beam modified samples showed a fine and homogenous dispersion of Si in the α-matrix, together with a content reduction of Si in the treated layer. Hard anodic oxides grown on electron beam pre-treated alloys exhibited a higher microhardness, increased by 65%, and a lower corrosion current density, decreased by 94%. Cross-sectional SEM morphology and EDX elemental maps showed less defective anodic oxides, in contrast with oxide formed on as-cast hypoeutectic Al–Si alloys.

The features of the formation of TiN–Cu composite coatings using the hybrid method of vacuum-arc evaporation of titanium and magnetron sputtering of copper are considered. It has been shown that under the selected conditions for the TiN synthesis copper does not form chemical compounds with titanium and nitrogen. The structure and properties of TiN–Cu composite coatings are examined. The introduction of copper into the coating composition leads to the grinding of the nitride phase crystallites. A maximum microhardness of coatings of 37–41 GPa is achieved at a copper concentration of ~3–7 at %. The technological parameters allowing the application of wear-resistant functional TiN–Cu coatings on T15K6 alloy substrates have been determined.

For objects with topological and fractal dimensions (using the example of a “Coulomb explosion”), the physics of modification of electron-stimulated processes in porous media under irradiation with multiply charged ions is considered. A quasi-one-dimensional model has been constructed, which is a convenient methodological approach that describes characteristic phenomena in various media. The results obtained are assessed within the framework of the “complexity” concept.

Changes in the structure of the surface of K-208 glass irradiated in vacuum (10^–4 Pa) by protons with energies of 30 keV have been studied. It has been established that the nature of the changes depends on the proton flux density (φ_р). At φ_р < 3.0 × 10¹⁰ cm^–2 s^–1, the changes are mainly associated with the emergence of percolation channels on the irradiated surface. Percolation channels during proton irradiation of glass are formed as a result of migration of Na⁺ ions in the field of the charge injected into the glass. As φ_р increases, the formation of gas-filled bubbles begins to play a significant role. The appearance of bubbles is due to the fact that the field migration of Na⁺ ions is accompanied by the release of nonbridge oxygen atoms, which provided electrical neutrality in the vicinity of the localization of these ions. At values of φ > 2 × 10¹¹ cm^–2 s^–1, gas-filled bubbles and sodium microarrays form and grow in pairs. The authors believe that under these irradiation conditions the accelerated field migration of sodium ions through the percolation channel ensures intensive release of nonbridge oxygen atoms in its vicinity, followed by their migration and the formation of gas-filled bubbles.

Test structures in the form of rectangular boxes fabricated on thermal silicon dioxide substrates under normal and oblique ion bombardment using the focused ion beam technique were studied by transmission electron microscopy and energy-dispersive X-ray microanalysis. The experimentally obtained depth distribution profiles for gallium atoms, as well as the sputtering yields, were compared with the results of Monte Carlo simulations. Calculations were carried out using standard continuous and discrete-continuous variation models for the surface binding energy of atoms in silicon dioxide. For the normal incidence of the ion beam, based on minimizing the value of the R-factor, which characterizes the agreement between the calculated and experimental data, the optimal values of the parameters of the discrete-continuous variation model were found, which turned out to be close to the values used in the continuous model. It is shown that the obtained parameters make it possible to simulate silicon dioxide sputtering with acceptable accuracy at ion beam incidence angles of 15° and 30°. However, at a grazing incidence angle of 80°, significant differences arise between the experimental and calculated profiles of the concentration of gallium atoms implanted in silicon dioxide.

This paper presents an atomic-molecular and topological description of widely used in the semiconductor and material construction industries erbium compounds obtained by temperature annealing during doping of porous silicon samples. The samples were instilled with an aqueous-alcoholic solution of erbium pentahydrate. The heat treatment lasted 30 minutes at an annealing temperature of 950°C. The obtained two powder phases of erbium were analyzed experimentally and theoretically. Decoded X-ray diffraction and Raman spectroscopy data of erbium powders are presented. The crystal-chemical approach has been applied to the topological analysis of the free space in sesquioxide and pentahydrate structures. The phase change in the chemical bond structure of annealed erbium compound led to changes in its optical and electrical properties. The main results of the study illustrate the importance of the stage of temperature doping with erbium ions of nanocrystalline structures of porous silicon and similar other dielectric materials for optoelectronic and photonic advances.