PCSS, V.15, №2, 2014

Abstracts

V.B. Brytan¹, R.M. Peleschak¹, A.А. Velchenko², I.P Kremer³, Yu Ugrun¹

Electrostatically Deformation Mechanism of Hydrogen Passivation of Electrically Active Centers in CdTe and Cd_1-xZn_xTe Semiconductors

¹Ivan Franko Drohobych State Pedagogical University, 24 I. Franko St., Drohobych 82100 E-mail:vbrytan@yandex.ra
²East-Ukrainian Volodymyr Dal National University, 20a, kv. Molodezhniy, Lugansk, 91034, Ukraine 3National university «Lviv politekhnika», street Stepan Banderi st. 12, Lviv, 79000

The model of hydrogen passivation of electrically active centers in CdTe and Cd_1-xZn_xTe is proposed in the frame of electrostatically deformation model. It was determined that passivation effect is increased when the concentration of atomic hydrogen does not exceed the acceptor concentration N_A(N_HN_A), while degree of passivation tends to zero for the case N_HN_A .

R.Ya. Stetsiv, O. Vorobyov

Phase Diagrams of Ion Conductor

Institute for Condensed Matter Physics National Academy of Sciences of Ukraine 1 Svientsitskii Str., Lviv, UA-79011, Ukraine, E-mail:stetsiv@icmp.lviv.ua

Equilibrium states of one-dimensional ion conductor are investigated on the bases of the lattice model where ions are treated as Pauli particles. The frequency dependencies of single-particle spectral densities are calculated using exact diagonalization technique for the finite ion chain and diagrams of states are obtained analyzing the features of this spectra. The regions of existence of various phases are obtained.
Keywords: Pauli particles, ion conductor, spectral density, phase diagrams.

D.V. Kondryuk¹, V.M. Kramar¹, I.Ya. Petryk²

Concentration and Size Dependences of a Polaron Binding Energy in AlxGa_1-xAs/GaAs/Al_xGa_1-xAs Nanolayers

¹Chernivtsi National University,2 Kotsyubynsky Str., Chernivtsi, 58012, Ukraine
²Ivano-Frankivsk National Technical University of Oil and Gas, 15 Karpatska Str., Ivano-Frankivsk, 76019, Ukraine

On approximation of dielectric continuum by Greene's function method, it is researched the influence of three-dimension constraints and interaction with optical phonons on the value of polaron energy in the quantum well of finite depth. For example nanolayer – a plane nanoheterostructure of quantum well, the binding energy of electron and hole polarons at different its values of thickness and different concentrations (x) of barrier material is calculated by of double heterojunction AlxGa1-xAs/GaAs. It is shown that the change in x affects on binding energy of the polaron in ultra-thin (50 nm) layers, where its value is formed mainly by interaction of the carrier and interface phonons.

M.I. Terebinska

Frequencies of Normal Vibrations Adsorptions Complexes of Oxygen on Silicon (111) Face, Calculation within a Cluster Approach

Chuiko Institute of Surface Chemistry of National Academy of Sciences of Ukraine 17 General Naumov Str., Kyiv, 03164, Ukraine, Е-mail: terebinska_m.i@bigmir.net

The structure of molecular adsorption complex of O2 molecule on Si(111) face as well as those of the products of its further transformations up to formation of SiO4 - tetrahedron has been examined by means of density functional theory method (B3LYP, 6-31G**) within a cluster approach. Theoretically found IR-spectra of the adsorption structures have been compared with available literature data.
Keywords: silicon surface, oxygen adsorption, infrared spectra, density functional theory method, cluster approach.

O.M. Hontaruk, O.V. Konoreva, M.B. Pinkovska, V.P. Tartachnyk

Simulation of Self-Diffusion Effect in Gallium Phosphide Monocrystals

Institute for Nuclear Research of NASU, 47, Nauky Av., Kyiv, 03028, Ukraine

The processes of self-diffusion of P and Ga atoms by molecular dynamics method were considered. Shown that interstitial P atoms starts its movement through the crystal at T = 1 K, Ga – at T = 100 K. The transition from interstitial diffusion mechanism to the vacancy for P atom starts at 900 K, for Ga – at 500 K. Diffusion constants for Pi and Gai atoms were calculated.
Keywords: gallium phosphide, interstitial atom, defect, diffusion, molecular dynamic.

І.V. Gorichok, N.D. Freik, S.D. Bardashevska

Thermodynamics of Point Defects and Homogeneity Zinc Telluride

Vasyl Stefanyk Prekarpathian University, Shevchenko Str., 57, Ivano-Frankivsk, 76025, Ukraine, e-mail: goritchok@rambler.ru

Based on the model crystal defect subsystem zinc telluride crystals which considers possibility of the formation of neutral, singly and doubly ionization cationic and anionic vacancies calculated homogeneity ZnTe, and the temperature dependence of the equilibrium concentration of point defects and free carriers in the crystals under conditions of two-temperature annealing at the maximum vapor pressure of additional component (zinc PZn or tellurium PTe).

M.V. Moroz¹, O.G. Mykolaychuk², M.V. Prokhorenko³, V.M. Moroz¹

Thermodynamic Properties of Intermediate Phases of the Ag-Bi-Se System in the Temperature Range 535-578 K

¹Department of physics National University of Water Management and Nature Resources Use, 11, Soborna Str., Rivne, 33000, e-mail:riv018@i.ua
² Department for metal physics Ivan Franko National University, 8a, Kyryla and Mefodiya Str., Lviv, 79005 3 Department of cartography and geospatial modeling Lviv Polytechnic National University, 12, Stepana Bandery Str, Lviv, 79013

In the galvanic elements C|Ag|AgI|glass Ag2GeS3|D|C (C – current electrodes, D – heterophase alloys of the Ag–Bi–Se system, AgI|glass Ag2GeS3 – two layer membrane with pure ionic (Ag+) conductivity) synthesis Ag with heterophase alloys of system was exercise. Data on the emf temperature dependence of galvanic elements are used to calculate the values of thermodynamic function of B-AgBiSe2, Bi2Se3 and BiSe phases in the temperature range 535–578 K.

T.O. Parashchuk

Temperature Dependences of Thermodynamic Parameters of CdSe and CdTe Crystals

Department of Physics and Chemistry of Solid State, Physical Chemical Institute Vasyl Stefanyk PreCarpathian National University 57, Shevchenko Str., 76018, Ivano-Frankivsk, Ukraine, E-mail:taras-parashchuk@i.ua

Based on the analysis of the crystal and electronic structure of CdX (X=Te, Se) crystals in the cubic phase cluster models have been built for calculation of the geometric and thermodynamic parameters. According to density functional theory (DFT) and using the hybrid B3LYP functional the temperature dependence of formation energyDE, formation enthalpy DH, Gibbs free energy DG and entropy DS have been defined. In the work have been derived analytical expressions of temperature dependences of the presented thermodynamic parameters, which have been approximated by a quantum-chemical calculation data using mathematical package Maple 14.
Keywords: DFT, model clusters calorimeter measuring the thermodynamic parameters.

D.M. Freik, Т.О. Parashchuk, B.P. Volochanska

Heat Сapacity and Debye Temperature of CdTe, CdSe Crystals

Physical-Chemical institute, Department of physics and chemistry of solide state SHEE “Vasyl Stefanyk PreCarpathian National University” 57, Shevchenko Str., 76018, Ivano-Frankivsk, Ukraine, E-mail: taras-parashchuk@i.ua

Based on the results of ab initio quantum-chemical calculations of the crystal structure of molecular clusters the temperature dependence of the specific heat of CdTe and CdSe crystals at constant volume CV and constant pressure have been defined. Computer calculations of thermodynamic parameters was carried out using density functional theory (DFT), using the B3LYP valence hybrid basic set. Also the analytical expressions of presented temperature dependences of the thermodynamic parameters have been gotten, and based on them, using the mathematical package Maple 14, the Debye temperature for these materials have been calculated.

D.M. Freik¹, S.I. Mudryy², Ts.A. Kryskov³, I.V. Gorichok¹, T.S. Luba¹, O.S. Krynytsky¹, O.M. Matkivsky¹

Thermoelectric Properties of Bismuth Doped Lead Telluride PbTe:Bi

¹Vasyl Stefanyk Prekarpathian University, Shevchenko Str., 57, Ivano-Frankivsk, 76025, Ukraine, e-mail: fcss@pu.if.ua
²Ivan Franko National University of Lviv, Kyryla and Mefodiya Str., 8, Lviv, 79005 Ukraine
³Kamyanets-Podilsky Nationality University, Ogienko Str. 61, Kamyanets-Podilskiy, 32300, Ukrainе, E-mail:fizkaf@ua.fm

X-ray research was established with measurement of thermoelectric parameters (Seebeck coefficient α and specific conductivity σ) of lead telluride doped by bismuth. Textures’ presence in researched materials was witnessed; the phase of Pb1-xBix was identified and present in all doped samples irrespectively from the impurity content. This research demonstrates that introduction of bismuth in amounts (0,1-0,3) at. % promotes the growth of thermoelectric power α2σ of PbTe, due to increasing of Seebeck coefficient α and the electrical conductivity σ in comparison with undoped material.
Keywords: thermoelectricity, lead telluride, doping.

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

Thermoelectric Properties of the Silver Doped Lead Telluride PbTe:Ag

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

Thermoelectric parameters of the PbTe:Ag using the variational principle were calculated. Analyzed the behavior of the conductivity, Seebeck coefficient and thermal conductivity from the impurity content. Established that the impurity of silver gives p-type of conductivity for all samples, regardless of its content. Optimized material composition for the maximum thermoelectric figure of merit.
Keywords: doping, scattering mechanisms, thermoelectric parameters, optimization.

B.V. Pavlyk, R.M. Lys, R.I. Didyk, J.A. Shykoryak

Investigation of Conductibility Changes of Irradiated p-Si Crystal by X-rays During the Recoverable Deformation

Ivan Franko National University of L’viv, 79000 L’viv, Ukraine

Changes in conductivity of irradiated and exposed to room temperature single-crystal p-Si samples in the process of compressing and removing mechanical stress were investigated. It was found that the resistance of the sample increases during its exposure under the load. Gradual and prolonged increases in sample resistance were noticed amid separate deformation cycles. "Radiation memory effect" was found out. It was also found that the sample resistance increases proportionally the square root of irradiation dose during the irradiation by X-rays.
Keywords: single-crystal silicon, uniaxial deformation, ohmic contacts, X-ray irradiation.

P.O. Gentsar, O.I. Vlasenko, S.M. Levytskyi, I.B. Yanchuk, S.R. Lavoryk

Influence of Laser Radiation on the Optical Properties of Thin Layers Ge_1-хSi_x

V. Lashkoryov Institute of Semiconductors Physics, prospect Nauki, 41, Kyiv, 03028, E-mail: rastneg@isp.kiev.ua

In this work are the optical studies (reflectance and transmission spectrum) of solid solutions Ge1-хSix (х = 0.85) before and after laser irradiation in the energy range 46.6 mJ/cm2 to 163.5 mJ/cm2. It is shown that in the fundamental optical transition reflecting the ability of the material decreases and the transmittance increases with increasing power laser irradiation.
Keywords: Ge1-хSix, laser irradiation, reflectance spectrum, transmission spectrum.

D.M. Freik¹, Ja.S. Yavorskyj¹, S.I. Mudryj², C.A. Kryskov³

Structure and Thermoelectric Properties of Pb-Sb-Te, Pb-Bi-Te Vapor-Phase Condensates on Glass Substrates

¹Vasyl Stefanyk PreCarpathian National University 57, Shevchenko Str., 76018, Ivano-Frankivsk, Ukraine, E-mail:freik@pu.if.ua
²Ivan Franko Lviv National University, Str. Cyril and Methodius, 8, Lviv, 79005, Ukraine
³Ivan Ogijenko Kamenetz-Podolsk National University, Str. Ogijenko, 61, c. Kamenetz-Podolsk, 32300, Ukraine, e-mail:fizkaf@ua.fm

The results of ACM- research of processes of structure and thermoelectric properties of vapor-phase condensates doped by Sb and Bi Lead telluride and solid solutions PbTe-Sb2Te3, PbTe-Bi2Te3, deposited on substrates of polished glass have been proposed. The influence of the deposition time τ = (3-75) s with (thick condensate ) on the characteristics of individual nanoformation and change of thermoelectric parameters. It is shown that the main mechanism of nucleation is Folmera –Weber mechanism of individual nanoclusters formation and implementation processes nukleatsiy, aggregation and koalestsentsiy. A significant impact of donor impurities Sb and Bi and "giant" value of Seebeck coefficient S = (800-1400) mV/K of solid solutions has been found. A crystal doping and mechanisms of formation of solid solutions of the studied condensates have been proposed. Specified on the dominance of substitution of cationic impurities of the crystal lattice of PbTe (     ).

I.I. Chaviyak

The Processes of Structure Formation in Condensates SnTe/mica Obtained by Method "Hot Wall"

Ivano-Frankivsk National Medical University, 2, Galyzka Str, Ivano-Frankivsk, 76018, Ukraine, Е-mail: freik@pu.if.ua

Presented by results of AFM studies and electrical properties of vapor-phase condensates SnTe on fresh chipped (0001) single crystals of muscovite mica at deposition temperature TS = (100-250)°C. Shown that there is a mechanism of nucleation Folmer-Weber implementation stages of the formation of nonequilibrium nanocrystals and their avtocoalescence and crossing over to the rounded shape faceted structures. Established that the defect structure is characterized by twin boundaries and voids created by splice parallel and antiparallel trihedral nanoformations. Discovered increase of the lateral size and height nanokrystals with increasing deposition temperature. Stable p-type conductivity of condensate explained offset the homogeneity of the compound SnTe on the side of tellurium, the value of which depends on the temperature of the substrate.
Keywords: vapor-phase condensates Tin Telluride, structure, defects, electrical properties.

D.M. Freik¹, B.S. Dzundza¹, A.B. Kostyuk¹, V.I. Makovyshyn¹, I.A. Arsenyuk²

Surface Layers and Thermoelectric Properties of Thin Films Based on Pure and Bismuth Doped SnTe

¹Vasyl Stefanyk PreCarpathian National University 57, Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine, E-mail:fcss@pu.if.ua
²Kamyanets-Podilsky Nationality University, Ogienko Str. 61, Kamyanets-Podilskiy, 32300, Ukrainе, E-mail:fizkaf@ua.fm

Investigated the thermoelectric properties of the thin films based on pure and bismuth doped tin telluride, obtained by vapor condensation in the high vacuum on ceramics and mica substrate. Based on a Petritz two-layer model defined electrical parameters of surface layers. The obtain results are interpreted by oxygen adsorption on the surface and its diffusion inside of the condensate.
Keywords: thin film, tin telluride, surface, thermoelectric properties.

V.A. Romaka^1,2, P. Rogl³, Yu.V. Stadnyk⁴, L.P. Romaka⁶, D. Kaczorowski⁵, R.O. Korzh², V.Ya. Krayovskyy², O.I. Lakh ⁴

Features of the Structural, Energetic and Kinetic Properties HfNi1-xRuxSn Solid Solution

¹Ya. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics, NAS of Ukraine, Naukova str., 3-b, Lviv, 79060, Ukraine;
²National University “Lvivska Politechnika”, Bandera str., 12, Lviv, 79013, Ukraine;
³Institut fur Physikalische Chemie, Universitet Wien, Wahringerstrasse, 42, Wien, A-1090, Austria;
⁴Ivan Franko National University of Lviv, Kyryla and Mefodiya Str., 6, Lviv, 79005, Ukraine;
⁵Institute of Low Temperature and Structure Research Polish Academy of Sciences, P.O. Box 1410, 50-950, Wroclaw, Poland;
⁶V.I. Lakh NVO “Termoprylad”, Naukova Str., 3, Lviv, 79060, Ukraine

The crystal and electronic structure, energy and kinetic properties of semiconducting HfNi_1-xRu_xSn solid solution in the ranges : T = 80÷400 K, ≈ 9,5•10¹⁹ см^-3 (х = 0,005) ÷ 5,7•10²⁰ см^-3 (х = 0,03), was investigated. The nature of the mechanism of generation of structural defects, leading to a change in the band gap and the degree of compensation of the semiconductor and agreement with experimental data.
Keywords: semiconductor, conduction, electronic structures.

I.P. Prits¹, M.V. Potoriy², P.М. Мilyan¹, S.F. Motrya¹, V.M. Dzyamko²

The Nature of the Formation of the Compounds MeIMeIIIP₂S₆(Se₆) (where MeI - Cu, Ag; MeIII - In, Bi, Cr) and Methods of Growing for Their Single Crystals

Physico-chemical interaction in the systemsMeIMeIIIS₂(Se₂) -“P₂S₄(Se₄)” was studied using X-ray powder diffraction and differential thermal analysis. The technological conditions of growing single crystals for the compounds MeIMeIIIP₂S₆(Se₆) has been developed based on their nature of formation.
Keywords: phase diagrams, X-ray phase analysis, differential thermal analysis, single crystals.

H.Ya. Hurhula, T.P. Vintoniak, N.D. Freik

Crystalchemistry Models of Defect Subsystem in Nonstoichiometric Cadmium Telluride Crystals

Physical-Chemical Institute at the ‘Vasiliy Stefanyk’ Precarpathian National University, 57, Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine, E-mail:freik@pu.if.ua

Analysis of the defective subsystems in clean cadmium telluride was performed using methods of crystal chemistry. There were developed crystalquasichemical formulae for the non-stoichiometric n-CdTe, p-CdTe crystals, determined type and charge status of the dominating point defects, found dependences of their concentration (N), concentration of free carriers (n, p), Hall concentration of current carriers (nH) on size and character of stoichiometry deviation.

R.O. Denysyuk

Compensation Effect in the Kinetics of the Cd_1-xMn_xTe Solid Solution Chemical Etching

Ivan Franko Zhytomyr State University 10008, Zhitomir, 40 V. Berdichevsky, e-mail:denisuk@zu.edu.ua

The kinetics of the chemical dynamic polishing of CdTe and Cd1-xMnxTe (0,04< х <0,5) using iodine containing (I2–HI) and iodine emerging etchants based on Н2О2–НІ and the temperature dependence of the chemical dissolution have been investigated. Apparent activation energy and preexponential factor of the chemical polishing of the mention above semiconductor materials have been determined. The existence of the compensation effect at the chemical etching of CdTe and Cd1-xMnxTe solid solutions has been established using obtained experimental data. It was shown that the etchant solution influences on the compensation effect and the semiconductor materials does not influence on this effect.

H.O. Sirenko, T.R. Tatarchuk, M.V. Myslin

Synthesis and Crystallochemiсal Study of Spinels MgAl_2-xCr_xO4 Obtained by Co-Precipitation Method

Vasyl Stefanyk Precarpathian National University, 57, Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine Tel. (0342) 77.64.15; (050) 086.73.45, e-mail:tatar_ch@inbox.ru

The samples of solid solutions MgAl2-xCrxO4 (where x = 0…2 by step 0.2) were synthesized by co-precipitation method. Crystal parameters of spinel solid solutions were calculated: cell parameter a, anion parameter u, the deviation from the ideal structure δ, tetrahedral and octahedral distances α and β, the volume V and density of the unit cell, the angles between chemical bonds AOB and the BOB. It is shown that α does not change (0.1938 nm), β varies from 0.1903 – 0.1987 nm; unit cell parameter changes from 0.8057 to 0.8281 nm; anionic parameter that indicates the deviation from the ideal structure varies from 0.3889 to 0.3851; δ varies from 0.0139 to 0.0101, the volume of the unit cell changes from 0.5229 to 0.5678 nm3; X-ray density varies from 3606.74 to 4491.55 kg/m3; angle tetrahedral cation–Оxygen–octahedral cation increases ( AOB = 160.19…o – 161.53…o), and the angle of the octahedral cation–Оxygen–octahedral cation decreases ( BOB = 96.63…o – 94.82…o).
Keywords: magnesium aluminate, spinel, co-precipitation, anion parameter.

Ya.A. Kryl’, P.M. Prysyazhnyuk

Thermodynamic Analysis of Compatibility of Niobium Carbide with Hadfield Steel for Cermets Development

Ivano-Frankivsk National Technical University of Oil and Gas, 15, Carpathian Str., Ivano-Frankivsk, 76001, Ukraine

Hadfield steel due to its high wear resistance under impact conditions is currently being considered as perspective material for using as a binder phase in carbide – steels. One of the key factors in the selection of a refractory carbide component of carbide – steels is its chemical stability with respect to metal phase. In this study, chemical interactions between niobium carbide and Hadfield steel, were analyzed from thermodynamic considerations. It is shown that niobium carbide due to its low limited solubility in manganese austenite determines the structure of the two-phase steels with hardenable binder.
Keywords: Hadfield steel, niobium carbide, carbide-steels, equilibrium solubility.

I.F. Myronyuk¹, V.I. Mandzyuk¹, N.A. Bezruka¹, Ye.P. Voronin², O.V. Goncharuk², V.M. Ogenko³

The Rheological Properties of Organosilica Suspensions with Different Ratio of Silanol and Trymethylsilyl Groups

¹Vasyl Stefanyk Precarpathian National University, 57 Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine, myrif@rambler.ru
² Chuiko Institute of Surface Chemistry of NAS of Ukraine, 17 General Naumov Str., Kyiv, 03164, Ukraine
³V.I. Vernadsky Institute of General and Inorganic Chemistry, 32-34 Acad. Palladina Ave., Kyiv, 03680, Ukraine

The rheological properties of water organosilica suspensions with different ratio of silanol and trymethylsilyl groups are investigated in the article. It is set that substitution of 50 % silanols on fumed silica surface for (CH3)3Si-groups is results in decrease of hydrophilicity coefficient of superfine silica from 2,0 to 1,4. The grafted groups change substantially the electrostatic potential distribution on SiO2 surface. The areas with negative potential appear near Si atoms of grafted groups. Suspensions of modified silicas have higher equilibrium viscosity compared to that of base silica. Superfine particles do not lose a thickening power even at destruction of their fractal structure by the ultrasonic field. New rheological properties of modified silicas are conditioned by domination on its surface areas with negative electrostatic potential, which reduces the interparticle interaction in suspension and increases the interaction of the surface with molecules of aqueous medium.
Keywords: superfine silica, suspension, viscosity of dispersions, electrostatic potential, silanol groups.

V.F. Zinchenko¹, V.E. Chygrynov², O.V. Mozkova², I.R. Magunov¹, I.V. Stoyanova¹

Interaction and Optical Properties of Specimens in Sb₂S₃ - Ge System

¹A.V. Bogatsky Physico-Chemical Institute of NAS of Ukraine, 86 Lustdorfska Doroga Str., 65080, Оdesа, Ukraine, e-mail:vfzinchenko@ukr.net
²Central Design Office "Аrsenal", 8, Moscovska Str., 02010, Kyiv, Ukraine,e-mail:borisgor@i.com.ua

General character of interaction of Sb2S3 with elemental Germanium resulting in formation of the glass - manocrystal composite is established. Sufficient shift of the borders of optical transparency domain of the composite compared to Sb2S3 is explained from the positions of arising Ge–S bonds with different coordination types. Thin-film coating obtained from the composite has high optical and operational parameters.
Keywords: composite, metal sulfide, Germanium, optical properties, thermal evaporation, thin-film coating.

Е.А. Лисенков¹, Ю.В. Яковлев², В.В. Клепко²

Вплив особливостей полімерної матриці на перколяційну поведінку систем на основі поліетерів та вуглецевих нанотрубок

¹Миколаївський національний університет ім. В.О.Сухомлинського, вул. Нікольська 24, Миколаїв, 54030, Україна
²Інститут хімії високомолекулярних сполук НАН України, Харківське шосе 48, Київ, 02160, Україна

Методами імпедансної спектроскопії були досліджені системи на основі поліетерів та вуглецевих нанотрубок. Встановлено, що кристалічність полімерної матриці значно впливає на електричні та діелектричні характеристики нанонаповнених полімерних систем: значення порогів перколяції обернено пропорційні кристалічності. Запропоновано механізм утворення перколяційного кластера для систем з високим ступенем кристалічності. Показано, що діелектрична проникність нанонаповнених полімерних систем залежить від структури перколяційних кластерів. Встановлено, що топологія полімерної матриці не впливає на перколяційну поведінку систем на основі поліетерів.
Ключові слова: перколяційна поведінка, вуглецеві нанотрубки, кристалічність, електропровідність, поляризаційні ефекти.

H.O. Sirenko, Yu.D. Pakhomov

Scientific Rationale for the Model Situation of Destruction of Carbon Fibers and Crack Formation in the Matrix

Vasyl Stefanyk Precarpathian National University, 57, Shevchenko Str., Ivano-Frankivsk, 76018, Ukraine Tel. (0342) 77.64.15; (096) 813.93.53

By results of researches where found depends of stored energy before rupture of various types of carbon fibers, and found their dependence on physical and mechanical properties of samples. Displaying influence of stored energy in the fiber before rupture on the processes of propagation of cracks in composite polymer materials. Were found optimal physical and mechanical properties of fibers, that impede processes of propagation of cracks.
Keywords: carbon fibers, composite polymer material, stored energy, destruction of the matrix, effective length of fiber.

S.G. Orlovskaya, M.S. Shkoropado, U.A. Shevchenko, A.O. Odnostalko

Research of High-Temperature Heat and Mass Transfer and Oxidation of Samples of Refractory Metals in the Air

Odessa I.I. Mechnikov National University Odessa, Ukraine, Dvoryanskaya str. 2, 65082, (048) 723-62-27, svetor@rambler.ru

The stationary modes of high temperature heat and mass transfer and the oxidation of conductors of refractory metals (tungsten and molybdenum) in the air are studied. The kinetics of oxides growth on the surface of these metals is investigated; the law of oxidation at different temperatures is established. The activation energy values for the reaction of tungsten and molybdenum oxidation in the air are defined.
Keywords: heat and mass transfer, kinetics of oxidation, metals, metal oxides, activation energy.

V.О. Kotsyubynsky¹, A.B. Hrubiak¹, V.V. Moklyak²

Synthesis of Mesoporous Iron Oxides by Citrate Sol-Gel Method. II. Morphological Characteristics Control

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

The mechanism of mesoporous maghemite g-Fe2O3 by thermal decomposition of iron citrate hydrate was investigated and the influence of sol-gel synthesis conditions on its morphological characteristics was studied. It was shown that the gelation process in aqueous solution of iron citrates monomers depends on pH level of reaction medium. Thermal decomposition of iron citrate xerogels allows to obtain the mesoporous maghemite with predictable specific surface area and pore size distribution.
Keywords: sol-gel synthesis, iron citrate, xerogel, mahemit g-Fe2O3, mesoporous structure.

O.Yu. Popov, O.O. Bobryshev, O.Yu. Klepko, V.A. Makara

Structure and Mechanical Characteristics of Reaction Hot Pressed Ti-B-Al Composites

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

Reaction hot-pressing method was developed to produce ТіВ2 – Al composites using Ті, Al, and В non-grinned powders. In-situ exothermic reaction allowed to obtain dense materials with high HV (23 GPa) and K1C (9 MPa*m^1/2) at temperatures 1600 – 1800 ⁰C during 8 minutes.
Keywords: ceramics, reaction hot pressing, mechanical characteristics, titanium boride.

M.A. Kovbuz, L.M. Boichyshyn, O.M. Hertsyk, T.G. Pereverzeva, R.Ya. Serkiz, B.Ya. Kotur

Influence of Polarization of Amorphous Metallic Electrodes on Forming Surface Oxide Layers with Catalytic Properties

Ivan Franko Lviv National University, Kyryla and Mefodiya Str. 6, UA-79005 Lviv, Ukraine, o_hertsyk@yahoo.com

Parameters of surface protective layers formed on the amorphous alloys Fe84Nb2B14 and Fe82Nb2B14Y2 in alkaline environment have been investigated by microscopic and electrochemical methods. The presence of Nb in amorphous alloys determines appearing of clearly developed diffusive areas of secondary hydroxide-oxide tapes with microfibrillar structure. At presence of Y protective layers become more compact and prevent active corrosion of electrodes surface, that assists the prolonged electro-catalysis.
Keywords: electrocatalysis, amorphous alloy, oxide-hydroxide layers.

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

Application of Gas Atomised MmNi_4,3A_l0,2Mn_0,5 Alloy as Material of the Negative Electrode in Ni-MH Batteries

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

The electrochemical properties of the gas atomised MmNi4,3Al0,2Mn0,5 alloy electrodes such as activation rate, discharge capacity and high rate discharge ability have been investigated. Determined using electrochemical impedance spectroscopy total resistance of the electrodes are in good agreement with those calculated from other electrochemical dependencies. It is shown that the use of lightweight carbon nanocomposite as the electrode conductive additive slightly reduces the discharge capacity of the electrode and the electrode reactions kinetics compare to the electrode with copper additive. The corrosion stability of the electrodes in alkaline electrolyte has been studied.
Keywords: gas atomised alloy, fraction, kinetics, hydride, nanocomposite additive, corrosion.

Т.О. Manyk¹, V.R. Bilynskyj-Slotylo²

Calculations of Segmented Modules Based on Bi₂Te₃ / PbTe Materials for Thermoelectric Generators

¹Bukovyna State University of Finance and Economics, 58000, Shterna Str. 1, Chernivtsi, Ukraine
²Yuriy Fedkovych Chernivtsi National University, 58012, Kotsyubynskogo Str. 2, Chernivtsi, Ukraine e-mail:manykto@rambler.ru, slotulo@mail.ru

The results of segmented thermoelectric generator modules calculations by computer simulation methods are presented. Found that use of Bi2Te3-based materials as cold sections and PbTe-based materials as hot sections for two-section modules in the temperature range 303-773 K, allows to multiply their efficiency by 1,28 as compared to single-section ones.
Keywords: segmented thermoelement, recuperators, efficiency.

A.S. Zavojko

Experimentalise Strength Surface Electric Ligature and Givn Work Upon Concentration System Energy

Chernivtsi Department of the National Technical University "Kharkiv Polytechnic Institute"; 58000, Chernivtsi, Golovna st., 204, Ukraine

In article considered the new basic phizical-technical treatment with help double procesis electric lightning ligature and gas connection condensation on steel in the new picture.This process penetration the theory binding material,electrodinamic frictional indaction electrode material on steel basic and developed practical making gas solution dipping with the obtained new composite tipes will continue of protective coatings based on metals with new mechanical and physical-chemical process of need. Special priority rating in future research will be given to working out theoretical bases and production processes of obtaining higth-strength materials reinforced with metal and ways of predetermining lasting stress-processes of obtaining higth-strength materials reinforced with metal and ways of predetermining lasting stress-strain characteristics with a view to establishing principles of desining composite materials with clear-cut aniso-strain characteristics with a view to establishing principles of designing composite materials with clear-cut aniso-tropic characteristics,outlining new spheres of national economy which could use composite materials; theoretical and experimental research in material for outer space; stadying process which take place in materials under the effect of vacuum ,low temperatures ,various types of radiation and meteoritic particles; developing materials for space engeneering, machine interpolice contact ligature in steel, and laser strain strand laser technology.
Keywords: еlectric ligature, lazer process and ligature, combination gas process соndensation, physical-chemical process termal оbtained material.