bluuebunny/crossref_metadata_2025 huggingface dataset:
Fracture-Resistant Zirconia-Based Composite Ceramics with Increased Surface Layer Hardness
Authors: Vasyukov V. M. , Grigoriev G. V. , Dmitrievskiy A. A. , Zhigacheva D. G. , Efremova N. Yu.
Published: April 2024

A two-layer alumina toughened zirconia composite ceramic stabilized with calcium oxide (Ca-ATZ) was produced using a relatively economical powder metallurgy method. One of the layers contains silica additive (Ca-ATZ + SiO2). The structure, elemental and phase composition as well as the complex of mechanical properties nearby of the Ca-ATZ/Ca-ATZ + SiO2 interface has been investigated. It was shown that the presence of a sharp interface of layers with different elemental composition did not cause structural disorders (appearance of pores, cracks and other macroscopic defects that contribute to the deterioration of strength properties) or changes in the phase composition (more than 90% of zirconia in both layers was in the tetragonal phase, which provided a high role of the transformation toughening mechanism). Demonstrated preservation of structural integrity and ratio of monoclinic, tetragonal and cubic zirconia phases at formation of sharp interface of the mentioned layers, provides possibility of manufacturing of zirconia-based ceramics with thin (100–200 μm) modified layer. Taking into account the difference in mechanical properties of Ca-ATZ and Ca-ATZ + SiO2 ceramics, this provides the basic material (containing SiO2) increased fracture toughness (not less than 12 MPa m1/2), and near surface layer (not containing SiO2) high hardness (not less than 14 GPa).
Changes in the Energy of Surface Adsorption Sites of ZnO Doped with Sn
Authors: Shomakhov Z. V. , Nalimova S. S. , Kondratev V. M. , Maksimov A. I. , Ryabko А. А. , Moshnikov V. A. , Molokanov O. A.
Published: April 2024

Nowadays an important task is the development of nanostructures of Zn–Sn–O ternary oxide system, which are of practical interest for various fields, including gas sensors and photocatalysts, lithium-ion batteries, and solar cells. Zinc stannate nanowires were formed by hydrothermal treatment of preliminary synthesized zinc oxide nanowires in a solution of potassium stannate and carbamide. Using scanning electron microscopy and backscattered electron diffraction, the samples were found to have a Zn2SnO4 structure, and their geometric dimensions did not change compared to the initial zinc oxide nanowires. The diameter of the obtained structures is about 300 nm, and the length is about 2 μm. According to X-ray photoelectron spectroscopy data, as a result of hydrothermal treatment, the surface structure changes, tin atoms are incorporated into the crystal structure of zinc oxide. A study of the gas-sensitive properties of the Zn2SnO4 layers have shown that they are more efficient in detecting isopropyl alcohol vapors compared to the initial zinc oxide nanowires. Zn2SnO4 layers allow detecting isopropyl alcohol vapors at temperatures of about 150°C. The sensor signal with respect to 1000 ppm C3H7OH is 3.79.
Kinetics of Hydrogen Evolution during Amminborane Hydrolysis with Cobalt-Based Catalysts
Authors: Dyankova N. Ya. , Lapin N. V. , Grinko V. V. , Vyatkin A. F.
Published: April 2024

The kinetics of hydrogen evolution during the hydrolysis reaction of aqueous solutions of amminborane with cobalt-based catalysts deposited on various substrates – Co3O4/ZnO, Co/ZnO, Co3O4/zeolite, Co/zeolite, as well as Co(OH)2 powder, was studied. In each case, the reaction order, the rate constants and apparent activation energy of the reaction, and the rate of hydrogen evolution during hydrolysis in the temperature range 35–80°C were determined. In all cases, an amminborane solution with a concentration of 0.078 M was used. The amount of the active part of the catalysts was determined by the chemical method and was 7.5–10% of the total weight of the catalyst. For low-temperature Co–B and Co(OH)2 catalysts, the kinetic dependences corresponded to the zero or close to zero reaction order. When using the catalysts Co3O4/ZnO, Co/ZnO, Co3O4/zeolite, Co/zeolite, the first order of the reaction was observed. The maximum rate of hydrogen evolution at 80°C was 3125 mL H2 · (g-cat–1) · min–1 for Co/ZnO catalyst (turnover frequency TOF = 8.2 min–1) and 3750 mL H2 · (g-cat–1) · min–1 for Co–B catalyst (TOF = 11.7 min–1), respectively. The values of the apparent activation energy of the reaction of catalytic hydrolysis of amminborane were calculated for the catalysts: Co3O4/ZnO – 26.0, LT Co–B – 44.8, Co(OH)2 black – 43.4, Co(OH)2 blue – 47.4 kJ/mol, respectively.
Investigation of the Corrosion Properties of Bulk Amorphous Metal Alloys Based on Zirconium
Authors: Yakovlev A. V. , Balybin D. V. , Fedorov V. A. , Pluzhnikova T. N. , Fedotov D. Yu. , Shlykova A. A.
Published: April 2024

Corrosion resistance of zirconium-based amorphous alloys in simulating a biological fluid, as well as in aqueous solutions of hydrochloric acid (with HCl concentration 0.1, 0.2, 0.4 mol/L) was studied in this work. When studying the effect of simulating a biological fluid, the samples were exposed to the environment in two ways. In the first case, the sample was completely immersed in a corrosive liquid. In the second case, the sample was subjected to local action of a drop of biological fluid deposited on the surface. It has been established that prolonged exposure to the medium leads to the dissolution of the surface layer of the sample, while the local impact of drops practically does not affect the surface. Preliminary ion implantation of argon and nitrogen ions leads to a decrease in the effect of the biological fluid on the samples. Polarization curves are obtained for all investigated alloys. On the curves obtained during measurements on alloys in simulating a biological fluid, the cathode and anode branches have a standard form. It has been established that the polarization curves for zirconium-based alloys in an aqueous solutions (with HCl concentration 0.1, 0.2, 0.4 mol/l) depend on the elemental composition of the alloys. It has been established that in a sample without copper, the corrosion potential at different concentrations of HCl changes insignificantly. For a sample with a copper content of 15%, the corrosion potential shifts to the cathodic region with an increase in the concentration of hydrochloric acid. The polarization curves of the sample with a higher copper content of 45% are qualitatively different from the curves of the other samples. It is noted that, as in the previous sample, with an increase in the concentration of hydrochloric acid, the corrosion potential shifts to the negative region. It has been established that the corrosion resistance of amorphous alloys based on zirconium, which is the basis of the alloys under study, in the studied solutions increases in comparison with the crystalline one, which is due to the amorphous structure of the electrode material, which complicates the transition of the metal to the ionic state.
Synchrotron Radiation Technological Station at the VEPP-4M Storage Ring
Authors: Goldenberg B. G. , Gusev I. S. , Zubavichus Y. V.
Published: April 2024

On the beam line № 1 of the VEPP-4M storage ring located at the Institute of Nuclear Physics named after Budker SB RAS, a new technologically oriented terminal station has been put into operation. First of all, the station is intended for conducting visual didactic experiments with an active beam for teaching university students of related training profiles and novice users, developing and testing measuring instruments, as well as conducting preliminary or additional measurements. Such a direct involvement of students into the design of beamline components and deployment of different synchrotron techniques increase their motivation towards professional and efficient utilization of synchrotron radiation techniques and instrumentation development, which is highly demanded for the ongoing project SRF SKIF. The modular design of the end station enables implementation of diverse techniques in the mode of continuous upgrade. The present paper describes the optical scheme of the beamline and emphasizes synchrotron beam parameters therein with respect to other beamlines operating in the Budker Institute of Nuclear Physics SB RAS. Selected examples of experimental results obtained by students using various techniques in the course of training are given. In particular, the automized operation of a photodiode-based X-ray beam monitor is demonstrated, which is required to visualize the incident X-ray beam, measure its exact position and intensity. The implementation of X-ray fluorescence analysis technique in a dedicated vacuum chamber enables quantification of light elements, which was unattainable at other beamlines. Prospects for further development of the technology-oriented end station are envisage.
Observation of Surface Plasmon Resonance in Monochromatic Terahertz Radiation on Indium Antimonide
Authors: Khasanov I. Sh. , Gerasimov V. V. , Kameshkov O. E. , Nikitin A. K. , Kassandrоv V. V.
Published: April 2024

Currently, the terahertz frequency range, which is on the border of the microwave and optical ranges, is being intensively mastered. One of the widely used materials in terahertz optics is indium antimonide (InSb), the plasma frequency ωp of which depends on the degree of doping, temperature, and surface illumination. The possibility of generating surface plasmon polaritons, a type of surface electromagnetic waves, on the surface of an InSb sample using the attenuated total reflectance method (ATR) (Otto scheme) is discussed. Using the scattering matrix formalism, the conditions for the highest efficiency of excitation of surface plasmon polaritons are established. If terahertz radiation with a frequency slightly less than ωp is used for this, the propagation length of such plasmons and the depth of their field penetration into the environment (air) are comparable to the radiation wavelength. It is possible to achieve surface plasmon resonance in the form of a sharp decrease in the intensity of monochromatic radiation reflected from the base of the ATR prism with a change in the angle of incidence and the size of the air gap. Test experiments were performed to observe surface plasmon resonance on an InSb wafer using a high-resistance silicon prism and monochromatic radiation (λ = 141 μm) from the Novosibirsk free electron laser. The dependence of the resonant dip on the size of the air gap separating the prism from the sample surface is studied, and its optimal (in the case of resonsnce) value is established for semiconductors with a plasma frequency in the terahertz range.
Effect of Structural Reorganization of the Surface Layer in AMN-P and OPMN-P Membranes on the Transport Characteristics of the Electronanofiltration Separation of Aqueous Ammonium Chloride Solution
Authors: Lazarev S. I. , Konovalov D. N. , Khorokhorina I. V. , Lua P.
Published: April 2024

The absorption spectra of infrared radiation by membranes of the AMN-P and OPMN-P brands are analyzed. In the spectra of the surface layer of the AMN-P membrane, there is a decrease in the relative intensity of the frequencies of the carbonyl group (1724, 3392 cm–1 for air dry). For the cellulose acetate AMN-P membrane, the number of hydrophilic OH groups increases, which changes its molecular structure and transport characteristics. In the infrared radiation spectra of the surface layer of the OPMN-P membrane, the 1650–1670 cm–1 band characteristic of C=O group shows changes in the frequency of the spectrum: for air-dry and water-saturated samples, it shifts from 1652 to 1666 cm–1, respectively. Interactions of carbonyl (C=O) and amide (H–N) groups form the supramolecular structure of polyamides. Changes in the infrared radiation spectrum of the water-saturated sample of the OPMN-P membrane can be explained by the fact that the C=O…–…H–N bonds of the amide fragment do not break. Therefore, membrane swelling partially affects the structural rearrangement of the polyamide at the supramolecular level. In the electron nanofiltration separation of an aqueous solution of ammonium chloride, two intervals of change in the specific output flux are noted at fixed transmembrane pressure and experiment time. The first period occurs at a current density of 12.82 to 15.38 A/m2 and is associated with the penetration of the solvent with a slight gas formation on the electrodes. The second period is observed from 15.38 to 25.64 A/m2 and is associated with membrane degradation and intense gas formation, especially chlorine. It is noted that in the intermembrane channels the migration of cations and anions is affected by the processes of throttling, heat release, when operating in the limiting mode (when current carriers – H+ and OH–) appear, which is confirmed by the data of studies of the electrochemical parameters of the membrane system.
Obtaining Magnesium Nanoparticles by Receiving Flow Levitation
Authors: Markov A. N. , Kapinos A. A. , Suvorov S. S. , Barysheva A. V. , Kleiman G. M. , Vorotyntsev V. M. , Atlaskin A. A. , Grachev P. P. , Vorotyntsev I. V. , Vorotyntsev A. V.
Published: April 2024

Due to the development of the chemical industry, the need to obtain high-purity monodisperse nanoparticles is increasing. Therefore, it is necessary to choose the right method of obtaining. The paper demonstrates a unique method – induction flow levitation, which allows to obtain a large list of metal nanoparticles on one installation. In this work, magnesium nanoparticles were obtained using this method. The morphology was studied using scanning electron microscopy, where the resulting nanoparticles were clusters of primary particles. Energy dispersive analysis showed that the surface of magnesium nanoparticles after interaction with atmospheric air is completely covered with a small layer of oxide. Analysis of the phase composition showed that the powder consists of magnesium without traces of oxide. Mass spectrometry with inductively coupled plasma showed the purity of the obtained particles 99.99%. The characteristics of the porous structure were determined by low temperature porosimetry. The size of the obtained particles did not exceed 40 nm, and the average size was 23 nm. The used method of obtaining nanoparticles demonstrated high productivity (up to 50 g/h) and continuity of the process of obtaining nanoparticles (NP), the ability to control the size of the obtained nanoparticles (NP) in a wide range, non-contact heating, which leads to a high purity of the resulting product confirmed by mass spectrometry with inductive plasma bound.
Changes in the Optical Properties under Sequential and Separate Irradiation with Solar Spectrum and Protons of a BaSO4 Powder Modified with SiO2 Nanoparticles
Authors: Mikhailov M. M. , Lapin A. N. , Yuryev S. A.
Published: April 2024

A comparative analysis of changes in the diffuse reflectance spectra ρλ and the integral absorption coefficient in the region of 0.2–2.2 μm after separate and sequential irradiation with 5 keV protons and solar radiation quanta of a barium sulfate powder modified with silicon dioxide nanoparticles mBaSO4/nSiO2 was performed with registration of the spectra after each period of irradiation in vacuum in the area of irradiation (in situ). The integrated solar radiation absorption coefficient of the modified mBaSO4/nSiO2 pigment before irradiation is 0.048, which is several times lower than that of the ZnO pigment widely used in all countries. It has been found that the additivity coefficient calculated from the results of sequential and separate irradiation of the mBaSO4/nSiO2 powder decreases from 7.5 to 1.052 times with an increase in the fluence of protons with an energy of 5 keV. An assessment of the changes in the additivity coefficient under the influence of the spectrum of charged particles in the geostationary orbit (as one of the most used and with harsh radiation conditions) showed that the non-additivity of the separate and sequential action of protons and solar radiation quanta on the pigment for thermal control coatings mBaSO4/nSiO2 at such irradiation parameters will be kept for 1.27 years.
Fine Crystal Structure, Spectral Properties and Surface Micromorphology of 1,3,5-Triamino-2,4,6-trinitrobenzene, 1,1-Diamino-2,2-dinitroethylene, and Benzotrifuroxane Films Obtained by Crystallization from a Gas Phase
Authors: Gretsova A. N. , Streltsova M. S. , Frolova O. A. , Stankevich A. V. , Sobolevskaya A. V.
Published: April 2024

We studied the structure of thin films of various thicknesses made of benzotrifuroxan, triaminotrinitrobenzene, diaminodinitroethylene, obtained by crystallization from the gas phase on various substrates: polyethylene terephthalate, parchment, aluminum, quartz glass, polymer resin, silicon and sapphire. Preliminary preparation of gaseous products, which were obtained by the method of thermal vacuum sublimation, was carried out. It has been established that the molecular structure of the obtained thin films corresponds to the studied substances. The texture of the films has been determined. In the bulk, their morphology is determined by particles having a columnar shape, nonequilibrium faceting, and a developed surface. The measurements were carried out by X-ray powder diffraction, Raman spectroscopy, IR spectroscopy, spectrophotometry in the visible, ultraviolet, and near infrared regions, optical and electron microscopy. The surface topology and electronic properties of the obtained textured films were studied.
Formation of Whisker-Like Morphology on the Surface of Carbon Fiber under Magnetron Sputtering
Authors: Andrianova N. N. , Borisov A. M. , Metel A. S. , Ovchinnikov M. A. , Sleptsov V. V. , Tsyrkov R. A.
Published: April 2024

The effect of irradiation with hydrogen, helium, nitrogen and neon ions with an average energy of 0.8 keV on the surface morphology under magnetron sputtering of a high-modular carbon fiber made of polyacrylonitrile was studied experimentally. In all cases, a whisker-like relief was formed on the surface. The greatest height of whiskers was obtained under irradiation with nitrogen and neon ions, the lowest height and lower density of whiskers was obtained under irradiation with hydrogen ions. Comparison with irradiation of polyacrylonitrile carbon fiber with noble gas and nitrogen ions with energies of 10–30 keV shows that the whisker-like morphology complements the variety of types of ion-induced fiber surface morphology. The results obtained are discussed within the framework of existing models of formation of ion-induced morphological elements on the surface of graphite-like materials. It is assumed that there is a threshold in the number of radiation displacements created in the surface layer, leading to the observed qualitative difference in ion-induced morphology at low and high energies. The evaluations of the displacement profiles for the case of irradiation with hydrogen ions show several-fold fewer displacements than for other ions, which correlates with the observed differences in whiskering by selected ions and whisker growth factors observed in the experiment performed.
Superconducting Solenoid (7 T) Indirectly Cooled by Cryocoolers for THz Radiation
Authors: Bragin A. V. , Volkov A. A. , Kubarev V. V. , Mezentsev N. A. , Tarasenko O. A. , Khrushchev S. V. , Tsukanov V. M. , Shkaruba V. A.
Published: April 2024

The test results and performance characteristics of an indirectly crycooled superconducting solenoid to be used at the THz spectroscopy experimental station of free-electron laser at the Institute of Nuclear Physics, are presented. The superconducting solenoid with a winding diameter of 102 mm and a length of 0.5 m was designed for a magnetic field of 6.5 T. The warm bore diameter of 80 mm is available for THz spectroscopy experiments. The superconducting wire Cu/NbTi = 1.4 was used. The design implements passive protection methods due to sectioning and secondary connected circuits in case of a sudden quench. The required field uniformity of 0.5% was ensured by using an iron yoke and additional side windings. The cryogenics of the solenoid is based on two Sumitomo HI cryocoolers. The solenoid and iron yoke are cooled by the second stage of the cryocooler via copper links. The manufacturing technology of the solenoid is described in detail. The solenoid was tested in a liquid helium bath and in its own cryostat. Its characteristics meet the requirements of the experimental station. The obtained filed of 7.5 T is greater than the designed one due to overcooling up to 3.6 K. The magnetic field was measured both in a bath cryostat and in a design cryostat; the results corresponded to the design calculations. The solenoid cooling time is 13 days. The quench happened only twice, at 5.6 and 7.5 T.
Surface Preparation and Investigation of Ohmic Film Contacts Formed by Various Methods to Thermoelements
Authors: Shtern M. Yu. , Sherchenkov A. A. , Shtern Yu. I. , Rogachev M. S. , Korchagin E. P.
Published: April 2024

Methods were proposed and criteria were established for surface preparation of nanostructured thermoelectric materials for deposition of thin and thick film ohmic contacts. The parameters of the mechanical and chemical methods of thermoelectric material surface treatment before the deposition of contacts were established. The roughness and morphology of the surface of thermoelectric material samples and the films obtained have been studied. Criteria and optimal values of surface roughness of thermoelectric materials were established. The conditions of obtaining thin and thick film contacts were determined. Thin film contacts (thickness up to 300 nm) were obtained by magnetron sputtering of Ni. Thick film contacts were formed by chemical and electrochemical deposition of Ni. The obtained films contained various amounts of Ni. The electrical resistivity of Ni films obtained by chemical deposition was significantly higher than that of Ni films obtained by electrochemical deposition. The specific contact resistance of the metal–thermoelectric material system in the case of deposition of Ni films by magnetron sputtering was the smallest among the considered samples. And in the case of forming contacts by chemical deposition, it is comparable to that for Ni films formed by electrochemical deposition. The adhesion strength of Ni films obtained by various methods has high values exceeding the industry standard for film coatings in microelectronics. All obtained ohmic contacts satisfy the requirements for the construction of the efficient thermoelements by the electrical properties and adhesive strength.
Study of the Influence of Ion-Beam Etching on the Surface Roughness of Single-Crystal Sapphire
Authors: Mikhailenko M. S. , Pestov A. E. , Zorina M. V. , Chernyshev A. K. , Chkhalo N. I. , Shevchuk I. E.
Published: April 2024

To increase the average and peak power of modern laser systems, there is a need for new materials or the possibility of modifying existing ones to create composites based on them. Such composite materials using optical materials with high thermal conductivity can serve to remove heat from the active medium. Most often, this is achieved by planting materials on an optical contact. One of the promising materials for these purposes is single-crystal sapphire, since it has a sufficiently high thermal conductivity (~23–25 W/(m · K) at 323 K) and a low temperature coefficient of linear expansion (~10–6 K–1 at T = 323 K). The effect of the energy and angles of incidence of argon ions on the surface roughness of A-cut single-crystal sapphire was studied in this work. In the course of the work, the effect of smoothing the surface roughness by 30% relative to the initial value of roughness in the spatial frequency range 0.049–63 μm–1 was demonstrated. The possibility of ion treatment of such surfaces is also shown, in particular, at angles of incidence of ions ± 40° on the sample surface, the value of effective roughness does not change much, which allows local correction of shape errors without leading to significant changes.
Dynamical Correlations in the Ground State: Transitions between One-Phonon Nuclear States
Authors: Shitov M. I. , Kamerdzhiev S. P , Tolokonnikov S. V
Published: April 2024

The probabilities of the E1 transition between the firstand @ excited levels in nuclei with pairing have been calculated within the self-consistent many-body nuclear theory and Green’s function method. Calculations for a long chain of even–even tin isotopes have been performed for the first time. The known Fayans energy density functional has been used to calculate the characteristics of phonons and E1 transitions between excited states. A good description has been achieved for existing experimental data for the reduced probabilities of E1 transitions between the first one-phonon states for the 116–124Sn isotopes but not for the 112Sn and 114Sn isotopes. Possible reasons for this discrepancy have been discussed; the most probable reason is the deformation in the ground or excited states. It has been shown that new dynamical three-quasiparticle correlations in the ground state should be taken into account to explain the experimental data for 116–124Sn.
Theoretical Foundations of Quantum Spectral-Domain Optical Coherence Tomography with Frequency Scanning
Authors: Ushakov N. A , Makovetskaya T. A , Markvart A. A , Liokumovich L. B
Published: April 2024

A quantum spectral-domain optical coherence tomography technique based on the control of the joint spectral amplitude of a biphoton has been developed. An analytical expression for a quantum spectral-domain optical coherence tomography signal has been obtained in the case of a Gaussian joint spectral amplitude. The effect of the shape of the joint spectral amplitude of the biphoton on the resulting interference signal has been analyzed. The possibility of improving the quality of the interference signal by controlling the parameters of the joint spectral amplitude has been considered. It has been shown theoretically that the proposed approach provides a higher longitudinal spatial resolution than other optical coherence tomography techniques.
Electronic Structure of InCo2As2 and KInCo4As4: LDA + DMFT
Authors: Pavlov N. S , Shein I. R , Pervakov K. S , Nekrasov I. A
Published: April 2024

A comparative analysis of the electronic structure obtained in the DFT/LDA and LDA + DMFT approaches of the possible isostructural analogues of iron superconductors InCo2As2 and KInCo4As4 with the electronic structure of the parent high-temperature superconductor system BaFe2As2 is carried out. It is established that in spite of the rather large value of the electron-electron correlations (local Coulomb interaction on the Co-@ shell @ eV, the Hund exchange interaction @ eV), in the considered systems a relatively small quasiparticle mass renormalization 1.2–1.35 at the Fermi level is observed. The correlation effects lead to the remarkable shift and compression of the spectrum below –0.8 eV. The band structure of InCo2As2 near the Fermi level is qualitatively similar to the previously studied BaCo2As2, and differs significantly from the band structure of BaFe2As2. In the KInCo4As4 system, the bands near the Fermi level resemble the band structure of BaFe2As2, and the Fermi surfaces have a similar topology. This indirectly points to the possibility of superconductivity in KInCo4As4. Also according to the results of LDA + DMFT calculations it is seen that with a rather small hole or electron doping in the KInCo4As4 system will experience topological Lifshitz transitions. We believe that the synthesis of the InCo2As2 and KInCo4As4 compounds considered in this paper is important for the study of superconductivity in this class of materials.
Optical Properties of Silicon Nanowires Obtained by Metal-Assisted Chemical Etching Using Gold Nanoparticles
Authors: Gonchar K. A , Bozh'ev I. V , Shalygina O. A , Osminkina L. A
Published: April 2024

Owing to their unique structural and physical properties, silicon nanowires are a promising material for electronics, photovoltaics, photonics, sensors, and biomedicine. Despite the many methods available for the synthesis of silicon nanowires, metal-assisted chemical etching is currently one of the most promising for their cost-effective production. In most works, silver nanoparticles are used as a catalyst for the chemical reaction of crystalline silicon etching. However, the use of gold nanoparticles in metal-assisted chemical etching can significantly affect the morphology and optical characteristics of the prepared samples. In this work, silicon nanowires are synthesized by metal-assisted chemical etching of crystalline silicon using gold nanoparticles. According to high-resolution scanning and transmission electron microscopy, the resulting nanowires have a diameter of about 100 nm and consist of a crystalline core about 50 nm in diameter coated with a SiO2 shell about 25 nm thick with silicon nanocrystals at the interface. The porosity of the silicon nanowire arrays, which has been estimated from their specular reflection spectra and has been calculated using the Bruggeman effective medium model, is 70%. At the same time, the samples exhibit an extremely low (3–7%) total reflection in the spectral region of 250–1000 nm and an increase in the intensities of interband photoluminescence and Raman scattering compared to the initial crystalline silicon substrate, caused by the light localization effect. In addition, the photoluminescence of nanowires has been detected in the range of 500–1000 nm with a maximum at 700 nm, which is explained by the radiative recombination of excitons in silicon nanocrystals with a size of 3–5 nm.
Electronic and Magnetic Properties of the ε-Fe Phase at High Pressures up to 241 GPa in the Temperature Range of 4–300 K
Authors: Gavrilyuk A. G , Struzhkin V. V , Aksenov S. N , Mironovich A. A , Troyan I. A , Ivanova A. G , Lyubutin I. S
Published: April 2024

The magnetic and electronic states of iron in the hexagonal close-packed ε-Fe phase have been studied by synchrotron Mössbauer spectroscopy on Fe-57 nuclei (nuclear forward scattering method) at pressures of @ GPa in the temperature range of 4–300 K in external magnetic fields up to 5 T. It has been found that Fe atoms are in a nonmagnetic state in the entire studied P–T region. Theoretically implied magnetic instability and quantum spin fluctuations, which can be stabilized by magnetic perturbation (e.g., external magnetic field), have not been confirmed by our measurements of nuclear forward scattering spectra in an external magnetic field. It has been established that the isomer shift IS(P) has a nonlinear pressure dependence and reaches a colossal value of about –0.8 mm/s at a maximum pressure of 241 GPa, indicating a very high electron density on the Fe nucleus. A sharp change in the electron density on the Fe nucleus at temperatures of 100–200 K indicates a phase transition with a change in the electronic structure, which can be due to an abrupt increase in the conductivity or even to the appearance of superconductivity.
Generation of Short Pulses by Filtering Phase-Modulated CW Laser Radiation
Authors: Shakhmuratov R. N
Published: April 2024

A method for generating short pulses with a high repetition rate is proposed. It is based on periodic modulation of the radiation phase of a CW laser and subsequent filtering through a narrow-band frequency filter. At the output of the filter, a sequence of short pulses is generated with a period equal to half the modulation period. In the case of a resonant filter using atoms, ions or molecules with a narrow absorption line, the appearance of pulses can be explained by constructive interference of the incident radiation with radiation coherently scattered by resonant particles. An alternative explanation of the pulse generation in the general case, when frequency filters operating on other principles are used, is based on the interference of the spectral components remaining after filtering. The method can be applied for time division multiplexing to transmit digital information through a single channel at high speed. The advantage of the proposed method is the use of phase modulation (not strictly periodic), integrated with frequency filtering to generate pulses and encode information simultaneously in one circuit, while in other known methods, information is introduced into a sequence of regularly generated pulses using additional amplitude modulation.
Anomalous Picosecond Optical Transmittance Dynamics in Au-Bi:YIG Hybrid Metasurface
Authors: Kir'yanov M. A. , Ostanin G. S. , Dolgova T. V. , Inoue M. , Fedyanin A. A.
Published: April 2024

The sub- and picosecond optical response dynamics of the metal–dielectric metasurface based on gold nanospheres placed in a layer of bismuth-substituted yttrium iron garnet has been studied via the pump–probe femtosecond spectroscopy with time resolution. It is shown that the plasmon modes of the metasurface demonstrate bulk gold dynamics, while the observed relaxation of the polariton mode is slowed down by several picoseconds. The difference arise because of the detection of different processes at the wavelengths of the plasmon and polariton modes by the probe beam.
Influence of Free Motion of Atoms on Atomic Density-Dependent Effects in Nonlinear Laser Spectroscopy of Resonant Gas Media
Authors: Yudin V. I , Taychenachev A. V , Basalaev M. Yu , Prudnikov O. N , Pal'chikov V. G , Zanon-villett T. , Bagaev S. N
Published: April 2024

We develop a nonlinear theory of propagation of a monochromatic light wave in a gas of two-level atoms under the condition of inhomogeneous Doppler lineshape broadening, while considering a self-consistent solution of the Maxwell–Bloch equations in the mean-field approximation using a single atom density matrix formalism. Our approach shows a significant deformation of the Doppler resonant lineshape (shift, asymmetry), which depends on the atomic density. These effects are a consequence of only the free motion of atoms in a gas and is not associated with interatomic interaction. In particular, the frequency shift of the field-linear contribution to the transmission signal is more than an order of magnitude greater than the shift due to the interatomic dipole–dipole interaction, and the first nonlinear correction has an even stronger deformation, which exceeds the effect of the interatomic interaction by three orders of magnitude. The found effects caused by the free motion of atoms require a significant revision of the existing picture of spectroscopic effects, which depend on the atomic density in a gas.
On the Formation of Clouds in the Dusty Ionosphere of Mars
Authors: Reznichenko Yu. S , Dubinskiy A. Yu , Popel' S. I
Published: April 2024

Dusty plasma clouds observed at altitudes of about 100 km in the mesosphere of Mars have been considered. Features of the dusty ionosphere of Mars compared to the dusty ionosphere of the Earth have been listed. The equations of the model describing self-consistently dusty plasma structures in the ionosphere of Mars have been presented. This model involves features that are important for the ionosphere of Mars but are ignored when describing the dusty plasma system in the ionosphere of the Earth. In particular, the model for Mars involves effects of deceleration of dust particles because of the adhesion of condensed molecules to them. An altitude distribution of particles constituting mesospheric clouds on Mars has been calculated with the self-consistent model. It has been shown that an important factor for the formation of dusty plasma clouds in the ionosphere of Mars is the Rayleigh–Taylor instability, which limits both the maximum size of dust particles that can form dusty plasma clouds and the maximum thickness of the dusty plasma clouds.
Study of the Antiferromagnetic State Nematics in EuFe2As2 by Using Spin-Resonance and Magnetic Measurements
Authors: Talanov Yu. I , Gimazov I. I , Zaripov R. B , Pervakov K. S , Vlasenko V. A , Pudalov V. M , Teytel'baum G. B
Published: April 2024

Using electron spin resonance spectroscopy and SQUID-magnetometry we obtained direct evidence of the occurrence of magnetic domains in the antiferromagnetically ordered state of asingle crystal. The resonance spectra of europium ions were measured in the temperature range from 4 to 200 K. Using an equation for the resonance field in an antiferromagnet that takes into account the exchange and anisotropy fields, we have performed an analysis of the angular dependence of the spectrum at a temperature of 4.8 K, measured upon the crystal rotation around the c axis. Data analysis showed thatis the antiferromagnet with easy anisotropy plane. Besides, we found in the-plane the second order axes of easy magnetization for each of the two types of magnetic domains, related to the structural transition and the formation of twins. Magnetic anisotropy caused by the exchange interaction of europium ions with iron ions indicates the occurrence of nematic magnetic ordering in the basalplane. An estimate of the magnitude of the exchange field and the anisotropy field is obtained from the angular dependence of the resonance fields.
Active Suppression of the Light Shift in an Atomic Clock Based on Coherent Population Trapping in 87Rb Vapor Using the Phase Jump Technique
Authors: Radnatarov D. A , Kobtsev S. M , Andryushkov V. A , Basalaev M. Yu , Taichenachev A. V , Radchenko M. D , Yudin V. I
Published: April 2024

The active suppression of light shift of the reference coherent population trapping (CPT) resonance in 87Rb vapor to improve the long-term stability of compact atomic clocks has been demonstrated experimentally. The approach is based on the phase jump technique used to synthesize an error signal, which is proportional to the light shift of the CPT resonance, from an optical transmission signal. The use of this error signal in an additional feedback loop allows one to stabilize the amplitude of a microwave signal for the phase modulation of laser radiation near a value at which the light shift of the CPT resonance is absent. This technique has made it possible to reduce the long-term instability of CPT atomic clocks in our experiments by a factor of 15 at an integration time of 10 000–20 000 s.
Effect of Motion of Atoms on the Character of Subradiance of Cold Dilute Ensembles Excited by Resonant Pulsed Radiation
Authors: Sokolov I. M
Published: April 2024

The dynamics of the fluorescence of dilute atomic ensembles excited by resonant pulsed radiation has been analyzed. It has been found that the motion of atoms in ensembles cooled to sub-Doppler temperatures in certain time intervals noticeably enhances subradiance rather than suppressing it. It has also been shown that the time dependence of the spontaneous decay rate can be nonmonotonic. The revealed features occur because the character of the slow decay of the atomic excitation is determined after a certain time mainly by the dynamics of subradiant two-atom quantum states, which are due to the resonant dipole–dipole interaction between atoms.
Optomechanical Heating and Cooling via Tip-Enhanced Raman Scattering in Epsilon-Near-Zero Medium
Authors: Gazizov A. R , Salakhov M. Kh , Kharintsev S. S
Published: April 2024

Media with the dielectric permittivityclose to zero (epsilon-near-zero or ENZ) maintain conditions for enhanced light-matter interactions. In this paper, we propose to use these media to enhance the optomechanical coupling of vibrational excitations of the medium with the optical near-field of the nanoantenna. It is shown that the ENZ medium significantly increases the optically induced decay rate of a vibration, which can be used for cooling (when the incident light frequency is less than the ENZ frequency) or heating (when the incident light frequency is greater than the ENZ frequency). Due to the proximity of the refractive index to zero as well, oscillations of the polarization of the medium are coherent, which further enhances the optomechanical effects. Analytical expressions are obtained for the optical shift of the resonance and the induced decay rate.
Runge–Lenz Operator in the Momentum Space
Authors: Efimov S. P
Published: April 2024

The fundamental quantum Coulomb problem in the momentum space is considered. A differential equation with SO(4) symmetry has been obtained in the momentum space instead of the integral Fock equation. The corresponding equation in the coordinate space is the sum of the squares of the angular momentum and Runge–Lenz operators. This approach is unknown in the momentum space where the Runge–Lenz operator is not applied. The Runge–Lenz operator obtained in the momentum space is simpler than that in the coordinate space and allows one to effectively consider the Coulomb problem in the momentum space. A relation of new operator to the infinitesimal rotation operator of the three-dimensional Fock sphere has been determined.
Diffraction-Limited Focusing of Acoustic Waves by a Mesoscopic Flat Janus Lens
Authors: Minin O. V , Dzhou S. , Baranov P. F , Minin I. V
Published: April 2024

Anisotropic focusing by a mesoscopic (Mie size parameter of about 18) acoustic cubic lens based on V-shaped plate structures has been simulated numerically and confirmed experimentally. It has been shown for the first time that this lens with an edge dimension of about three wavelengths ensures the focusing of an acoustic wave in air into a diffraction-limited region. In the inverse geometry of the structure, the lens completely reflects the incident acoustic wave.
Characteristics of “Dust” Fluxes from the Surface of Copper and Lead Liners Exposed to One or Two Successive Shock Waves
Authors: Ogorodnikov V. A , Erunov S. V , Panov K. N , Chudakov E. A , Blinov I. A , Georgievskaya A. B , Zamyslov D. N , Farin I. R
Published: April 2024

Comparative experimental studies of the shock-induced particle ejection (“dusting”) from the free rough (Rz20) surface of copper and lead liners exposed to one or two successive shock waves separated in time by 0.2 μs have been carried out for the first time. This situation usually occurs in cumulative systems for the compression of the plasma by cylindrical or spherical liners shock or quasi-isentropically accelerated by explosion products. Using pulsed X-ray diffraction, laser optical recording, piezoelectric pressure sensors, and heterodyne interferometry, a qualitative picture has been studied and the quantitative characteristics of particle ejection from the free surface such as the velocities of the free surface and the particle flux front and the density (mass) distribution of particle flux in the direction of its motion, which are necessary for more accurate determination of features and the development of more appropriate models of the effect, have been evaluated.
Influence of the Magnetic Domain Structure on Polarization Effects in the Mössbauer Spectra of Iron Borate FeBO3 Single Crystals
Authors: Snegirev N. I , Chuev M. A , Lyubutin I. S , Starchikov S. S , Yagupov S. V , Strugatskiy M. B
Published: April 2024

The Mössbauer spectra of FeBO3 single crystals are studied at temperatures above and below the magnetic transition point at different orientations of the crystals with respect to the propagation direction of γ rays. To describe the Mössbauer spectra, a theoretical model is developed with allowance for different orientations of magnetic moments in the crystal plane. It is found that the magnetic domain structure in iron borate significantly affects the shape of the Mössbauer spectra and the intensity of resonant transitions. The proposed model may be useful for determining the configuration of the magnetic domain structure of materials from Mössbauer spectroscopy data.
Elastic neutrino-atom scattering as a probe of neutrino millicharge and magnetic moment
Authors: Donchenko G. V , Kouzakov K. A , Studenikin A. I
Published: April 2024

Neutrino scattering on a target at low-energy transfer is one of the basic tools for searching for neutrino electromagnetic properties. We consider the effects of the neutrino millicharge and magnetic moment on the atomic recoil spectrum in elastic neutrino–atom scattering. The results of our calculations of differential cross sections for elastic collisions of tritium neutrinos with the H, 2H, 3He, and 4He atomic targets show that the corresponding experiments can achieve sensitivity to the indicated neutrino electromagnetic characteristics by orders of magnitude better than the available measurements of elastic neutrino–electron and neutrino–nucleus collisions.
Light-shining-through-wall cavity setups for probing alps
Authors: Salnikov D. , Satunin P. , Fitkevich M. , Kirpichnikov D. V
Published: April 2024

We discuss the aspects of axion-like-particles searches with Light-Shining-through-Wall experimental setups consisted of two radio-frequency cavities. We compare the efficiencies of four setups which involve the cavity pump modes and external magnetic fields. Additionally, we discuss the sensitivity dependence both on the relative position of two cylindrical cavities and on their radius-to-length ratio.
Casimir–Lifshitz Friction Force and Kinetics of Radiative Heat Transfer between Metal Plates in Relative Motion
Authors: Dedkov G. V
Published: April 2024

The Casimir–Lifshitz friction force and the heating rates of two metal plates with a narrow vacuum gap between them during nonrelativistic motion of one of them are calculated within the framework of fluctuation electrodynamics taking into account the temperature change in material properties. It is shown that identical plates with the same initial temperature have the same heating rate, determined by the power of the friction force, and the possibility of measuring the friction force from the heating kinetics of nonmagnetic metal plates with temperatures of 1–10 K is substantiated.
pq-Duality: a Set of Simple Examples
Authors: Zakirova Z. , Lunev V. , Beloborodov N.
Published: April 2024

A series of two-particle examples of the Ruijsenaarspq-duality is considered in detail, the dual Hamiltonians are constructed. Of special interest is the case of the sinh-Gordon model.
Quasiclassical Quantization of the Motion of a Particle in the Presence of a Drag Force Proportional to the Square of the Velocity
Authors: Sazonov S. V.
Published: April 2024

The quasiclassical one-dimensional motion of a particle in a medium, where the drag force is proportional to the square of the particle velocity, is considered using the Caldirola–Kanai approach. The coherent state of the particle in the presence of a constant conservative force in addition to the drag force is studied. It has been shown that the wave packet undergoes quantum extension to a certain limit, forming a steady propagating profile. Thus, the drag force suppresses the quantum properties of the particle, and the classical features become more pronounced in its motion with time. This property allows one to consider such a medium as a classical instrument continuously measuring the state of the particle. For this reason, the restriction of the spatial extension of the wavefunction can be interpreted as one of the manifestations of the quantum Zeno effect.
Temperature-Induced Transition Between Resistive Switching Modes of Parylene-Based Memristive Crossbar Structures
Authors: Matsukatova A. N. , Trofimov A. D. , Emel'yanov A. V.
Published: April 2024

In order to create neuromorphic computing systems (NCSs) capable of efficiently solving artificial intelligence problems, elements with short- and long-term memory effects are required. Memristors are promising candidates for the implementation of such elements since they demonstrate volatile and nonvolatile resistive switching (RS) modes. Of particular interest are structures that realize both RS modes in a single device. In this work, parylene-based nanocomposite memristors with MoO3nanoparticles have been studied in crossbar architecture, which is convenient for NCS implementation. For these structures, a reversible temperature-induced transition between volatile and nonvolatile RS modes was found if local, controlled via the compliance current, or external temperature is fine-tuned. In addition, the crossbar structures showed high endurance to cyclic RS, ability to retain states in nonvolatile mode and multilevel nature of RS. The obtained results open the possibility of using parylene-based crossbar structures in bioinspired NCSs.