bluuebunny/crossref_metadata_2025 huggingface dataset:
Planar Defects as a Way to Account for Explicit Anharmonicity in High Temperature Thermodynamic Properties of Silicon
Authors: Kondrin M. V. , Lebed' Yu. B. , Brazhkin V. V.
Published: April 2024

Silicon is indispensable in semiconductor industry. Understanding its high-temperature thermodynamic properties is essential both for theory and applications. However, first-principle description of high-temperature thermodynamic properties of silicon (thermal expansion coefficient and specific heat) is still incomplete. Strong deviation of its specific heat at high temperatures from the Dulong–Petit law suggests substantial contribution of anharmonicity effects. We demonstrate, that anharmonicity is mostly due to two transverse phonon modes, propagating in (111) and (100) directions, and can be quantitatively described with formation of the certain type of nanostructured planar defects of the crystal structure. Calculation of these defects' formation energy enabled us to determine their input into the specific heat and thermal expansion coefficient. This contribution turns out to be significantly greater than the one calculated in quasi-harmonic approximation.
Vortex Dynamics in Superconducting MoN Strip with a Side Cut
Authors: Ustavshchikov S. S. , Levichev M. Yu. , Pashen'kin I. Yu. , Gusev N. S. , Gusev S. A. , Vodolazov D. Yu.
Published: April 2024

Transport characteristics of superconducting MoN strips with a single side cut near one of the superconductor edges in zero and weak magnetic fields are studied experimentally and theoretically. The presence of the cut makes it possible to observe regimes with one and several simultaneously moving Abrikosov vortices, the number of which is controlled by the value of the applied current. A change in the number of vortices is accompanied with the emergence of a “kink” on the current–voltage characteristic, which can be clearly distinguished in the dependence of the differential resistance on the current. This makes it possible to find average velocityv¯of vortices (including a single vortex) and the current/voltage ranges with the known number of moving vortices. The vortex velocity determined in this way for our superconducting strips turns out to be weakly depending on the current and is close to maximal valuev¯max≈ 3 km/s, for which a superconductor transition to the normal state occurs. The maximal velocity value is comparable with the known values for superconductors of types Nb, NbN as well as, and YBCO, but is several times smaller than for superconductors of types MoSi, NbC, and Pb. The fact that difference in the maximal velocities of vortices is associated with different times of variation of the superconducting order parameter magnitude in different superconducting materials is considered.
Higher-Order Harmonics in Hexagonal Graphene Quantum Dots
Authors: Sedrakyan Kh. V. , Kazaryan A. G. , Avchyan B. R. , Pogosyan K. S. , Markosyan T. M.
Published: April 2024

We have considered the high-order harmonic generation in plane graphene quantum dots of hexagonal shape by the independent quasiparticle approximation-tight binding model. We have investigated how such a nonlinear effect is affected by a strong optical wave field, quantum dot typical band gap and lateral size, and dephasing processes. The equation of motion for the density matrix is solved by performing the time integration with the eight-order Runge–Kutta algorithm. If the optical wave frequency is much less than the quantum dot intrinsic band gap, the main aspects of multiphoton high harmonic emission in quantum dots are revealed. In such case dependence of the cutoff photon energy on the strength of the optical pump wave is almost linear. But when the wave frequency is comparable to the bandgap of the quantum dot, the cutoff photon energy shows saturation behavior with an increase in the wave field strength.
Jahn–Teller Ordering Dynamics in the Paraelectric BiMn7O12 Phase: 57Fe Probe Mössbauer Diagnostics
Authors: Sobolev A. V. , Nitsenko V. I. , Belik A. A. , Glazkova Ya. S. , Kondrat'eva M. S. , Presnyakov I. A.
Published: April 2024

The electrical hyperfine interactions of the57Fe probe nuclei stabilized in the structure of the BiMn7O12manganite are studied by Mössbauer spectroscopy. Mössbauer spectra are measured in the para-electric temperature range, which includes the structural phase transitionsI2/m↔Im3¯(T1≈ 600 K) andIm↔I2/m(T2≈ 450 K). The calculation of the parameters of the electric field gradient tensor with allowance for the dipole contributions of Bi3+cations in the range of the first phase transition allowed us to confirm a random orientation of the dipole momentspBiin the cubic phase of the manganite (Im3¯). Based on an analysis of the Mössbauer spectra recorded atT2TT1, we considered various scenarios for the manifestation of the dynamic Jahn–Teller effect, which leads to the “melting” of the orbital order in the manganese sublattice, in terms of a two-level relaxation model.
Effect of Surface Barrier on the Sputtering Yield of Tungsten by Hydrogen Isotopes
Authors: Mikhaylov V. S. , Babenko P. Yu. , Shergin A. P. , Zinov'ev A. N.
Published: April 2024

The sputtering yields of a tungsten target by hydrogen isotopes in the energy range of bombarding particles from 50 eV to 100 eV, as well as the dependence of the sputtering yields on the angle of incidence of the beam on the target and the energy and angular distributions of sputtered particles are obtained by the code developed by us. The strong influence of the type of surface barrier on the results of calculation of the sputtering yield, as well as on the characteristics of sputtered particles is demonstrated. The results obtained make it possible to more accurately assess the tungsten impurity inflow into the hot plasma zone of tokamak.
Magnetic Properties of the Double Perovskite Sr2CrNbO6
Authors: Popov D. V , Batulin R. G , Cherosov M. A , Yatsyk I. V , Chupakhina T. I , Deeva Yu. A , Fazlizhanov I. I , Eremina R. M , Maiti T.
Published: April 2024

A double perovskite Sr2CrNbO6 powder compound was studied by using X-ray diffraction, AC and DC magnetization, and ESR measurements. Two transitions in antiferromagnetically ordered regimes were observed through magnetization measurements at T = 5 and 2 K and were confirmed by the linear dependence of the magnetization on the applied magnetic field at these temperatures, approximations of the temperature dependence of the ESR linewidth, and AC magnetization. The zero field cooling curve was approximated by Bonner–Fisher law for quasi one dimensional chain with the exchange integral J/kB = 1 K between chromium spins. An approximation of linear part of magnetic susceptibility temperature dependence was performed using Curie–Weiss law. To describe the obtained effective moment μeff = 3.577μB, the presence Cr3+ and Cr4+ ions is estimated at a respective ratio about 0.8 : 0.2.
Specific Features of g ≈ 4.3 EPR Line Behavior in Magnetic Nanogranular Composites
Authors: Drovosekov A. B , Kreynes N. M , Ziganurov D. A , Sitnikov A. V , Nikolaev S. N , Ryl'kov V. V
Published: April 2024

Films of metal-insulator nanogranular composites MxD100 – x with different composition and percentage of metal and dielectric phases (M = Fe, Co, CoFeB; D = Al2O3, SiO2, LiNbO3; x ≈ 15–70 at %) are investigated by magnetic resonance in a wide range of frequencies (f = 7–37 GHz) and temperatures (T = 4.2–360 K). In addition to the usual ferromagnetic resonance signal from an array of nanogranules, the experimental spectra contain an additional absorption peak, which we associate with the electron paramagnetic resonance (EPR) of Fe and Co ions dispersed in the insulating space between the granules. In contrast to the traditional EPR of Fe and Co ions in weakly doped non-magnetic matrices, the observed peak demonstrates a number of unusual properties, which we explain by the presence of magnetic interactions between ions and granules.
Magnetooptical Kerr Spectroscopy of Nanocomposites
Authors: Gan'shina E. A , Garshin V. V , Perova N. N , Pripechenkov I. M , Yurasov A. N , Yashin M. M , Ryl'kov V. V , Granovskiy A. B
Published: April 2024

Magnetooptical spectroscopy is an effective method for studying the magnetic microstructure of homogeneous and heterogeneous magnets. This review is devoted to analysis of numerous factors affecting the intensity and spectral dependence of a magnetooptical signal of the equatorial Kerr effect in nanocomposites “ferromagnetic metal–dielectric” in the visible and near infrared spectral regions. Examples of the influence of the metal concentration, nanoparticle size and shape, the substrate, the material of the dielectric, the amorphization of grains, the deposition method, and other factors on the magnetooptical spectrum are considered. The differences in the magnetooptical spectra for the superparamagnetic, superferromagnetic, and ferromagnetic states are demonstrated. It is noted that in the presence of fractions with different field dependences of the magnetization in a nanocomposite, the magnetooptical signal is not proportional to the total magnetization. Examples of enhancement and sign inversion of the magnetooptical signal in nanocomposites are considered. The possibility of the description of magnetooptical spectra using the methods of the effective medium (the Bruggeman method and the Maxwell–Garnett symmetrized approximation) is discussed.
Growth Kinetics of 4He Quantum Crystals at a Temperature of 0.1–0.2 K
Authors: Gusev R. B. , Tsymbalenko V. L.
Published: April 2024

The growth kinetics of 4He crystals nucleated in a metastable liquid at a supersaturation of up to 10mbar is studied in the temperature range 90–180 mK. An optical dilution cryostat is used to observe and film crystal growth. The boundary supersaturation separating the normal (slow) and abnormal (fast) growth regions is determined. The growth rate of crystal facets in the normal growth mode is measured. The kinetics of fast crystal growth is investigated as a function of supersaturation and temperature.
Spin States of Cobalt Ions and a Metal–Semiconductor Transition in Layered Cobaltites PrBaCo2O5 + δ (δ = 0.52, 0.74)
Authors: Solin N. I. , Naumov S. V. , Korolev A. V. , Galakhov V. R.
Published: April 2024

The spin states of Co atoms in PrBaCo2O5 + δ with regard to the paramagnetic contribution of Pr3+ ions have been determined from magnetic property studies for δ = 0.52 and 0.74. Results obtained without considering the paramagnetic contribution of Pr3+ ions are inconsistent with available experimental data. With a decrease in temperature, the metal–insulator transition in PrBaCo2O5.52 becomes sharper according to a sharp change in spin states (from HS/LS to LS/IS) of Co3+ ions. In this case, Co3+ ions occupying octahedra pass from the high-spin state (HS, S = 2) to the low-spin one (LS, S = 0) and those occupying pyramids pass from the LS-state to the intermediate spin state (IS, S = 1), as follows from the available structural data. In PrBaCo2O5.74, the metal–semiconductor transition occurs smoothly from HS/LS to the HS/IS state upon the smooth transition of the Co3+ ion state from (LS, S = 0) to the (IS, S = 1) state in pyramides without change in the spin state of ions Co3+ (HS, S = 2) and Co4+ (LS, S = 1/2) in octahedrons.
Spin Glass Model for GaAs/AlGaAs Quantum Wells Doped by Nonmagnetic Impurities near the Metal-Insulator Transition
Authors: Agrinskaya N. V. , Kozub V. I.
Published: April 2024

In a previous report, we presented experiments which suggested that ferromagnetic ordering of the spins of localized holes in GaAs/AlGaAs quantum wells could be observed when doped with shallow (Be) acceptors at impurity concentrations near the metal-insulator transition. The compensating impurity (Si) was introduced into a narrow region at the center of the barriers [4]. In this paper, we present results from magnetotransport experiments performed on similar structures, but without the compensating impurity (Si). In these samples, the compensation degree is expected to be controlled by the background defects located at the edges of the quantum wells and within the barriers. At low temperatures T ≤ 10 K, we observed isotropic, linear magnetoresistance, anomalous behavior of the Hall effect as a function of the magnetic field, and slow relaxation of resistance after the application of a magnetic field. We explain this anomalous magnetotransport as the manifestation of a ferromagnetic transition or spin glass, originating from indirect spin exchange between localized holes on impurities near the metal-insulator transition. However, we note that perfect disorder, including signs of interspin interactions, leads to unstable configurations. In what follows, we present a model in which we start with this perfect disorder, but apply a procedure to obtain a stable configuration. We show that the resulting spin structure, a “closely packed” structure of “droplets,” can reproduce the features observed in the experiment, particularly isotropic, linear magnetoresistance.
“Dark” States As a Particular Case of the Emission Spectrum of an Exceptional Surface Wave
Authors: Sukhorukova O. S. , Tarasenko A. S. , Tarasenko S. V. , Shavrov V. G.
Published: April 2024

Under conditions of total internal reflection (TIR) of a plane bulk electromagnetic wave incident from outside on the surface of an optically transparent layered structure, the case where the numerator and denominator of the input surface wave impedance turn simultaneously to zero may correspond to the formation of a “dark” state. This is related to the occurrence of a point of degeneracy of the spectra of leaking exceptional surface waves (ESWs) of the first and second kind against the background of the continuous spectrum of radiative modes. For these waves, the instantaneous energy flux through the interface with a semibounded optical denser medium in an open radiative channel is zero at any instant. When approaching the point of dark state occurrence, the local maxima of the effects of first-order nonspecular reflection, accompanying resonant excitation of leaky ESWs, unlimitedly increase.
Improved Cosmological Bounds for Mixing Scenarios of Three Sterile Neutrino Generations
Authors: Dubinin M. N. , Kazarkin D. M.
Published: April 2024

The gauge SU(2)L × U(1) model with the extension of the lepton sector by three right-handed Majorana sterile neutrinos is considered. The complete mass matrix of 6 × 6 active and sterile neutrinos is diagonalized. The cosmological bounds following from the lifetime of sterile neutrinos and the fraction of energy carried by sterile neutrino dark matter are obtained. The deviations from the “fine-tuned” mixing scenario sensitive to the mass of the lightest standard (active) neutrino are considered, and the regions of the model parameter space corresponding to these deviations are distinguished.
Search for a New Internucleon Interaction Using Neutron Powder Diffraction
Authors: Voronin V. V. , Shapiro D. D. , Semenikhin S. Yu. , Khansen T. S.
Published: April 2024

The application of neutron powder diffraction to search for a new internucleon Yukawa-like interaction is considered. The essence of the method is in the investigation of dependency of the neutron scattering amplitude on the momentum transfer. The possible contributions to the scattering amplitude and to the integrated intensity of diffraction maxima were analyzed. The neutron diffraction experiment with silicon powder at D20 diffractometer of the ILL reactor (Grenoble, France) was performed. From the data obtained constraints on the coupling constant of the considered interaction were made. It is shown that in the interaction radius range of λ = 10–13–10—11 m they improve the values already existing in the literature. The result obtained is limited by imperfections of the experimental setup. Eliminating the instrumental contribution may allow increasing the sensitivity of the method by at least an order of magnitude.
Magnetic Interparticle Interactions and Superparamagnetic Blocking of Powder Systems of Biogenic Ferrihydrite Nanoparticles
Authors: Krasikov A. A. , Knyazev Yu. V. , Balaev D. A. , Stolyar S. V. , Ladygina V. P. , Balaev A. D. , Iskhakov R. S.
Published: April 2024

The magnetic-field dependence of the superparamagnetic-blocking temperature TB of systems of antiferromagnetically ordered ferrihydrite nanoparticles has been investigated and analyzed. We studied two powder systems of nanoparticles: particles of “biogenic” ferrihydrite (with an average size of 2.7 nm), released as a result of vital functions of bacteria and coated with a thin organic shell, and particles of biogenic ferrihydrite subjected to low-temperature annealing, which cause an increase in the average particle size (to 3.8 nm) and burning out of the organic shell. The character of the temperature dependences of magnetization, measured after cooling in a weak field, as well as the shape of the obtained dependences TB(H), demonstrate peculiar features, indicating the influence of magnetic interparticle interactions. A detailed analysis of the dependences TB(H) within the random magnetic anisotropy model made it possible to estimate quantitatively the intensity of magnetic particle–particle interactions and determine the magnetic anisotropy constants of individual ferrihydrite particles.
Thermoelectric Power and Hall Effect in Correlated Metals and Doped Mott–Hubbard Insulators: DMFT Approximation
Authors: Kuchinskiy E. Z. , Kuleeva N. A. , Sadovskiy M. V.
Published: April 2024

We present comparative theoretical investigation of thermoelectric power and Hall effect in the Hubbard model for correlated metal and Mott insulator (considered as prototype cuprate superconductor) for different concentrations of current carriers. Analysis is performed within standard DMFT approximation. For Mott insulator we consider the typical case of partial filling of the lower Hubbard band (hole doping). We calculate the dependence of thermopower on doping level and determine the critical concentration of carriers corresponding to sign change of thermopower. An anomalous dependence of thermopower on temperature is obtained significantly different from linear temperature dependence typical for the usual metals. The role of disorder scattering is analyzed on qualitative level. The comparison with similar studies of the Hall effect shows, that breaking of electron-hole symmetry leads to the appearance of the relatively large interval of band-fillings (close to the half-filling) where thermopower and Hall effects have different signs. We propose a certain scheme allowing to determine the number of carriers from ARPES data and perform semi-quantitative estimate of both thermopower and Hall coefficient using the usual DFT calculations of electronic spectrum.
Computational–Experimental Study of the Liquid Drop Fragmentation Caused by an Air Shock Wave
Authors: Anisiforov K. V. , Georgievskaya A. B. , Levkina E. V. , Nevmerzhitskiy N. V. , Raevskiy V. A. , Sen'kovskiy E. D. , Sotskov E. A.
Published: April 2024

The fragmentation of a drop of liquid (water, alcohol, glycerin) under the action of an air shock wave with a pressure of 0.2 and 3.2 atmg is studied experimentally and theoretically. The experiments are carried out using an air shock tube, and the liquid drop diameter is approximately 0.6 and 2 mm. The process is studied using high-speed video recording. Dispersed liquid particles from ≈5 μm in size are detected, liquid particle size distributions are plotted, and the particle velocities are determined. The experimental results are compared with the results of computational–theoretical estimation.
Use of SiO2 Nanoparticles Modified with Polyethylene Glycol to Increase the Hydrophilicity of Epoxy Coatings
Authors: Evdokimova E. N. , Kondratenko Yu. A. , Ugolkov V. L. , Kochina T. A.
Published: April 2024

SiO2 nanoparticles were modified with polyethylene glycol with a molecular weight of 2000, 6000, and 10000 g mol–1. For modification, the method based on the sequential interaction of polyethylene glycol with 3-(triethoxysilyl)propyl isocyanate with further treatment of the reaction product with nanodispersed SiO2 was used. The resulting product was characterized by IR spectroscopy, thermal analysis, and scanning electron microscopy. Modified nanodispersed SiO2 was introduced into epoxy resin in order to obtain coatings characterized by increased hydrophilicity. To improve the physical and mechanical characteristics, fillers were introduced into the composition of the coating with 30 wt % modified SiO2 nanoparticles: mica-muscovite and TiO2. It was shown that the process of biological fouling of epoxy coatings in the South China Sea proceeds more slowly in the case of a composition containing SiO2 nanoparticles modified with polyethylene glycol 6000.
HABITAT STRUCTURE AND HETEROGENEITY DETERMINE A SUCCESSFUL BREEDING PROBABILITY OF THE LONG-EARED OWL (ASIO OTUS, STRIGIDAE, STRIGIFORMES)
Authors: Sharikov A. V. , Massalskaia T. S. , Volkov S. V. , Kovinka T. S.
Published: April 2024

In 2001 to 2020, for each Long-eared owl nest in the Crane Homeland Nature Reserve territory with an area of 48 km2, the following microhabitat parameters were determined using standard field methods: the nest type built by different bird species, the presence of a nest roof, the nesting tree species, and the nest height above the ground. In most cases, for nesting the Long-eared owl reused magpie nests (Pica pica) (77%), and half of the nests were found on willow trees (family Salicaceae) (50%). The nest height above the ground varied from 1.5 to 22 m. Vegetation on the nesting area with a radius of 500 m was determined using the “Semi-Automatic Classification Plugin” automatic vegetation classifier of QGIS software. Five habitat types were so classified: forests, shrubs, meadows, arable land, and satellite image mistakes. Village areas were allocated separately. The average shares of the largest habitat types for over 20 years on the nesting sites included meadows (51.1%) and shrubs (16%). From 2001 to 2020, a habitat change in the breeding area was observed: forest and shrub areas decreased, while the meadow, village and arable land areas increased. An analysis of the effect of habitat types on the nesting success was evaluated by means of the “gbm” and “dismo” modules in the R program using the Boosted Tree classifier algorithm. The presence of such habitat types in the nesting area as villages (24.2%), shrubs (19.3%), meadows (11.8%), and habitat heterogeneity (11.6%) most strongly affected the probability of owl successful nesting. That owls tend to use anthropogenic and agricultural territories is associated with the diversity, easy foraging and more effective protection from predators during the breeding season.
EVALUATION OF THE INFLUENCE OF HUMAN ACTIVITY ON THE SPATIO-TEMPORAL DISTRIBUTION PATTERNS OF LARGE CARNIVORES USING CAMERA TRAPS IN THE CENTRAL FOREST NATURE RESERVE
Authors: Ogurtsov S. S. , Zheltukhin A. S.
Published: April 2024

The possibilities for assessing the impact of human activity on mammals using camera traps are demonstrated in Russia for the first time, three species of large carnivores taken as examples: the brown bear (Ursus arctos), the Eurasian lynx (Lynx lynx), and the grey wolf (Canis lupus). To do this, a single-season species-level occupancy analysis and an analysis of daily activity were utilized. The study was carried out in 2022 in the territory of the Southern Forestry of the Central Forest Nature Reserve, western European Russia during the period of maximum human activity (July–August). The relative abundance indices of pedestrians, all-terrain vehicles, as well as the distance to villages were used as variables. The maximum predicted occupancy was found for the lynx (ψ = 0.97), vs the minimum for the wolf (ψ = 0.78). The detection probability was the highest for the brown bear (p = 0.18), in contrast to both lynx and wolf (0.08 each). For the lynx and the brown bear, large degrees of overlap of daily activities with pedestrians (\({{\hat {\Delta }}_{4}}\) = 0.57 and \({{\hat {\Delta }}_{4}}\) = 0.47) and all-terrain vehicles (\({{\hat {\Delta }}_{4}}\) = 0.51 and \({{\hat {\Delta }}_{4}}\) = 0.41) were noted, in contrast to those for the wolf (\({{\hat {\Delta }}_{1}}\) = 0.37 and \({{\hat {\Delta }}_{1}}\) = 0.35, respectively). Human activity had no noticeable effect on either the spatial or temporal distribution patterns of the brown bear and lynx. In contrast, the wolf showed a shift in both patterns away from human activity. The combined use of occupancy and daily activity analyses based on data from camera traps is the optimal method for assessing and regulating the human activity in particularly strictly protected natural areas.
Two new species of oribatid mites (Acari, Oribatida) from Mexico
Authors: Ermilov S. G.
Published: April 2024

Based on adults collected from leaf litter of a secondary semi-evergreen tropical forest in Mexico, two new oribatid mites (Oribatida) are described: Epilohmannia mexicana sp. n. (Epilohmanniidae) and Plateremaeus bifurcatus sp. n. (Plateremaeidae).
Double Pseudopolymeric [Au{S2CN(CH2)5}2]2[Ag2Cl4]·CH2Cl2 Complex: Preparation, Principles of Supramolecular Self-Assembly, Thermal Behavior, and Biological Activity against Mycolicibacterium smegmatis Strain
Authors: Korneeva E. V. , Lutsenko I. A. , Bekker O. B. , Isakovskaya K. L. , Ivanov A. V.
Published: April 2024

The double Au(III)–Ag(I) complex crystallizing as the solvated form of [Au{S2CN(CH2)5}2]2[Ag2Cl4]· CH2Cl2 (I) was obtained by the reaction of silver(I) N,N-pentamethylenedithiocarbamate with a solution of Na[AuCl4]/5.15 M NaCl. According to X-ray diffraction data (CIF file CCDC no. 2062810), the structural units of the compound are nonequivalent [Au{S2CN(CH2)5}2]+ cations (noncentrosymmetric A and centrosymmetric B and C in a ratio of 2 : 1 : 1), cyclic tetrachlorodiargentate(I) anions, [Ag2Cl4]2–, and solvating CH2Cl2 molecule. The latter is retained in the structure due to two nonequivalent C–H···Cl hydrogen bonds formed with the cyclic [Ag2Cl4]2– anion involving its terminal Cl(1) and bridging Cl(2) chlorine atoms. The supramolecular self-organization of I is based on a system of multiple Ag···S and Cl···S secondary interactions that сombine the ionic structural units of the complex into an intricate two-dimensional pseudopolymer layer. A study of the thermal behavior of I by simultaneous thermal analysis established the conditions for quantitative reduction of bound gold(III) and silver(I). The studied Au(III)–Ag(I) compound exhibits a high level of biological activity against the nonpathogenic M. smegmatis strain.
Heteroleptic Zinc Catecholate Complexes with N-Donor Ligands
Authors: Maleeva A. V. , Trofimova O. Yu. , Yakushev I. A. , Aysin R. R. , Piskunov A. V.
Published: April 2024

New heteroleptic zinc catecholate complexes based on 3,6-di-tert-butyl-o-benzoquinone and containing metal-coordinated N-donor ligands (2,2'-bipyridine and phenanthroline) were prepared by ligand exchange. According to X-ray diffraction data, both complexes were dimers with multiple intermolecular π–π interactions between the aromatic moieties of neighboring molecules (CCDC nos. 2222704 (I), 2222705 (II)). The electronic transmission spectra of crystalline samples of I and II and their solutions show broad absorption bands in the visible region with a maximum at about 500 nm.
Specific Features of the Oxidative Addition of Triarylantimony to Dihydroxybenzoic Acids
Authors: Sharutin V. V. , Sharutina O. K. , Belov V. V.
Published: April 2024

Tris(2-methoxyphenyl)antimony and tris(3-fluorophenyl)antimony react with 2,3-dihydroxybenzoic and 3,4-dihydroxybenzoic acids in the presence of tert-butyl hydroperoxide to form carboxycatecholato-О,О'-triarylantimony. Under similar conditions, tris(4-fluorophenyl)antimony reacts with 2,3-dihydroxybenzoic acid to form tris(4-fluorophenyl)antimony dicarboxylate. Structural features of the reaction products are determined by X-ray diffraction (XRD) (CIF files CCDC nos. 2126358 (I), 2124252 (II·H2O·Et2O), 2121839 (III·0.5С6Н6), and 2131083 (IV·2.5С6Н6).
Novel Cobalt Bis-o-semiquinonato Complexes with Bidentate N-Donor Ligands
Authors: Zolotukhin A. A. , Bubnov M. P. , Rumyantsev R. V. , Fukin G. K. , Bogomyakov A. S. , Cherkasov V. K.
Published: April 2024

Two new cobalt bis-o-semiquinonato complexes, (Pyz-Phen)Co(3,6-DBSQ)2 (I) and (Bpyz)Co(3,6-DBSQ)2 (II) (Pyz-Phen = pyrazino[2,3-f][1,10]phenanthroline, Bpyz = bipyrazine, 3,6-DBSQ = 3,6-di-tert-butyl-o-benzoquinone radical anion), were synthesized. According to X-ray diffraction data, both complexes have a trigonal-prismatic geometry of the inner coordination sphere. The distribution of C–O and Co–O bond lengths, which reflects the valence state of the metal and the ligands, indicates that the complexes are formed by cobalt(II) surrounded by two semiquinone radical anions. The results of magnetochemical measurements show that the pyrazino[2,3-f][1,10]phenanthroline complex is a derivative of low-spin divalent cobalt, whereas its bipyrazine structural analogue is a high-spin cobalt(II) derivative.
Abnormally Long Absence of Polar Stratospheric Clouds in the Arctic in Midwinter According to Satellite Observations
Authors: Zuev V. V. , Savelieva E. S. , Sidorovsky E. A.
Published: April 2024

Polar stratospheric clouds (PSCs) play a significant role in ozone depletion in the polar regions, acting as “surfaces” for heterogeneous reactions proceeding with the release of photochemically active molecular chlorine from late winter to early spring. Moreover, during the winter, chlorine “reservoirs”, which are reagents for heterogeneous reactions, accumulate on PSC particles. When PSC particles are destroyed in midwinter, the accumulation of chlorine compounds is interrupted, and from late winter to spring, ozone depletion is not observed even under conditions of the strong polar vortex, in the presence of newly formed PSCs. Using the vortex delineation method, we studied the dynamics of the Arctic polar vortex in the winters of 1984/1985, 1998/1999, 2001/2002, 2012/2013 and 2018/2019, as the reasons for the abnormally long absence of PSCs in the Arctic in midwinter, when they existed in January within no more than 5 days according to satellite observations. The PSC melting in these years was observed when the dynamic barrier of the polar vortex weakened due to a local decrease in wind speed along the vortex edge below 20 m/s in the lower stratosphere, which was recorded throughout almost the entire January. The described cases are the only examples of unusual weakening of the Arctic polar vortex in midwinter for the period from 1979 to 2022.
Characteristics of the Wind Field in the Upper Troposphere as Indicators of Climatic Variability
Authors: Nerushev A. F. , Visheratin K. N. , Ivangorodsky R. V.
Published: April 2024

The paper presents the results of a study of spatiotemporal variability of the characteristics of the wind field in the free atmosphere of the Northern Hemisphere in the SEVIRI radiometer field of view of European geostationary meteorological satellites of the second generation Meteosat 8–Meteosat 11 in the time interval 2007–2021. It is noted that the maximum wind speeds, as well as the maximum average monthly and seasonal anomalies of the wind speed module, are observed over the Atlantic. A feature of the temporal variability of the area-averaged wind speed modulus is revealed, which consists in a change in the sign of the trend at the turn of 2015–2017 from positive to negative. At the same time, positive linear trends in the time intervals from 2007 to the points of a change in the sign of the trend over the Atlantic, the entire region under consideration and Eurasia, including the European territory of the Russian Federation, are significantly different from zero with a probability of more than 95%. And the negative trend is significant only over the Atlantic. A high correlation was noted in the area of seasonal wind speed variations with the area of Arctic sea ice and temperature characteristics of the troposphere at levels of 500 and 200 hPa. Based on the analysis of the relationship between wind speed variability and the main climatic characteristics and large-scale atmospheric processes, a scheme is proposed for the effect of the accelerating reduction in the area of Arctic sea ice associated with global warming on wind speed in the free atmosphere.
Broadband sound source hologram formation and application in oceanic waveguides
Authors: Kuz’kin V. M. , Pereselkov S. A.
Published: April 2024

The physical and mathematical basics of holographic interferometry of broadband signal processing in oceanic waveguides are presented. The application of holographic processing for localization of low-noise sources is considered.
Surface cracks and texture influence on residual stresses in tungsten after plasma exposure
Authors: Balash I. I. , Kazantsev S. R. , Shmakov A. N. , Piminov P. A. , Borin V. M.
Published: April 2024

Tungsten samples have been studied after being irradiated by the BETA facility’s electron beam for the purpose of simulating plasma heat loads in a fusion reactor’s vacuum chamber. X-ray diffraction methods were used for residual stress measurement in the irradiated samples, some of which were manufactured according to the ITER specifications.
SR-XRFA in research of Siberian shrubs of the urban ecosystem
Authors: Lyakh E. M. , Khramova E. P. , Lugovskaya A. Yu. , Rakshun Ia. V. , Sorokoletov D. S.
Published: April 2024

A study has been first made of the element composition of the plants of three species of two genus Spiraea and Myricaria, growing in the Novosibirsk Urban Ecosystem and the soil samples from their habitat by method of Xray fluorescence analysis using synchrotron radiation (SR-XRFA). The most severe heavy metal pollution in urban conditions was noted in Myricaria bracteata plants. The species Spiraea chamaedryfolia, the most tolerant to pollution in urban conditions may be recommended as a standard and M. bracteata is recommended as a bioindicator plant for environmental pollution. The data obtained on the elemental composition of plant samples and soils may be included in the databases.
Superconducting undulator cryogenic system based on indirect cooling
Authors: Khrushchev S. V. , Tsukanov V. M. , Shkaruba V. A. , Mezentsev N. A. , Safronov A. N.
Published: April 2024

The indirect cooling cryogenic system of the superconducting undulator with 15.6 mm period and 8 mm magnetic gap is described in this article. Nitrogen heat pipes are used in this system to accelerate cooling down process. The cooling down without liquid helium was tested (only helium gas was used). The cryogenic system design is described and process of cooling down is presented.
Superconducting undulator with period of 15.6 mm and magnetic field of 1.2 T
Authors: Shkaruba V. A. , Bragin A. V. , Volkov A. A. , Erokhin A. I. , Zorin A. V. , Kazantsev F. P. , Kanonik P. V. , Mezentsev N. A. , Safronov A. N. , Sedov A. A. , Tarasenko O. A. , Khrushchev S. V. , Tsukanov V. M.
Published: April 2024

A superconducting undulator with a period of 15.6 mm and a field of 1.2 T created at Budker INP SB RAS was tested in its own cryostat based on indirect cooling with zero helium consumption. The report presents the main characteristics and design features of the magnetic and cryogenic systems of this insertion device. The results of measurements of the magnetic field are presented and the features of the operation of the cryogenic system in various modes are shown.
Hall probe magnetic measurements of the superconducting undulator
Authors: Tsukanov V. M. , Khrushchev S. V. , Volkov A. A. , Zorin A. V. , Kanonik P. V. , Mezentsev N. A. , Shkaruba V. A.
Published: April 2024

The superconducting undulator with 15.6 mm period and 1.2 T magnetic field described in this article has 8 mm magnetic gap. The magnetic measurements system in such conditions required using of special tube (ante-chamber) inside of undulator magnetic gap. The thermal insulation between cold magnet and this measurement tube does not allow to have stable temperature along this tube length. The temperature range into this tube is 70–300 K. Hall probe measurements in this case are a rather complicated problem. The features of the method of measurement and processing of results are described.
Multiparticle events in cosmic rays registered by means of drift chambers
Authors: Vorobev V. S. , Zadeba E. A. , Nikolaenko R. V. , Troshin I. Yu.
Published: April 2024

Results of the analysis of multiparticle events in cosmic rays in coordinate-tracking setups on the drift chambers CTUDC and ProtoTREK are presented. The analysis of the ProtoTREK data show that it is possible to reconstruct events with a density of up to 15 particles per square meter. The estimation of the energies of primary cosmic rays responsible for the generation of muon bundles detected in the CTUDC was made.
Phase formation and structure in the solid solutions of the (1 – х)BiFeO3–x/2PbFe1/2NB1/2O3–x/2PbFe2/3W1/3O3 system
Authors: Glazunova E. V. , Shilkina L. A. , Nagaenko A. V. , Verbenko I. A. , Reznichenko L. A.
Published: April 2024

The solid solutions of the (1 – х)BiFeO3–x/2PbFe1/2Nb1/2O3–x/2PbFe2/3W1/3O3 system in the concentration range 0.05 ≤ х ≤ 0.50 were produced by solid state method and sintering using conventional ceramic technology. In the range 0.25 x 0.35, a morphotropic phase transition from the rhombohedral phase to the cubic phase was found. The difference in symmetry when “scaling” the material is shown. The influence of PbFe1/2Nb1/2O3 and PbFe2/3W1/3O3 on the grain structure formation was established.
A novel method for the preparation of nanosized tysonite phases
Authors: Zakalyukin R. M. , Levkevich E. A. , Grebenev V. V. , Glazunova T. Yu. , Buzoverov М. E. , Kumskov A. S.
Published: April 2024

Nanopowders of tysonite solid solutions La1 – xBaxF3 – x (х = 0–0.07) were synthesized for the first time by thermal decomposition of lanthanum and barium trifluoroacetates. The samples obtained were characterized by electron microscopy, X-ray phase analysis, and impedance spectroscopy. Nanoparticles are crystalline and have characteristic sizes of 20–75 nm. The ionic conductivity of solid solutions in the range up to 300°C is determined by surface phenomena at the particle boundaries.
FeNi nanowires as a promising filler for magnetic sensitive gel
Authors: Filippova Y. A. , Bizhetskiy A. S. , Papugaeva A. V. , Panov D. V. , Bedin S. A. , Shibaev A. V. , Philippova O. E. , Razumovskaya I. V.
Published: April 2024

A method for obtaining iron-nickel nanowires 5 μm in length and 100 nm in diameter using template synthesis based on track membranes is described. The actual length of the obtained FeNi nanowires was estimated by scanning electron microscopy, and their elemental composition and structure were studied. The possibility of using the synthesized nanowires to obtain magnetic polymer gels is described.
Neutron facilities of the compact neutron source DARIA: parameters and features
Authors: Grigoriev S. V. , Kovalenko N. A. , Pavlov K. A. , Moskvin E. V. , Syromyatnikov V. G. , Grigorуeva N. A.
Published: April 2024

The compact neutron source DARIA based on a linear proton accelerator is designed to create neutron beams for a diffractometer, a reflectometer, and a small-angle scattering setup. The experimental setups are optimized in terms of the range of momentum transfer, instrumental resolution, geometric dimensions, as well as in terms of the repetition rate and duration of neutron pulses.
Features of the crystal structure of 2D honeycomb frustrated magnet Li2Ni2TeO6
Authors: Susloparova A. E. , Fokin N. S. , Kurbakov A. I.
Published: April 2024

Using neutron powder diffraction at a temperature of 35 K, slightly above the Neel temperature, the features of the crystal structure of two samples of layered honeycomb oxides of the same stoichiometric composition Li2Ni2TeO6 synthesized from precursors, Na2Ni2TeO6 and K2Ni2TeO6, were determined. They have a similar crystal structure, hexagonal space group P63/mcm, structure type P2, but there is a significant difference in the distances between the layers. Both Li2Ni2TeO6 samples crystallize into the orthorhombic space group Cmca, with minor differences in the unit lattice parameters. If Li2Ni2TeO6 from the potassium precursor is single-phase, then the compound from the sodium precursor contains 16 wt % of an additional phase with the same Li2Ni2TeO6 stoichiometry, but more deformed with monoclinic distortions described by the С2/m space group.
Optical pumping of rubidium isotopes by Cr3+:BeAl2O4 laser radiation
Authors: Antipov A. A. , Putilov A. G. , Shepelev A. E.
Published: April 2024

We consider the use of a Cr3+:BeAl2O4 laser in free-running operating as a source of emission for optical pumping rubidium alkali metal vapors. The use of dispersive elements in the composition of the laser cavity makes it possible to smoothly tune lasing wavelength and to realize generation at wavelengths corresponding to the D1 and D2 lines of the 85Rb and 87Rb isotopes. Optical pumping of rubidium isotopes by laser emission with wavelengths of 795 and 780 nm, respectively, is experimentally implemented, and their fluorescence is demonstrated. The question of using a wavelength-tunable laser in the method of spin-exchange optical pumping of noble gases is discussed.
Features of magnetic ponderomotive interaction of magnetized to saturation profiled magnetic films
Authors: Piatakov M. A. , Akimov M. L. , Polyakov P. A.
Published: April 2024

We calculated the force of magnetic ponderomotive interaction between two micromagnetic films having a corrugated semi-cylindrical surface represented as a lattice of half magnets in the form of long cylindrical rods. It is found that the lattice interaction force is substantially determined by the distance between the half-cylinders and, depending on this parameter, can manifest itself as an attraction or repulsion force.
Evolution of the domain structure in a FeNiCo nanowire under the action of a magnetic field
Authors: Shevtsov V. S. , Kaminskaya T. P. , Polyakov O. P. , Polyakov P. A.
Published: April 2024

Based on the experimentally discovered domain structure and its evolution in an external magnetic field in thin films of FeNiCo composition with uniaxial anisotropy, a theoretical model of the magnetization distribution is proposed. The analytical dependence of the domain size on the magnitude of the magnetic field is obtained. The change in magnetoresistance because of the evolution of the magnetic domain structure is calculated.
Some features of electrostatics of uncharged thin-walled cylindrical and conical conductors
Authors: Savin V. P. , Koksharov Yu. A.
Published: April 2024

It is shown that for thin-walled uncharged cylindrical and conical conductors in the field of a point charge, there is an electrostatic “repulsion effect” previously predicted for conductors with a non-through cavity. Axial symmetry of the cavity is not necessary for the manifestation of the effect. This proves the possibility of a “repulsion effect” for conductors with different types of cavities.
Modification of the local structure and properties of zinc-substituted hexagonal barium ferrites for microwave devices under magnetic pulsed processing
Authors: Shipko M. N. , Korovushkin V. V. , Stepovich M. A. , Trukhanov A. V.
Published: April 2024

The results of studies of the effect of magnetic pulse treatment on the local structure and magnetic properties of substituted ferrite for microwave devices are presented. The change in the magnetic properties of ferrites as a result of exposure to them by pulses of a weak magnetic field indicates the possibility of controlling the parameters of ferrites by means of a magnetic field and thereby influence the resonant characteristics of microwave devices based on them.
Temperature measurements based on a composite of nanosized phosphors [Ru(dipy)3]2+@SiO2 and NaYF4:Eu,Gd
Authors: Nurtdinova L. A. , Leontyev A. V. , Zharkov D. K. , Shmelev A. G. , Zairov R. R. , Mereshchenko A. S. , Fedorenko S. V. , Mustafina A. R. , Nikiforov V. G.
Published: April 2024

The results of temperature testing of the two-phosphor composite ([Ru(dipy)3]2+@SiO2 and NaYF4:Eu,Gd) are presented in order to assess the prospects for its further application as a luminescent thermal sensor in the range of 200–310 K. By calibrating the temperature dependences of individual spectral components of the emission produced under irradiation by cw laser at 405 nm, the possibilities of temperature sensing by means of ratiometric method are analyzed in four different spectral ranges of the composite’s visible luminescence.
Current density in a nonlinear medium of carbon nanotubes under the action of diffraction free laser pulses
Authors: Dvuzhilova Yu. V. , Dvuzhilov I. S. , Konobeeva N. N. , Belonenko M. B.
Published: April 2024

Based on the spatial distribution of the electric field strength of diffraction-free extremely short Bessel and Airy–Bessel optical pulses, patterns of the temporal evolution of the current density in a nonlinear array of semiconductor carbon nanotubes with a spatial modulation of the refractive index are constructed. The dependences of the maximum value of the current density on the modulation parameters of the refractive index of the medium are established.
Simulation of the dynamics of laser beams in an array of carbon nanotubes using the hydrodynamic approach
Authors: Konobeeva N. N. , Trofimov R. R. , Belonenko M. B.
Published: April 2024

We simulated the propagation of a quasi-monochromatic laser beam in a medium with carbon nanotubes. Equations describing the dynamics of laser beams in an array of carbon nanotubes are obtained based on the hydrodynamic approach for the nonlinear Schrödinger equation. This equation is solved numerically using the smoothed particle method. The evolution of the beam is analyzed depending on the frequency of the electric field.
Non-resonant absorption of the X-band electromagnetic wave power in a narrow-gap PbS semiconductor at temperatures of 2.6–8 K in the range of magnetic fields 0–100 mT
Authors: Ulanov V. A. , Zainullin R. R. , Sinitsyn A. M. , Potapov A. A. , Shustov V. A.
Published: April 2024

Studies of magnetically dependent effects of nonresonant absorption of electromagnetic wave energy in the resonator of the X-band EPR spectrometer related to the superconductivity of metallic lead inclusions and microscopic structural defects in crystals of narrow-band semiconductors PbS1 – x and PbS1 – x:Mn have been performed. It is shown that nanoscale lead particles present in polycrystalline material PbS0.96 with a high content of sulfur vacancies at temperatures of 2.6–8 K manifest themselves as superconductors of the 2nd kind and demonstrate high thermomagnetic stability. It was found that in a single-crystal sample PbS0.996 with a significantly lower concentration of sulfur vacancies under the influence of the electric component of the microwave field in the resonator of the ESR spectrometer, non-periodic bursts of microwave power absorption associated with avalanches of Abrikosov vortices and demonstrating the absence of thermomagnetic stability of superconducting regions associated with defects in the crystal structure of the sample PbS0.996 are observed.
Development and Investigation of Carbon-Mineral Catalyst Based on Natural Clay and Tire Crush for Oxidative Decomposition of Nonionic Surfactants by Hydrogen Peroxide in Wastewater
Authors: Fidchenko M. M. , Alekhina M. B. , Beznosyuk A. N. , Varnavskaya A. D. , Mishchenko E. V.
Published: April 2024

Samples of a carbon-mineral catalyst based on natural clay and tire crumb for the reaction of oxidative decomposition of nonionic surfactants by hydrogen peroxide in wastewater have been developed and studied. The iron content in the samples varied in the range of 2.3–3.9 wt %. The effect of sample pyrolysis temperature in the range of 350–800°С on characteristics, the number and type of acid sites on the surface, and the ζ (zeta) potential of colloidal systems based on prepared samples was studied. Using model solutions under static and dynamic conditions, the effect of sample pyrolysis temperature on catalytic properties in the reaction of oxidative decomposition of H2O2 and nonionic surfactant (NS) nonoxynols N-9 by hydrogen peroxide was studied. The best result in the oxidation of nonoxynols N-9 with hydrogen peroxide was obtained in the presence of a carbon-mineral catalyst sample calcined at 650°C.