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Aero-engine turbine blades may suffer overheating during service, which can result in severe microstructural and mechanical degradation within tens of seconds. In this study, the thermal cycling creep under (950°C/15 min+1100°C/1 min)-100 MPa was performed on a directionally solidified superalloy, DZ125. The effects of overheating and thermal cycling on the creep properties were evaluated in terms of creep behavior and microstructural evolution against isothermally crept specimens under 950°C/100 MPa, 950°C/270 MPa, and 1100°C/100 MPa. The results indicated that the thermal cycling creep life was reduced dramatically compared to the isothermal creep under 950°C/100 MPa. The plastic creep deformation mainly occurred during the overheating stage during the thermal cycling creep. The thermal cycling creep curve exhibited three stages, similar to the 1100°C isothermal creep, but its minimum creep rate occurred at a lower creep strain. The overheating events caused severe microstructural degradation, such as substantial dissolution of γ' phase, earlier formation of rafted γ' microstructure, widening of the γ channels, and instability of the interfacial dislocation networks. This microstructural degradation was the main reason for the dramatic decrease in thermal cycling creep life, as the thermal cycling promoted more dislocations to cut into γ' phase and more cracks to initiate at grain boundaries, carbides, and residual eutectic pools. This study underlines the importance of evaluating the thermal cycling creep properties of superalloys to be used as turbine blades and provides insights into the effect of thermal cycling on directionally solidified superalloys for component design.

Local resistive switching in a contact between the probe of an atomic force microscope (AFM) and ZrO2(Y) films (including with a Ta2O5 sublayer) on conducting substrates has been studied. Switching has been initiated by triangular voltage pulses on which an rf sine-wave signal was imposed. The dependence of the difference between currents through the AFM probe in low- and high-ohmic states of dielectric films on the frequency of the rf sine-wave signal exhibits maxima at characteristic frequencies corresponding to hops of O2– ions between oxygen vacancies in ZrO2(Y) and Ta2O5 at 300 K. This effect is related to the resonance activation of O2– ion migration over oxygen vacancies by an external rf electric field.

The specific features of resistive switching, which was initiated by triangular pulses with a high-frequency sine signal imposed on them, in experimental memristor prototypes based on thin films of yttria-stabilized zirconia were examined. It was found that memristors switched by these complex signals have lower switching voltage, higher ratio of currents in low- and high-resistance states, and better long-term current stability than memristors switched by triangular pulses without the sine signal. This improvement of switching parameters is associated with resonance activation of migration of oxygen ions via vacancies in the alternating external electric field.

Siberian Traps magnetic viscosity affects and makes it difficult to interpret TEM sounding data obtained during oil and gas exploration in the south of the Siberian platform. In this paper, we present and discuss a method for decreasing magnetic viscosity effect on TEM data. The method is based on estimating magnetic viscosity contribution to the total transient response using TEM data measured with multi-offset arrays.

In this paper, we consider the effect of the introduction of functionally active structures of the supramolecular type on the physical and mechanical, thermophysical and heat-resistant characteristics of elastomeric compositions based on ethylene–propylene–diene rubber. The presence of aluminosilicate microspheres, carbon microfiber, and organophosphorus oligomer in the composition of these structures contributes to the manifestation of a synergistic effect, which consists in increasing the heat-shielding properties of the material due to increasing the strength of the coke and enhancing the processes of carbonization of the material. This leads to an increase in the heating time of the unheated sample surface by 8–17% and a decrease in the rate of linear combustion by 6–17% as compared with known analogues. Microspheres allow compensating the negative effect of microfiber on the density and thermal conductivity of the composition.

The phenomena that occur during internal heating (release of the control radio power) of an acousto-optic deflector based on paratellurite with heat removal from the piezoelectric transducer through a liquid contact were experimentally investigated. It was found that, in addition to the temperature drift of the velocity of sound and the refractive indices, the temperature inhomogeneity has a significant effect on the deflector characteristics. In this case, the volume of the crystal behaves like an optical wedge, which is optically denser near the transducer and less dense at a distance from it. The effect of internal compensation of the thermal deviation of the diffracted-beam position at a certain deflector orientation is detected.

The article investigates the possibility of replacing the AlSi7Mg0.3 alloy used for manufacturing automotive wheel disks with eutectic silumin alloyed with magnesium. The crystal lattice constant, structure, hardness and mechanical properties of eutectic and hypoeutectic silumins have been determined, and their comparative analysis has been performed. It is shown that the heat hardenable eutectic silumin can be used for manufacturing cast automotive wheel disks instead of a less adaptable to manufacture AlSi7Mg0.3 alloy.

Results are presented from an analysis of the nano- and magnetic domain structures of high coercive Sm(CoCuFe)5 alloy using fractal geometry. Fractal dimension Df of the nano- and domain structures are determined at different stages of heat treatment. It is shown that Df ~ 2.08 corresponds to the nanostructure of samples with a coercive force of 7 kOe, while Df ~ 2.3 corresponds to the nanostructure of samples with a coercive force of 32 kOe.

The characteristics of composite materials in the system Al2O3– carbon nanotubes – eutectic additives are investigated. The effect of the content of the reinforcing component as well as high-temperature heat treatment in vacuum on the strength of the material is examined. The obtained samples with 0.4 wt.% carbon tubes had the following characteristics: average tensile strength in three-point bending 380 MPa, open porosity 0.9%, average density 3.71 g/cm3.

Machines operating in aqueous environments may be subjected to cavitation damage during operation. This study aims to evaluate the cavitation resistance of WC-10Co4Cr and WC-20CrC-7Ni coatings under cavitation erosion conditions with additional electrochemical effects. The coatings were deposited on AISI 1040 steel substrates using a high velocity air fuel thermal spray process. The microstructure of the coatings was observed by a scanning electron microscope, while their phase composition was analyzed using an energy-dispersive microanalysis system. In addition, the microhardness of the coatings and substrate was measured, and the surface topography of the eroded surface layers was observed using a 3D optical profilometer. The results revealed that the cavitation resistance of the WC-20CrC-7Ni coatings was better than that of the WC-10Co4Cr coatings. The observation of the structure and surface topography made it possible to identity the reasons for the differences between the cavitation resistance of both coatings: The WC-20CrC-7Ni coatings had a finer grain structure, lower pore density, and lower as-sprayed surface roughness. These differences, along with the presence of a high Cr and Ni content in the feedstock powder, that increased the coating corrosion resistance, contributed to improving the cavitation resistance and reducing the material loss of the WC-20CrC-7Ni coatings.

Bioelectromagnetic influence on the eyes of a group of 336 subjects with various vision disorders: amblyopia, myopia and hypermetropia were investigated with high-frequency black-white and color coronal discharge, infrared thermography and visual acuity measurements. The authors have performed registration of the biggest part of electromagnetic fields – infrared and electric fields. Positive correlation with r=0.55­0.65 at a level of significance of p

We report on the electronic structure and magnetic properties of hybrid heterostructures combined the ferromagnetic double perovskite Sr2CrOsO6 (SCOsO) and ferroelectric BaTiO3 (BTO) calculated in the GGA approach using the fully relativistic spin-polarized Dirac LMTO method. The electronic band structure is studied in the BTO and SCOsO oxides as well as in SCOsO/BTO hetero structures with different supercells: (1 × 1 × 1) monolayered, (2 × 2 × 1), and (1 × 1 × 2) SCOsO/BTO heterostructures. The optical and magneto-optical spectra of pure BTO and SCOsO oxides as well as of the SCOsO/BTO heterostructures are investigated theoretically and compared with avaliable experimental data. The element-specific x-ray absorption spectra as well as the x-ray magnetic circular dichroism at the Ti, Ba, and Os L2,3 edges in SCOsO/BTO heterostructures are investigated theoretically. Good agreement with experimental spectra has been found.

We have studied the influence of detuning of quasimonochromatic seeding vacuum ultraviolet (VUV)/X-ray radiation from the frequency of the inverted transition of the hydrogen-like active medium of the plasma-based X-ray laser dressed by an intense infrared (IR) laser field on the formation of a subfemtosecond pulse train. For the active medium (plasma) of Li2+ ions with the inverted transition wavelength of 13.5 nm, it is demonstrated that the use of the seeding radiation detuned from the resonance by double the frequency of the modulating field allows a fourfold increase in the peak intensity of the formed pulses relative to the case of the exact resonance, while the maximum contrast is preserved.

A mathematical model affording satisfactory representation of experimental values for the characteristics of the ignition of organic coal–water fuel droplets has been developed. Numerical investigations of the processes of ignition of droplets of the fuels based on typical wastes from dressing hard coals, enriching industrial oils, and water have been carried out. The delay times in ignition of organic coal–water fuel droplets with their radii varying from 0.25 to 1.5 mm, at oxidant flow velocity varying from 0.5 to 3 m/s and of its temperature varying from 700 to 1000 K, have been established. A satisfactory correspondence of the results of mathematical simulation to the familiar experimental data has been obtained. The possibility of using the ANSYS Fluent package for numerical simulation of the ignition of organic coal–water fuel droplets has been substantiated. The temperature fields of such droplets on ignition, as well as the coordinates of the zones of their intense chemical transformations, have been calculated. Prediction of the limiting conditions of stable ignition of organic coal–water fuels on relatively low-temperature heating has been made.

In this paper, we present the results of a study of the effect of finish carbon microfibers on the fire and heat protection and adhesion properties of elastomeric materials. The best order of introducing the components of the rubber mixture to obtain the best indicators of physical-mechanical and fire–heat-resistant properties was determined. The preliminary treatment of fibers with a solution of phosphorus-boron-containing oligomer is shown to contribute to an increase in the performance of elastomeric materials operating under extreme conditions.

This study aimed to compare the X3CrNiMo17-13-3 stainless steel based plasma transferred arc (PTA) cladded hardfacings, reinforced with the in-situ synthesized Cr and Ti carbides. Carbon black and either pure Cr, pure Ti, or TiO2 were utilized as reinforcement precursors (the respective hardfacings are further referred to as Cr+C, Ti+C and TiO2+C). The pre-placed mixtures of matrix and reinforcement precursor powders were remelted by the plasma transferred arc, applying the preliminarily optimized process parameters (95 A, 22 – 24 V, 0.2 mm/s). As a reference, the unreinforced stainless steel hardfacing was used. The carbide reinforcement was successfully in-situ synthesized in all the hardfacings. The Cr + C hardfacing exhibited the largest average hardness (556 ± 29 HV1), while the TiO2 + C hardfacing had the largest average Young’s modulus (156.3 ± 19.7 GPa). The Cr + C and Ti + C hardfacings demonstrated the 2.3 and 2.1 times higher resistance to abrasive wear than the reference hardfacing. The TiO2 + C hardfacing showed 1.5 times lower wear resistance than the reference hardfacing presumably due to a lack of the reinforcement and a lower strain hardening ability.

In this manuscript surface roughness, coefficient of friction (COF) and tensile properties of a post-consumer cotton fabric are evaluated. Fabric roughness, COF, effective tensile force and breaking force measured by optical profilometer, CETR tribometer and Instron tensile machine, respectively. The results proved that COF could rely on fabric pattern. Moreover, microscopically roughness influences on friction and tensile properties due to surface defects. It was found that increase in roughness of textile cotton relates to increase of number of random directional fibers. These fibers intensify friction and reduce tensile properties. The reduced values of tensile (140.49 N), breaking (123.23 N) and effective tensile force (251.43 N) of warp direction are greater than values of tensile (79.54 N), breaking (67.97 N) and effective tensile force (179.69 N) of weft direction. These effects can lower cutting performance of post-consumer textile.

Hierarchical α microstructure in a metastable β Ti-5Al-5Mo-5V-3Cr (wt%, Ti-5553) alloy has been investigated using scanning electron microscopy and transmission electron microscopy. Novel high-index {10 9 3} β type deformation twins were characterized in the 10% cold-rolled Ti-5553. Without the pre-formed deformation twins, refined α microstructure and super-refined α microstructure were achieved in Ti-5553 using rapid up-quenching and slow heating treatment, respectively. On the contrary, with the pre-formed {10 9 3} β deformation twins in the β matrix, hierarchical α microstructure was generated in Ti-5553, whether rapid up-quenching or slow heating treatment was adopted. It is observed that a layer of α phase precipitates from pre-formed {10 9 3} β twin boundary and grows along the twin boundary. α sub-layers and fine-scale α precipitates form in the interior of pre-formed {10 9 3} β twin. It is speculated that the large number of dislocations, metastable ω particles and α″ phase present as the substructure in the {10 9 3} β twin may act as favorable nucleation sites for α sub-layers and fine-scale α precipitates. Thus, our work indicates that high-index {10 9 3} β twin may assist the formation of hierarchical α microstructure in the metastable β Ti-5553 alloy.

The circular economy is still a hypothetical field in Europe. Different shredding and manufacturing machinery parts in textile industries are presumed to enhance product quality and performance. The quality and performance of recycled textile products play a vital role in the development of textile recycling technologies. The quality is principally associated with the mechanical and tribological properties of machinery parts. In this article, TiCN Coating is used to determine the coefficient of friction of post-consumer cotton fabric. The scanning electron microscope, optical and mechanical profilometer, and tribometer were used for surface and tribological evaluations. The TiCN coating was found smooth and homogeneous. The average coating surface roughness parameters Rmax, Rz, Rp were 0.24 µm, 0.21 µm, and 0.20 µm, respectively. The dynamic coefficient of friction values was found 0.38 to 0.30 in the warp and 0.33 to 0.28 in weft directions. The increase in sliding distance is used for industrial applications and evaluations. The increase in distance deformed and fractured cotton fabric surface. The coefficient of friction and deformation becomes constant after 40 m of sliding distance. Based on coefficient of friction values, permanent deformation, fracture, and morphologies evaluations TiCN coatings could be used operationally for surface modification of textile machinery parts. The surface modification of textile machinery parts with TiCN coating can enhance the quality and performance of textile products.

Focusing Fresnel lenses are used in many fields of applied optics. These devices are used in optical sensor systems for imaging and optoelectronic integration. The traditional Fresnel lens concentrates the light intensity on the center of the formed image. We present a microprismatic Fresnel lens that transforms a circular incident parallel light beam into a homogeneous light circle with the necessary diameter at a certain distance from the lens. These transforming Fresnel concentrators can be successfully used, for example, in monitoring devices to automatically adjust the output signal from four-quadrant photodetectors. Traditional focusing Fresnel structures are manufactured by photolithographic methods or adjustable direct laser recording with photoresists. These methods enable the formation of stepped optical structures, which have inherent surface defects, resulting in the formation of images that are not high in quality. The proposed specialized Fresnel concentrators can be easily fabricated via the diamond cutting method, which enables the manufacturing of flat working surfaces with exceedingly high optical quality. We also develop a method for simulating the Fresnel transforming lenses with flat conical working facets and calculate the geometric parameters of the circular concentrators. We then apply the simulation results to the diamond cutting method and fabricate the microprismatic light transforming lens samples. These samples are then investigated experimentally with a collimated laser beam. The obtained data agree with the theoretical predictions.

Powder samples of TaH0.89 and TaD0.96 are synthesized under a hydrogen (deuterium) pressure of 2.8 GPa and a temperature of 250 °C, then quenched to the liquid nitrogen temperature, recovered to ambient pressure and studied by neutron diffraction (ND) and inelastic neutron scattering (INS). The ND study shows that both hydrogen and deuterium atoms occupy tetrahedral interstitial sites in a distorted body centered cubic (bcc) crystal structure of metal atoms, while the ordering scenarios in TaH0.89 and TaD0.96 are different. Hydrogen and deuterium atoms are ordered in a layered fashion, forming long period superstructures with space groups P 4 ¯ and P222, respectively, so that the unit cells of the crystal structures of TaH0.89 and TaD0.96 are 2 × 2 × 7 and 2 × 2 × 8 supercells of the initial cubic unit cell. The INS study demonstrates a pronounced “soft” (trumpet-like) anharmonicity of the potential well for H and D atoms.

Currently, due to the appearance of instrumental objective methods for determining grain vitreousness, it is possible to ensure the uniformity of measurements of this indicator in a number of laboratories. The article proposes a model for describing grain as an inhomogeneous optical medium and an interpretation of the vitreousness index as a characteristic of light scattering. A method for calculating the parameters of mathematical model and estimating the scattering coefficient using an RGB camera is presented. It is shown that the implementation of the grain vitreousness measurements based on the scattering coefficient makes possible to obtain a satisfactory reproducibility in between-lab measurements.

Results of field experiments on determination of the macroscopic mechanisms of heat and mass transfer in the localization of a ground forest fire with the use of a barrier strip in the form of a wetted layer of forest combustible materials (needles, leaves, twigs, and their mix), positioned upstream of the front of combustion of such materials, are presented. Most attention has been concentrated on the complex analysis of the influence of the dispersity of a water aerosol (the concentration of the water droplets in it and their sizes), used for the formation of a barrier strip, on the parameters of this strip. It is shown that the conditions of effective localization and suppression of the flaming and thermal decomposition of forest combustible materials can be realized in the case where a group of barrier strips of different widths, wetted to different depths, is formed in front of a forest fi re. The parameters of barrier strips (the volume of water supplied to a strip, the width of the strip, the depth of its wetting, and the specific density of the water in it) necessary and sufficient for the localization of ground forest fires of different sizes were estimated.

The thermoelectric properties of thin Cr0.33Si0.67 films in amorphous and crystalline states, as well as at different annealing stages in the temperature range 100–900 K have been studied. The crystallization of amorphous films at a temperature of ~550 K is accompanied by an increase in the resistivity and thermoelectric power. Amorphous films crystallize with the formation of CrSi2 nanocrystals with an average grain size of 10–20 nm. The increase in resistivity is due to the appearance of a crystalline phase and the formation of interphase boundaries between the crystalline and amorphous phases. The scattering of charge carriers at interphase boundaries is selective, which leads to the appearance of an additional contribution to the thermopower.

The photoinduced birefringence of two 4-substituted phthalimide 2-hydroxy Schif bases, containing salicylic (4) and 2-hydroxy-1-naphthyl (5) moieties has been investigated in PMMA matrix. Their optical behaviour as nanocomposite flms was revealed by combined use of DFT quantum chemical calculations (in ground and excited state) and experimental optical spectroscopy (UV–Vis and fuorescence). The results have shown that solid-state reversible switching takes place by enol/keto tautomerization and Z/E isomerization. Birefringence study was performed in the PMMA nanocomposite flms using pump lasers at λrec = 355 nm and λrec = 442 nm. Fast response time and high stability of anisotropy up to 58% for (4) and 95% for (5) after turning of the excitation laser, was observed, which makes these materials appropriate candidates for cutting-edge optical information technology materials. The possibility for multiple cycles of recording, reading and optical erasure of the photoinduced birefringence at λrec = 442 nm in 5 has been demonstrated. The obtained results have shown that the maximum value of the measured birefringence is close to the anisotropic characteristics of the most frequently used azo materials.

We study the thermoelectric and galvanomagnetic properties of cobalt monosilicide (CoSi) and its solid solutions with FeSi and NiSi. Recent CoSi band structure calculations, confirmed by ARPES measurements, revealed several differences of the electronic structure from the previous standard two-band model for semi-metallic compounds. The discovered features of the CoSi band structure require modifications of previously used models for description of material transport properties. We investigate the temperature dependences of the Seebeck coefficient, electrical resistivity, and Hall coefficient in the temperature range from 100 to 800 K for CoSi and for its solid solutions with FeSi and NiSi. The ab initio calculation of the band structure and transport coefficient were carried out using the Quantum Espresso software package. The results of the study showed that the main features of the thermoelectric and galvanomagnetic properties of CoSi and its solid solutions with FeSi and NiSi at high temperatures can be adequately described using the ab initio calculated band structure, taking into account the energy dependence of the relaxation time.

The major trends in the development of grease products are described in an analysis of the relevant research and patent literature, including research on superalkaline calcium greases for heavilyloaded friction units and possible applications of nanoparticle additives to multifunctional greases. Developments in lowtemperature greases derived from biodegradable polyester bases and lubricants for electric car friction units are also examined.

Polymer hot-melt adhesives are obtained on the basis of poly(ethylene-vinyl acetate), polyethylene wax, and aromatic (C9) hydrocarbon resins differing in the degree of hydrogenation of aromatic groups (from 0 to 37%). The content of poly(ethylene-vinyl acetate) is varied from 30 to 80%, and the concentration of other components of the adhesive is within 10–35%. The rheology of adhesive components and blend compositions is studied in detail, and the adhesion characteristics of the adhesives are determined. It is found that the use of a nonhydrogenated resin leads to high adhesion properties of the adhesive but imparts viscoplasticity to it. The use of a hydrogenated resin provides better rheological properties of the adhesive, but a higher content of poly(ethylene-vinyl acetate) is required to achieve good adhesion characteristics.

State of the art in the field of using biodegradable lubricating materials is considered, and data on recent achievements in their use are summarized. The major factors influencing the progress of studies in this field are associated with the environmental regulations becoming more and more stringent. Along with the use of poly(alkylene glycol) and ester liquids, raw materials of vegetable origin attract considerable interest of researchers developing biodegradable oils; cellulose can be used as a promising thickener for multipurpose lubricants.

Традиційна фокусуюча лінза Френеля концентрує інтенсивність світла в центр сформо­ваного зображення. Однак іноді необхідно перетворювати паралельний потік променів у світлове коло. Такі трансформуючі плоскі лінзи Френеля часто використовуються в сис­темах обробки сигналів. Наведено алгоритм моделювання мікропризматичних структур Френеля, які формують у фокальній площині рівномірно освітлене коло. Цей алгоритм подібний до алгоритму моделювання, розробленого для створення фокусуючих мікро­призматичних елементів з плоскими кільцевими фокусуючими гранями. Запропоновані структури з дискретною зміною кутів заломлення для трансформації світлових потоків можна легко виготовити методом алмазного різання, який дозволяє отримувати плоскі конусні робочі поверхні високої оптичної якості. Розмір призматичних заломлюючих зон не повинен бути занадто великим для зменшення дискретності сформованих зобра­жень. Тому передбачається створення зон заломлення з декількох однакових малих мікро­призм. Запропоновано модифікований алгоритм моделювання параметрів трансфор­муючої лінзи, який враховує процеси концентрації світла лінзою та звуження світлових по­токів мікропризмами.

The micro-explosion of two-component fuel droplets (water and rapeseed oil) are investigated with a variable initial temperature (273, 300, and 353 K) of the noncombustible component. We record the threshold heating temperatures sufficient for the micro-explosive breakup, dispersion delay times, as well as the outcomes of this process. According to the findings, the greater the difference between the initial temperatures of the water core and combustible envelope, the shorter the delay until the micro-explosion. With a decrease in the initial water temperature to the ice melting point, we observe the minimum heating delays until micro-explosion. The average size of child droplets becomes 80–90% smaller if we reduce the initial water temperature from 353 to 273 K, if the relative water concentration in a fuel droplet is less than 30 vol%. The micro-explosive breakup of two-component droplets can increase the liquid surface area by 8–12 times.

The importance of the problem of improving the quality of electrical energy grew along with the development and widespread introduction of various high-performance technological installations in production, such as arc steel-making furnaces, welding installations, induction furnaces, etc. in accordance with the requirements of the standard GOST 30804.4.7–2013 and in accordance with the measurement program. A method for processing the research results obtained during the experiment is described. All power quality indicators are processed using computer programs created in the Labview graphical programming environment. The analysis of indicators of the quality of electrical energy to the requirements of GOST 32144-2013 was carried out, according to the results of which conductive low-frequency electromagnetic interference was detected in the 0.4 kV electrical network according to the coefficient of the n-th harmonic voltage components. The obtained values ​​of the indicators of the quality of electrical energy, characterizing the coefficient of the n-th harmonic components of the voltage, confirm the need to use technical means to reduce the influence of higher harmonics on electrical networks.

The structure and properties of glasses in the 30Na2O–xV2O5–(70 – x)B2O3 system for x varying from 30 to 47.5 mol % were studied using experimental approaches and non-constant force field molecular dynamics. The replacement of boron oxide by vanadium oxide was found to decrease the glass transition temperature and the thermal stability of glasses. According to the results of infrared spectroscopy, over the whole range of concentrations studied, there is no significant changes in the type of structural groups that form the glass network. This conclusion is supported by the absence of abnormal changes in the concentration dependences of characteristic temperatures and conductivity, which monotonically increases with increasing V2O5 content. The procedure of glass self-assembly from a melt in the non-constant force field molecular dynamic simulation was used for the first time to obtain the structural model. The interatomic distances between the vanadium cations and the trajectories of ion motion in the system were determined. The conductivity was found to be due to electron transfer.

The possibility of modifying the properties of a (Ga,Mn)As layer on the surface of a quantum-size InGaAs/GaAs-structure by laser annealing with the conservation of its emitting properties is studied. To perform these studies by a combination of the methods of MOC-hydride epitaxy and pulsed laser deposition, the structures have been prepared with four quantum wells InGaAs/GaAs (indium contents from 0.08 to 0.25) located at various distances from the (Ga,Mn)As layer. The radiation energy density of an LPX-200 pulsed excimer laser was varied during the experiments from 200 to 360 mJ/cm2, and the depth of the laser action was determined from the changes in the photoluminescence spectra of the quantum wells. The results are described using the laser annealing model based on the solution of the problem of heat propagation in a one-dimensional GaAs system, taking into account a (Ga,Mn)As layer on the surface. The changes in the structural and galvanomagnetic properties of the samples under action of laser irradiation are analyzed. It is shown that the pulsed laser irradiation with the laser radiation energy density 250–300 mJ/cm2 enable one to conserve the emitting properties of the active region (quantum wells InGaAs/GaAs) disposed at the distances 10–12 nm from the (Ga,Mn)As layer and to modify the ferromagnetic properties of the (Ga,Mn)As semiconductor, namely, to increase the ferromagnet–paramagnet phase transition temperature to values no lower than 120 K. The results are promising for the development of the technology of devices of spin optoelectronics.

The spectra of 16 optical functions of the group of compounds Mg2X (X=Si, Ge, Sn) in the range of 1–11 eV at 77 K were determined and compared. Their main features and general relationships were established. Calculations were performed on the basis of the experimental reflectance spectra R(E) using the Kramers–Kronig relations and analytical formulas connecting the optical functions. The integral spectra of the imaginary part of the dielectric function e2(E) were broken down into elementary transition bands in the region of 1.5–6.0 eV using the improved nonparametric method of combined Argand diagrams with allowance for the effective number of valence electrons forming the individual elementary bands. For Mg2X compounds (X = Si, Ge, Sn), instead of 5–6 maxima and steps, an average of six times more elementary components of transitions caused by exciton and interband transitions were found in the integral spectra. The energies of the maxima and the areas of the selected elementary components of the transition bands of the three compounds were determined and compared. The supposed nature and localization of the identified elementary components of the transitions are proposed on the basis of known theoretical calculations. The dependence of the energies of the maxima of the selected transition bands on the lattice parameters of the three compounds is plotted.

We investigated room-temperature pulsed lasing in heavily doped Fe:ZnSe single crystals. The active elements were pumped by a Q-switched Cr3+:Yb3+:Ho3+:YSGG laser operating at 2.87 μm. Our results show that the generation of short laser pulses has a deep high-frequency modulation associated with relaxation dynamics in Fe:ZnSe. The lasing regime obtained in this study provides a straightforward way to generate mid-IR single nanosecond pulses at moderate pump energies. Moreover, we found a relation between the lasing pulse duration and the concentration of Fe2+ doping ions, and we experimentally demonstrated pulse shortening in heavily doped active crystals. Single-pulse lasing with an FWHM pulse duration of ~2.8 ns was achieved in ZnSe crystals doped with 2.3 · 1019 cm-3 Fe2+ ions. The demonstrated single-pulse lasing regime is applicable for seeding high-power mid-IR laser systems.

We report on the results of the experimental investigations of the local resistive switching (RS) in the contact of a conductive atomic force microscope (CAFM) probe to a nanometer-thick yttria stabilized zirconia (YSZ) film on a conductive substrate under a Gaussian noise voltage applied between the probe and the substrate. The virtual memristor was found to switch randomly between the low resistance state and the high resistance state as a random telegraph signal (RTS). The potential profile of the virtual memristor calculated from its response to the Gaussian white noise shows two local minima, which is peculiar of a bistable nonlinear system.

We report on a comparative study of resistive switching in the memristors based on ZrO2(Y) films and on ZrO2(Y)/Ta2O5 bilayer stacks by triangle voltage pulses with superimposed high-frequency sinusoidal signal. The dependencies of the current difference in the low resistance state and in the high resistance one on the sinusoidal signal frequency for the ZrO2(Y)-based memristor and for the ZrO2(Y)/Ta2O5-stack based one manifested one and two maxima, respectively attributed to the resonant activation of the migration of the oxygen ions via the oxygen vacancies by the alternating external electric field in ZrO2(Y) and in Ta2O5.

Local resistive switching by complex nonstationary signals in zirconium-dioxide-stabilized films on conducting substrates has been studied by atomic-force microscopy with a conducting probe. Film resistance was switched by triangular voltage pulses on which a high-frequency sinusoidal signal was superimposed. It is found that the ratio of currents through the junction between the probe and film surface in high-resistance and low-resistance states increases after the superposition of a sinusoidal signal (as compared to switching by simple triangular pulses). An increase in the temporal stability of the current strength in these states was also found when switching with a sinusoidal signal. This effect is associated with resonant activation of oxygen ion migration over vacancies in an external ac electric field.

The local transverse photoconductivity of ultrathin (~4 nm) ZrO2(Y) films with embedded single-layer arrays of Au nanoparticles (~2 nm in diameter) is studied by conductive atomic force microscopy. The ZrO2(Y) films with Au nanoparticles are formed on glass substrates with transparent conductive indium-tin-oxide sublayers using layer-by-layer magnetron deposition followed by annealing. The peaks observed in the optical absorption spectra of the samples at the wavelength λ ≈ 660 nm are attributed to collective plasmon resonance in dense arrays of Au nanoparticles. The photocurrent between the microscope probe and the indium-tin-oxide sublayer is measured during photoexcitation of the contact between the probe and the sample surface through the transparent substrate by the radiation of a semiconductor laser diode at the plasmon-resonance wavelength. The increase in current through the probe of the atomic force microscope under photoexcitation is attributed to the photon-assisted emission of electrons from the Au nanoparticle into the conduction band of ZrO2(Y) in a strong electric field applied between the probe and the indium-tin-oxide sublayer under plasmon resonance conditions.

The results of research on reducing the errors of molded parts by the method of free thermoforming are presented. A design method based on the use of expansion joints is proposed, which makes it possible to eliminate the change in the volume of the workpiece material.

The known experimental absorption spectra were used to calculate the dielectric spectra of GeTe, SnTe, and PbTe crystals in the region of electron transitions from the core d-bands of cations. Their characteristic features and general regularities are revealed. Using the combined Argand diagram method, the dielectric spectra of each crystal were decomposed into six elementary oscillators and their main parameters were determined. The nature of formation of these oscillators is proposed on the basis of the theory of interband and exciton transitions.