PCSS, V.15, №1, 2014

Abstracts

O.S. Krunutcky

Thermoelectric Nanocomposite Materials Based on Doped Lead Telluride (Review)

Ivano-Frankivsk National Technical University of Oil and Gas, 15, Carpathian Str., Ivano-Frankivsk, 76001, Ukraine e-mail:oleksandr.krynytsky@gmail.com

A review of the problems of obtaining and research complex thermoelectric properties of composite materials doped Update the various elements of the periodic table of lead telluride semiconductor promising compound for medium temperature region (500-850) K. Found that the doping of lead telluride elements Na and K, in the content of more than 0.5 at.% Observed the formation of nano-sized particles, and the maximum value of the thermoelectric figure of merit (ZT) for PbTe: Na1, 75 at.% 1.6. When doped Lead Telluride III elements of the periodic table form resonant states within the allowed zones, resulting in a significant increase in thermopower, the maximum value of which is 360 μV/K and ZT = 1,6. When doping Sb and Bi nanoparticles are formed that contribute to strong scattering by acoustic phonons, which contributes to a significant decrease in thermal conductivity. When doped PbTe La and I formed a very small donor states, so each dopant atom adds one electron in the conduction band, in general ZT values for these materials is 1.2. When europium doped PbTe formed nanoparticles clearly improves thermal conductivity that varies (1,4-2,4) W/m•K.
Keywords: thermoelectricity, Lead telluride, composites, semiconductors.

M.V. Tkach, Ju.O. Seti, I. Boyko, Ju.B. Grynyshyn

Interaction of Electrons with Confined Phonons in Multilayer Resonant Tunneling Structure

Chernivtsi National University, Chernivtsi, Kotsubynsky str., 2, 58012, e-mail:ktf@chnu.edu.ua

The theory of electron stationary spectrum and wave functions in plane multilayer resonant tunneling structure placed into the electric field is developed using the model of the active band of the quantum cascade laser. For the same nanostructure the theory of confined optical phonons spectra is established within the dielectric continuum model. Using the obtained electron wave functions and phonon polarizational potentials the theory of electron – confined phonons interaction in multilayer nanostructure is developed. The Hamiltonian of this interaction is obtained in the representation of second quantization. The calculations of the electron and the phonon spectra and potential of polarization of confined phonons are performed for the experimental resonant tunneling structure. The partial shifts are calculated for the electron spectrum renormalized by the interaction with confined phonons. The obtained results are in good correlation with the experimental data.
Keywords: quantum cascade laser, resonant tunneling structure, confined phonons, electron-phonon interaction.

V.I. Gutsul, О.М. Мakhanets, A.I. Kuchak

Energy Spectrum of Optical Phonons in the Plane Multi-Layer Resonance Tunnel Nanostructure

Chernivtsi National University, 58012 Kotsiubynsky Str., 2, Chernivtsi, Ukraine, e-mail:ktf@chnu.edu.ua

In the paper, using the dielectric continuum model, we present the investigation of energy spectra of confined and interface optical phonons in the plane multi-layer resonance tunnel nanostructure produced at the base of heterotransitions GaAs/AlAs. We show that the energies of confined optical phonons in this semiconductor nanoheterostructure are determined by the energies of longitudinal polarization vibrations in the respective massive crystals, creating the nanostructure. We observe the dependences of the energies of interface optical phonons on their quasi-momentum and geometrical sizes of GaAs and AlAs nanoshells.
Keywords: optical phonons, resonance tunnel nanostructure, polarization potential, nanolayer, dielectric continuum model.

E.Ph. Shtapenko, V.A. Zabludovsky, E.O. Voronkov, V.V. Dudkina

Quantum Mechanical Approach to Identify Young's Modulus for Metals With a Cubic Lattice

Dnepropetrovsk National University of Railway Transport them. ak. B. Lazarian, Dnepropetrovsk, Ukraine

This paper proposes a quantum-mechanical approach to calculate the Young's modulus of metals. Young's modulus is determined by the ratio of change in the total energy of the crystal lattice in a particular crystallographic direction of change in the crystallographic direction. The energy of the crystal lattice are in approximation of density functional theory (DFT). Young's moduli are found in different crystallographic directions for iron grille with a body, nickel and copper with a face-centered cubic lattice. A comparison of the theoretical valuesof Young's modulus with experimental films electrodeposited for these metals.
Keywords: Young's modulus, the quantum-mechanical approach, the energy of the crystal lattice, of density functional theory.

O.V. Bovgyra, M.V. Kovalenko

Electronic-Adsorption Properties of Nonpolar ZnO Surface

Ivan Franko National University of Lviv, Lviv, Ukraine

The adsorption of H2O, CO, NH3, O2, H2, methanol, ethanol, and acetone on nonpolar ZnO surface were investigated using first principles calculations. The optimal adsorption positions and orientations of considered molecules on ZnO surface are determined and the adsorption energies are calculated. Two mechanisms of adsorption process are considered: adsorption-induced reconstruction of the ZnO surface; charge transfer between the molecules and the surface, that lead to the changes of electronic structure of the ZnO surface.

D.M. Freik¹, T.O. Parashchuk¹, B.P. Volochanska¹, M.A. Rehteta², R.V. Dinjos²

Thermodynamic Parameters of CdS Sphalerite Crystals in Quantum Chemistry Representation

¹Physical-Chemical Institute, SHEE " Vasyl Stefanik Precarpathian National University” 57, Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine
²Laboratory of Polymer Physics Mykolayiv National University named after V.A. Sukhomlynskiy, 24, Nikolska Str., 54030 Nikolaev, UkraineE-mail:taras-parashchuk@i.ua

Based on the analysis of the crystal and electronic structure of cubic phase CdS crystals of sphalerite the cluster models have been built for calculation of the geometric and thermodynamic parameters. According to density functional theory (DFT) and using the hybrid valence base set B3LYP the temperature dependence of the energy ΔE and the enthalpy ΔH of formation, Gibbs free energy ΔG, entropy ΔS, specific heat at constant volume CV and pressure CP of the crystals have been found. The analytical expressions of the temperature dependences of presented thermodynamic parameters which was approximated from the quantum- chemical calculations data and with using mathematical package Maple 14 have been received. There is compared the results of ab initio calculations and experiment.
Keywords: DFT, cluster models, calorimeter measuring, the thermodynamic parameters.

R.O. Dzumedzey, L.I. Nukuruy, V.V. Boryk, Yu.V. Bandura, T.P. Gevak

Thermoelectric Efficiency of Solid Solutions PbTe1-xSex Over a Wide Temperature 300-800 K

Vasyl Stefanyk Precarpathian National University 57, Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine, E-mail:fcss@pu.if.ua

The results of research of kinetic parameters (mobility, coefficients thermo power, electrical conductivity and thermal conductivity) samples PbTe1-xSex with different composition х = 0; 0,5; 0,15 та 0,25 produced sintered method. The optimum composition and temperature range of maximum thermoelectric figure of merit.
Keywords: solid solution, kinetic parameters, synthesis.

G.P. Gaidar¹, P.I. Baranskii², V.V. Kolomoets¹

Тensoresistance of n-Si and n-Ge Multi-Valley Semiconductors Over a Wide Range of Concentrations

¹Institute for Nuclear Research of NAS of Ukraine, 47, prospect Nauky, 03680 Kyiv, Ukraine, е-mail: gaydar@kinr.kiev.ua
²V. Lashkaryov Institute of Semiconductor Physics of NAS of Ukraine, 45, prospect Nauky, 03028 Kyiv, Ukraine

In this paper, at Т = 77.4 К the tensoresistance of n-Si and n-Ge single crystals over a wide concentration range 10¹<n_e <2 ^. 10¹⁹ cм ³ and the mechanical stresses 0 < Х < 1.5 GPa were studied and some of its features that appear at the breaking point of degeneration of the electron gas in these crystals were discussed. The physical basis of the results obtained was presented.
Keywords: silicon, germanium, uniaxial elastic deformation, tensoresistance, charge carrier concentration.

V.M. Pylypiv, V.O. Kotsuybynsky, I.M. Gasyuk, О.Z. Garpul, V.V Kurovec

Mathematical Modeling of Radiation Defects Implanted of Ions Fluoride in Single Crystals of Gadolinium Gallium Garnet

Vasyl Stefanyk Precarpathian National University, 57 Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine

Presented the results of mathematical modeling of process of radiation disordering the structure of the surface layer of single crystal gadolinium gallium garnet - implanted by ions of fluorine. Received distributions with depth in the surface layer of energy in elastic and inelastic braking implant in the structure of implanted ions аnd of shifted of ions matrix of structural disordering in the crystal, calculated cascades of atomic collisions with the atoms of the target of the implant and the probability of formation of secondary displacement cascades with different numbers of ions.
Keywords: mathematical modeling, ion implantation, gadolinium gallium garnet.

V.M. Rubish1, O.G.Guranich1, O.V.Gorina1, S.M. Gasinets1, A.M. Solomon2, P.P. Guranich3, V.P. Perevuznyk1

Dielectric Properties of (As₂Se₃)_100-x(SbSeI)_x Glasses and Composites

¹Uzhgorod Scientific-Technological Center of the Institute for Information Recording, NASU, Uzhgorod, Ukraine
²Institute of Electron Physics, NASU, Uzhhorod, Ukraine
³Uzhgorod National University, Uzhgorod, Ukraine,

Dielectric properties and structure of the (As2Se3)100-x(SbSeI)x (x = 60, 70, 80, 90) glasses and composites on their basis have been investigated. It is established that the phase structure arising in the matrix of glasses during crystallization corresponds to the structure of SbSeI crystal. Glass crystallization is accompanied by a sharp increase of dielectric parameters. The influence of annealing temperatures and time on the sizes of crystalline inclusions and dielectric properties of ferroelectric glass-ceramics are discussed.

V.О. Kotsyubynsky¹, L.V. Regush¹, V.V. Moklyak², A.B. Hrubiak¹, N.Ya. Ivanichok¹

Structural, Magnetic and Electrical Properties of Highly Dispersed Lithium Iron Spinel Synthesized by Ion Exchange Method

¹Vasyl Stefanyk Precarpathian National University, 57 Shevchenko Str., Ivano-Frankivsk, 76025, Ukraine, v_kotsuybynsky@mail.ru
²Institute of Metal Physics, National Academy of Science, 36 Aс. Vernadsky Boulevard., Kyiv, 03680, Ukraine, mvvmcv@mail.ru

Highly dispersed lithium pentaferrite β-LiFe5O8 was synthesized by ion-exchange method at temperatures up to 120оС. Magnetic structure and specific surface area changes as a function of the ion-exchange reaction duration were analyzed. Obtained β-LiFe5O8 samples have random distribution of lithium and iron ions in oc¬tahedral sublattice of spinel structure that enhances their electrical conductivity. The model that explains of the conductivity dependence on the synthesis duration was proposed. It is expected that the combination of obtained materials electrical and morphological parameters will allow lithium pentaferrite β-LiFe5O8 become an effective cathode material for lithium power sources.
Keywords: lithium pentaferrite, ion-exchange reaction, Mossbauer spectroscopy, electrical conductivity.

A.A. Druzhinin^1,2, I.P. Ostrovskii ¹, Yu.N. Khoverko^1,2, R.N. Koretskyy ¹, S.I. Nichkalo¹

Impedance of Sі Wires at Metal-Insulator Transition

¹National Lviv Polytechnic University, Lviv, Ukraine, tel. (032)2582627, druzh@polynet.lviv.ua
²International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw, Poland

Impedance spectroscopy for Si wires with dopant concentrations near the metal-insulator transition in the low temperature range 4.2 - 70 K and frequencies 0.01 - 250 kHz has been conducted. The studies allow us to obtain parameters of hopping conduction (localization radius, density of localized states and average length of carrier jumping) and compare them with theoretical data.
Keywords: Si wires, magnetoresistance, impedance spectroscopy, localization radius.

Y.P. Saliy, D.M. Freik, I.S. Bylina, I.M. Freik

Orientation Aspects and Simple Crystallographic Form Nanostructures in Thin Films of PbTe:Bi on Ceramics

Vasyl Stefanyk Precarpathian National University, 57, Shevchenko Str., Ivano-Frankivsk, 76000, Ukraine, Е-mail: freik@pu.if.ua

Using atomic force microscopy shows the results of the research orientation of structure formation processes in vapor-phase condensates PbTe:Bi/Sital received open evaporation under vacuum at deposition temperature T_S = (420-520) K, the sample temperature evaporation T_V = (920-1020) K and deposition time τ = (3-120) s. It is shown that the surface of ceramics formed single nanocrystals with combinations of faces {100} and {110} NaCl structure and presented their hnomostereohrafichni projection. The peculiarities of crystalline forms nanocrystals PbTe: Bi explained electrically neutral state crystallographic planes of the substrate surface and the nature of ceramics. The dependence of azimuthal φ and polar angles ρ of various technological factors, namely the deposition time τ and the temperature of the evaporator T_V.
Keywords: vapor-phase condensates of lead telluride, crystalline form, the polar and azimuthal angles.

R.R. Romanyuk^{1, 2}

The Time Stability of Changes of the Fundamental Optical Absorption Edge of Amorphous GeSe Films Induced by g-Irradiation

¹Western Scientific Centre, 4, Mateyko Str., Lviv, 79007, Ukraine, е-mail: rrr_roman@rambler.ru
²Ivan Franko L'viv National University, 8, Kyryl and Mephodiy Str., Lviv, 79005, Ukraine

The influence of ((Со60)-radiation at 104–106 Gy doses on the structure and optical properties of amorphous GeSe thin films obtained by the method of flash evaporation on the substrates at Ts = 293 K is being investigated. The gamma-irradiation of GeSe films caused low-energetic shift of their fundamental optical absorption edge, while the energy gap and steepness of Urbach edge were decreased. Radiation-induced effects are unstable in time and partially damped within one year of storage. Radiation-induced changes of physical properties in amorphous GeSe thin film are explained in the framework of radiation defect-formation processes as results of destruction-polymerization transformations. Keywords: GeSe, amorphous films, absorption edge, (-irradiation.

Y.P. Saliy, M.V. Kotyk

Modeling of Growth Processes of Nanostructures by Monte Carlo Method

Vasyl Stefanyk Precarpathian National University 57, Shevchenko Str., 76018, Ivano-Frankivsk, Ukraine,

Considered one of the basic numerical methods for modeling the processes of evolution systems with many particles - Monte Carlo. A survey of two algorithms implement Monte Carlo: Metropolis and planning events on the timeline. A new algorithm using cellular automata, temperature level is set by the number of existing connections between neighboring, time corresponds to the number of complete cycles of passage for all particles. The simulation of two-dimensional systems with rigid boundary conditions and different initial concentrations of atoms are made. Dependence forms nanoclusters that formed on the choice of the type of kinematic correlations of the ensemble of atoms are shown.

V.G. Lytovchenko, V.P. Melnyk, V.G. Popov, G.V. Fedulov, V.A. Danko, I.Z. Indutnyi, K.V. Mykhaylovska, P.E. Shepelyavyi

Photoluminescence nc-Si/SiOx Porous Structures Implanted Carbon Ions

V. Lashkoryov Institute of Semiconductors Physics NAS of Ukraine, Kyiv, Ukraine

The influence of carbon ions implantation on photoluminescence (PL) of porous nc-Si/SiOx layers with columnar structure, formed by vacuum glance angle deposition and subsequent high temperature annealing of SiOx films. The PL spectra of the implanted structures covers almost the entire visible and near-infrared region, and includes two main components with maxima in the area 520-570 and 620-680 nm. Long wavelength PL band associated with silicon nanoparticles and radiation in the visible region of the spectrum can be caused by luminescence of carbon precipitates and SiC nanoclusters. As a result of the selective etching of these structures in HF vapor the intensity of PL throughout the spectral range increases significantly (up to two orders of magnitude) due to passivation of nonradiative recombination centers.

D.M. Freik¹, G.D. Mateik², Ya.S. Yavorskiy¹, G.D. Shimko³

The Structure, Optical and Thermoelectric Properties of Vapor-Phase PbTe:Sb/(0001) Mica Condensates

¹Vasyl Stefanyk Precarpathian National University, 57 Shevchenko Str., Ivano-Frankivsk, 76025, Ukraine, E-mail:freik@pu.if.ua
²Ivano-Frankivsk National Technical University of Oil and Gas, 15, Carpathian Str., Ivano-Frankivsk, 76001, Ukraine
³Institute of Physics of B.I. Stepanova NAS of Belarus 220072, Minsk, Independence Avenue 70, Belarus, E-mail:iyakin@ifanbel.bas-net.by

There is spending the study of vapor-phase thin film PbTe:Sb structures, which have been obtained in open vacuum on (0001) mica - muscovite brand MTA . Using atomic force microscopy (AFM) there is revealed that the origin of the vapor-phase condensates have been done by Folmera-Weber mechanism of synergistic implementation processes associated with stages of nucleation islands , their aggregation and coalescence, and formed nanocrystals are trigonal pyramids with {100} facets and ( 111) base, parallel to the substrate surface . It is shown that the infrared (IR ) “absorption – reflection” spectra of PbTe:Sb/( 0001) mica condensates with thickness (0,27-2,43 ) micron are containing reflection of mica and intense band interference. Optical bandgap of 0.25 atomic % Sb is Eg300K = (0,11-0,13) eV, which is four times less in comparison with the undoped material ( Eg300K = 0.32) eV). Stable n- type conductivity and high concentration of electrons (1019-1020) cm -3 doped condensates have been explained by the dominance of substitution of lead Sb3+ ions of Pb2+ in the cationic sublattice of the basic matrix (Sb3+ → Sb1+Pb) that are effective donors.
Keywords: Thin Films, Lead Telluride, the Processes of Structure, Optical Properties, Thermoelectricity.

B.S. Dzundza, I.I. Chaviyak, L.Yo. Mezhylovska, O.B. Kostyuk

Surface Layers and Thermoelectric Properties of Thin Films of Tin Telluride

Vasyl Stefanyk Precarpathian National University 57, Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine, E-mail:fcss@pu.if.ua

The thermoelectric properties of tin telluride films obtained by vapor condensation on the high vacuum on ceramics and mica substrate are researched. Based on a two-layer Petritz’s model defined electrical parameters of surface layers. The results are interpreted by adsorption of oxygen on the surface and its diffusion into the interior of the condensate. Keywords: thin film, tin telluride, surface, thermoelectric properties.

I.I. Chav'yak, L.Y. Mezhylovska, V.I. Makovyshyn, V.V. Prokopiv

Thermoelectric Properties and Defect Subsystem Vapor-Phase Condensates Tin Telluride on Glass-Ceramic Substrates

Investigated the thermoelectric properties of SnTe thin films with thickness ( 40-900 ) nm obtained by condensation of vapor on the high vacuum on substrates of glass ceramics under different growing technological factors : evaporation temperature Тe and Тs deposition and pressure of tellurium РТе₂. Showing that elected the conditions for receiving condensate has only p-type conductivity and it is characterized by a large concentration of carriers (10²⁰ -10²¹ )см^-3. Established trend in the changes of the kinetic coefficients (conductivity σ, Seebeck coefficient S, thermoelectric power S2σ, carrier concentration P and mobility of carriers μ) condensates with thickness d and the variable Тs , Тe, РТе. The obtained experimental results are explained by the peculiarities of the defect subsystem of point defects, dominant among which are two- and four- charge vacancies stanum, the ratio between them determines the full range of properties under different conditions of their formation. Determined that the thin-film condensation tin telluride unlike bulk samples have high Seebeck coefficient S ≈ 80 μW/К та S2σ ≈ 18 μW/К2cm, which makes them perspective for use of p-branches in thermoelectric micromodules.
Keywords: Tin telluride, vapor-phase condensates, thermoelectricity, point defects.

V.I. Mandzyuk, V.M. Sachko, I.F. Myronyuk

Anode Materials of Lithium Power Sources on Silicon and Silicon-Based Compounds (Review)

Vasyl Stefanyk Precarpathian National University 57, Shevchenko Str., 76018, Ivano-Frankivsk, Ukraine, е-mail: mandzyuk_vova@rambler.ru

This review analyzes the trend of using silicon and silicon-containing materials used as electrodes of lithium power sources (LPS). The reasons that do not allow effectively use them for industrial production of LPS are indicated and basic ways for their removal are outlined. The basic operating parameters of LPS on the silicon and silicon-based compounds are resulted and their interrelation with technology of receipt, structure and methods of further modification of electrode materials is found out.
Keywords: lithium power sources, silicon-based anode materials, volume changes, specific capacity.

M.P. Levkun

Physical-Chemical Properties and Crystal-Chemical Doping Mechanisms of ZnSe Crystal by Co, Ni Transition Elements

Physical-Chemical Instituteatthe‘VasiliyStefanyk’PrecarpathianNationalUniversity, 201, GalytskaStr., Ivano-Frankivsk, 76000, Ukraine, E-mail:freik@pu.if.ua

Based on the analysis of physical and chemical properties there is made the point defect model of the doped by transition metals (Co, Ni) Selenium Zinc crystals. Based on the proposed crystal-quasichemical formulae of the defects concentration depending, free charge carriers, Hall concentration on the doping content have been calculated.
Keywords: zinc selenide, point defects, crystal- quasichemical formulae, doping, transition.

M.I. Spodaryk, L.G. Shcherbakova, A.V. Samelyk, Yu.M. Solonin

Electrochemical Characteristics of Gas Atomized LaNi2.5Co2.4Al0.1 Alloy Electrodes

Institute for Problems of Materials Science, NAS of Ukraine, Krzhyzhanovsky Str., 3, 03680, Kyiv-142, Ukraine email: poshtamary@ukr.net

The electrochemical investigation of the gas atomized alloy LaNi2.5Co2.4Al0.1 electrodes of two powder factions has been carried. The electrochemical properties of the electrodes, such as activation rate, discharge capacity and high rate discharge ability, with increasing of alloy fraction size are improving. It is shown that the use of lightweight carbon nanomaterials as electrode conductive additive does not reduce the stability of the hydride, but slightly reduces the discharge capacity of the electrode compare to electrode with copper additive.
Keywords: gas atomized alloy, fraction, hydride, discharge capacity, impedance, nanocomposite additive.

M.Yu. Barabash¹, E.L. Martynchuk¹, Yu.A. Kunitsky²

Gas-Phase Synthesis of Carbazole Compounds and Properties of the Films Nanocomposites

¹Technical Center, National Academy of Science of Ukraine, Kiev, Ukraine
²Taras Shevchenko Kyiv National University, Kyiv, Ukraine

Thin films made on the basis of Poly (N-vinylcarbazole (PVCa) doped with acceptor organic and inorganic semiconducting compounds and gold is investigated. It is envisaged that the doping PVCa donor-acceptor compounds in particular CdSe, should lead to an increase in the values of the photoinduced the charge. The combination of the properties held by PVCa with other materials makes these materials attractive multifunctional systems with great potential that can be used to elektrophoto as sensors and templating technologies.

M.M. Vorobets

Effect of Finishing Chemical Treatment of Si-Wafers Surface on the Desorption of Ag+, Fe3+, Ca2+ Ions

Yuriy Fedkovych Chernivtsi National University, 58000, Kotsyubinskogo St. 2, Chernivtsi, Ukraine, e-mail:m.vorobets@chnu.edu.ua

The effectiveness of different methods of finishing chemical treatment, which are used to reduce uncontrolled technological impurity, of surface Si-wafers is investigated by the method of radioactive indicators. Criterion of qualitative and quantitative evaluation of the effectiveness of finishing chemical treatment chosen as value change of contact potential difference, work function of electron and surface resistance. Experimentally, the adsorption of Fe3+ and Ca2+ ions decreases and Ag+ ions – to increase the value of the contact potential difference. It is shown, that in the case of Si-wafer processing in ammoniac-peroxide solutions the degree of desorption of ions iron does not exceed 40 %, while the ions Ag+ the degree of desorption 100 %. Introduction to ammoniac-peroxide solutions potassium hydroxide, treatment of acid-peroxide solution or combination treatment in ammoniac-peroxide solutions and acid-peroxide solution increase the degree of desorption of ions Fe3+ to 100 %. Desorption of Ca2+ ions to study options of finishing chemical treatment occurs with less efficiency than ions Fe3+ and Ag+.
Keywords: semiconductor, Si-wafer, finishing chemical treatment, the contact potential difference, adsorption, desorption.

H.O. Sirenko, Yu.D. Pakhomov

Antifriction Properties of Carbon Fibers and Carbon Textiles (Review)

Vasyl Stefanyk’ Precarpathian National University, 57, Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine, , e-mail:orijant@gmail.com

By results of researches of influence orientational effects on the antifriction properties of carboplastic and mechanism of wear of unidirectional carboplastics have been made a review. Anisotropy of properties of unidirectional fibers and textiles occurs in all schemes of research.
Keywords: carbon fibers, the intensity of wear, composite polymer material, reinforcing of layered composites schemes.

S. Mudry, Yu. Kulyk, S. Zhovneruk

Short Range Order Change at Structural Relaxation in Fe75Si6B14Mo5 Amorphous Alloy

Ivan Franko National University of Lviv, Lviv, Ukraine, Kyrylo and Mefodiy Str., 8, UA 79005, szhovneruk@gmail.com

Structural relaxation process in Fe75Si6B14Mo5 amorphous alloy has been studied by means of X-ray diffraction method. Structure parameters, obtained from analysis of structure factors and pair correlation functions are used in order to clarify this phenomenon on the short range order scale. More detailed analysis was done for profile of second maxima in structure factors. Results showed that rearrangement of atomic clusters occurs at high temperature relaxation.The structure relaxation is accompanied by formation the clusters of less size due to which an atomic distribution becomes more close to perfect amorphous structure.
Keywords: Amorphous alloys, structural relaxation, structure factors.

V.S. Bushkova^1,2, B.K. Ostafiychuk¹, А.V. Kopayev¹

Features of Synthesis of Complex Oxide Systems by Means of SGA-Method

¹Vasyl Stefanyk PreCarpathian National University 57, Shevchenko Str., Ivano-Frankivsk, 76025, Ukraine
²Ivano-Frankivsk National Medical University, 2, Galician Str., Ivano-Frankivsk, 76000, Ukraine, E-mail:bushkovavira@rambler.ru

In this paper studies the mechanisms of complex oxide systems formation obtained by the method of sol-gel autocombustion. It was found that at the mixing of precursors hydrolysis reaction occurring, leading to the formation of a sol. Neutralization of the dispersion environment using 25 % aqueous ammonia solution to pH = 7 leads to intense formation of aggregates of particles. It is shown that the process of the dry gel autocombustion occurred the resulting exothermic reaction at a temperature of about 483 K.
Keywords: nanoparticles, nanotechnology, sol-gel method, complex oxide systems.

B.J. Deputat

Temperature Dependences Conductivity of Ceramics with Composition Li₂O - Fe₂O₃ - Al₂O₃ from the Content of Aluminium

The Ivano-Frankivsk National Technical University of Oil and Gas, 15 Karpatska St., Ivano-Frankivsk, 76019, Ukraine e-mail:bdeputat@gmail.com

The method of impedance spectroscopy was used for research temperature dependences of electrophysical properties ceramic with composition Li2O-Al2O3-Fe2O3. It is shown that in general with increasing temperature conductivity increases, however, the Arrhenius curves for systems designs, depending on the method of synthesis, show the dominance of different mechanisms of conduction in some areas temperatures. In addition, with increasing content of aluminum in engines activation energy at which the change in the mechanism of conductivity shifts to higher temperatures. For samples slowly cooled with the oven was detected existence in the temperature range (350-400 K) ferroelectric properties, which are confirmed by temperature dependencies of the real part of the dielectric constant.
Keywords: impedance spectroscopy, spinel, activation energy, Arrhenius curves, the method of Mott.

V.V. Lopushansky

Formation and Annealing of Radiation Defects in High-Energy Electron-Irradiated Lead Silicate Glass

Institute of Electron Physics, Ukrainian National Academy of Sciences, Universytetska Str. 21, Uzhhorod, 88017, Ukraine

Optical absorption and Raman scattering spectra of lead silicate glass irradiated by 5- to 10-MeV electrons are studied. No irradiation-induced changes in the Raman spectra are observed. The absorption spectra show the high-energy electron irradiation to result in the formation of colour centres basically similar to those being formed by X-ray and gamma irradiation. Variation of the absorption spectra of the electron-irradiated lead silicate glass under thermal annealing and long-time post-irradiation storage are discussed.

O.Yu. Popov

Porosity Influence on the Kinetics of Boride Strength Degradation Due to Helium Swelling under Neutron Irradiation

Taras Shevchenko National University of Kyiv, Faculty of Physics, 4, Hlushkov Ave, 03187 Kyiv, Ukraine

A theoretical model for the estimation of boride porous ceramic strength degradation due to swelling during neutron irradiation is represented. Transmutation helium accumulation in two-dimensional defects considered to be the main reason for the radiation stimulated destruction of boride ceramics. Trapping of helium atoms within spherical nanopores is shown to unload cracks and to slow material degradation under neutron irradiation.
Keywords: borides, radiation resistance, strength, swelling.

S.P. Novosyadlyy, S.M. Marchuk, V.M. Varvaruk, L.V. Melnyk

Design and Technological Aspects of SC Structures on Silicon Epitaxial Structures

Vasyl Stefanyk PreCarpathian National University 57, Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine, E-mail:fcss@pu.if.ua

Investigated parameters and characteristics of CE structures made from silicon epitaxial structures. Presented system: activated boron or phosphorus silicon substrate and epitaxial layer, which coincides with the substrate by type conductivity.
Keywords: solar cells (SC) silicon epitaxial structure (SES) epitaxial technology.

L.M. Vikhor, V.Ya. Mikhailovsky, R.M. Mochernyuk

Material Optimization and Parameter Estimation of Generator Modules for Heat Recuperators

Institute of Thermoelectricity of the NAS and MES of Ukraine, 58029, 1 Nauky Str., Chernivtsi, Ukraine

Use of thermoelectric power converters in heat recuperators is considered as an efficient, cheap and environmentally safe method for recovery of thermal waste from industrial installations and internal combustion engines. Results are presented of composition optimization for materials based on BiTe, PbTe, TAGS (AgSbTe-GeTe), ZnSb, Mg and Mn silicides, CoSb scutterudites that are reasonable to be used for generator modules in recuperators with the operating temperature range 30 to 500 °C. Estimates are made and comparative analysis is performed of maximum efficiency of modules of these materials with the legs of homogeneous, functionally-graded, segmented and stage structures. Optimization and efficiency calculation are performed by computer methods based on optimal control theory. The results of calculations are confirmed by an example of experimental research on characteristics of two-stage modules made of materials based on BiTe, PbTe and TAGS.
Keywords: computer design, optimal materials, thermoelectric modules.

R.O. Denysyuk

Chemical and Mechanical Polishing of Cd_1-xMn_xTe by Solutions Based on H₂O₂–HI–Citric Acid

Zhytomyr State University named by Ivan Franko 10008, Zhitomir, 40 V. Berdichevsky, T. (0412 37-27-63), e-mail denisuk@zu.edu.ua

UThe process of chemical and mechanical polishing CdTe and Cd1-xMnxTe (0.3 <x <0.5) solid solutions by the solutions HI–H2O2–citric acid has been established. There is investigated the influence of the nature of the viscous component on the etching rate and quality of the polished surface single crystals. It is shown that at the dissolving by the basic polishing etchant with organic solvents (lactic acid, ethylene glycol or glycerol) surfaces of the studied crystals with high quality have been formed. It is found that by slowest etching rate of the chemical mechanical polishing are characterized the solvents with lactic acid, and the polishing quality improves with increasing kinematic viscosity of the organic solvent. Profilografy and microstructure analyzes examined the condition of the polished surface and defined their roughness after polishing (Rz ≤ 50 nm).