bluuebunny/crossref_metadata_2025_split huggingface dataset:
Model of hydrogen diffusion in titanium with the formation of hydride phases
Authors: Zaika Yu V , Denisov E A , Rodchenkova N I 
Published: December 2019

Abstract
The problem of predicting the behavior of structural materials in hydrogen-bearing media (including extreme operating environments) cannot be solved without a thorough understanding of the mechanisms of hydrogen accumulation and transfer inside these materials. This issue is especially pressing for hydride-forming materials, such as widely used titanium alloys. Titanium and its alloys are used, in particular, in designing power and chemical reactors, for the geological disposal of highly radioactive waste. The paper presents a nonlinear mathematical model of hydrogen permeability taking into account the possible formation of hydride phases (after certain concentrations of dissolved atomic hydrogen are attained), and the iterative method for solving the corresponding boundary value problem based on implicit difference schemes.
The phenomenon of nonstationary nutation in the system of two-level quantum wells of a periodic superlattice with strong magnetic quantization
Authors: Nikoghosyan H S , Manukyan V F , Nikoghosyan G H 
Published: December 2019

Abstract
We investigate the superposition of nonstationary nutation processes that arose during the interaction of two-level systems of quantum wells of a superlattice with two exciting coherent optical pulses with various resonance detunings. According to the model under consideration, dipole transitions in two-level systems of quantum wells under the action of exciting pulses occur between the Landau levels of the main mini-band of the superlattice conduction band. This gives a direct opportunity to study the controlled variation of the course of optical nutation processes, by changing the intensity of an external quantizing magnetic field.
Gold nanoclusters on GaAs(001) surface: atomic force microscopy and optical spectroscopy of plasmons
Authors: Berkovits V.L. , Alekseev P.A. , Kosobukin V.A. , Ulin V.P. , Soldatenkov F.Yu. , Zgerskii I.V. 
Published: December 2019

Abstract
Gold nanoclusters of two different kinds are found to occur on annealing of thin Au films deposited on either oxidized or nitridized GaAs(001) surfaces. The morphology of Au/GaAs interfaces is characterized, and the gold nanoclusters are established to cause two resonant peaks in optical reflectance spectra at the energies of 1.6 eV and 2.15 eV. Using the data of reflection spectroscopy and theoretical analysis, we assign the latter peak to localized plasmons of Au nanoislands located on Au/GaAs surface. The former peak is attributed to plasmons of prolate Au nanoclusters buried in GaAs crystal just near its surface. As well, plasmonic anisotropy of Au nanoclusters formed on nitridized GaAs surfaces is detected using reflectance anisotropy spectroscopy.
Resistive switching of CuO nanofibers embedded into hollow channels of SiO2 layer
Authors: Belov A.N. , Pavlova L.M. , Shevyakov V.I. , Pestov G.N. , Perevalov A.A. , Demidov Yu.A. 
Published: December 2019

Abstract
In this work, we have formed CuO memristive array embedded into porous SiO2 layer. Such an approach would create synaptic system on silicon substrate using standard integrated electronics operations. It also provides control over the geometric parameters of artificial synapses, which determines their synaptic weights. The results of synaptic behavior have shown that the value of synaptic weights and currents are dependent on the thickness of the CuO filled SiO2 porous layer.
Study of the formation of functional ceramic coatings on metals
Authors: Bykova A D , Markov M A , Krasikov A V , Belyakov A N , Makarov A M 
Published: December 2019

Abstract
The paper presents the results of experimental studies in the field of the formation of ceramic coatings using a complex method combining the benefits of microarc oxidation and cold gas-dynamic spraying. These coatings are characterized by high hardness, wear resistance and are an economical alternative to structural alumina ceramic materials for machine supports.
Silicon nanowires and their characterization in the process of metal-assisted chemical etching of c-Si using spectroscopic ellipsometry
Authors: Zharova Yu.A. , Tolmachev V. A. , Pavlov S.I. , Ermina A.A. 
Published: December 2019

Abstract
In this work, the preparation of c-Si nanowires was investigated using a two-stage metal-assisted chemical etching process. For characterization of structures at all stages of the process, spectroscopic ellipsometry was used and two approaches were used: a) determining and analysing the complex pseudo-dielectric function ε and b) determining parameters of simulated multilayer structures using the effective medium approximation. Taking into account the structure parameters measured from SEM images the spectra of ψ and Δ were calculated and fitted to the experimental ones to obtain best convergence. The study of metal-assisted chemical etching process the Si process is intended for the development of silicon technology for obtaining structures of various topology (morphology) with functional components and creating on their basis sensory elements for bio and chemical reagents, taking into account the possibility of integration with micro and nanodevices on the chip.
An investigation of the thermodynamic properties of long-chain molecular crystals and the possibility of their application as phase change materials
Authors: Borisov A K , Egorov V M , Marikhin V A 
Published: December 2019

Abstract
The thermodynamic properties of n-alkanes have been investigated by using differential scanning calorimetry. The impact of the chain length on the thermodynamic characteristics of the first order phase transitions in n-alkanes has been estimated. The n-alkanes homologous series has been analyzed using the theory of diffused phase transitions. The nuclei sizes of a new phase within the bulk of the initial phase have been estimated.
Effect of growth technological conditions on the heterointerface thickness in the InAs/GaSb strained-layer superlattices grown by MOCVD
Authors: Fedorov I V , Prasolov N D , Levin R V , Nevedomsky V N , Gordeeva A B , Pushnyi B V 
Published: December 2019

Abstract
In this article, we investigated the effect of technological growth parameters by metal-organic chemical vapor deposition (MOCVD) method on the thickness of the transition layers, which affect the value of tensile strain in the structure, in the InAs/GaSb superlattice. We consider that the thickness of transition layers depends on the roughness of the growth surface and the technological conditions of growing single layers in the superlattice. At the first stage, we have determined the optimal annealing parameters for the minimization of the substrate roughness as T = 650 °C and t = 8 min, with a minimum value of 1.1 nm. At the second stage, studies were carried out on the effect of the sequence of elements and the delay time of reagent supply during the growth of InAs and GaSb layers on the quality of heterointerface. The stress analysis of the obtained structures was performed by reflectance anisotropy spectroscopy. It was shown that a superlattice becomes less tense with the increase in the number of pairs of alternating layers.
Elastic properties of Ti and its alloys nanostrctured due to severe plastic deformation
Authors: Kardashev B K , Narykova M V , Betekhtin V I , Kadomtsev A G 
Published: December 2019

Abstract
Studies of elastic properties of titanium and its alloys processed by severe plastic deformation are presented. The evolution of the modulus of elasticity resulting from the transformation from a coarse-grained state to an ultrafine-grained one due to severe plastic deformation (SPD) was investigated. The acoustic composite oscillator technique was used to measure the elastic modulus in a wide strain amplitude range. The microstructure was studied in detail by scanning electron microscopy and electron backscatter diffraction methods. Parameters of nanoscale porosity were measured by small-angle X-ray scattering before and after treatment with a high hydrostatic pressure (1.5 GPa). In addition, densities of titanium and its alloys in various structural states were determined by the precision method of hydrostatic weighing. As experiments showed, noticeable changes in the elastic properties resulting from the change in the grain state can be attributed to several factors, such as dislocations, nanoporosity, high internal stresses, and the structure of the materials before SPD processing.
In situ study of elastic strain relaxation in metamorphic InAs(Sb)/In(Ga,Al)As/GaAs heterostructures by using reflection high energy electron diffraction
Authors: Fominykh N A , Solov’ev V A , Chernov M Yu , Ivanov S V 
Published: December 2019

AbstractWe report on a comparative study of the elastic strain relaxation in InAs(Sb)/In(Ga,Al)As heterostructures grown by molecular beam epitaxy on GaAs substrates via InAlAs metamorphic buffer layer (MBL) with and without a highly strained 5 nm-thick GaAs insertion. Reflection high energy electron diffraction was used forin situmonitoring an in-plane lattice parameter of the epitaxial layers during growth. As a result, critical thickness of the initial stage of the InAlAs metamorphic buffer layer as well as its corresponding composition were determined for the structures with different position of the GaAs insertion within the MBL. The structure with 5 nm-thick GaAs layer inserted in the InAlAs MBL directly after achieving the In content of 37 mol.% demonstrates the highest room temperature photoluminescence at a wavelength of about 3.5 μm.
Synthesis and optical properties study of GaAs epitaxial nanoparticles on silicon
Authors: Sapunov G A , Koval O Yu , Sharov V A , Dvoretckaia L N , Mitin D M , Bolshakov A D 
Published: December 2019

Abstract
The integration of direct bandgap III-V materials on Si is one of the main tasks on the way to the development of cheap and highly effective optoelectronic devices. The goal of this work is to study the morphology and optical properties of GaAs nanoparticles grown on Si(111) by molecular beam epitaxy (MBE). Nanostructure morphology is studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Optical properties are studied by photoluminescence (PL) and Raman spectroscopy. Interestingly, despite large lattice mismatch between the silicon substrate and GaAs no sufficient change of Raman spectra was observed for both continuous layer and nanoparticles indicating that they are relaxed. The room temperature PL signal in the red spectral range was obtained from the epitaxial structure. It is demonstrated that high pump optical excitation of the nanostructures can lead to sufficient change of the PL signal typical for photo-oxidized GaAs.
Characterization of optically inhomogeneous polymer layers with silver nanoparticles by spectroscopic ellipsometry
Authors: Lihachev A I , Brunkov P N , Nashchekin A V , Tolmachev V A , Vasileva M V 
Published: December 2019

Abstract
In this work it was shown the applicability of the spectroscopic ellipsometry technique for characterization of an optically inhomogeneous polymer film with silver NPs. The histogram of silver NPs distribution based on SEM images shows the largest number of NPs have a size in the range 15-35 nm and the filling factor as large as 6%. By using the possibilities of ellipsometry it was suggested a 3-layer inhomogeneous structure with different sizes of silver NPs covered by thin polyamide-6 film. Also existence of localized plasmon resonance in such NPs was observed by optical absorption measurements.
Clustering kinetics of fullerene C60 in a composite of polymethylmethacrylate – fullerene
Authors: Bogdanov Alexander A 
Published: December 2019

Abstract
The paper presents the results of studying the absorption spectra of a composite polymethylmethacrylate – fullerene C60. In this composite, a gradual process of fullerene clustering upon heating is registered. This made it possible to determine the diffusion coefficient of C60 molecules in this polymer.
AgInS2/ZnS nanocrystals as an active medium for cobalt detection
Authors: Korepanov O A , Mazing D S , Aleksandrova O A , Moshnikov V A 
Published: December 2019

Abstract
In this work, the effect of photoluminescence (PL) quenching of ternary chalcogenide AgInS2 nanocrystals (NCs), as well as the core/shell structure, with variation of the cobalt ions (Co2+) concentration in aqueous solution, was studied. The quenching effect is described using the Stern-Volmer equation. The PL spectra were modelled in the range of 450–800 nm using four Gaussian functions, which makes it possible to identify several bands of the PL spectrum.
Si(Li) detector with ultra-thin entrance window on the diffusive lithium side
Authors: Bazlov N. V. , Derbin A. V. , Drachnev I. S. , Gicharevich G. E. , Kotina I. M. , Konkov O. I. , Pilipenko N. V. , Chmel E. A. , Abolmasov S. N. , Terukov E. I. , Unzhakov E. V. 
Published: December 2019

Abstract
Present work reports the results of activities intended to reach thin Si(Li) detector entrance window on the diffusive lithium layer side. It was established that the new n-contact represented by a heterostructure of unalloyed amorphous n-type silicon a-Si:H allows one to achieve the entrance window thickness 3 – 4 orders of magnitude smaller than the lithium-side entrance window of standard Si(Li) detectors. The films of amorphous silicon were synthesized with MASD (magnetron assisted silane decomposition) method in mixture of SiH4 (25%) and Ar (75%) gases. Lithium layer surface resistivity and silicon target type (n- or p-) affection on electrical properties of Si(Li) detector contact produced were studied. The investigation performed had led to a technology of Si(Li) detector production with thickness of the entrance window on the diffusive lithium layer side below 0.1 µm.
Crystallization kinetics and luminescent properties of chromium-doped borate glass-ceramics
Authors: Babkina A N , Zyryanova K S , Agafonova D A , Nuryev R K , Kolobkova E V , Ignatiev A I 
Published: December 2019

Abstract
Chromium-doped alkali alumina borate glass was synthesized. The DSC studies exhibited glass transition temperature to be 425°C and glass crystallization temperature to locate in the 600 – 700°C range. After isothermal treatment of glass samples at temperatures from 540 to 700°C the chromium-doped borate glass-ceramics was obtained. The two bands of the glass absorption spectra shifted towards small wavelength region after the heat treatment with changing the glass colour. The XRD studies revealed the LiAl7B4O17: Cr3+ nanocrystals nucleation with the mean size of 12 – 25 nm. The glass-ceramics photoluminescence spectra possessed three intense bands in the 685 – 715 nm spectral region indicating high symmetrical environment around the chromium ions. The maximum value of the quantum yield was obtained after the heat treatment at 700°C was 50%.
Raman spectra of interface phonons in long-period AlN/GaN superlattices as a tool for determination of the structure period
Authors: Davydov V Yu , Smirnov A N , Eliseyev I A , Rodin S I , Zavarin E E , Lundin W V , Pankin D V , Smirnov M B 
Published: December 2019

Abstract
AlN/GaN superlattices (SL) grown by metalorganic vapor-phase epitaxy with the period of SLs varied from 20 nm to 140 nm, and the thickness of the structures ranged from 0.7 to 1 µm were studied by polarized Raman spectroscopy technique. The peaks within a complex spectral feature of the symmetry A1(TO) observed at about 580 cm−1, were assigned to the interface and quasi-confined phonons. Frequency splitting between the peaks was found monotonously increasing along with the SL period. This dependence was explained using the dielectric continuum model. A method based on this finding was proposed for estimating the period SL using Raman spectroscopy. This method extends the traditional approach based on the studies of folded acoustic phonons in the short-period SLs.
Phonons in short-period (GaN)m(AlN)n superlattices: ab initio calculations and group-theoretical analysis of modes and their genesis
Authors: Davydov V Yu , Roginskii E M , Kitaev Yu E , Smirnov A N , Eliseyev I A , Nechaev D V , Jmerik V N , Zavarin E E , Lundin W V 
Published: December 2019

Abstract
The results of experimental and theoretical studies of phonon modes in short-period (GaN)
m
(AlN)
n
superlattices (SLs) grown by MOVPE and PA MBE on the (0001) Al2O3 substrate are reported. Using a comprehensive group-theoretical analysis, the genesis of the SL vibrational modes from the modes of bulk AlN and GaN crystals has been established, which is important for interpreting the SL Raman spectrum. In the framework of Density Functional Theory, the lattice dynamics and the structural properties of (GaN)
m
(AlN)
n
SLs (m+n⩽12) were studied. An analysis of the eigenvectors of the phonon modes made it possible to reveal their microscopic nature. We established that the E(TO) modes are localized in the layers constituting the SL. It is shown that the localized nature of this mode is kept even in the SLs with the thinnest layers (m+n=4). In turn, the A
1(TO) mode demonstrates a delocalized nature and reflects the averaged characteristics of the SL as a whole. A combined analysis of the ab initio calculations and Raman data was performed. Thus, the above studies open new possibilities for analyzing the structural properties of GaN/AlN SLs by Raman and IR spectroscopy.
Dielectric metamaterials with quasicrystal structure
Authors: Maslova E E , Rybin M V 
Published: December 2019

Abstract
Three types of quasicrystal lattices based on the Penrose tiling are considered. We analyze the maximum filling fraction of these structures and find a design with the filling fraction corresponding to the case of periodic lattices. By using simulations of a Gaussian beam propagation through the quasicrystal structure we obtain a homogeneous field distribution that is a hallmark of near-zero regimes in metamaterials.
Optical confocal spectroscopy of SiC and AlN interfaces using Raman scattering and Optically Detected Magnetic Resonance
Authors: Breev I D , Anisimov A N , Baranov P G , Mokhov E N 
Published: December 2019

Abstract
The thesis contains the investigation of transition layer between AlN and SiC and the investigation of AlN Raman peaks evolution with distance till interface. Moreover, ODMR spatial research of nonuniformly irradiated 4H-SiC was performed together with PL spatial spectroscopy.
Analysis of the mineral component for cortical bone tissue by Raman spectroscopy after ovariectomy and its treatment with allogeneic hydroxyapatite
Authors: Timchenko E , Timchenko P , Pisareva E , Vlasov M , Volova L , Fedorova I , Tumchenkova A , Gorchenkova M , Subatovich A 
Published: December 2019

Abstract
In the work results of experimental researches of mineral component of cortical tissue after ovariectomy and estimation of correction using allogeneic hydroxyapatite (HAP) by the method of Raman spectroscopy are presented. A comparative analysis of bone samples from non-ovariectomized and ovariectomized animals after HAP injection was carried out using the Raman spectra. Coefficients which allow to estimate resorption of cortical tissue after ovariectomy and correction using HAP was entered. Introduction of HAP suspension showed that the consequences of ovariectomy can be almost compensated for the cortical tissue.
Holographic formation of photon structures by Bessel-like and Gaussian light fields in photopolymer materials taking into account two-beam interaction and small contrasts
Authors: Dolgirev V O , Sharangovich S N , Semkin A O , Dudnik D I 
Published: December 2019

Abstract
This paper presents a theoretical model of the holographic formation of photon structures (PS) in a photopolymer material (PPM) by Bessel-like and Gaussian light beams, taking into account the self-diffraction of recording light beams in areas of low contrast of the interference pattern. It was demonstrated by numerical simulation and experiment that the influence of the self-diffraction effect leads to an increase in the level of the side maxima of the diffracted light beam.
Selective volumetric modification of transparent dielectric media by femtosecond laser radiation
Authors: Chernikov A S , Chkalov R V , Kochuev D A , Khorkov K S , Prokoshev V G , Davydov N N 
Published: December 2019

Abstract
The paper describes the possibility of modifying transparent solid media by ultrashort laser pulses of femtosecond duration. The mechanism of fabricating second- and third-order fiber Bragg gratings in a standard single-mode Corning SMF-28e+ fiber is considered. Examples of multilayer ordered structures formation in a bulk of the glass samples are show.
Roughness measurement with nanoscale resolution by symmetric array of optical vortices
Authors: Sokolenko B V , Poletaev D A , Shostka N V , Karakchieva O S , Ismailov I A , Fitaev I , Shevchenko A I , Kudrian N V , Halilov S I 
Published: December 2019

Abstract
In present report we review the principles and applications of interference vortex method for the real time determination of polished optical surface roughness for transparent and reflecting materials with using of symmetric Laguerre-Gaussian array as a probe beams and reference beams with low topological charge. High spatial resolution caused by interference of vortices and their phase sensitivity, which is automatically analyzable to retrieve the 2D and 3D shape of micro- and nanostructured surfaces is applicable for non-destructive roughness testing of thin films and solid microstructures. The longitudinal and transverse resolution down to 1.75 nm and 7 nm respectively for visible light sources is achieved by the proposed method. The dependence of the rotational angle of the resulting interference pattern in form of two-petal laser beams on the optical path difference and sample thickness for two singular beams superposition is considered in detail.
Merging resonant frequencies and changing the sign of the g-factors of different atoms with frequent spin exchange
Authors: Okunevich A I , Dovator N A 
Published: December 2019

Abstract
The paper discusses the high-temperature spin-exchange of a mixture of vapors of alkali metals. It is shown that in a small magnetic field, an increase in temperature can lead to a sharp decrease in the frequency of transverse relaxation and to a significant decrease in the frequency of oscillation of the angular moments of atomic sublevels. Such changes in relaxation and frequency are well known in the case of a vapor of a single alkali metal. New in the case of a mixture was the merging of the resonance frequencies of different atoms into one frequency, which is the frequency of rotation of the total angular momentum of the atoms of the mixture. It also turned out that with an increase in temperature, the sign of the g-factors of atoms changes.
Impact of refractive index profile of nanostructured ITO films on light extraction efficiency
Authors: Pavluchenko A.S. , Markov L.K. , Smirnova I.P. , Levitsky V.S. 
Published: December 2019

Abstract
In this paper, we study composite nanostructured ITO films with different refractive index profiles, obtained by e-beam evaporation and magnetron sputtering, which can be used as a transparent conducting contacts in a wide variety of optoelectronic devices, e.g. AlInGaN light-emitting diodes. The composite ITO films that comprise of an underlying dense layer and a structured layer deposited on a glass substrate surface have been fabricated. Reflectance and transmittance spectra were measured. Numerical calculations have been utilized to obtain refractive index profiles of the studied films. Light extraction efficiencies of the studied films have been calculated.