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11.
Gun'ko VM Zarko VI Goncharuk EV Andriyko LS Turov VV Nychiporuk YM Leboda R Skubiszewska-Zieba J Gabchak AL Osovskii VD Ptushinskii YG Yurchenko GR Mishchuk OA Gorbik PP Pissis P Blitz JP 《Advances in colloid and interface science》2007,131(1-2):1-89
Applications of thermally stimulated depolarisation current (TSDC) technique to a variety of systems with different dispersion phases such as disperse and porous metal oxides, polymers, liquid crystals, amorphous and crystalline solids, composites, solid solutions, biomacromolecules, cells, tissues, etc. in gaseous or liquid dispersion media are analysed. The effects of dipolar, direct current (dc) and space charge relaxations are linked to the temperature dependent mobility of molecules, their fragments, protons, anions, and electrons and depend on thermal treatment, temperature and field intensity of polarisation, heating rate on depolarisation or cooling rate on polarisation. Features of the relaxation mechanisms are affected not only by the mentioned factors but also by morphological, structural and chemical characteristics of materials. The interfacial phenomena, especially the role of interfacial water, received significant attention on analysis of the TSDC data. Comparison of the data of TSDC and dielectric relaxation spectroscopy (DRS), differential scanning calorimetry (DSC), 1H NMR spectroscopy with layer-by-layer freezing-out of bulk and interfacial water, adsorption/desorption of nitrogen, water and dissolved organics demonstrates high sensitivity and information content of the TSDC technique, allowing a deeper understanding of interfacial phenomena. 相似文献
12.
R. V. Mazurenko G. M. Gunya S. N. Makhno P. P. Gorbik 《Russian Journal of Applied Chemistry》2014,87(2):179-183
Electrical properties of synthesized nanostructured materials based on nanocrystalline tin dioxide modified with copper iodide and polychlorotrifl uoroethylene were studied. It was shown that the complex dielectric permittivity in the microwave range and the low-frequency electrical conductivity of the polymeric composites depend on the copper iodide concentration on the surface of tin dioxide and reach the maximum values at a volume fraction of CuI of about 0.5. The percolation thresholds were determined for the three-component system. Their values increase from 0.04 to 0.05 vol. fraction as the content of copper iodide in the CuI/SnO2 system is raised from 0.04 to 0.6 vol. fraction. 相似文献
13.
V.M. Gun’ko Y.M. Nychiporuk E.V. Goncharuk R. Leboda E. Skwarek G.R. Yurchenko Y.G. Ptushinskii P.P. Gorbik K. Gude 《Applied Surface Science》2007,253(6):3215-3230
Fumed oxides SiO2/Al2O3 (SA), SiO2/TiO2 (ST) and Al2O3/SiO2/TiO2 (AST) at different content of alumina and titania were investigated by one-pass temperature-programmed desorption (OPTPD) time-of-flight mass-spectrometry (TOFMS), Auger electron spectroscopy (AES), NMR, FTIR, thermally stimulated depolarization current (TSDC), microcalorimetry, adsorption of nitrogen, water, (dimethylamino)azobenzene (DMAAB) and metal ions (Pb(II) and Ni(II)). It was shown that all the studied adsorption/desorption and energetic properties of mixed fumed oxides depend strongly on the surface content of alumina (shown as a surface content of aluminum, ) in SA and AST and titania (shown as a surface content of titanium, ) in ST and AST. Many of these properties demonstrate clear correlations with the and values over the total range of alumina and titania content in the materials. 相似文献
14.
A method is developed for the synthesis of nanosized Fe3O4-(SiO2)
x
[NH2(CH2)3SiO3/2]
y
magnetic composites with varied SiO2: NH2(CH2)3SiO3/2, weight/weight, ratios. The structure, texture, morphology, and magnetic properties of the obtained materials are studied
by several physicochemical methods. It is shown that the composites represent systems of magnetite nanoparticles coated with
poly(aminopropylsiloxane). The specific surface areas, pore volumes, and saturation magnetizations of the composites are in
the ranges of 21–27 m2/g, 0.03–0.04 cm3/g, and 59–62 G cm3/g, respectively. 相似文献
15.
16.
V. M. Gunko V. I. Zarko I. F. Mironyuk E. V. Goncharuk N. V. Guzenko M. V. Borysenko P. P. Gorbik O. A. Mishchuk W. Janusz R. Leboda J. Skubiszewska-Ziêba W. Grzegorczyk M. Matysek S. Chibowski 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,240(1-3):9-25
Adsorption of Pb(II), Sr(II), and Cs(I) on fumed silica, alumina, titania, silica/titania (ST), silica/alumina (SA), and alumina/silica/titania (AST) reveals that mixed oxides containing titania have a greater adsorptive capability in respect to metal cations than individual and SA oxides. Pyrocarbon deposits on fumed oxides enhance the adsorption of metal ions. Calculations of electrophoretic potential (ζ) with consideration for the porosity of aggregates of primary particles of AST show a significant influence of surface alumina (at pH<8) and titania and silica (at pH>8) on the ζ values. The effective diameter of particles (Def) of fumed oxides in aqueous media depends on pH for AST stronger than for ST (between isoelectric points (IEPs) of titania and alumina). A significant difference in the pH values of IEP and point of zero charge is observed for AST samples. A pyrocarbon influence on the ζ potential depends on the type of oxide matrix, since ζ increases for certain samples but for others it decreases. These changes depend nonlinearly on pH as well as the secondary particle size distributions (SPSDs) and Def. 相似文献
17.
Gun'ko VM Mironyuk IF Zarko VI Voronin EF Turov VV Pakhlov EM Goncharuk EV Nychiporuk YM Vlasova NN Gorbik PP Mishchuk OA Chuiko AA Kulik TV Palyanytsya BB Pakhovchishin SV Skubiszewska-Zieba J Janusz W Turov AV Leboda R 《Journal of colloid and interface science》2005,289(2):427-445
Several series of fumed silicas and mixed fumed oxides produced and treated under different conditions were studied in gaseous and liquid media using nitrogen and water adsorption-desorption, mass spectrometry, FTIR, NMR, thermally stimulated depolarization current (TSDC), photon correlation spectroscopy (PCS), zeta potential, potentiometric titration, and Auger electron spectroscopy methods. Aggregation of primary particles and adsorption capacity (Vp) decrease and hysteresis loops of nitrogen adsorption-desorption isotherms becomes shorter with decreasing specific surface area (S(BET)). However, the shape of nitrogen adsorption-desorption isotherms can be assigned to the same type independent of S(BET) value. The main maximum of pore size distribution (gaps between primary nonporous particles in aggregates and agglomerates) shifts toward larger pore size and its intensity decreases with decreasing S(BET) value. The water adsorption increases with increasing S(BET) value; however, the opposite effect is observed for the content of surface hydroxyls (in mmol/m2). Associative desorption of water (2(SiOH)-->SiOSi+H2O) depends on both the morphology and synthesis conditions of fumed silica. The silica dissolution rate increases with increasing S(BET) and pH values. However, surface charge density and the modulus of zeta-potential increase with decreasing S(BET) value. The PCS, 1H NMR, and TSDC spectra demonstrate rearrangement of the fumed silica dispersion depending on the S(BET) value and the silica concentration (C(SiO2)) in the aqueous suspensions. A specific state of the dispersion is observed at the C(SiO2) values corresponding to the bulk density of the initial silica powder. 相似文献
18.
P. P. Gorbik I. V. Dubrovin Yu. A. Demchenko M. N. Filonenko 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2008,2(1):142-145
The technique of low temperature synthesis of single-domain magnetite particles at the solid-liquid phase boundary was developed. Spherical magnetite particles 6–50 nm in size were obtained. The phase structure, elemental composition and morphology of the particles were studied using X-ray phase analysis, Auger spectroscopy, and scanning electron and atomic force microscopy. 相似文献
19.
Turov V. V. Gorbik P. P. Ogenko V. M. Shulga O. V. Chuiko A. A. 《Journal of Thermal Analysis and Calorimetry》2000,62(2):473-478
A study has been made on samples of dispersed vanadium dioxide (VO2) in a matrix of polyethylene glycol (PEG) doped with a quaternary ammonium salt (QAS), namely tetraethylammonium bromide.
It has been established that under the influence of the dopant the heating of a sample up to the temperature of the metal-semiconductor
phase transition (MSPT) results in a phase in homogeneity of the sample. On the basis of the results of this study it is possible
to conclude that small concentrations of QAS in a PEG matrix can exert a strong effect on the electronic structure of dispersed
VO2 particles. This is accompanied by the appearance of phase heterogeneity of VO2 which manifests itself in the fact that - with the onset of MSPT with increasing temperature - one portion of the substance
passes into the metallic state, and the other remains in the semiconductive state.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
20.
P. P. Gorbik I. V. Dubrovin N. V. Abramov A. I. Nastasienko 《Crystallography Reports》2004,49(2):275-278
A laboratory technological procedure has been developed for the synthesis of high-temperature superconducting YBa2Cu3O7 ? δ single crystals (T c ~ 90 K, ΔT c ~ 1.0 K) up to 0.25 cm2 in size from a nonstoichiometric fluorine-containing flux of (YO1.5)(BaO)4 ? x(BaF2)x(CuO)10, where 2 ≥ x ≥ 0, using a combination of enhanced nucleation and directional crystallization by the Czochralski method. Studies using differential thermal analysis demonstrated that the addition of BaF2 decreased the eutectic-crystallization temperature and increased the crystal-growth rate. The optimum concentration of BaF2 in the starting melt composition was found (x = 0.2). The single-crystal surface was studied by atomic-force nanoscopy. The morphology of single crystals that have been synthesized from a melt of their own components differs substantially from that of crystals grown from a BaF2-containing melt. 相似文献