bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural, Opto-Physical, Photoluminescence, and Optical Limiting Properties of Polyvinyl (Pyrrolidone and Alcohol) Blend Film Doped with Co-Metal
Authors: Ali H Elhosiny.  , Khairy Y.  , Abdellahi M. O.  , Sayed M. A.  , Abd-Rabboh H S. M.  , Awwad N. S.  , Shkir M.  , Abdel-Aziz M. M.
Published: January 2023

The optical properties of polyvinyl (pyrrolidine and alcohol) and PV(P/A) blend polymer have been improved using Co-metal as a filler for optoelectronic and optical shielding applications. The casting technique of solutions was used in order to prepare composite films with different Co-ratios (x: 0-18.5). XRD, FT-IR, SEM, and UV-visible spectrophotometry were operated to study the structure, morphology, and optical features of the flexible plain blend and composite films. The semi-crystalline nature of the films was influenced by the filler ratio of nanoparticles. Homogenous dispersion with some agglomeration of Co-particles has been observed in the host blend matrix. Then again, a successful interaction between the host matrix and particles was ensured by the FT-IR spectroscopic and XRD measurements. The cut-off absorbance edge of composite films is red-shifted from 200 nm (host blend) to 228 nm. The indirect transition optical band gap was confirmed from the Tauc's and optical dielectric loss calculations. Its value goes back from 5.15 eV (plain blend) to 4.43 eV for 18.5 wt% Co-blend composite film. An improvement in the extinction coefficient, optical conductivity, and refractive index of the composite films was achieved compared with the plain blend. The non-linear parameters of the composites were also enhanced. Photoluminescence (PL) emission spectra of PV(P/A) blend films doped with various weight percentages of Co-metal were examined at a wavelength of 750 nm. The optical shielding performance of the prepared composites is recommended for laser cut-off. Furthermore, the ability to tailor the optical properties of blend film makes it more effective for various applications including optical devices, non-linear optoelectronics, and reflective coating. Keywords: extinction coefficient, PV(P/A) polymer blend, transition band gap, photoluminescence, NL optical parameters, optical shielding.
Nonaffine deformations and local elastic properties of amorphous nanostructures
Authors: Semenova A. A.  , Konyuh D. A.  , Beltyukov Ya. M.
Published: January 2023

Nonaffine deformations of amorphous nanostructures have been studied within the framework of a random matrix model. Near the boundary between amorphous and crystalline solids, nonaffine deformations of amorphous solids lead to the formation of a boundary region with altered effective elastic properties. It is shown that the thickness of the boundary region has the same order of magnitude as the scale of non-affine deformations. Keywords: nonaffine deformations, amorphous bodies, random matrices. Keywords: nonaffine deformations, amorphous bodies, random matrices.
Thermal properties of matter within the model of a two-phase system
Authors: Terehov S. V.
Published: January 2023

It has been established that the relations of the two-phase system model are applicable for describing the thermal properties of solids with disordered and crystalline structures. It is shown that the model adequately describes the curves of isochronous and isothermal crys-tallization of amorphous alloys and thermal changes in the volume of their samples. It is also suitable for calculating the heat capacities and thermal expansion coefficients of sub-stances that are diverse in their physical nature. Keywords: two-phase system, thermal expansion coefficient, heat capacity, amorphous alloys, com-plex oxides.
Thermoelectric coefficient of nanoscale transition metals films
Authors: Boltaev A. P.  , Pudonin F. A.  , Sherstnev I. A.  , Egorov D. A.
Published: January 2023

We study the thermoelectric coefficient of island transition metal films as a function of temperature and film thickness. We show that the thermoelectric coefficient value is determined by the properties of the film metal element and is different for different metals at dimensionless conductance value g>1 and g<1. The main factor in the behavior difference of the thermoelectric coefficient as a function of temperature is the individual characteristics of the Fermi surface of each metal. Dependence of the thermoelectric coefficient on the film thickness is also determined by the Fermi surface shape change. Keywords: Island film, Thin film, Thermopower, Thermoelectric coefficient, Conductivity.
X-ray photoelectron spectra of oxygen molecules adsorbed on ytterbium nanofilms
Authors: Mittsev M.A.  , Kuzmin M.V.
Published: January 2023

The adsorption of oxygen molecules on ytterbium nanofilms of various thicknesses has been studied by X-ray photoelectron spectroscopy and contact potential difference measurements. It has been established that the maximum number of O2 molecules that can be adsorbed on the films increases with the film thickness. Such behavior is observed at thicknesses less than 10 monolayers. This size effect is ultimately due to the fact that an indispensable condition for the adsorption process at high doses of oxygen is the electron transfer from the film to molecules, and that the maximum number of electrons that can participate in this process depends on the nanolayer thickness. Localization of a negative charge on O2 molecules occurring in at high doses of adsorbate, causes a weakening of the bonding of 1s-electrons in these molecules. In addition, it should lead to a weakening of the bond between oxygen atoms in O2 molecules. Keywords: oxygen, ytterbium, adsorbed molecules, nanofilms, X-ray photoelectron spectroscopy, work function.
Features of the Band Structure and the Mechanism of Lateral Photoconductivity in Hybrid Structures T/SiO-=SUB=-2-=/SUB=-/Si(T=Fe,Fe-=SUB=-3-=/SUB=-O-=SUB=-4-=/SUB=-, TiO-=SUB=-2-=/SUB=-)
Authors: Pisarenko T. A.  , Korobtsov V. V.  , Dimitriev A. A.  , Balashev V. V.  , Zheleznov V. V.
Published: January 2023

This paper presents the results of studying the lateral photovoltaic effect in hybrid structures based on SiO2/Si depending on the nature of the conductivity of the material of the upper layer (Fe is a metal, Fe3O4 is a semimetal, TiO2 is a semi-insulator). It is shown that this effect is observed in hybrid structures in which a depleted region with a significant band bending is formed at the SiO2/Si interface. Theoretical calculations of the lateral photovoltage based on the energy parameters of the band diagrams showed that an increase in the sensitivity of the lateral photoelectric effect is associated with an increase in the built-in potential at the SiO2/Si interface. It has been established that the transient characteristics of the lateral photoelectric effect, such as the rise and fall times of the photovoltage signal, are determined by the configuration of the RC-filter in the near-contact region, which depends on the conductivity of the upper layer. It is shown that, in the case of the lateral photovoltaic effect, current transfer occurs along the inversion layer, and the upper layer serves to generate a quasi-p-n junction at the SiO2/Si interface. Keywords:lateral photovoltaic effect, hybrid structures, iron, magnetite, titanium dioxide.
Nanocomposites based on thermoplastic aromatic polyimides with cerium dioxide nanoparticles: dielectric spectroscopy
Authors: Nikonorova N. A.  , Kononov A. A.  , Kastro R. A.  , Gofman I. V.  , Nikolaeva A. L.  , Abalov I. V.  , Yakimansky A. V.  , Baranchikov A. E.  , Ivanov V. K.
Published: January 2023

The molecular mobility of films of thermoplastic aromatic polyimides and nanocomposites based on them with 3% cerium dioxide has been studied by dielectric spectroscopy. Three relaxation regions of dipole polarization were found for the initial polyimides, γ and β (in the glassy state) and α (transition to a highly elastic state).The introduction of 3% cerium dioxide into the matrix polyimide leads to the suppression of the γ process and to the appearance in the spectra of nanocomposites, along with the β process, of the second relaxation process β1.The temperature dependences of the relaxation time for the γ, β and β1 processes are linear and correspond to the Arrhenius equation, and for the α process are curved and described by the Vogel-Tamman-Hesse equation. The interpretation of the molecular mechanisms of the observed processes is given. Keywords: Polymer-inorganic nanocomposites, aromatic polyimides, nanoscale cerium dioxide, dielectric characteristics, transition temperatures, molecular mechanisms of dielectric processes.
Two- and three-component alloys nanowires: correlation of structural and magnetic properties
Authors: Khayretdinova D. R.  , Doludenko I. M.  , Panina L. V.  , Zagorsky D. L.
Published: January 2023

Several types of nanowires (NWs) made of alloys of various compositions obtained by the method of matrix synthesis based on track membranes have been studied. Electrolytes were selected to obtain NWs of the desired composition. The control of electrodeposition by chronoamperograms made it possible to systematically change the geometric parameters and morphology. The topographies of the resulting NW arrays and their elemental composition were studied using electron microscopy with an X-ray spectral analyzer. The magnetic properties of the samples were studied on a vibrating magnetometer. The structures of binary alloys were studied: for NWs of FeCo alloys, the dependence of the coercive force on the composition was studied. The obtained dependence has two maxima --- at an equiatomic composition and at a cobalt content of about 90%. For Fe0.3Co0.7 NWs, a sharp increase in the coercive force with decreasing diameter is shown. It is assumed that this effect is due to the formation of single-domain crystallites, the processes of magnetization reversal of which are associated with a uniform rotation of the magnetization. For NWs made of FeNi alloys, the influence of the aspect ratio on the coercive force has been proved. Ternary alloys of the FeCoCu system have been studied: it has been shown that the addition of copper significantly increases the coercive force, which reaches a maximum at a copper content of about 5%. The obtained X-ray data suggest that the effect of an increase in the coercive force is associated with the formation of fine-grained inclusions based on copper, which lead to effective deceleration of the domain walls. The data obtained expand the range of possibilities for controlling the magnetic properties of NW arrays obtained by the method of matrix synthesis. Keywords: nanowires, matrix synthesis, microscopy, elemental analysis, magnetic properties, coercive force. Keywords: nanowires, matrix synthesis, microscopy, elemental analysis, magnetic properties, coercive force.
Superconducting spin-valve effect in heterostructures with ferromagnetic Heusler alloy layers
Authors: Kamashev А. А.  , Garif’yanov N. N.  , Validov A. A.  , Fominov Ya. V.  , Garifullin I. A.
Published: January 2023

The transport properties of two types of spin valves are analyzed, in which the Heusler alloy Co2Cr1-xFexAly was used as one of the two ferromagnetic layers in the F1/F2/S structures. The Heusler alloy layer was used: 1) as a weak ferromagnet, in the case of the F2 layer; 2) as a halfmetal, in the case of the F1 layer. In the first case, a large classical effect of the superconducting spin valve Delta Tc was obtained, which was facilitated by a significant triplet contribution to the effect of the superconducting spin valve Delta Tctrip. In the second case, a gigantic effect value Delta Tctrip was found reaching 0.5 K. Keywords: superconductivity, ferromagnetism, thin films, superconducting spin valve.
Structure, Morphology, Transport, and Mechanism of Oxygen Loss in YBa-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-7-delta-=/SUB=- Thin Films Obtained by Pulsed Laser Deposition with Velocity Filtration in Erosion Plume
Authors: Il'in A.I.  , Ivanov A.A.  , Egorov V.K.
Published: January 2023

We report the study of YBa2Cu3O7-delta films, synthesized on SrTiO3(100) substrates by pulsed laser deposition with velocity filtration, using X-ray diffractometry, transport measurements, and scanning electron microscopy. We have revealed the dependence of the structure of 100-200 nm thick YBa2Cu3O7-delta films on deposition time and velocity of particles in erosion plume, set by velocity filter. After deposition, the films, or their part, close to the substrate, consisted of 3-10-nm crystals with oxygen index delta=0.08, the same as in the target. For deposition time from 10 to 60 min, we observed the growth of regular pyramids with triangular and quadrangular bases from 20 to 500 nm in size at the base and spiral pyramids with polygonal bases on the film surface. The maximum oxygen loss up to delta=0.35 and T(R=0) up to 77.4 K coincided with the appearance of spiral pyramids up to 100 nm-high. These findings evidence in favor of oxygen depletion of the top layers of YBa2Cu3O7-delta thin films through the formation and growth of oxygen-deficient pyramids on their surface. The oxygen index in the range of delta=0.08-0.15 in both nanocrystals and regular pyramids of 20-300 nm in size provided T(R=0)=84-87 K and the width of superconducting transition Delta T=2.5-3.5 K. Keywords: pulsed laser deposition, surface morphology, film transport properties, film evolution, SrTiO3.
Particularities of spin wave propagation in magnonic crystals with nonuniform magnetization distribution across the thickness
Authors: Sakharov V. K.  , Khivintsev Y. V.  , Dudko G. M.  , Dzhumaliev A. S.  , Vysotskii S. L.  , Stognij A. I.  , Filimonov Yu. A.
Published: January 2023

With the help of micromagnetic modeling, we considered particularities of dispersions and amplitude-frequency response of spin waves in a magnonic crystal (MC) formed by etching an array of grooves in the surface of yttrium iron garnet film having linear distribution of magnetization across the thickness from 1.7 kG at the upper surface till 2.02 kG at the bottom. For the geometry of surface magnetostatic spin waves (MSSW), it is shown that nonuniformity of magnetization distribution across the thickness leads to the appearance of frequency regions in the MC spectrum where MSSW propagation is unidirectional and, as the consequence, does not have Bragg resonances. It was also demonstrated that the MC spectrum is determined by the choice of surface used for the formation of the array of grooves. Keywords: spin wave, micromagnetic modelling, film of yttrium iron garnet, magnonic crystal.
Dipole-dipole interaction weakening in ensembles of cobalt microspheres with a nonmagnetic core
Authors: Komogortsev S. V.  , Chekanova L. A.  , Shabanova O. V.  , Shabanov A. V.  , Nemtsev I. V.  , Neznakhin D. S.  , Denisova E. A.  , Felk V. A.  , Mohov A. A.  , Iskhakov R. S.
Published: January 2023

Magnetic microspheres with nonmagnetic acrylic glass core were fabricated using electroless deposition. There are favorable conditions for magnetic flux closure within each particle. As a result, the dipole-dipole interaction in the powder of such microspheres is reduced drastically. This is the key difference between powders of magnetic microspheres and powders of full magnetic spherical particles witch behavior is significantly affected by the dipole-dipole interaction. The magnetic hysteresis in the cobalt microspheres with nonmagnetic core is significantly large then in the full cobalt particles produced using the same technique. Keywords: Magnetic microspheres, magnetic dipole-dipole interaction.
Formation of skyrmion states in ion-irradiated CoPt thin films
Authors: Kalentyeva I. L.  , Vikhrova O. V.  , Danilov Yu. A.  , Zdoroveishchev A. V.  , Zdoroveishchev D. A.  , Dorokhin M. V.  , Dudin Yu. A.  , Timiryazeva M. P.  , Timiryazev A. G.  , Sadovnikov A V.  , Yunin P. A.
Published: January 2023

The possibilities of controlled exposure to ion irradiation (He+ with an energy of 20 keV and a fluence in the range from 3·1014 to 3·1015 cm-2) as a method for modifying the magnetic properties and domain structure of Co0.35Pt0.65 thin ferromagnetic films have been studied. It was found that the ion irradiation causes a change in the Dzyaloshinskii--Moriya interaction constant and a change in the skyrmion density that correlates with it. This result shows the possibility of homogeneous ion irradiation as a way to control the micromagnetic structure, namely the process of formation of skyrmion states. Keywords: ferromagnetic thin films, ion irradiation, domain structure, magnetic force microscopy, Dzyaloshinskii-Moriya interaction, skyrmions.
Photovoltaic effect in a ferromagnet with spin-orbit coupling
Authors: Karashtin E.A.
Published: January 2023

The effect of the appearance of an electric current induced by the electromagnetic radiation at the interface of a ferromagnet and a non-magnetic material is calculated theoretically, taking into account the Rashba spin-orbit coupling. It is shown that the electric dipole transitions between the spin subbands of the conduction electrons of a ferromagnet due to the Rashba interaction lead to a photocurrent. This current has a resonance at a frequency corresponding to the energy of the exchange splitting of spin subbands. The resonance width is determined by the spin-orbit interaction constant. The estimates show the possibility of experimental observation of this effect in specially prepared multilayer systems. Keywords: Ferromagnet, exchange coupling, Rashba spin-orbit coupling, photovoltaic effect.
Micromagnetic modeling of Fe-=SUB=-3-=/SUB=-O-=SUB=-4-=/SUB=--Fe-=SUB=-3-x-=/SUB=-Ti-=SUB=-x-=/SUB=-O-=SUB=-4-=/SUB=- composites
Authors: Kharitonskii P. V.  , Anikieva Yu.A.  , Zolotov N. A.  , Gareev K. G.  , Ralin A. Yu.
Published: January 2023

Theoretical modeling of the magnetic properties of Fe3O4-Fe3-xTixO4 composites obtained by the sol-gel method with subsequent hydrothermal treatment has been carried out. The magnetization reversal fields and the number of particles in different magnetic states of an ensemble of two-phase particles with an infinitely thin boundary between the phases and a characteristic size varying in the range from 30 to 80 nm were calculated using the "magnetic rectangles" method. Hysteresis characteristics of an ensemble of chemically inhomogeneous magnetostatically interacting particles were obtained, consistent with experimental data. Keywords: Composites, magnetic granulometry, micromagnetism, two-phase particles, magnetostatic interaction.
Influence of elastic strains on the dipole spin wave spectrum in the lateral system of magnonic crystals with a piezoelectric layer
Authors: Grachev A. A.  , Mruczkiewicz M.  , Beginin E. N.  , Sadovnikov A. V.
Published: January 2023

In this work, we will reveal the regularities in the control of the dipole spin-wava spectra of in lateral heterostructures formed from two magnonic crystals with a piezoelectric layer placed on one of them. The electric field control of the spatial and transfer characteristics of dipole spin waves in lateral heterostructures is shown. Based on the finite element method, the influence of distributed elastic deformations on the magnitudes of internal magnetic fields in magnonic crystals is evaluated. Based on the results of numerical simulations, a physical interpretation of the transformation of the eigenmode spectrum of coupled magnon crystals is given. Keywords: spin waves, magnonics, straintronics, lateral structures.
Influence of transmission line parameters on the degree of matching of the generator with the SIS-mixer in the frequency range 200-700 GHz
Authors: Atepalikhin A. A.  , Khan F. V.  , Filippenko L. V.  , Koshelets V. P.
Published: January 2023

This work is aimed at the development, research and optimization of superconducting integrated circuits designed to match the impedances of a long Josephson junction generator, the so-called flux generator (FFO) and a superconductor--insulator--superconductor (SIS) detector in the sub-terahertz frequency range. Numerical calculations of integrated circuits designed to optimize the parameters of transmission lines are presented. The main parameters of the lines and their influence on signal propagation are determined. The results of optimization of integrated matching circuits in the range of 450-700 GHz are demonstrated. Keywords: integrated matching circuits, Josephson junctions, sub-terahertz generator.
Two-layer logic elements for classic cryogenic computers
Authors: Gurovich B. A.  , Prikhodko K. E.  , Kutuzov L. V.  , Goncharov B. V.  , Komarov D. A.  , Malieva E. M.
Published: January 2023

In this paper, for the first time, two-layer logic elements "NOT", "AND", "OR" and "NOR" were manufactured, in which the heating element of a nanowire in one layer is located in the place where the heated element of another superconductive nanowire is located in a nearest NbN layer. The film thickness of NbN (5-7 nm) was used to form of superconducting nanowires in different layers, and the thickness of Al2O3 (25 nm) was used as an interlayer dielectric. The paper shows the design of logic elements, and also demonstrates their operation in pulse mode. The use of multilayer structures without galvanic coupling between nanowires allows the design of multi-level logic devices. Keywords: NbN thin superconducting films, contactless switching of the superconductor state, cryoelectronic devices, integrated cryogenic resistors, logic elements "NOT"/"AND"/"OR"/"NOR", cryogenic computers.
Thin films of dielectric strontium iridates --- materials for superconducting cryoelectronics and spintronics
Authors: Kislinsky Yu. V.  , Konstantinyan K. I.  , Moskal I. E.  , Petrzhik A. M.  , Shadrin A. V.  , Ovsyannikov. G. A
Published: January 2023

The structural and electrophysical properties of epitaxial thin films of strontium iridate Sr2IrO4, which were obtained by laser ablation, have been studied. Data on the effect of deposition modes on the electrophysical properties of films are presented. Electronic transport models are discussed. Keywords: strontium iris, band conductivity, hopping conductivity.
Magneto-optical effects in composite hyperbolic metamaterials
Authors: Malysheva I.V.  , Sotnichuk S. V.  , Leontiev A. P.  , Napolskii K. S.  , Kolmychek I.A.
Published: January 2023

The results of experiments on measuring the magneto-optical response of hyperbolic metamaterials based on nanorods containing segments of gold and nickel are presented. A comparative analysis of the spectral behavior of the magnetic contrast in the geometry of Voigt and Faraday for samples was carried out, and a phenomenological description of phenomena was proposed. Keywords: magneto-optical effects, plasmons, metamaterials.
Investigation of local internal stresses under conditions of uniaxial compression of a quartz single crystal
Authors: Damaskinskaya E.E.  , Hilarov V.L.  , Drozdov S.O.
Published: January 2023

Based on the analysis of the time intervals between acoustic emission signals obtained in the process of uniaxial compression of a cylindrical sample of a quartz single crystal, local stresses were estimated. It is shown that a decrease in the ability of a material to monotonic stress relaxation with time can serve as a signal for the imminent breakdown of the material. Keywords: acoustic emission, kinetic concept of strength, local mechanical stresses.
Energy of electron-hole relative motion in exciton in external electric field in thick GaAs plate
Authors: Dmitriy K. Loginov  , Aleksey Donets
Published: January 2023

The dependence of the energy of the relative electron-hole motion in an exciton on the magnitude of applied electric field for various thicknesses of an ideal flat semiconductor plate is theoretically calculated. It is shown that the variation of the plate thickness significantly affects the dependence of the energy on the electric field. The effect should be observed in plates whose thickness exceeds the Bohr exciton radius by two orders of magnitude. Keywords: exciton, electrick field, thick plate.
Effect of gamma-induced defects on the activator glow in Lu-=SUB=-2-=/SUB=-SiO-=SUB=-5-=/SUB=- : Ce scintillator crystals
Authors: Islamov A. Kh.  , Ibragimova E. M.  , Kudratov Kh. N.  , Vildanov R. R.
Published: January 2023

Correlations were studied between the optical absorption (OA) spectra and the integral curves of thermal glow (TG) in 300-600 K after irradiation of Lu2SiO5 : Ce scintillation crystals with 60Co gamma-quanta (1.17 and 1.33 MeV) at the dose rate 1.1 Gy/s in the dose range 70-5·107 Gy at 310 K and their gamma-luminescence (GL). There are intrinsic defects caused by technological process, such as neutral VO5-centers with OA band at 193 nm and charged =Si-VO5 --- 213 nm, Lu1-F^+-Si --- 238 nm, Ce3+/Ce4+ --- 263 nm, and Ce3+/F --- 295 nm centers. Irradiation to the dose 5·104 Gy resulted in decreasing in VO5-center concentration, but did not influenced on others. While, after doses >5·104 Gy concentrations of all other mentioned defects grew. The observed recovery of OA at 193 nm and decrease in TG peak at 335 K with the ageing time (1, 3 and 10 hours) at 305 K, and also the correlated growth of OA at 238 nm and TG peak at 540 K after serial irradiations to doses from 70 to 2.3·106 Gy are due to releasing electrons from these color centers followed by radiative recombination at Ce1-centers. However Ce3+ GL yield decrease at 400 and 420 nm at doses >105 Gy is possible related with increasing concentrations of =Si-VO4, Lu1-F^+-Si and Ce3+/F centers, which compete with Ce1 ones in trapping electrons. Thus, the upper limit for stable Lu2SiO5 : Ce gamma-scintillation is 105 Gy. Keywords: Lu2SiO5 : Ce, color centers, gamma-induced luminescence, scintillation dose limit.
Influence of the Jahn-Teller effect on magnetic anisotropy in single crystals of fluorine hexahydrates of transition metals
Authors: Dubrovskiy A. A.  , Knyazev Y. V.  , Gerasimova Yu V.  , Udovenko A. A.  , Laptash N. M.
Published: January 2023

The magnetic properties of fluorine hexahydrates of transition metals have been studied. It was found that the presence of spin-orbit interaction of the transition metal ion has a significant effect on anisotropy of magnetic properties. Depending on the direction of interaction of the orbital magnetic moment of a transition metal cation with a crystal field easy direction of magnetization changes from the crystallographic b-axis to the c-axis. Keywords: single crystal, magnetic anisotropy, Jahn-Teller effect.
CaMoO-=SUB=-4-=/SUB=--NaGd(MoO-=SUB=-4-=/SUB=-)-=SUB=-2-=/SUB=- Solid Solutions: simulation of properties and local structure by the method of interatomic potentials
Authors: Dudnikova V. B  , Antonov D. I.  , Zharikov E. V.  , Eremin N. N.
Published: January 2023

Simulation of CaMoO4-NaGd(MoO4)2 solid solutions by the method of interatomic potentials is carried out. It is shown that solid solutions exist in the entire range of compositions and are close to ideal. Dependences on the composition of the lattice parameters and volume of the unit cell, density, bulk modulus, enthalpy, vibrational entropy and heat capacity are obtained. Temperature dependences of heat capacity and vibrational entropy are constructed. Analysis of the local structure and its changes depending on the composition of the Ca1-xNax/2Gdx/2MoO4 solid solution showed that in solid solution the interatomic distances of Gd-O are on average 2.62% less, and Na-O is 3.15% greater than the distances of Ca-O. In general, this leads to an increase in the lattice parameters and volume of the unit cell during the formation of Ca1-xNax/2Gdx/2MoO4 solid solutions compared to CaMoO4. Keywords: simulation, molybdates, the solid solutions, local structure.
Study of the piezoelectric properties of rubidium acid phthalate crystals by time-resolved three-crystal X--ray diffractometry
Authors: Ibragimov E. S.  , Kulikov A. G.  , Marchenkov N. V.  , Pisarevsky Yu. V.  , Blagov A. E.  , Kovalchuk M. V.
Published: January 2023

Using the method of time-resolved X-ray diffractometry in a three-crystal scheme, the lattice deformation of a rubidium biphthalate (C8H5RbO4) crystal was measured in an external electric field. Under the action of an external pulsed electric field along the [001] polar direction, the piezoelectric moduli d31,d32, and d33 were determined independently using three reflections 400, 070, and 004; the obtaind values are -32.8±0.6, 12.8±0.3, and 21.8±1.2 pC/N, respectively. A good agreement was found between the values of the piezoelectric moduli obtained in this work and the values obtained earlier by the quasi-static method. Keywords: piezoelectric effect, time-resolved X-ray diffractometry, three-crystal diffraction scheme, acid phthalate crystals, external electric field.
Preparation, structural features, elemental composition of and dielectric properties of a two-layer structure based on thin films of multiferroic BiFeO-=SUB=-3-=/SUB=- and ferroelectric (Sr, Ba)Nb-=SUB=-2-=/SUB=-O-=SUB=-6-=/SUB=-
Authors: Pavlenko A. V.  , Stryukov D. V.  , Kudryavtsev Yu. A.  , Matyash Ya. Yu.  , Malomyzheva N. V.
Published: January 2023

BiFeO heterostructures were manufactured using intermittent sputtering technology on the surface of a single crystal substrate MgO(001) BiFeO3/(Sr, Ba)Nb2O6. Studies of the structure, thickness profile of the composition, surface morphology and dielectric characteristics of materials have been carried out. It is established that despite the formation of two types of orientation domains (±18.4o) in the layer (Sr, Ba)Nb2O6, the upper layer of BiFeO3 is in the ratio of the total parallel orientation with the substrate MgO(001). It is shown that the composition of the films of bismuth ferrite and barium-strontium niobate does not change in film thickness, corresponds to the compositions of the sprayed ceramic targets, no signs of the presence of buffer layers were revealed. The results of the study of dielectric and ferroelectric characteristics of the heterostructure are presented. The reasons for the revealed patterns are discussed. Keywords: thin films, heterostructure, barium-strontium niobate, bismuth ferrite.
Relaxation processes in the region of structural phase transitions on the example of ceramics based on sodium niobate
Authors: Malyshkina O. V.  , Ali M.  , Malysheva N. E.  , Patsuev K. V.
Published: January 2023

Comparative studies of the temperature dependences and dispersion of the complex permittivity of sodium niobate and sodium-lithium niobate ceramics have been carried out. It is shown that the structural transition to the R-phase (370oC) of sodium niobate ceramics is a ferroelectric phase transition. For sodium niobate ceramics, the existence of three fundamentally different mechanisms of relaxation processes has been established: classical (Debye type), linear, and relaxation, the existence of which is determined by the structural phase. The addition of 10% lithium niobate to the sodium niobate ceramics not only increases the temperature of the structural phase transition, but also eliminates the mechanisms for the occurrence of relaxation polarization. Keywords: piezoelectric ceramics, lead-free materials, permittivity, relaxation processes.
Structural and spectral characteristics of La-=SUB=-0.99-x-=/SUB=-Tb-=SUB=-x-=/SUB=-Eu-=SUB=-0.01-=/SUB=-BO-=SUB=-3-=/SUB=- orthoborates and energy transfer from Tb-=SUP=-3+-=/SUP=- to Eu-=SUP=-3+-=/SUP=-
Authors: Shmurak S. Z.  , Kedrov V.V.  , Kiselev A.P.  , Fursova T.N.  , Zver'kova I.I.
Published: January 2023

The structure, infrared (IR) absorption spectra, luminescence spectra (SL), and luminescence excitation spectra (LES) of La0.99-xTbxEu0.01BO3 orthoborates synthesized at 970oC at 0≤ x≤ 0.99 were studied. An increase in x leads to the successive emergence of three structural states of these compounds. At 0≤ x≤0.2, orthoborates have an aragonite structure; then, at 0.2<x <0.89, they become two-phase and contain the aragonite and vaterite phases. At 0.89≤ x≤ 0.99, the compounds have a vaterite structure. A correspondence between the structure and spectral characteristics of these compounds was established. It is shown that in La0.99-xTbxEu0.01BO3 orthoborates, as well as in La0.99-xYxEu0.01BO3, the band with λex=369 nm (7F0->5D2) in the LES and the band in the wavelength range of 577-582 nm (5D0->7F0) in the SL of these compounds can serve as indicators of the structural state of the sample. In the SL of the samples containing the aragonite and vaterite phases, two bands corresponding to these structures were simultaneously observed for the first time. It was established that the luminescence of Eu3+ ions in La0.99-xTbxEu0.01BO3 orthoborates, which occurs when the sample is excited by light in the absorption bands of Tb3+ ions, is due to the transfer of the electron excitation energy from Tb3+ ions to Eu3+ ions. The efficiency of this process in La0.9Tb0.09Eu0.01BO3 samples with an aragonite structure is 86%. Keywords: rare earth orthoborates, crystal structure, X-ray diffraction analysis, IR spectroscopy, luminescence spectra, phosphors for LEDs.
The evolution of the spectral and structural characteristics of La-=SUB=-0.98-x-=/SUB=-Lu-=SUB=-x-=/SUB=-Eu-=SUB=-0.02-=/SUB=-BO-=SUB=-3-=/SUB=- orthoborates
Authors: Shmurak S. Z/  , Kedrov V. V.  , Kiselev A. P  , Fursova T. N  , Zver'kova I. I.  , Khasanov S. S.
Published: January 2023

The structure, IR absorption, luminescence, and luminescence excitation spectra of La0.98-xLuxEu0.02BO3 orthoborates synthesized at 970oC were studied at 0≤ x≤0.98. An increase in x leads to a sequential change of the structural state of the orthoborates. At first, the compound has the aragonite structure. Then, it becomes two-phase and contains the aragonite and vaterite phases. With a further increase in x, the compounds have the vaterite structure, then the vaterite and calcite structure, and, finally, the calcite structure. Correspondence between the structure and spectral characteristics of these compounds was established. Luminescence spectra were investigated at different wavelengths of exciting light. This allowed obtaining information on the structure of a near-surface layer and the bulk of microcrystals of the investigated samples. It is shown that the vaterite phase arises in the bulk of microcrystals of samples that have the aragonite structure. Keywords: phosphors for LEDs, rare earth orthoborates, X-ray diffraction analysis, IR spectroscopy, luminescence spectra.
Effect of thermomagnetic treatments on the domain structure of Finemet amorphous films
Authors: Ivanov V. E.  , Lepalovskij V. N.
Published: January 2023

Thermomagnetic processing of films of the Finemet type with an easy magnetization axis in the plane under the action of a constant and rotating magnetic field was carried out in order to obtain an isotropic state. After heat treatment in a constant field, the easy magnetization axis was reoriented along the line of action of the field, as a result of which the domain walls were oriented along the new axis. After thermomagnetic treatment in a rotating field, regions with different anisotropy patterns, including isotropic regions, were revealed. Keywords: domain structure, thermomagnetic treatment, rotating magnetic field.
The limiting energy capabilities of high-power AlInGaN LEDs
Authors: Zakgeim A.L.  , Aladov A.V.  , Ivanov A.E.  , Talnishnikh N.A.  , Chernyakov A.E.
Published: January 2023

The object of study in this work was the most advanced AlInGaN LEDs of the "UX : 3" design with a distributed system of reflective contacts located on the back side of the emitting chip. The current dependences of the output optical power and emission spectral characteristics, including their distribution (mapping) over the emitting surface in a wide range of operating currents up to ~ 30 A have been studied. An analysis of the near-field emission by intensity and spectrum revealed a high uniformity of the current density distribution at all levels of excitation (no current crowding). Thus, the saturation of the optical power and the quantum efficiency droop are explained by purely internal factors, which are well described by the ABC model. Keywords: AlInGaN LED, quantum efficiency, emission spectrum, near-field emission.
Dynamics of a localized ring nonlinear wave in a carbon nanotube
Authors: Glukhova O. E.  , Chetverikov A. P.  , Shunaev V. V.
Published: January 2023

The propagation of nonlinear localized soliton-like super-acoustic longitudinal waves in a carbon nanotube was explored by the molecular dynamics modeling. Ring waves were excited by pulsed action on all the atoms of the edge zigzag layer and they got an initial velocity along the axis of the nanotube. It was shown that the velocity of a localized (soliton-like) ring super-acoustic wave increased with an increase in the initial velocity of the edge atoms. The calculated dependence of the propagating wave velocity on the initial velocity of the edge atoms was given. Keywords: carbon nanotube, ring nonlinear waves, molecular dynamics.
Nonequilibrium states in the second-generation HTS composites under overcritical pulsed current impact
Authors: Anischenko I.V.  , Pokrovskii S.V.  , Osipov M.A.  , Abin D.A.  , Gritsaenko D. I.  , Rudnev I. A.
Published: January 2023

This paper presents the results of studying the processes of epy HTS composites switching from the superconducting to the resistive state at microsecond current pulses. Two modes of pulsed current load were used: with an amplitude of ~1.1Ic (the so-called "soft" mode) and with an amplitude of ~3Ic ("hard" mode). The possibility of passing supercritical currents through the tape without superconductor characteristics degradation is shown. To explain the processes occurring in the tape during the current pulse, 2D FEA (finite element analyzes) was developed, with the help of which the dynamic resistance of the HTS composite superconducting layer was calculated in the "hard" load mode and nonstationary processes of current redistribution between the different tape layers were demonstrated. Keywords: HTS composites, superconducting switch, nonequilibrium states, stable switching, irreversible switching.
Double electron capture probability at He-=SUP=-2+-=/SUP=- ion Xe atom collisions with different impact parameters
Authors: Basalaev A. A.  , Panov M. N.  , Smirnov O. V.
Published: January 2023

Differential cross sections for scattering of helium atoms formed at collisions of He2+ ions with kinetic energies of 1.97, 3.00, and 7.17 keV/a.m.u with Xe atoms in processes with the formation of slow xenon ions with charges 2-4 have been measured. The projectiles deflection function is calculated. The probability of all these processes occurring at various values of the impact parameter of colliding particles is determined. The role of the electron shells of the Xe atom 5(s,p) and 4(s,p,d) for the capture of two electrons is determined depending on the speed of approach of the colliding particles, the impact parameter and the charge of the formed xenon ions. Keywords: Double electron capture, capture with ionization, scattering differential cross section, impact parameter.
Circularly polarized electroluminescence at room temperature in heterostructures based on GaAs:Fe diluted magnetic semiconductor
Authors: Ved M. V.  , Dorokhin M. V.  , Lesnikov V. P.  , Kudrin A. V.  , Demina P. B.  , Zdoroveyshchev A. V.  , Danilov Yu. A.
Published: January 2023

In this work, we demonstrate the possibility of using a diluted magnetic semiconductor GaAs:Fe as a ferromagnetic injector in a spin light-emitting diode based on a GaAs/InGaAs quantum well heterostructure. It is shown that in such a device it is possible to observe partially circularly polarized electroluminescence at room temperature. Keywords: spin light-emitting diodes, diluted magnetic semiconductors, A3B5 semiconductors, spin injection.
Dynamic model of the underwater discharge
Authors: Khlyustova A. V.
Published: January 2023

A dynamic model of an underwater electric discharge is presented. The method is based on a mathematical description of the dependence of the solution conductivity on its thickness during the formation of a vapor-gas bubble. The time dependences of the current and the voltage drop across the cell were calculated using expressions relating the current and voltage to the resistance (conductivity) of the solution and taking into account the periodicity of the processes. The presented model makes it possible to accurately describe the dynamic characteristics of underwater discharges based on the physicochemical properties of the solution, which makes it possible to predict the behavior of the discharge when using solutions with specified properties. Keywords: underwater electrical discharge, dynamic model, conductivity.
Intermodal fiber interferometer based on broadband light source and optical spectrum analyzer for external perturbations measurement
Authors: Petrov A.V.  , Chapalo I.E.  , Bisyarin M.A.  , Kotov O.I.
Published: January 2023

An intermodal fiber interferometer based on broadband light source and spectral signal processing is proposed and experimentally investigated. The perturbation of the parameters of the spectrum analyzer (scanning range and width of the instrumental spectral response function) on the output signal is demonstrated. It is shown that the method of correlation signal processing makes it possible to obtain linear and stable response to external fiber perturbations. The proposed interferometer scheme can be prospective for development of real-time sensors of physical quantities. Keywords: intermodal fiber interferometer, fiber-optic sensors, fiber optics, multimode fiber, interferometers.
Fiber Optic SMS Sensor for Simultaneous Measurement of Strain and Curvature
Authors: Markvart A. A.  , Liokumovich L. B.  , Ushakov N. A.
Published: January 2023

The article presents a fiber-optic sensor based on a singlemode-multimode-singlemode (SMS) structure for simultaneous measurement of strain and curvature. It is shown that the simultaneous demodulation of strain and curvature can be realized using the Fourier analysis of the recorded interference oscillations. Keywords: optical fiber sensors, intermode interference, single mode-multimode-single mode, stretching, bending.
Method for measuring periods of waveguide diffractive optical elements
Authors: Kopenkin S. S.  , Kesaev V. V.  , Putilin A. N.
Published: January 2023

An original method of the periods of waveguide diffractive optical elements (DOEs) measuring is proposed. In contrast to standard techniques, the proposed method provides measurements of waveguide gratings periods while the diffracted light is propagating in the substrate material. The method is simple and has a small error Keywords: waveguide holograms, diffractive optical elements.
Acoustoelectric transducer based on electrokinetic phenomenon flow potential
Authors: Sharfarets B. P.  , Dmitriev S. P.  , Kurochkin V. E.  , Legusha F. F.
Published: January 2023

A mathematical model of an acoustoelectric transducer based on the use of the electrokinetic phenomenon of the flow potential is proposed. It is shown theoretically that the flow potential increases in proportion to the strength of the constant electric pumping field, which is confirmed experimentally. The described converter has variable sensitivity. Rather large values of the sensitivity of an electrokinetic microphone have been obtained experimentally. The results of the work can be used in the design of acoustoelectric transducers. Keywords: Acoustoelectric conversion, Electrokinetic phenomena, Current potential, Flow potential hydrodynamics, Energy pumping. Electrokinetic microphone sensitivity.
The Accuracy of a Web-Based Visual Acuity Self-assessment Tool Performed Independently by Eye Care Patients at Home: Method Comparison Study
Authors: Claessens Janneau , van Egmond Juultje , Wanten Joukje , Bauer Noël , Nuijts Rudy , Wisse Robert
Published: January 2023

Background

 Telehealth solutions can play an important role in increasing access to eye care. Web-based eye tests can enable individuals to self-assess their visual function remotely without the assistance of an eye care professional. A web-based tool for self-assessing visual acuity (VA) has previously been studied in controlled, supervised conditions. The accuracy of this tool when performed independently by patients in their home environment, using their own devices, has not yet been examined.

Objective

 The objective of this paper was to examine the accuracy of a web-based tool with respect to measuring VA in ophthalmic patients in their home environment, compared with a conventional in-hospital assessment using a Snellen chart (the gold standard).

Methods

 From April through September 2020, consecutive adult patients with uveitis at the University Medical Center Utrecht, the Netherlands, performed the web-based VA test at home (the index test) before their upcoming conventional VA assessment at the hospital (the reference test). The agreement between the 2 tests was assessed by the Bland-Altman analysis. Additional analyses were performed to investigate associations between clinical characteristics and the accuracy of the web-based test.

Results

 A total of 98 eyes in 59 patients were included in the study. The difference in VA between the index and reference tests was not significant, with a mean difference of 0.02 (SD 0.12) logMAR (P=.09) and 95% limits of agreement of –0.21 to 0.26 logMAR. The majority of the differences (77%) fell within the predetermined acceptable deviation limit of 0.15 logMAR. In addition, no patient characteristics or clinical parameters were found to significantly affect the accuracy of the web-based test.

Conclusions

 This web-based test for measuring VA is a valid tool for remotely assessing VA, also when performed independently by patients at home. Implementation of validated web-based tools like this in the health care system may represent a valuable step forward in revolutionizing teleconsultations and can provide individual patients with the opportunity to self-monitor changes in VA. This is particularly relevant when the patient’s access to ophthalmic care is limited. Future developments should focus on optimizing the testing conditions at home to reduce outliers.
The Role of Compassionate Technology in Blended and Digital Mental Health Interventions: Systematic Scoping Review
Authors: van Lotringen Charlotte , Lusi Benedetta , Westerhof Gerben J , Ludden Geke D S , Kip Hanneke , Kelders Saskia M , Noordzij Matthijs L
Published: January 2023

Background

An essential value in mental health care is compassion: awareness of suffering, tolerating difficult feelings in the face of suffering, and acting or being motivated to alleviate suffering. Currently, technologies for mental health care are on the rise and could offer several advantages, such as more options for self-management by clients and more accessible and economically viable care. However, digital mental health interventions (DMHIs) have not been widely implemented in daily practice. Developing and evaluating DMHIs around important mental health care values, such as compassion, could be key for a better integration of technology in the mental health care context.

Objective

This systematic scoping review explored the literature for previous instances where technology for mental health care has been linked to compassion or empathy to investigate how DMHIs can support compassion in mental health care.

Methods

Searches were conducted in the PsycINFO, PubMed, Scopus, and Web of Science databases, and screening by 2 reviewers resulted in 33 included articles. From these articles, we extracted the following data: technology types, goals, target groups, and roles of the technologies in the intervention; study designs; outcome measures; and the extent to which the technologies met a 5-step proposed definition of compassion.

Results

We found 3 main ways in which technology can contribute to compassion in mental health care: by showing compassion to people, by enhancing self-compassion in people, or by facilitating compassion between people. However, none of the included technologies met all 5 elements of compassion nor were they evaluated in terms of compassion.

Conclusions

We discuss the potential of compassionate technology, its challenges, and the need to evaluate technology for mental health care on compassion. Our findings could contribute to the development of compassionate technology, in which elements of compassion are explicitly embedded in its design, use, and evaluation.