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  • Effects of degradation of phase transitions in segnetoelektrichesky perovskites

    In a classical ferroelectric material the real condition of the crystals, caused different type defects, leads to insignificant effects of degradation. In systems of firm solutions and difficult oxides эфти effects are the integral physical properties. The features of degradation of phase transitions are available and in a ferroelectric material-relaksorakh.

    Keywords: Phase transitions, ferroelectric material, perovskites, difficult oxides, ferroelectric material-relaksory

  • "Methods of determining the grain boundary diffusion coefficient impurities in metals on the basis of numerical solutions for the Fisher model"

    In the introduction the relevance of the study of diffusion along grain boundaries in metals. The aim of the work was to develop a method for determining the diffusion coefficient of impurity atoms at the grain boundaries in metals based on the numerical solution of the model by Fisher. The methodology laid plotting the ratio of the depth of bulk diffusion and grain boundary diffusion on the ratio of the diffusion coefficients of impurity atoms in them. In the construction of numerical solutions available to simplify the modeling of the physical nature of the process of diffusion along grain boundaries. The technique may be used in experiments with widely varying parameters diffusion annealing. Examples of the application procedure. The estimation of the coefficient of grain-boundary diffusion of copper in polycrystalline nickel. Also calculated the ratio of maximal depth of diffusion of silver in the grain and the grain boundary in the SMC copper.

    Keywords: diversification of management, production diversification, financial and economic purposes of a diversification, technological purposes of ensuring flexibility of production

  • Effects of degradation of phase transitions in segnetoelektriakh-relaksor

    In a ferroelectric material of difficult structure with structure of a perovskite it isn't observed accurate phase transition. In this a ferroelectric material relaxation nature of dielectric polarization in the field of phase transition is observed.

    Keywords: Phase transitions, ferroelectric material, perovskites, difficult oxides, ferroelectric material-relaksory

  • Topological defects are located on a spherical surface.

    The simulation of two-dimensional spherical crystals consisting of a large number of particles is carried out. These shells were analyzed based on their geometric structure and energy distribution. Various types of defects formed in a state of equilibrium  is considered. Being shown the ambiguity of the existing method of their interpretation. A new way of describing such defects in the close-packed two-dimensional crystals with different topology is suggested.  

    Keywords: topological defects, two-dimensional materials, spherical crystals, topological charge

  • Gold nanoparticles functionalisation by long-chain thiol and amine ligands: study of local atomic and electronic structure of ligand-gold bond

    In the present work we report on the study of local atomic and electronic structure of gold nanoparticles funnctionalised by thiol and amine containing long-chain ligands. The study of nanoscale atomic structure is performed by means of X-ray absorption spectroscopy (XANES: X-ray Absorption Near-Edge Structure) and computer simulation. In consequence of the experimantally obtained data analysis and computer simulation it was obtained that strong bonding takes place when 11-mercaptoundecanoic acid is bound to the gold nanoparticles surface, forming a chemical bond Au-S 0.25 nm in length. Weaker bonding is observed when forming bond between dodecylamine and gold nanoparticles surface atom resulting in Au-N bond 0.23 nm in length. Supplementary XANES spectra analysis by means of density functional theory reveals the nature of formation of the investigated nanoscale structure.

    Keywords: nanoscale structure of matter, X-ray absorption spectroscopy, XANES, density functional theory, nanoparticles functionalisation

  • Modeling the ab initio structure of layered aluminosilicates.

    This work deals with the study of atomic and electronic structure of kaolinite samples (Glukhovtsy deposit) and montmorillonite (Millerovsky deposit) by density functional theory. The applicability of existing exchange-correlation potential in the local density approximation (LDA) and the generalized gradient approximation (GGA) is analised for an adequate description of the physical properties of layered aluminosilicate. An experimental and theoretical study of the IR spectra of minerals, as well as the identification of the most intense absorption bands, performed in the approximation of DFT using the exchange-correlation potential PW91. The analysis of the band structure of these minerals, which showed that these compounds are direct-gap insulators.

    Keywords: DFT, clay, clay minerals, phyllosilicates, atomic and electronic structure, crystalline systems, IR spectrum band strukutra, the electron density

  • Comparative analysis of porous piezoceramics modelling by effective moduli and finite element methods with experimental data

    The results of computational experiments to determine the characteristics of the porous piezoelectric ceramics based on the methodology, including the effective modules method, simulations of representative volumes on a simple random method and the method of Witten-Sander, finite element method to solve static piezoelectric problems for heterogeneous composite media and the accounting of inhomogeneous polarization near the pores are presented. A comparison of the results of computer simulation with the known experimental data for the porous material PZT-4 and its analogs is realized. It is concluded that the accounting of inhomogeneous polarization in the vicinity of porous provide the better agreement between numerical results and large number of known experimental data. Thus, for most effective constants the smallest errors are obtained for a representative volume of the porous piezoelectric material, constructed by Witten-Sander method.

    Keywords: piezocomposite, porous piezoelectric ceramics, inhomogeneous polarization, mathematical modelling, models of representative volumes, finite element method, effective moduli

  • Study of the catalytic ability of the nanosized catalysts based on CeO2 during catalytic reaction

    The nano-catalyst ceria (CeO2), activated by Pt nanoparticles, is known for being prospective and efficient material widely used in catalysis, fuel elements, and sensors. One of the most up-to-date methods of catalysts' reasearch is X-ray absorption spectroscopy (XAS) that is sensitive to the chemical state of catalyst's active centers [1,2]. Using XAS in the fluorescense detection mode at CeL1 line with high precision we studied electronic structure of Pt-activated nanoparticles of ceria at various redox conditions. In order to detect partial X-ray fluorescence yield the emission line CeLγ3 was used, which allowed us to increase spectral resolution. We researched local atomic and electronic structure of the materials under study. Oxygen vacansies were found to appear on the nanoparticles surface of ceria at 5% CO He atmosphere. Theoretical modeling of the obtained spectra at CeL1-edge demonstrated good agreement with experiment.

    Keywords: X-ray absorption spectroscopy, HERFD, XAS, Ce-based catalysts, oxygen vacansies

  • Local Atomic Structure and Computer Modeling of the Copper Ion in Amyloid Beta Peptide: XAS Study

    Alzheimer's disease is an incurable illness. It affects about half a million people in Russia, and due to the general trend towards aging of the population the number of Alzheimer's disease cases will steadily increase. Insoluble deposits of amyloid beta in the brain tissue (amyloid plaques) are the major morphological characteristic of Alzheimer's disease. It has been found that the increased concentration of copper in amyloid plaques results in copper ions bound to the protein. It is the presence of copper in the binding site triggers of the formation of amyloid plaques. Therefore, the study of the binding site in amyloid beta is of great scientific interest. The local atomic structure of the Cu(I) copper ion binding site in the amyloid beta peptide has been studied by means of XANES spectroscopy. Several model structures obtained by molecular mechanics and density functional theory (ADF code) have been tested. Theoretical analysis of X-ray absorption spectra based on the finite difference method implemented in FDMNES code was performed. An appropriate model structure of the Cu(I) copper ion binding site in amyloid beta peptide has been found.

    Keywords: amyloid beta, binding site, Alzheimer's disease, the method of finite differences, Cu(I)

  • In-situ XANES technique to study of the catalysts

    This paper describes an in-situ experimental technique to study of ceria nanocatalysts by using X-ray absorption near edge spectroscopy XANES. This technique allows us to determine Ce3+ concentration inside ceria nanoparticles in the course of catalytic reaction based on the comparison and divergence minimization of the Ce L3 XANES spectrum of the ceria nanoparticles under catalysts (atmosphere, temperature) with a linear combination of two independent components corresponding to spectra of Ce4+ ion of the CeO2 structure and Ce3+ ion of the theoretical Ce2O3 structure. The calculated weight ratio determines the Ce3 + concentration in the sample during the catalytic reactions.

    Keywords: in-situ X-ray absorption spectroscopy, HERFD, XAS, ceria nanoparticles, Ce-based catalysts, Ce3+ concentration

  • Raman spectra on three phase transitions of perchlorate of natrium

    The analysis of temperature dependence of frequencies of lines  is conducted active in the spectrums of combination dispersion of  perchlorate of natrium. The theory analysis of spectrums is conducted.

    Keywords: Perchlorat of natrium, anion, spectrums of combination dispersion, phase change

  • Digital voltammograph

    A compact digital voltammograph for electrochemical analysis of aqueous solutions was created. Device’s construction and drawings of the electrochemical cell for the studying of small amounts of fluids are described. Electronic circuits are assembled on modern high-precision components. The device implemented using cyclic, normal pulse and differential pulse voltammetry. Experiments were carried out with solutions of copper ions and hydrogen peroxide to test operability and characteristics of the voltammograph. All implemented methods gave reproducible results that are consistent with the theory. Typical results of the experiments with solutions of copper ions are shown.

    Keywords: voltammetry, voltammograph, voltammogram, electrochemical cell, analysis of solutions

  • Symmetry of anions in molten solts and raman spectra

    The values  the frequencies of the stretching vibrations of anions  SCN-,  NO2-, NO3-, CℓO4- in molten salts of alkali metals and their point group symmetry. There is a correlation with an increase in the frequency of symmetry  

    Keywords: Raman Spectra; anions; molten solts; group symmetry.

  • Investigation of ZnO nanorods by photoluminescence technique for optimization characteristics of sensitive element SAW of CO sensor

      Sensitive element of CO sensor was created by pulsed laser deposition and it was integrated in device of surface acoustic waves (SAW). Photoluminescence was used to control of oxygen-related defects of ZnO nanorod arrays. It is shown that the deficiency of oxygen in zinc oxide nanorods can be increased by change in temperature synthesis of nanorods of 850 to 915 ° C with a high argon pressure, and control of the deficiency of oxygen by increasing the ratio of the intensity of radiation in the visible region of the luminescence intensity in the ultraviolet region of the spectrum can help to increase the sensitivity of CO.

    Keywords: ZnO nanorods, photoluminescence, CO sensor

  • Local atomic structure dynamics of new nanostructured condensed materials for rechargeable current sources on the basis of V2O5/Fe/LiF nanocomposite within charge-discharge cycle

    In this paper we study the dynamics of the local atomic structure of new nanostructured condensed material for for rechargeable current sources on the basis of 15mas.%V2O5/Fe/LiF nanocomposite within charge-discharge cycle on the basis of X-ray diffraction (XRD), X-ray absorption spectroscopy (XANES) and of computer simulation. The analysis of the experimental data obtained during the first charge cycle reveals the transformation of iron to more than 50% of iron fluoride (II) , Li ions intercalate into the structure of amorphous V2O5 forming LiVO2 compound.

    Keywords: diversification of management, production diversification, financial and economic purposes of a diversification, technological purposes of ensuring flexibility of production

  • Investigation of influence of adsorbtion of CO on characteristics of hold-up line on SAW with ZnO nanorods sensitive element

    Structure of  surface acoustic waves(SAW) of CO sensor was developed. SAW sensor include transceiving IDT and catoptric IDT, which is loaded on the impedance of ZnO nanorods. Peak of reflection SAW from IDT clearly observed as result Fourier transformation of time function of pulsed response. IDT loaded on resistance paralleled ZnO nanorods, which depends on the concentration of CO.

    Keywords: ZnO nanorods, device on SAW, CO sensor

  • Development of the new method for determination of 3D nano atomic and electronic structure of materials based on XAFS, XRD and Raman techniques

    Combined method which allows analyzing parameters of the nanoscale atomic and electronic structure of materials relying on three different methods (x-ray absorption spectroscopy (XAFS), x-ray diffraction (XRD) and Raman spectroscopy) was developed. The method was applied for the study of nickel oxide nanoparticles, which serve as an efficient catalyst for the artificial photosynthesis process. 

    Keywords: solar energy, artificial photosynthesis, NiO, Raman, x-ray diffraction, XAFS

  • Operando dynamics of the nanoscale atomic and electronic structure of materials for hydrogen storage

    We have carried out the analysis on the scientific and technological literature on methods of calculation and analysis of the x-ray diffraction, x-ray absorption and Raman spectra used to analyse the structure of the materials for hydrogen storage under realistic operating conditions. The simulations were carried out for the series of small palladium nanoclusters with embedded hydrogen. Multiscale computer modelling was used to simulate the dynamics of structure of the materials during charge/discharge phases.

    Keywords: hydrogen storage, XANES, x-ray diffraction, Raman scattering, fuel cell

  • Anomalous electron emission in the soft X-ray irradiation of the surface of electrets

     Theoretical model of anomalous electron emission has built for an soft x-ray irradiation of  surface elektrets, explaining the different character of correlation between energy and emission intensity of ferroelectric  solid solution PbTiO3 - CaTiO3 and nonferroelectric  ceramics CaTiO3.  Shown that  due electret surface irradiation the  Schottky area is  depleted by nonequilibrium charge carriers.

    Keywords: Emission, electret, ferroelectricity, Schottky area

  • The passive wireless sensor on surface acoustic waves for measurement of gas and liquid environments parameters

    The sensor design on surface acoustic waves (SAW), representing the delay line with unidirectional inter-digital transducers (IDT) is considered. The factor of reflection of SAW from the unidirectional IDT loaded on impedance depending on value of resistance connected to it is investigated. On dependence of factor of reflection on size of resistance there is almost linear site at values of resistance more than 50 Ohm. The new design of the connected lattices of nanowire of zinc oxide, having the general resistance in a range of 50-250 Ohm which is connected to reflective IDT as loading is developed.

    Keywords: passive sensors, ZnO nanowire, surface acoustic waves, interdigital transducer.

  • Technological methods of increasing the Curie point of PZT piezoceramic phase

    It was investigated the influence several additives and process parameters on the properties of piezoelectric ceramics based on PZT phase systems. It was shown that the use of the substitution of Pb2+ ions on the Bi3+, and Ti4+ ions, and Zr4+ to Fe3+ and Mn4+, as well as the method of "chemical assembly «allows to obtain increase the Curie temperature of ceramic samples of 50 - 170°C. The theoretical aspects of this area of research have been discussed in this article.

    Keywords: ferroelectric phase, Curie temperature, ceramics, precursors, perovskite, a solid-state method, a method of «chemical assemblage

  • Convergence of the method of theoretical modeling X-ray absorption spectra for Ru XANES L 2,3-edges in the density functional theory (DFT) crystals as an example [Ru (NH3) 6 3 +

    The results of analysis of computational aspects of the method of obtaining the XANES spectra for Ru L2 ,3-edges by integrating the dipole transition matrix elements involving DFT. The convergence of the numerical integration procedure for the parameters used in the earlier papers, crystals as an example [Ru (NH3) 6] 3 +. More specifically, it is proved that it is possible to use a small area of ​​integration and big enough step between points, which helps to minimize the requirements for computing power and offers the prospect of using this method for the simulation of the XANES spectra in coordinated ruthenium catalysts for splitting water research in the field of solar energy.
    Keywords: RuLedge, XANES, DFT, density functional theory, X-ray absorption spectroscopy, geksoaminoruteny, Ru (NH3) 6.

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  • Determination piezomodule of piezoceramic element material

    The new method of piezomodule determination of piezoceramic element is offered. It is implemented in devices without memory elements and allows to form the output electrical signal of the corresponding piezomodule automatically right after measurements.

    Keywords: piezomodule, piezoceramic element, active component of conductivity, derivative, automated devices.

  • Two-dimensional trigonal chiral and hexagonal quasilattice

    The construction of a two-dimensional tiling by a specific projection of three-dimensional cubic lattice is considered. Different a periodic tiling’s, consisting of equal rhombi, are obtained by different choice of the projection region. They are ordinary a periodic tiling, having local elements of symmetry group С6v and chiral trigonal stacking, built like chiral pentagonal Penrose’s quasilattice [1], which occurs in virus cap sides.

    Keywords: Quasicrystal, quasilattice, two-dimensionalquasicrystal, chiral quasicrystal.

  • Study of the growth of ZnO nanorods carbothermal synthesis method for thin film sublayers ZnO: Ga

    Carbothermal synthesis method on substrates of a-Al2O3 thin film with sublayers ZnO: Ga, using copper as a catalyst for the arrays obtained by varying the zinc oxide rod morphology. It was established that growth of the rods occurs direction perpendicular to the substrate using a thin (~ 1 nm) layers of the catalyst. With increasing thickness of the catalyst layer to 3 nm rods growth occurs at an angle to the surface of the rod with a mutual orientation in the plane of the substrate surface at angles that are multiples of 60 °. Also, the selectivity demonstrated growth ZnO rods arrays on portions of the substrate coated with the catalyst.
    Keywords: zinc oxide, micro - and nanorods carbothermic synthesis method, film sublayer growth catalyst.

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