bluuebunny/crossref_metadata_2025 huggingface dataset:
Jump quantum phase transitions in a vortex sistem and the dinamiccomplex magnetic permeability of high-temperature binaryYBa-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-7-x-=/SUB=- superconductors
Authors: Rostami H P.
Published: September 2022

A nonlocal high-frequency method for measuring the dynamic complex magneticpermeability with enhanced spatial resolution is developed to simultaneouslydetermine the bulk and local character of stepwise penetration of a magneticflux through twin boundaries (TBs) into a YBa2Cu3O7-x HTSC sample during itsstepwise decomposition into twins. By the values of fields corresponding tothe regions of steps, the thermodynamic first critical magnetic fields aredetermined: the penetration of a flux into a sample --- a Josephson medium;the development of a critical state in the Josephson medium; the penetrationof a flux into twins; and the values of the critical fields of phasetransitions in the vortex system of the HTSC sample, such as the meltingfields of a vortex crystal, the formation of a superconducting glass statein the sample, and the transition to the vortex glass and Bragg glassstates. Keywords: high-frequency inductance, bulk and local dynamic complexmagnetic permeability, magnetic flux trapping, effective demagnetizationfactor, twins (monodomains, crystallites, sub- and nanocrystallites), twinboundaries.\
Interaction modes of magnetized HTSC tapes stacks
Authors: Podlivaev A. I.  , Rudnev I. A.
Published: September 2022

On the basis of the critical state model, the interaction force of a pair of magnetic lines, which are sets of magnetized stacks of second-generation HTSC tapes, is calculated. The modes of magnetization of interacting rulers by an external magnetic field and the origin of the magnetization reversal of the stacks of tapes during multiple cycles of approaching --- moving the rulers away from each other are considered. The force of interaction of the rulers is determined depending on the distance between them and the number of the cycle. Keywords: high-temperature superconductors, second-generation HTSC tapes, magnetic levitation, force of interaction, critical state
Crystal chemistry and magnetic properties of BaFe-=SUB=-12-=/SUB=-O-=SUB=-19-=/SUB=- hexaferrite upon heterovalent substitution of iron with zirconium
Authors: Kostishin V. G.  , Korovushkin V. V.  , Isaev I. M.  , Salogub D. V.  , Trukhanov S.V.  , Trukhanov A.V.
Published: September 2022

Samples of BaFe12O19 M-type barium hexaferrite with partial iron substitution by zirconium ions (concentration up to 10 at.%) have been synthesized and investigated. Studies of crystal features, phase composition, and magnetic properties were carried out using X-ray diffraction, Messbauer spectroscopy, and VSM respectively. The presence of limited heterovalent isomorphism by the 2Fe3+->Zr4++Fe2+ mechanism was shown. The limit of heterovalent isomorphic substitution by zirconium ions in barium hexaferrite (x=0.6) was established. It was noted that additional sextets in the Messbauer spectra of barium hexaferrite can be formed during the localization of Zr4+ ions predominantly in the 12k and 4f2 positions due to the frustration of the magnetic structure. The correlation between the chemical composition (concentration of zirconium ions), impurity phase formation, the peculiarities of the distribution of substituents over oxygen coordination, and the magnetic properties was established. Keywords: M-type barium hexaferrite, heterovalent substitution, limited isomorphism, Messbauer spectroscopy, magnetic properties
Change in structure and luminescent properties of ZnSe and ZnCdSe films irradiated by electron beam
Authors: Kravets V. A.  , Dementeva E. V.  , Sitnikova A. A.  , Zamoryanskaya M. V.  , Kravets V. A.
Published: September 2022

Layers of ZnSe and ZnCdxSe (x ~ 0.32-0.35) grown on GaAs (001) substrates by molecular beam epitaxy method were investigated. The electron beam impact on changes in crystal structure of specimens under examination and on their luminescent properties was studied. Methods of cathode luminescence, transmission electron microscopy, and electron microprobe analysis were applied. It is found that irradiation of specimens in the transmission electron microscope results in stacking faults annealing accompanied by formation of ZnO precipitates with hexagonal crystal structure. Irradiation of specimens in the cathode luminescence plant results in decreased intensity of cathode luminescence layers of ZnSe and ZnCdxSe in question due to radiation-stimulated degradation processes. Key words: point defects, irradiation by electron beam, cathode luminescence, structural changes.
Elastic properties and anharmonicity of solids
Authors: Sanditov D.S.
Published: September 2022

The squares of the velocities of the longitudinal and transverse acoustic waves separately are practically not associated with anharmonicity, and their ratio (νL2/νS2) turns out to be a linear function of the Gruneisen parameter γ --- the measure of anharmonicity. The obtained dependence of (νL2/νS2) on γ is in satisfactory agreement with the experimental data. The relationship between the quantity (νL2/νS2) and anharmonicity is explained through its dependence on the ratio of the tangential and normal stiffness of the interatomic bond λ, which is a single-valued function of the Gruneisen parameter λ(γ). The relationship between Poisson's ratio μ and Gruneisen parameter γ, established by Belomestnykh and Tesleva, can be substantiated within the framework of Pineda's theory. Attention is drawn to the nature of the Leont'ev formula, derived directly from the definition of the Gruneisen parameter by averaging the frequency of normal lattice vibration modes. The connection between Gruneisen, Leontiev and Belomestnykh--Tesleva relations is considered. The possibility of a correlation between the harmonic and anharmonic characteristics of solids is discussed. Keywords: elastic properties, Gruneisen parameter, formulas of Belomestnykh--Tesleva, Leont'ev, Gruneisen equation, tangential and normal stiffness of interatomic bond, crystals, glasses.
Fabrication of textured FeCo(110) and FeCo(200) films by DC magnetron sputtering
Authors: Dzhumaliev A. S.  , Sakharov V. K.
Published: September 2022

The results of study of bias voltage Ub and substrate temperature Ts influence on the texture of FeCo films with the thickness of 180 nm deposited on Si/SiO2 substrates by DC magnetron sputtering are presented. It is shown that the change of Ub from -250 V to 80 V leads to the growth of films with (110) texture. Further change of Ub from 80 V to 250 V causes the growth of films having (200) texture. Films deposited at Ub=0 and Ts=60-300oC have (200) texture. Further increase of Ts results in the change of film texture to (110). Keywords: FeCo films, magnetron sputtering, texture, coercitivity.
Thermophysical properties of multiferroics Bi-=SUB=-1-x-=/SUB=-Tm-=SUB=-x-=/SUB=-FeO-=SUB=-3-=/SUB=-
Authors: Kallaev S. N.  , Bakmaev A. G.  , Omarov Z. M.  , Reznichenko L. A.
Published: September 2022

Investigations of the heat capacity, thermal diffusivity, and thermal conductivity of multiferroics Bi1-xTmxFeO3 (x=0, 0.05, 0.10, 0.20) have been carried out in the high temperature range of 300-1200 K. and thermal conductivity in the region of phase transitions. The temperature dependences of the specific heat for compositions with x=0.10 and 0.20 exhibit an additional anomaly characteristic of the phase transition at T=580 K. The dominant mechanisms of phonon heat transfer in the region of ferroelectric and antiferromagnetic phase transitions are considered. The temperature dependence of the average phonon mean free path is determined. Keywords: multiferroics, heat capacity, thermal diffusivity, thermal conductivity.
X-ray Study and Computer Simulation of the Structure of Amorphous-Crystalline Titanite
Authors: Sidorova O. V.  , Aleshina L. A.  , Fofanov A. D.
Published: September 2022

The structure of amorphous-crystalline titanite obtained by mechanical activation was studied by X-ray diffraction and simulation methods. The short-range order characteristics were calculated using Finbak-Warren's method. It was found that the coordination numbers of metal atoms decreased as the result of titanite grinding. The atomic configurations of short-range order of ground titanite were constructed by translation of titanite unit cell. The theoretical X-ray patterns were calculated using Debye's method and were compared with the experimental curves. The structure of ground titanite in the mill with centrifugal factor 40 g was described satisfactorily by the model of mechanical mixture of clusters containing 2016 atoms, disordered during the molecular dynamics with clusters containing 12096 atoms. The increase of grinding intensity led to the sharp decrease of sizes of small cluster. Keywords: amorphous-crystalline titanite, X-ray diffraction, computer simulation, mechanical activation, Debye's method.
The determinism of gold monolayers local atomic ordering in the formation of their electronic structure
Authors: Karbivskyy V. L.  , Romansky A. A.  , Karbivska L. I.  , Stonis V. V.
Published: September 2022

The total and partial densities of electronic states of gold monolayer structures of different symmetry are calculated by the quantum mechanical calculations methods in the DFT approximation. It is shown that the first coordination sphere is determinant in the formation of the fine structure and the extent of the valence bands of the monolayer gold structures under study. The peaks splitting of the TDOS curve, which leads to its finer structure, is influenced not only by the lengths of interatomic bonds but also by the mutual arrangement of atoms. The influence of long-range interactions on the electronic structure of gold monolayers has been established. For example, for the (110) plane, a change in the atomic ordering in the third coordination sphere as a result of the introduction of a vacancy leads to noticeable changes in the TDOS curve, which indicates either a significant role of the atoms of the third coordination sphere or a significant redistribution of the interaction of d-orbitals of different symmetries of close neighbours. A correlation between the packing density, as well as the number of neighbours in the first coordination sphere, and the width of the energy band of gold monolayers has been established. Keywords: gold, monolayer, electron density, defects.
Electrical resistance of Ni-=SUB=-42+x-=/SUB=-Mn-=SUB=-47-x-=/SUB=-Sn-=SUB=-11-=/SUB=- alloys
Authors: Volkova N. V.  , Chistyakov V. V.  , Patrakov E. I.  , Korenistov P. S.  , Perevalova A. N.  , Emelyanova S. M.
Published: September 2022

The electrical resistance and structure of Ni42+xMn47-xSn11 alloys have been studied; where x=0, 1, 2, 3, 4, At room temperature, Ni42+xMn47-xSn11 alloys are ordered in the cubic L21 Ni2MnSn structure characteristic of Heusler alloys. The phase transition between the cubic austenite phase and martensite with lower symmetry, characteristic of ferromagnetic non-stoichiometric Heusler alloys, is observed at temperatures below room temperature. It was found that the partial replacement of Mn atoms by Ni atoms leads to an increase in the phase transition temperatures and to their shift to room temperature. Keywords: Heusler alloys, electrical resistance, phase transition.
Radiation treatment of the edges of a crack in a superconducting layer during restoration of HTSC tape
Authors: Podlivaev A. I.  , Rudnev I. A.
Published: September 2022

Numerically, within the framework of the critical state model, the density of superconducting currents in a second-generation HTSC tape based on GdBa2Cu3O7-x is determined. It is shown that during the restoration of the transverse crack of the superconducting layer by shunting the crack with a piece of defect-free tape, the critical current of the restored area decreases by ~8%. It is shown that preliminary i rradiation of the crack edges with ions of hydrogen, helium, neon, and oxygen makes it possible to restore the initial value of the critical current. The calculation of the effect of radiation on a superconducting tape was carried out using the SRIM software package. Keywords: high temperature superconductor, irradiation, radiation defects, critical current.
Study of silicon-to-silicon carbide transformation stages in the process of atomic substitution by the methods of total external X-ray reflection and X-ray diffractometry
Authors: Kukushkin S. A.  , Osipov A. V.  , Osipova E. V.  , Stozharov V. M.
Published: September 2022

X-ray diffraction and total external reflection of X-rays (X-ray reflectometry) methods were used to study the successive stages of synthesis of epitaxial SiC films on Si (100) X-ray diffraction and total external X-ray reflection (XRD) methods were used to study successive stages of synthesis of epitaxial SiC films on Si (100) surfaces, (110) and (111) surfaces by the atom substitution method. The data on the transformation evolution of (100) surfaces were studied, (110) and (111) Si, into SiC surfaces. A comparative analysis of the X-ray structural quality of the SiC layers grown on Si by the atom substitution method with the quality of SiC layers grown by Advanced Epi by the standard CVD method. A modified technique for the total outer X-ray reflection method, based on measurements of the intensity of the reflected X-rays using a special parabolic mirror. It is shown that the method of total external reflection method makes it possible to obtain important information about the degree of surface roughness of SiC layers, the evolution of their crystal structure and plasmon energy in the process of Si to SiC conversion. Keywords: total external reflection, X-ray reflectometry, silicon carbide, plasmons.
Ab initio calculations and experimental study of the electronic properties of CdGa-=SUB=-2-=/SUB=-S-=SUB=-4-=/SUB=- single crystals by spectral ellipsometry
Authors: Jahangirli Z. A.  , Mamedova I. A.  , Huseynova Sh. T.  , Kerimova T. G.  , Seyidov R. G.  , Mamedov N. T.  , Abdullayev N. A.
Published: September 2022

The electronic properties of CdGa2S4 single crystals have been studied experimentally using spectral ellipsometry and theoretically from first principles using density functional theory (DFT). Using ellipsometric studies in the energy range of 0.7-6.5 eV, the imaginary and real parts of the dielectric function along and perpendicular to the optical axis, the dispersion of the refractive, extinction, and absorption coefficients are determined. The width of the direct band gap is estimated. The band structure, the origin of the energy states, the optical functions, and the partial densities of states (PDOS) projected onto the atoms are determined by ab initio calculations. The theoretically calculated results are compared with the experimental data of the present work obtained by the method of spectral ellipsometry and with the experimental results available in the literature. Keywords: spectral ellipsometry, ellipsometric angles, dielectric function, refractive index, extinction coefficient, Brillouin zone, band structure.
Structural transition and temperature dependencies of thermal expansion coefficients of NaNO-=SUB=-3-=/SUB=- embedded into the nanoporous glass
Authors: Naberezhnov A. A.  , Alekseeva O. A.  , Kudriavtzeva A. V.  , Chernyshov D. Yu.  , Vergentiev T. Yu.  , Fokin A. V.
Published: September 2022

The temperature evolution of the crystal structure of a nanocomposite material obtained by introducing sodium nitrate NaNO3 from a melt under pressure into a nanoporous alkali borosilicate glass with an average pore diameter of 7 nm has been studied by the method of diffraction of synchrotron radiation in a wide temperature range upon heating. Analysis of the experimental diffraction patterns revealed a significant decrease in the temperature of the structural (orientational) transition by more than 50 K (up to 496 K) compared to bulk sodium nitrate. From the temperature dependence of the intensity of the superstructure peak (113), the dependence of the critical exponent β(T) for this transition was obtained and a significant difference from the critical exponent for a bulk material was found in the temperature range from 455 K to the transition temperature. Analysis of the broadening of Bragg reflections made it possible to estimate the average size (~40 nm) of sodium nitrate nanoparticles into the pores. An increase in the linear coefficient of thermal expansion in the [001] direction was found in NaNO3 nanoparticles in comparison with bulk material at temperatures above 450 K. Keywords: porous glasses, phase transitions, nanocomposite materials, synchrotron radiation diffraction, sodium nitrate, restricted geometry, structure, size effects.
Space-charge-limited carrier localization in InGaN/GaN quantum wells
Authors: Bochkareva N.I.  , Shreter Y.G.
Published: September 2022

The mechanism of carrier tunneling through the potential walls of InGaN/GaN quantum well in the p-n-structures is studied by means of the deep center tunneling spectroscopy. A number of humps on the current and photocurrent tunneling spectra, as well as on the forward bias dependences of the intensity and the peak energy of photoluminescence band from the quantum well are detected. These findings allow us to propose a model of carrier localization in the quantum well that permit to relate the tunneling transparency of the potential walls of the QW to the space-charge of deep-level centers in the quantum well barriers and its changes under optical excitation and forward biasing of p-n-structure. Keywords: gallium nitride, quantum well, photoluminescence, deep center tunneling spectroscopy, impurity color centers.
Effect of neutron irradiation on the spectrum of deep-level defects in GaAs grown by liquid-phase epitaxy in hydrogen or argon ambient
Authors: Sobolev M M.  , Soldatenkov F. Y.
Published: September 2022

We present results of experimental studies of capacitance--voltage characteristics, spectra of deep-level transient spectroscopy of graded high-voltage GaAs p+-p0-i-n0 diodes fabricated by liquid-phase epitaxy at a crystallization temperature of 900oC from one solution--melt due to autodoping with background impurities, in a hydrogen or argon ambient, before and after irradiation with neutrons are presented. After neutron irradiation, deep-level transient spectroscopy spectra revealed wide zones of defect clusters with acceptor-like negatively charged traps in the n0-layer, which arise as a result of electron emission from states located above the middle of the band gap. It was found that the differences in capacitance--voltage characteristics of the structures grown in hydrogen or argon ambient after irradiation are due to different doses of irradiation of GaAs p+-p0-i-n0 structures and different degrees of compensation of shallow donor impurities by deep traps in the layers. Keywords: GaAs, neutron irradiation, capacitance spectroscopy, p0-i-n0-junction, liquid-phase epitaxy, hydrogen, argon.
Bimodality in the electroluminescence spectra of quantum well-dots InGaAs nanostructures
Authors: Kharchenko A. A.  , Nadtochiy A. M.  , Serin A. A.  , Mintairov S. A.  , Kalyuzhnyy N. A.  , Zhukov A. E.  , Maximov M. V.  , Breuer S.
Published: September 2022

The electroluminescence spectra of waveguiding structures based on quantum well-dots were investigated with polarization resolution in the temperature range of 60-300 K. It is found that the ground state emission consists of two peaks with different degrees of TE-polarization and these peaks are getting closer with temperature decrease. We attribute the bimodality to the existence of two different types of nanoobjects in the active region: the quantum well-dots, which have partially TE-polarized emission, and quantum dots emitting almost fully TE-polarized light. Keywords: Electroluminescence, quantum dots, InGaAs heterostructures, waveguide structures, emission polarization.
Thermoelectric properties of p-type Bi-=SUB=-0.5-=/SUB=-Sb-=SUB=-1.5-=/SUB=-Te-=SUB=-3-=/SUB=- films on flexible substrate
Authors: Granatkina Yu. V.  , Dashevsky Z. M.
Published: September 2022

Bi2Te3-based compounds are excellent candidates for the low-temperature thermoelectric application. In the present work, a technology for fabrication of p-Bi0.5Sb1.5Te3 films with high thermoelectric efficiency on a thin flexible polyimide substrate has been developed. The preparation of films was carried out by a flash evaporation method. A systematic study of the transport properties (Hall coefficient, Seebeck coefficient, electrical conductivity, transverse Nernst coefficient) over the entire temperature range of 80-400 K for p-Bi0.5Sb1.5Te3 films has been performed. The power factor (PF) for the Bi0.5Sb1.5Te3 (doped with 0.5 wt% Te) film reached the value of ~ 30 μW/cm · K2, which is among the highest values of the PF reported in the literature to date for a film on a flexible polyimide (amorphous) substrate. The measured thermal diffusivity along the film allowed us to accurately estimate the figure of merit Z for p-Bi0.5Sb1.5Te3 films considering the anisotropic effect of Bi2Te3-based materials. A significant enhancement of Z up to ~ 3.0·10-3 K has been obtained for these films, which is state-of-the-art even compared to bulk materials. This research can provide insight into the fabrication of p-type branch of the film thermoelectric modules (FTEM), which could be a candidate for application in micro-scale thermoelectric generators. Keywords: p-Bi0.5Sb1.5Te3 film, thin flexible substrate, thermoelectric properties.
Hybrid Operating Modes of Thermoelectric Modules
Authors: Drabkin I. A.  , Ershova L.B.
Published: September 2022

It is suggested that thermoelectric coolers designing should not be limited to the extreme modes of their operation. In some cases, it is convenient to use the so called hybrid modes --- a combination of the extreme mode of maximum coefficient of performance for large temperature differences and a general cooling mode for small ones. The proposed hybrid mode makes it possible to control the cooling capacity of the module and not to confine this value to that under the extreme operating conditions, the maximum coefficient of performance in particular. Keywords: Thermoelectric module, hybrid mode, cooling capacity per pellet.
Development of technology for high-strength thermoelectrics with a diameter of up to 35 mm based on Bi-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=- polycrystals by hot extrusion
Authors: Sorokin A. I.  , Ivantsov M. S.  , Tabachkova N. Yu.  , Bublik V. T.  , Skipidarov S. Ya.  , Dashevsky Z. M.
Published: September 2022

Hot extrusion of thermoelectric materials of large diameters is associated with the problem of preserving the deformation texture in them both in length and in cross-section. The paper shows for the first time the technology of obtaining polycrystals based on Bi2Te3 n- and p-type conductivity with a diameter of up to 35 mm, by hot extrusion. Detailed studies of the structural properties have been carried out. The mechanical properties (strength) of the crystals were measured. The thermoelectric properties of polycrystals of various diameters (the coefficient of thermal EMF α, electrical conductivity sigma and figure of merit Z by the Harman method) were measured. It is shown at the optimal technology polycrystals based on Bi2Te3 n- and p-type conductivity with a diameter of 35 mm were produced, which are comparable in thermoelectric and mechanical properties with polycrystals of traditional diameter (25 and 30 mm), which are currently commercially produced. Keywords: thermoelectricity, Bi2Te3, extrusion, thermoelectric properties, mechanical properties.
Block and single-crystal films of bismuth-antimony alloy 3-12 at.% with an underlayer of antimony
Authors: Efimov D. D.  , Komarov V. A.  , Kablukova N. S.  , Demidov E.V.  , Staritsyn M. V.
Published: September 2022

The influence of an antimony sublayer (10 nm) on the structure and galvanomagnetic properties of thin films of a bismuth-antimony solid solution (3-12 at.% Sb) up to 1 μm thick has been studied. The films were produced on mica substrates by discrete vacuum evaporation and zone recrystallization. We found that the misorientation of the crystallite plane (111) increases relative to the film plane as well as the crystallite sizes decrease. The antimony underlayer does not change the crystallographic orientation during recrystallization and increases the film adhesion. The change in the galvanomagnetic coefficients when using a sublayer is due to the classical dimensional effect and increasing plane deformation. Keywords: bismuth, antimony, thin film, antimony underlayer, single-crystal film, atomic force microscopy
Influence of carbon nanotubes on thermoelectric properties of p- and n-type Heusler alloys
Authors: Elsehly EM  , El-Khouly A.  , Hassan Mohamed Asran  , Novitskii A. P.  , Karpenkov D. Yu.  , Pashkova D. S.  , Chechenin NG  , Uchimoto T.  , Miki H.  , Parkhomenko Yu. N.  , Khovaylo V.V.
Published: September 2022

This paper presents the results of studying the effect of carbon nanotubes on thermoelectric properties of p-type (Nb0.6Ta0.4)0.8Ti0.2FeSb and n-type Ti0.5Zr0.25Hf0.25NiSn half Heusler alloys. The experimental data obtained indicate a strong effect of the carbon nanotubes on electrical conductivity and Seebeck coefficient of the n-type compound, while the changes in these properties in the p-type compound were significantly less. It is suggested that a possible reason for this difference is the formation of a conducting cluster of carbon nanotubes in the sample of the n-type Heusler alloy. Keywords: carbon nanotubes, thermoelectric properties, Heusler alloys, electrical conductivity, Seebeck coefficient.
29
Authors: Veis A. N.  , L.N. Lukyanova L. N.  , Usov O. A.
Published: September 2022

The spectral dependences of the absorption coefficient
α in a submicron samples of the n-Bi2Te3 + CdBr2 topological
insulator, which have optimal thermoelectric properties at high
values of the Seebeck coefficient at temperatures below room
temperature, are studied at temperatures of 205 and 300 K.
The components of optical absorption spectra associated with
interband and intersubband electron transitions are revealed and
analyzed. It was found that in bismuth telluride, with decreasing
temperature, the optical transition of electrons at the interband
absortion threshold remain direct and allowed. The values of
energy gaps between the absolute extrema of the conduction
and valence bands, as well as between the main and additional
subbands of conduction band, are estimated. It is shown that the
rates of their change with temperature are opposite in sign. The
energy band diagram of Bi2Te3 is constructed, which corresponds
to experimental data.
9727
Authors: Dorofeev S. G.  , Kononov N. N.  , Bubenov S. S.  , Popelensky V. M.  , Vinokurov A. A.
Published: September 2022

The electrical characteristics of thin films formed from Si nanoparticles (nc-Si) with various degrees of doping are studied.
To exclude the influence of ionic conductivity, the current parameters of the films were recorded in an ultrahigh vacuum (P ~ 3 – 5∙10–9 Torr) with preliminary high-temperature (9500C) annealing.
An analysis of the temperature dependences of the conductivity showed that in nc-Si films formed from heavily doped nanoparticles (the concentration of free electrons ne is greater than 1019 cm-3), the transport is determined by variable-length hopping (VRH). In these samples, the Mott conductivity prevails at temperatures above 300C and at lower temperatures, the Efros-Shklovskii type variable range hopping conduction is dominate.
In films with a medium level of doping of nanoparticles (ne <1019 cm-3), transport is realized by the Mott, Efros - Shklovskii and thermally activated conductivities. At the same time, thermally activated conductivity is dominated at temperatures above 560K.
In nc-Si films formed from undoped nanoparticles, the transport parameters are determined by thermally activated conductivity and Mott's conductivity. Conductivity of Efros - Shklovskii is not observed in such films.
From the analysis of the parameters corresponding to the Mott and Efros - Shklovsky conductivities, the localization lengths of wave functions, the density of states at the Fermi level (g (EF)), and average hopping lengths are found. The average hopping lengths in nc-Si films from nanoparticles pre-etched in HF are in the range 56 - 86 nm, which indicates that hopping in such films occurs via intermediate nanoparticles.
9748
Authors: Uvarov A. V.  , Sharov V. A.  , Kudryashov D. A.  , Gudovskikh A. S.
Published: September 2022

Investigations of atomic-layer deposition of GaP layers on Si substrates with different orientations and with different preliminary surface treatment have been carried out. The deposition of GaP was carried out by the method of plasma enhanced atomic-layer deposition using in situ treatment in argon plasma. It was shown that at the initial stage of the growth of GaP layers on precisely oriented (100) Si substrates and with misorientation, two-dimensional growth occurs both after chemical and plasma surface treatment. Upon growth on (111) substrates, after plasma treatment of the surface, a transition to three-dimensional growth is observed, at which the size of islands reaches 30–40 nm. The smallest root-mean-square roughness of the surface of the growing GaP layers (<0.1 nm) was achieved for (100) substrates with a misorientation of 4 °. The GaP layers grown on (100) substrates had a roughness of ~ 0.1 nm, and on substrates with the (111) orientation - 0.12 nm. It was found that the surface treatment of Si substrates with the (100) orientation in hydrogen plasma leads to a slight increase in the surface roughness of growing GaP layers (0.12–0.14 nm), which is associated with the effect of inhomogeneous etching of silicon in hydrogen plasma. When treating the (100) silicon surface in argon plasma, the surface roughness does not change significantly in comparison with the chemical surface treatment. On the surface of substrates with preliminary deposition of an epitaxial Si layer with a thickness of 4 nm, the morphology of GaP layers is the same as in the case of using hydrogen plasma.
9753
Authors: Smagin V. P.  , Isaeva A. A.  , Shelepova E. А.
Published: September 2022

Nanoscale particles ZnS:Nd3+, CdS:Nd3+ and (Zn,Cd)S:Nd3+ were synthesized and doped in a polymerizing methyl methacrylate medium during the production of optically transparent polyacrylate composites of the composition PMMA/ZnS:Nd3+, PMMA/CdS:Nd3+ and PMMA/(Zn,Cd)S:Nd3+. The excitation of photoluminescence (FL) and FL of semiconductor structures in composites is associated with the transition of electrons from the valence band to the conduction band and to the levels of structural defects of semiconductor particles, followed by recombination at these levels. Based on changes in the excitation spectra of FL and FL composites, assumptions are made about the structure of particles, the distribution of Nd3+ ions in it and their effect on photoluminescence.
Abnormal thermal expansion and thermal conductivity of CuIn-=SUB=-7-=/SUB=-Se-=SUB=-11-=/SUB=- single crystals
Authors: Bodnar I. V.  , Khoroshko  V. V.
Published: September 2022

Homogeneous CuIn7Se11 single crystals with a diameter of ~14 mm and length of ~ 40 mm have been grown from the melt using the Bridgman method. Composition and structure of the obtained single crystals have been defined. It was shown that the obtained single crystals crystallized in a hexagonal structure. The anisotropy of thermal expansion and thermal conductivity in the temperature range of 80-650 K has been investigated on oriented single crystals in parallel and at right angle to the main crystal axis c. Abnormal thermal expansion and thermal conductivity were observed on the single crystals oriented in parallel to the main crystal axis. Keywords: Bridgman method, single crystals, crystalline structure, thermal expansion, thermal conductivity.
9762
Authors: Gurbanov G.R.  , AdygezalovaM.B.
Published: September 2022

The thermoelectric properties of the solid solution
Sn1−x Pbx Sb4Te8 and Sn1−x Pbx Sb4−y Biy Te8 (y = 0.4, 0.8, 1.2)
were measured in a wide temperature range (100−800 K). The
substitution of Bi atoms for Sb atoms leads to an increase in the
thermo-emf coefficient and a decrease in the lattice component
of thermal conductivity in comparison with the corresponding
properties of the solid solution Sn1−x Pbx Sb4Te8. The lower
values of the lattice thermal conductivity in alloys y = 1.2 in
comparison with the solid solution Sn1−x Pbx Sb4Te8 are associated
with distortions due to the difference in the atomic masses
and sizes of Sb and Bi atoms. With an increase in the
Bi content in solid solutions, the lattice thermal conductivity
decreases and, accordingly, the thermoelectric efficiency increases.
Thermoelectric figure of merit Sn1−x Pbx Sb4−y Biy Te8 (y = 1.2)
has a maximum value of = 3.2 · 10−3 at 300 K.
9766
Authors: Tyschenko I. E.  , Spesivtsev E. V.  , Shklyaev A. A.  , Popov V. P.
Published: September 2022

The thermal stability of silicon-on-insulator films with
a thickness of 4.7 and 2.2 nm was studied as a function of the
annealing temperature in the range T = 800−1200◦ C by scanning
electron microscopy and spectral ellipsometry. No melting features
of the films were found. The films remained continuous over the
annealing temperature range. A decrease in the thickness of the
films and a change in their phase composition with an increase
in temperature were found. According to spectral ellipsometry, as
the annealing temperature increased, the content of the crystalline
phase in the films decreases, and the content of the amorphous
one increases. The activation energy of the film amorphization
was estimated. The revealed properties are discussed in the
frame of the oxygen atom diffusion in the silicon films and in
the rearrangement of Si-Si bonds.
9755
Authors: Muretova M.E.  , Zubov F.I.  , Asryan L.V.  , Shernyakov Yu.M.  , Maximov M.V.  , Zhukov A.E.
Published: September 2022

Using numerical simulation, a search is carried out for designs of asymmetric barrier layers (ABLs) for a laser diode having GaAs waveguide and emitting at the wavelength λ = 980 nm. A pair of ABLs, adjoining the active region on both sides, blocks undesired charge carrier flows and suppresses parasitic spontaneous recombination in the waveguide layers. Optimal designs of ABLs based on AlGaAsSb and GaInP for blocking electrons and holes, respectively, are proposed that make it possible to reduce the parasitic recombination current down to less than 1% of the initial value. To suppress electron transport, an alternative structure based on three identical AlInAs barriers is also proposed. The GaAsP spacers separating these barriers from each other have different thicknesses. Due to this, its own set of quasi-bound (resonant) states is formed in each spacer that is different from the neighbor spacer set of states. As a result of this, the resonant tunneling channels are blocked: the parasitic electron flow is reduced by several tens of times in comparison with the case of spacers of equal thickness.
Synthesis of polymeric CdS and its optical properties investigation
Authors: Prosanov I. Yu  , Sidelnikov A. A.  , Hanna S. A.
Published: September 2022

Producing of polymeric cadmium sulfide in polyvinyl alcohol matrix is reported. The result was achieved through solid state sulfurization of hybrid interpolymeric complex of polyvinyl alcohol with cadmium chloride. In this process CdS inherits polymeric chain structure of CdCl2 complexing with polyvinyl alcohol due to diffusion restriction. One-dimensional structure of CdS was verified by high degree of luminescence polarization and Raman spectra behavior. It was observed that Raman spectrum of produced material is similar to spectrum of polyacetylene. This similarity disappears at impurities addition. Appearance of Raman band at 228 cm-1 indicates formation of CdS chain structure. Resulting polyvinyl alcohol --- CdS system has a structure of Little's high temperature superconductor. Keywords: one-dimensional structures, inorganic polymers, conjugated polymers, hybrid polymeric complexes, polyvinyl alcohol, CdS.
Analysis of the response of a liquid surface to the pulse action of an inclined gas jet at low Reynolds number
Authors: Savenkov A. P.  , Sychev V. A.
Published: September 2022

A mathematical description of the motion of a cavity on the liquid surface under an oblique action of a gas jet is obtained using the well-known expressions for the movement of a gas bubble in a liquid. The boundary of the viscous drag force domination over the form drag force is determined. The impingement of the gas jet on the liquid surface is considered as a dynamic object of the automatic control theory. It is found that the dynamic properties of the two-phase system "gas jet-liquid" are described by the integrator equations. Using a specially designed setup, the transient response of the "gas jet-liquid" system were experimentally obtained for the aerodynamic action at angles of 20 and 50o to the surfaces of liquids with the viscosities of 0.71 and 26.1 Pa·s (Reynolds number Re<2). The research results are necessary for the analysis of the non-contact aerodynamic method of liquid viscosity measurements. Keywords: gas jet, impingement, liquid surface, measurement, non-contact, pulse, viscosity.
Influence of anode and cathode plasmas on the operation of an electronic diode with an explosive-emission cathode
Authors: Pushkarev A. I.  , Polisadov S.S.
Published: September 2022

The results of modeling and experimental investigation of the formation of anode and cathode plasmas in a vacuum diode with an explosive-emission cathode during the generation of a pulsed electron beam with a current density of 0.3-0.4 kA/cm2 and an accelerating voltage of 300-500 kV are presented. It is shown that the concentration of the anode plasma does not exceed 1010 cm-3 and it does not significantly contribute to the operation of the diode. However, the complete desorption of molecules from the working surface of the explosive-emission cathode and the high efficiency of shock ionization of atoms ensure the formation of a cathode gas plasma with a concentration of ~1016 cm-3. It is found that the charge of the explosive-emission plasma layer is significantly less than the charge of the electron beam and the main source of electrons is not an explosive-emission plasma, but a cathode gas plasma. In this case, the electron current is limited by the concentration of the cathode plasma. The use of a cathode with a developed surface (a cathode with a carbon fabric coating) allows increasing the total charge of the electron beam by more than 1.5 times without changing the cathode diameter and the anode-cathode gap. Keywords: high-current electron beam, explosive emission, plasma concentration, electronically stimulated desorption.
Physical approaches to the design of functional metal-dielectric systems based on opals in photonics
Authors: Khanin S. D.  , Vanin A. I.  , Kumzerov Yu. A.  , Solovyev V. G.  , Cvetkov A. V.  , Yanikov M. V.
Published: September 2022

The possibilities of practical implementation of physical approaches to the design of metal-dielectric photonic crystal systems based on opals, which allow controlling the propagation of electromagnetic waves, are shown. The implemented approaches are based on the effects of excitation of surface plasmon-polaritons capable of propagating along the metal-dielectric interface in plasmonic-photonic layered heterostructures, and modification of the photonic-energy structure of the nanocomposite as a result of dispersion of silver in the opal matrix. Experimental results are presented indicating the occurrence of extraordinary transmission and absorption of light in plasmonic-photonic heterostructures, as well as the asymmetric shape of curves in the reflection spectra of nanocomposites, which is associated with the Fano resonance. Keywords: photonic crystals, opals, surface plasmon-polaritons, metal-dielectric systems, Fano resonance.
Ionization probability of atoms sputtered under bombardment of metal surface with single and multiply charged ions
Authors: Belykh S.F.  , Bekkerman A.D.
Published: September 2022

The processes of ionization of atoms sputtered under bombardment of clean metal surface by singly and multiply charged ions with kinetic energy of several keV were studied. Within the framework of simple phenomenological model of ion formation, the relaxation of local electron excitation in metal was taking into account. Analytical expressions for estimation of ionization probability of sputtered atoms was obtain. It was shown, that in comparison with singly charged ions, bombardment of metals with multiply charged ions results to significant increase of ionization probability of sputtered atoms due to more efficient excitation of electrons and increase of relaxation time of this excitation. Keywords: ion sputtering, ionization probability, multiply charged ions, Auger electrons, collision cascades, secondary ion mass spectrometry.
Features of the application of the virial theorem for magnetic systems with quasi-force-free windings
Authors: Shneerson G.A.  , Shishigin S.L.
Published: September 2022

The article shows that in a magnetic system with a thin-walled balanced winding close to a force-free one, a significant increase in the parameter theta=W_Mγ/MsigmaM, is possible, which, according to the virial theorem, characterizes the ratio of the energy of the magnetic system WM to the weight of equipment with a material density γ, where under the action of electromagnetic forces there appears a mechanical stress sigmaM. In a quasi-force-free magnetic system, the main part of the winding is in a state of local equilibrium, and only a relatively small part of the equipment is subject to stress. This part determines the weight of the entire system, and this weight can be minimized. The configurations of balanced thin-walled windings are developed, at the boundaries two boundary conditions are fulfilled simultaneously --- the absence of the induction component normal to the boundary and the constancy of the product of induction and radius. The authors consider an example of a system consisting of a main part - a sequence of balanced "transverse" modules in the form of flat discs and end parts, consisting of a combination of "transverse" modules and "longitudinal" ones, having the form of rings elongated along the axis with balanced end parts. It is shown that in the system under consideration, the characteristic dimensionless parameter theta with an unlimited increase in the number of elements of the main part can reach a value of about 24, and when the number of these elements changes within 20 -40, it changes from 6 to 9. Keywords: Quasi-force-free magnetic field, field energy, mass of a magnetic system, virial theorem, minimization of the ratio of mass to energy.
Influence of microcracks on Poisson's ratio during plastic deformation of austenitic steel
Authors: Kirikov S. V.  , Mishakin V. V.  , Klyushnikov V. A.
Published: September 2022

We researched the influence of damage accumulation on the Poisson's ratio measured by echo-pulse acoustic method during plastic deformation of 12Kh18N10T steel. On the basis of the obtained experimental data we calculated the partial contributions to the change in the Poisson's ratio of damage accumulation and formation of the strain induced martensite phase. The characteristics of stable cracks forming near strain-induced martensite particles at small degrees of plastic strain have been analyzed by computer simulation. The theoretical dependence of the change in the Poisson's ratio due to crack formation during plastic deformation has been constructed. A good agreement between the experimental data and theoretical calculations has been obtained. Keywords: plastic deformation, austenitic steel, Poisson's ratio, martensite transformation, dislocation, mesodefect, configurational force method.
Dependence of the electrochemical parameters of composite SiO/C anodes for lithium-ion batteries on the composition and synthesis temperature
Authors: Lozhkina D.A.  , Astrova E.V.  , Rumyantsev A.M.
Published: September 2022

The results of a study of anodes obtained by carbonization of silicon monoxide by means of a reaction with solid-phase fluorocarbon CF0.8 are presented. Charge/discharge voltage profiles were studied at different currents depending on the composition and temperature of the synthesis of composites. The irreversible losses of the 1st cycle and the contribution to them of intrinsic losses due to the formation of lithium oxide and its silicates and losses associated with the formation of SEI are analyzed. A difference has been established in the behavior of anodes made of SiO carbonized by annealing with CF0.8 at T=800oC (SiO/C composite) and silicon monoxide annealed with CF0.8 at T>1000oC at which disproportionation occurs simultaneously with the carbonization of SiO (d-SiO/C composite). The difference consisting in a higher discharge capacity, a higher Coulomb efficiency, and better rate capability of d-SiO/C is explained by a change in the composition of the SiOx matrix that occurs during the disproportionation process. The effect of the formation of d-SiO/C anodes by preliminary lithiation with a low current, after which the electrodes can be charged and discharged with much higher currents, has been discovered. The effect is explained by the amorphization of silicon crystallites and the increasing diffusion coefficient of lithium. Keywords: composite anodes SiO/C, lithium-ion batteries, disproportionation silicon monoxide, carbonization with fluorocarbon.
Light-induced flexoantiferomagnetic effect in centroantisymmetric antiferromagnets
Authors: A.F. Kabychenkov  , F.V. Lisovsky
Published: September 2022

It is shown that an inhomogeneous circularly polarized light wave induces components of the antiferromagnetism vector in centroantisymmetric antiferromagnets; a narrow beam of light can create a skyrmion. The analysis of the possibility of practical use of the predicted effects is carried out. Keywords: optomagnetic effect, polyharmonic light field, light-induced magnetic field, centroantisymmetric antiferromagnet, circularly polarized light wave, flexoantiferromagnetic effect.
Electronic structure of variants of compositions of scandate and nickel-oxide cathodes of microwave devices
Authors: Kapustin V. I.  , Li I. P.  , Serpichev A. S.  , Shumanov A. V.  , Kozhevnikova N. E.
Published: September 2022

By methods of electron spectroscopy for chemical analysis and spectroscopy of characteristic losses of electron energy, the electronic structure of barium oxide crystallites doped with other chemical elements, including scandium from scandium-containing phases, was investigated. The physical and physicochemical conditions are formulated, the fulfillment of which allows to form the electronic structure of the scandate cathode with a high level of thermionic emission: the achievement of the minimum ratio of the surface volume concentration of oxygen vacancies and the maximum distance between the top of the valence band and the Fermi level. Keywords: microwave devices, cathodes, thermionic emission, output operation, electronic structure, electron spectroscopy.