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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : FILONOV A. N.
Заглавие : FINITE SUBSTRATE COMPRESSIBILITY EFFECT AT MONATOMIC FILM ADSORPTION
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1983. - Vol. 25, Is. 8. - P2524-2526. - ISSN 0367-3294
Примечания : Cited References: 9
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Nasluzov V. A., Rivanenkov V. V., Gordienko A. B., Neyman K. M., Birkenheuer U., Rosch N.
Заглавие : Cluster embedding in an elastic polarizable environment: Density functional study of Pd atoms adsorbed at oxygen vacancies of MgO(001)
Место публикации : J. Chem. Phys.: AMER INST PHYSICS, 2001. - Vol. 115, Is. 17. - P8157-8171. - ISSN 0021-9606, DOI 10.1063/1.1407001
Примечания : Cited References: 88
Предметные рубрики: TRANSITION-METAL ATOMS
AB-INITIO
OXIDE SURFACES
ELECTRONIC-PROPERTIES
ENERGY CALCULATIONS
MOLECULAR-DYNAMICS
MOTT-LITTLETON
MADELUNG FIELD
IONIC-CRYSTAL
MGO
Ключевые слова (''Своб.индексиров.''): atoms--binding energy--computer simulation--electron energy levels--electronic structure--magnesia--oxygen--palladium--polarization--probability density function--quantum theory--relaxation processes--charged defects--cluster embedding--elastic polarizable environment--electron affinity--oxygen vacancies--adsorption
Аннотация: Adsorption complexes of palladium atoms on F-s, F-s(+), F-s(2+), and O2- centers of MgO(001) surface have been investigated with a gradient-corrected (Becke-Perdew) density functional method applied to embedded cluster models. This study presents the first application of a self-consistent hybrid quantum mechanical/molecular mechanical embedding approach where the defect-induced distortions are treated variationally and the environment is allowed to react on perturbations of a reference configuration describing the regular surface. The cluster models are embedded in an elastic polarizable environment which is described at the atomistic level using a shell model treatment of ionic polarizabilities. The frontier region that separates the quantum mechanical cluster and the classical environment is represented by pseudopotential centers without basis functions. Accounting in this way for the relaxation of the electronic structure of the adsorption complex results in energy corrections of 1.9 and 5.3 eV for electron affinities of the charged defects F-s(+) and F-s(2+), respectively, as compared to models with a bulk-terminated geometry. The relaxation increases the stability of the adsorption complex Pd/F-s by 0.4 eV and decreases the stability of the complex Pd/F-s(2+) by 1.0 eV, but it only weakly affects the binding energy of Pd/F-s(+). The calculations provide no indication that the metal species is oxidized, not even for the most electron deficient complex Pd/F-s(2+). The binding energy of the complex Pd/O2- is calculated at -1.4 eV, that of the complex Pd/F-s(2+) at -1.3 eV. The complexes Pd/F-s and Pd/F-s(+) exhibit notably higher binding energies, -2.5 and -4.0 eV, respectively; in these complexes, a covalent polar adsorption bond is formed, accompanied by donation of electronic density to the Pd 5s orbital. (C) 2001 American Institute of Physics.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Sorokin P. B.
Заглавие : Density and thermodynamics of hydrogen adsorbed on the surface of single-walled carbon nanotubes
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 48, Is. 2. - P402-407. - ISSN 1063-7834, DOI 10.1134/S1063783406020351
Примечания : Cited References: 22
Предметные рубрики: MOLECULAR-DYNAMICS
ROOM-TEMPERATURE
STORAGE
ADSORPTION
H-2
TRANSITIONS
TUBES
Аннотация: A method is proposed for calculating the adsorption of hydrogen in single-walled carbon nanotubes. This method involves solving the Schrodinger equation for a particle (hydrogen molecule) moving in a potential generated by the surrounding hydrogen molecules and atoms forming the wall of the carbon nanotube. The interaction potential for hydrogen molecules is taken in the form of the Silvera-Goldman empirical potential, which adequately describes the experimental data on the interaction between H(2) molecules (including the van der Waals interaction). The interaction of hydrogen molecules with carbon atoms is included in the calculation through the Lennard-Jones potential. The free energy at a nonzero temperature is calculated with allowance made for the phonon contribution, which, in turn, makes it possible to take into account the correlations in the mutual arrangement of the neighboring molecules. The dependences of the total energy, the free energy, and the Gibbs thermodynamic potential on the applied pressure P and temperature T are calculated for adsorbed hydrogen molecules. These dependences are obtained for the first time with due regard for the quantum effects. The pressure and temperature dependences of the hydrogen density m(P, T) are also constructed for the first time.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Kuzubov A. A.
Заглавие : New principle of hydrogen adsorption inside nanotubes
Место публикации : Phys. Status Solidi B. - 2007. - Vol. 244: 21st International Winterschool on Electronic Properties of Novel Materials (MAR 10-17, 2007, Kirchberg, AUSTRIA), Is. 11. - P/4327-4330. - ISSN 0370-1972, DOI 10.1002/pssb.200776181
Примечания : Cited References: 4
Аннотация: A new principle of hydrogen (or other gases) adsorption inside single-wall nanotubes is proposed. This principle is based on the mixing of hydrogen with a small quantity of special additive molecules. The diameter of these molecules is chosen to be 2.5-4 angstrom smaller than the nanotube diameter, so these molecules can move along the tube axis. Due to interaction of the molecules and the nanotube walls this molecular movement has potential barriers which should be similar to 0.5-1 eV for the best effect. At those values the mobility of these molecules would be very low at ambient conditions. At high pressures and temperatures (600-900 K) the additive molecules have high mobility, so they can penetrate through open ends into nanotubes quite easily together with molecular hydrogen. These molecules divide the whole volume of the nanotube in separate parts in which the hydrogen molecular gas is locked under high pressure. The main part of the hydrogen is physically adsorbed on the inner walls of the nanotube. After decreasing the temperature the mobility of additive molecules is strongly decreased and hydrogen becomes accumulated inside all parts of the nanotube. As an example, hydrogen adsorption inside boron nitride nanotubes (8,8) is investigated. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Sorokin P. B., Kuzubov A. A.
Заглавие : Ab initio study of hydrogen chemical adsorption on platinum surface/carbon nanotube join system
Место публикации : Phys. Status Solidi B. - 2008. - Vol. 245, Is. 8. - P.1546-1551. - ISSN 0370-1972, DOI 10.1002/pssb.200844155
Примечания : Cited References: 31
Предметные рубрики: WALLED CARBON NANOTUBES
MOLECULAR-DYNAMICS
ROOM-TEMPERATURE
STORAGE
ENERGY
THERMODYNAMICS
GRAPHITE
DENSITY
POINTS
Аннотация: The process of hydrogen chemical adsorption on platinum cluster/single wall carbon nanotube (CNT) join surfaces is modelled at various temperatures and pressures. For that, the adsorption energy of hydrogen atoms on surfaces of both platinum (111) plate and CNT (5,5) or (8,8) types is calculated by density functional theory with the PBE approximation. At various temperatures the hydrogen atom hopping rate on both platinum and CNT surfaces is calculated by the transition state theory. Furthermore the hydrogen hopping rate from the platinum surface to the attached nanotube is obtained by calculation of the total energy profile. It is proved that hydrogen atoms can migrate easily at the platinum surface at all temperatures, but at the CNT surface they can migrate beginning at 400-500 K. By calculation of chemical potentials of hydrogen in gas or on CNT or platinum cluster surfaces the equilibrium density of adsorbed hydrogen was calculated at different temperatures and pressures. It is established that for all temperatures in the range 300-900 K and for all pressures less than 500 bar, the hydrogen is dissociated and chemically adsorbed on the platinum surface very effectively, but surface site occupation by hydrogen on attached CNT surface is rather small. But if CNT vacancies are present in the tube structure and the temperature is lower then 450 K, hydrogen atoms can be adsorbed effectively enough on these vacancies. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Serzhantova M. V., Kuzubov A. A.
Заглавие : Analysis of hydrogen adsorption in the bulk and on the surface of magnesium nanoparticles
Коллективы :
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 107, Is. 1. - P126-132. - ISSN 1063-7761, DOI 10.1134/S1063776108070121
Примечания : Cited References: 15. - This study was supported financially by the Russian Foundation for Basic Research ( project no. 06-02-16132). The authors are also grateful to the Institute of Computer Modeling of the Siberian Branch of the Russian Academy of Science for providing a cluster computer on which all quantum-chemistry calculations were performed.
Предметные рубрики: MOLECULAR-DYNAMICS
TRANSITION
METALS
Ключевые слова (''Своб.индексиров.''): adsorption--gas adsorption--hydrogen--light metals--magnesium--nonmetals--hydrogen adsorption--magnesium hydrides--magnesium printing plates
Аннотация: The stability of magnesium hydride (MgH (x) ) nanoparticles (x = 0.5,...,2) is investigated using ab initio calculations. It is shown that for a nanoparticle diameter of D similar to 5 nm, the internal pressure becomes lower than 3 kbar; for this reason, the structure of hydride nanoparticles coincides with the structure of this hydride in crystalline form. It is found that the phase of partly saturated MgH (x) hydrides (x 2) must decompose into the phase of pure hcp magnesium and the alpha phase of MgH(2). The frequencies of jumps of hydrogen atoms within the hcp phase of magnesium and in the alpha phase of MgH(2) are calculated; it is shown that slow diffusion of hydrogen in magnesium is due to the large height of potential barriers for motion of hydrogen within MgH(2). To attain high diffusion rates, the structures of Mg(53)Sc and Mg(53)Ti crystals and their hydrides are calculated. It is found that the frequency of jumps of H atoms in Mg(53)ScH(108) near the Sc atoms does not noticeably change as compared to the frequency of jumps in the alpha phase of MgH(2), while the frequency of jumps in Mg(53)TiH(108) near Ti atoms is higher by approximately a factor of 2.5 x 10(6). This means that diffusion in manganese hydride with small admixtures of titanium atoms must be considerably eased. Chemical dissociation of hydrogen molecules on the (0001) surface of hcp magnesium, on the given surface with adjoined individual Ti atoms, and on the surface of a one-layer titanium cluster on the given surface of magnesium is investigated. It is found that dissociation of hydrogen at solitary titanium atoms, as well as on the surface of a Ti cluster, is facilitated to a considerable extent as compared to pure magnesium. This should also sharply increase the hydrogen adsorption rate in magnesium nanoparticles.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A.S., Sorokin P.B., Kuzubov A. A.
Заглавие : Ab-initio study of hydrogen chemical adsorption on the platinum surface/carbon nanotube join system
Место публикации : Physica status solidi B - Basic Solid State Physics. - 2008. - Vol. 245, № 8. - С. 1546-1551
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kononova O.N., Melnikov A.M., Borisova T.V., Krylov A. S.
Заглавие : Simultaneous ion exchange recovery of platinum and rhodium from chloride solutions
Место публикации : Hydrometallurgy. - 2011. - Vol. 105, Is. 3-4. - P.341-349. - JAN. - ISSN 0304-386X, DOI 10.1016/j.hydromet.2010.11.009
Примечания : Cited Reference Count: 46
Предметные рубрики: GROUP-METALS PGM
SEPARATION
CATALYST
ANION
ADSORPTION
EXTRACTION
CHEMISTRY
RESIN
Ключевые слова (''Своб.индексиров.''): platinum--rhodium--sorption--anion exchangers--chloride solutions--anion exchangers--chloride solutions--platinum--rhodium--sorption--ammonium thiocyanate--anion exchangers--basic parameters--chemical structure--chloride solutions--diffusion coefficients--distribution coefficient--exchange capacities--kinetic properties--noble metals--purolite--rhodium chloride--separation factors--sorption ability--work focus--ammonium compounds--chlorine compounds--desorption--hydrochloric acid--ion exchange--ion exchange resins--ions--platinum--platinum compounds--potassium hydroxide--precious metals--recovery--rhodium--sulfuric acid--thioureas--urea--rhodium compounds
Аннотация: This work focuses on the sorption recovery of platinum (II, IV) and rhodium (III) simultaneously present in chloride solutions, freshly prepared and stored over 3 months, on commercial anion exchangers with different physical and chemical structure. The sorption was carried out from solutions with 0.001-4.0 mol/L HCl. The initial platinum and rhodium concentrations in contacting solutions were 0.25-2.5 mmol/L Sorption and kinetic properties of the chosen anion exchangers were investigated and the basic parameters of exchange capacity, recovery, distribution coefficients, separation factors, process rate, diffusion coefficients and half-exchange times were calculated. It is shown that anion exchangers investigated possess high sorption ability to platinum and rhodium chloride complexes, which does not deteriorate in case of stored solutions. Desorption of platinum and rhodium from the resins investigated was carried out with hydrochloric acid (2 mol/L), thiourea (1 mol/L) in sulfuric acid (2 mol/L) or in potassium hydroxide (2 mol/L) as well as by ammonium thiocyanate (2 mol/L). It was shown that complete separation of platinum and rhodium can be carried out with 2 mol/L HCl on anion exchanger Purolite S 985, whereas 2 mol/L NH(4)SCN as an elution agent leads to complete separation of noble metals on anion exchangers Purolite S 985, Purolite A 500 and AM-2B. (C) 2010 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ponomarenko I. V., Parfenov V. A., Zaitseva Y. N., Zharkov S. M., Kirik S. D.
Заглавие : Template synthesis of CMK-3 nanostructured carbon material and study of its properties
Место публикации : Glass Phys. Chem. - 2014. - Vol. 40, Is. 1. - P.79-87. - ISSN 1087-6596, DOI 10.1134/S1087659614010180
Ключевые слова (''Своб.индексиров.''): adsorption of n2--cmk-3 mesostructured carbon--mesoporous mesostructured silicates--sba-15--template synthesis--transmission electron microscopy--x-ray diffraction
Аннотация: Mesostructured carbon has been obtained by template synthesis. SBA-15 mesostructured silicate has been used as a template. The effect of the properties of a template on the ordering of a replica has been studied. It has been shown with the use of X-ray diffraction, gas adsorption, and electron microscopy that there are evident correlations of the conditions of synthesis of a template with the ordering of a carbon replica, which can be guided by the synthesis of materials. The ordering of a replica significantly depends on the mesopore volume of the initial template and thickness of the pore wall. One should use templates with the highest possible mesopore volume and minimal wall thickness to obtain highly ordered replicas. These templates can be prepared during the treatment of synthesized materials at temperatures close to 100 C. It has been determined that, when there is SBA-15, the presence of micropores is a necessary condition for the preparation of carbon replicas that retain the structure of the template. © 2014 Pleiades Publishing, Ltd.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Eliseeva N. S., Krasnov P. O., Kuklin A. V., Kovaleva E. A., Kholtobina A. S.
Заглавие : Theoretical investigation of the adsorption and diffusion of hydrogen on the surface and in the bulk of the intermetallic compound Mg2Ni
Место публикации : Phys. Solid State: Pleiades Publishing, 2014. - Vol. 56, Is. 10. - P.2035-2042. - ISSN 1063-7834, DOI 10.1134/S1063783414100187. - ISSN 1090-6460
Примечания : Cited References: 30
Предметные рубрики: STORAGE MATERIAL Mg2NiH4
INITIO MOLECULAR-DYNAMICS
AUGMENTED-WAVE METHOD
MINIMUM ENERGY PATHS
ELASTIC BAND METHOD
TEMPERATURE STRUCTURE
SADDLE-POINTS
ALLOYS
TRANSITION
MAGNESIUM
Аннотация: The intermetallic compound Mg2Ni as a potential material for hydrogen storage has been investigated theoretically. The sorption and diffusion of a hydrogen atom in the bulk and on the surface of this material, as well as the step-by-step process of dissociative chemisorption of a H-2 molecule on the surface, have been considered. The dependence of the sorption energy of atomic hydrogen on the structural characteristics of the intermetallic compound Mg2Ni has been analyzed.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kirik S. D., Parfenov V. A., Zharkov S. M.
Заглавие : Monitoring MCM-41 synthesis by X-ray mesostructure analysis
Место публикации : Micropor. Mesopor. Mater.: Elsevier Science, 2014. - Vol. 195. - P.21-30. - ISSN 1387-1811, DOI 10.1016/j.micromeso.2014.04.012. - ISSN 1873-3093
Примечания : Cited References: 70. - The investigation was made with financial support of the Program of Presidium RAS (Project 24.37), RF State contracts No 02.740.11.0629, RFBR Grants: 11-03-00610a and 11-03-12161-ofi, RSF 14-13-000025.
Предметные рубрики: ORDERED MESOPOROUS MATERIALS
ORDERED MESOPOROUS MATERIALS
IN-SITU
POWDER DIFFRACTION
SILICA/SURFACTANT COMPOSITES
ELECTRON-MICROSCOPY
MOLECULAR-SIEVES
STABLE MCM-41
SILICA
ADSORPTION
Ключевые слова (''Своб.индексиров.''): hydrothermal stability--mcm-41--mesostructure--tem--x-ray diffraction
Аннотация: The electron density maps calculated from X-ray diffraction patterns of the mesoporous silica material MCM-41 present averaged mesostructure images which in contrast to transmission electron microscopy (TEM) images are exceptionally repeating and represent the whole sample. It was shown that the averaged mesostructure parameters such as a unit cell parameter, a pore diameter, a wall width, a pore shape estimated from the X-ray powder diffraction data in combination with the continuous electron density function approach allow monitoring continuous set of the silica framework states at different stages of the material synthesis. The mentioned technique supplemented by N 2-adsorption measurements and transmission electron microscopy was applied for consideration of the MCM-41 hydrothermal stability. Attention has been given to the variations of the synthesis conditions affecting the hydrothermal stability, in particular the maintaining the basicity of the synthesis solution as well the substitution of the synthesis solution with water or a salt solution at hydrothermal treatment. The averaged pore shape was observed to be changed from cylindrical to hexagonal-prismatic form. The observed wall thickness was in the range from 0.75 to 1.25 nm. The competition of silica polycondensation and surface hydrolysis was shown to be responsible for the variety of framework geometry and hydrothermal stability. It has been established that the pore diameter increases generally due to the osmotic pressure of water. If the pores acquire the average prismatic hexagonal shape, the sample has low hydrothermal stability. Under the conditions favorable for the polycondensation the pores have averaged cylindrical shape and material demonstrates higher hydrothermal stability. Cooperative mechanism of mesostructure destruction under hydrothermal conditions was observed using TEM data and was discussed in connection with irregular polycondensation. © 2014 Elsevier Inc. All rights reserved.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhlin Y. L., Vishnyakova E. A., Romanchenko A. S., Saikova S. V., Likhatski M. N., Larichev Y. V., Tuzikov F. V., Zaikovskii V. I., Zharkov S. M.
Заглавие : Oxidation of Ag nanoparticles in aqueous media: Effect of particle size and capping
Место публикации : Appl. Surf. Sci.: Elsevier Science, 2014. - Vol. 297. - P.75-83. - ISSN 0169-4332, DOI 10.1016/j.apsusc.2014.01.081. - ISSN 1873-5584
Примечания : Cited References: 58. - This work was partially financially supported by the Ministry of Education and Science of RF (Grant 8580) and RFBR (12-03-31178).
Предметные рубрики: EX-SITU XPS
POLYCRYSTALLINE SILVER ELECTRODES
RAY PHOTOELECTRON-SPECTROSCOPY
METAL NANOPARTICLES
ELECTROCHEMICAL OXIDATION
ABSORPTION SPECTROSCOPY
PYROLYTIC-GRAPHITE
OXYGEN-ADSORPTION
TRANSFORMATIONS
DISSOLUTION
Ключевые слова (''Своб.индексиров.''): silver nanoparticles--oxidation--resistive switching effect--x-ray photoelectron spectroscopy
Аннотация: Many applications and environmental impact of silver-bearing nanomaterials critically depend upon their specific reactivity, which is still poorly understood. Here, silver nanoparticles (Ag NPs) of about 3-5 nm and 10-12 nm in diameter, uncapped and capped with l-glucose or citrate, were prepared, characterized using UV-vis absorption spectroscopy, SAXS, TEM, and their (electro) chemical oxidation was examined in comparison with each other and bulk metal applying scanning tunneling microscopy and spectroscopy, cyclic voltammetry, and XPS. A resistive switching effect was found in the tunneling spectra measured in air at the smaller uncapped Ag NPs deposited on HOPG and was interpreted in terms of Ag transfer between the particle and the probe. The anodic oxidation of these Ag NPs in 1 M NaOH yielded 3D Ag2O, while only a layer of "primary"Ag(I) oxide emerged on larger uncapped nanoparticles during the potential sweep. The formation of AgO at higher potentials proceeded readily at the "primary"oxide but was retarded at the smaller NPs. The citrate- and glucose-capping substantially impeded the formation both of Ag2O and AgO. The findings highlighted, particularly, a non-trivial effect of particle size and transient mobilization of Ag species on the reactions of silver nanoparticles. (c) 2014 Elsevier B.V. All rights reserved.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Паршин, Александр Михайлович, Зырянов, Виктор Яковлевич, Шабанов, Василий Филиппович
Заглавие : Конфигурации директора в структурах нематика, адсорбированного на поверхности полимера
Место публикации : Жидк. кристаллы и их практич. использ. - 2015. - Т. 15, Вып. 1. - С. 56-65. - ISSN 1991-3966; \b Liquid Crystals and their Application
Примечания : Библиогр.: 20. - Работа выполнена частично при финансовой поддержке программ Президиума РАН и РФФИ (грант № 15-02-06924).
Ключевые слова (''Своб.индексиров.''): нематический жидкий кристалл--полимер--адсорбция--дисклинация--конфигурация директора--nematic liquid crystal--polymer--adsorption--disclination--director configuration
Аннотация: Исследованы ориентационные структуры нематических жидких кристаллов, возникающие на поверхности полимера в результате адсорбции, и их устойчивость относительно шлирен-текстуры. Изучены особенности точечных и линейных сингулярностей в исследуемых структурах. Рассмотрены конфигурации директора в слое нематика, определяемые комбинацией двух ориентирующих факторов: воздействием линейной дисклинации, фактора, стремящегося задать однородное планарное упорядочение, а также влиянием точечного дефекта, задающего радиальную структуру директора. С использованием расчетного метода проведен сравнительный анализ энергии упругих искажений поля директора для различных видов конфигураций: радиально-планарной, радиально-гомеотропной и радиально-радиальной в зависимости от толщины слоя нематика.The orientational structures of nematic liquid crystals that form at the polymer surface due to adsorption and their stability with respect to the schlieren texture are investigated. Features of point and linear singularities in these structures are studied. The director configurations in nematic layer as a result of the combination of two aligning factors, which are the linear disclination that tends to impose uniform planar ordering and point defect that imparts the radial structure to the director are considered. The analysis of the elastic distortions energies of the director configurations for the radial-planar, radial-homeotropic and radial-radial structures, depending on the nematic layer thickness was performed using the calculation method.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Parshin A. M., Zyryanov V. Ya., Shabanov V. F.
Заглавие : The director field distribution with the strongly pinned alignment in nematic structures at the polymer surface
Коллективы : Russian Foundation for Basic Research [12-03-00816], Siberian Branch ofthe Russian Academy of Sciences (SB RAS) [30, 24.29, 24.32], SB RASthrough a Taiwan-SB RAS joint project
Место публикации : Liq. Cryst.: Taylor & Francis, 2015. - Vol. 42, Is. 1. - P.57-64. - ISSN 0267, DOI 10.1080/02678292.2014.960904. - ISSN 13665855(eISSN)
Примечания : Cited References:18. - This work was partially supported by the Russian Foundation for BasicResearch [project No. 12-03-00816] and by the Siberian Branch of theRussian Academy of Sciences (SB RAS) [grants nos. 30, 24.29, 24.32] andby SB RAS through a Taiwan-SB RAS joint project.
Предметные рубрики: LIQUID-CRYSTALS
DISCLINATION LINES
DEFECTS
Ключевые слова (''Своб.индексиров.''): orientational order--disclination--adsorption--nematic--polymer surface--director configuration
Аннотация: We investigate orientational nematic liquid crystal structures that form at the polymer surface due to adsorption, their stability against the schlieren texture and features of point and linear singularities in them. We demonstrate that surface disclination lines, which also occur due to molecular adsorption, can lead to azimuthal anchoring of a bulk layer and make the singularities with the charge m=+/- 1 stable. We consider the director field distribution in a nematic layer as a result of the combination of two aligning factors, which are the linear disclination that tend to impose uniform planar ordering and point defects that impart the radial configuration to the director. With the use of the calculation, we analyse the energies of elastic distortions of the director field for the radial-planar, radial-homeotropic and radial-radial configurations, depending on the nematic layer thickness.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhlin Y. L., Vorobyev S., Saikova S. V., Tomashevich Y., Fetisova O., Kozlova S., Zharkov S. M.
Заглавие : Preparation and characterization of colloidal copper xanthate nanoparticles
Коллективы : Russian Science Foundation [14-17-00280]
Место публикации : New J. Chem.: Royal Society of Chemistry, 2016. - Vol. 40, Is. 4. - P.3059-3065. - ISSN 1144-0546, DOI 10.1039/c6nj00098c. - ISSN 1369-9261(eISSN)
Примечания : Cited References:50. - This research was supported by the Russian Science Foundation grant 14-17-00280. We thank Dr Roberto Felix Duarte (HZB) and bilateral program "German-Russian laboratory at BESSY II" for assistance with the X-ray absorption experiments.
Предметные рубрики: X-ray-absorption
Self-assembled monolayers
Sulfide nanoparticles
Electronic-structure
Waste-water
Complexes
Flotation
Spectroscopy
Adsorption
Oxidation
Аннотация: Despite the important role of metal xanthates in a number of industrial processes and emerging applications, no attempts have been made to prepare the metal xanthate nanoparticles and to study colloidal solutions of insoluble heavy metal xanthates. Here, we examined the formation of colloidal copper xanthate particles during the reactions of aqueous solutions of cupric sulfate and various potassium xanthates, which occur in flotation and water treatment slurries and can be used to manufacture nanoparticles for materials science (e.g., as precursors for copper sulfide nanoparticles and biomedicine). The products were characterized using UV-vis absorption, dynamic light scattering, zeta potential measurements, transmission electron microscopy (TEM), electron diffraction, Fourier transform infrared spectroscopy, thermogravimetry, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy (XANES). Colloidal copper xanthates with compositions of ROCSSCu (R = ethyl, isopropyl, butyl, isobutyl, and amyl groups), disordered structures and average diameters of 20–80 nm easily formed and aggregated and were stable for at least several hours, especially if excessive xanthate was used. The hydrodynamic diameters of the nanoparticles were smaller at lower temperatures. Dixanthogens, which were produced in the reactions along with ROCSSCu, seemed to promote nanoparticle aggregation and precipitated with the copper xanthate, affecting their thermal decomposition. The TEM micrographs and S K- and Cu K-edge XANES spectra revealed core/shell particle morphologies, likely with Cu(I) bonded to four S atoms in the core and reduced copper coordination in the shell.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Kovaleva E. A., Avramov P. V., Kholtobina A. S., Mikhaleva N. S., Kuklin A. V.
Заглавие : Buckminsterfullerene's movability on the Fe(001) surface
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 410. - P.41-46. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2016.03.023
Примечания : Cited References: 32. - This work was supported by the Russian Scientific Fund (Project no. 14-13-00139) and the Foundation for Assistance to Small Innovative Enterprises (FASIE) (Project no. 0011742). The authors would like to thank Institute of Computational Modeling of SB RAS, Krasnoyarsk; Joint Supercomputer Center of RAS, Moscow; Center of Equipment for Joint Use of Siberian Federal University, Krasnoyarsk; ICC of Novosibirsk State University and Siberian Supercomputer Center (SSCC) of SB RAS, Novosibirsk for providing the access to their supercomputers.
Предметные рубрики: Initio molecular-dynamics
Total-energy calculations
Augmented-wave
Ключевые слова (''Своб.индексиров.''): buckminsterfullerene--c60--fe(001)--spintronics--adsorption--relocation--dft
Аннотация: Organic-based spintronics is one of the most fast-developing fields in nanoelectronics. Buckminsterfullerene-based composites are widely investigated due to its unique properties and there is a number of studies concerned with its interfaces with various types of substrates. Ferromagnetic surfaces are of a particular interest for potential spintronics applications. Based on the data reported in literature, we suppose that there are more than one stable structure in C60/Fe(001) composite system. Here we investigate different possible adsorption sites of C60 molecule and reveal the possibility of their coexistence and its influence on the composite properties. © 2016 Elsevier B.V.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Avramov P. V., Nikolaeva K. M., Mikhaleva N. S., Kovaleva E. A., Kuklin A. V., Fedorov A. S.
Заглавие : Study of interaction between transition metal atoms and bigraphene monovacancy by means of quantum chemistry
Место публикации : Comput. Mater. Sci.: Elsevier, 2016. - Vol. 112, Part A. - P.269-275. - ISSN 0927-0256, DOI 10.1016/j.commatsci.2015.11.002
Примечания : Cited References: 39. - The authors would like to thank Siberian Supercomputer Center (SSCC) of SB RAS, Novosibirsk; and L.V. Kirensky Institute of Physics of SB RAS, Krasnoyarsk, for providing the access to their supercomputers. This work was supported by the government contract of the Ministry of Education and Science of the Russian Federation to Siberian Federal University (Grant No. 16.1500.2014/K).
Предметные рубрики: INITIO MOLECULAR-DYNAMICS
MASSLESS DIRAC FERMIONS
GRAPHENE
VACANCIES
POINTS
GAS
Ключевые слова (''Своб.индексиров.''): bigraphene--spintronics--transition metal--adsorption--migration
Аннотация: First-row transition metal atoms adsorption on bigraphene monovacancy was studied within the framework of DFT in periodic boundary conditions. Electronic and magnetic properties of composites were analyzed and their potential utilization in spintronics was discussed. Barriers of metal atoms migration from bigraphene surface to the interlayer space through the vacancy were estimated in order to consider both thermodynamic and kinetic aspects of composites experimental preparation. Formation of metal atoms inner-sorbed on bigraphene was found to demand harsh synthesis conditions; whereas outer-sorbed composites demonstrate significantly higher degree of spin polarization which makes them perspective for usage in spintronic devices. © 2015 Elsevier B.V.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Паршин, Александр Михайлович, Сутормин, Виталий Сергеевич, Зырянов, Виктор Яковлевич, Шабанов, Василий Филиппович
Заглавие : Влияние ионного сурфактанта на энергию сцепления жидкого кристалла с поверхностью, исследованное с использованием магнитных пороговых полей перехода Фредерикса
Место публикации : Жидк. кристаллы и их практич. использ. - 2018. - Т. 18, № 3. - С. 59-66. - ISSN 1991-3966, DOI 10.18083/LCAppl.2018.3.59; Liq. Cryst. Appl. - ISSN 2499-9644
Примечания : Библиогр.: 25. - В. С. Сутормин благодарен РФФИ за поддержку исследований по гранту № 16-32-60036 мол_а_дк.
Предметные рубрики: WALL INTERFACE
TEMPERATURE-DEPENDENCE
NEMATIC DROPLETS
ADSORPTION
Ключевые слова (''Своб.индексиров.''): нематический жидкий кристалл--ионный сурфактант--энергия сцепления--магнитное поле--переход фредерикса--nematic liquid crystal--ionic surfactant--anchoring energy--magnetic field--freedericksz transition
Аннотация: Исследовано сцепление нематического жидкого кристалла 5ЦБ и 5ЦБ, допированного ионным сурфактантом ЦТАБ, в ячейках с плоскопараллельными ограничивающими поверхностями. Получены зависимости интенсивности проходящего лазерного излучения от величины магнитного поля для ячеек с различными толщинами слоя нематика при различных температурах. Из пороговых полей перехода Фредерикса определены значения полярной энергии сцепления жидкого кристалла с поверхностью. Изучено влияние ионного сурфактанта на энергию сцепления, установлено, что добавление в объем жидкого кристалла ионного сурфактанта ведет к ее ослаблению. Проведен анализ точности определения энергии сцепления на основе выражения, следующего из соотношения Рапини – Популара. Показано, что лучшее экспериментальное разрешение энергии сцепления достигается при использовании тонких слоев нематика, более сильных магнитных полей, а также слабого сцепления молекул жидкого кристалла с поверхностью.The coupling of nematic liquid crystal 5CB and 5CB doped with ionic surfactant CTAB in the cells with plane parallel interfaces was studied. For the cells with the varied nematic layer thickness at different temperatures, the dependencies of the passed laser radiation intensity on the magnetic field were obtained. From the threshold fields of Freedericksz transition, the polar anchoring energy of the liquid crystal to the surface was determined. The effect of the ionic surfactant on the anchoring energy was studied and it was found that the addition of the ionic surfactant to liquid crystal weakens the anchoring energy. The analysis of the accuracy of the anchoring energy determination based on the expression following from the Rapini - Popular relation was carried out. It was shown that the best experimental resolution of the anchoring energy is achieved when the thin nematic layers, stronger magnetic fields and weak anchoring of the liquid crystal molecules with the surface are used.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhlin Y. L., Vorobyev S. A., Saikova S. V., Vishnyakova E. A., Romanchenko A. S., Zharkov S. M., Larichev Y. V.
Заглавие : On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy
Место публикации : Appl. Surf. Sci.: Elsevier Science, 2018. - Vol. 427. - P.687-694. - ISSN 01694332 (ISSN), DOI 10.1016/j.apsusc.2017.09.026
Примечания : Cited References: 50. - We thank the Russian-German bilateral program “Russian-German laboratory at BESSY II” and the staff of the RGLab and HZB for their kind assistance with XANES experiments.
Ключевые слова (''Своб.индексиров.''): silver nanoparticles--adsorption--citrate capping--x-ray photoelectron spectroscopy
Аннотация: Citrate is an important stabilizing, reducing, and complexing reagent in the wet chemical synthesis of nanoparticles of silver and other metals, however, the exact nature of adsorbates, and its mechanism of action are still uncertain. Here, we applied X-ray photoelectron spectroscopy, soft X-ray absorption near-edge spectroscopy, and other techniques in order to determine the surface composition and to specify the citrate-related species at Ag nanoparticles immobilized from the dense hydrosol prepared using room-temperature reduction of aqueous Ag+ ions with ferrous ions and citrate as stabilizer (Carey Lea method). It was found that, contrary to the common view, the species adsorbed on the Ag nanoparticles are, in large part, products of citrate decomposition comprising an alcohol group and one or two carboxylate bound to the surface Ag, and minor unbound carboxylate group; these may also be mixtures of citrate with lower molecular weight anions. No ketone groups were specified, and very minor surface Ag(I) and Fe (mainly, ferric oxyhydroxides) species were detected. Moreover, the adsorbates were different at AgNPs having various size and shape. The relation between the capping and the particle growth, colloidal stability of the high-concentration sol and properties of AgNPs is briefly considered. © 2017 Elsevier B.V.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrilyuk A. P., Gerasimov V. S., Ershov A. E., Karpov S. V.
Заглавие : Temperature dependent elastic repulsion of colloidal nanoparticles with a polymer adsorption layer
Коллективы : Russian Foundation for Basic Research; government of the Krasnoyarsk territory and Krasnoyarsk Regional Fund of Science [18-42-243023]; RF Ministry of Science and Education,; State contract with Siberian Federal University for scientific research in 2017-2019; SB RAS Program [II.2P (0358-2015-0010)]
Место публикации : Colloid Polym. Sci. - 2018. - Vol. 296, Is. 10. - P.1689-1697. - ISSN 0303-402X, DOI 10.1007/s00396-018-4383-y. - ISSN 1435-1536(eISSN)
Примечания : Cited References: 49. - The reported research was funded by the Russian Foundation for Basic Research, the government of the Krasnoyarsk territory and Krasnoyarsk Regional Fund of Science, grant 18-42-243023, the RF Ministry of Science and Education, the State contract with Siberian Federal University for scientific research in 2017-2019, and SB RAS Program No II.2P (0358-2015-0010).
Предметные рубрики: STERICALLY-STABILIZED PARTICLES
DEPLETION FLOCCULATION
AGGREGATION
Ключевые слова (''Своб.индексиров.''): nanoparticle--adsorption layer--elastic deformation--coagulation--kinetics--elasticity modulus
Аннотация: The model of pairwise elastic repulsion of contacting colloidal nanoparticles with a rigid core and deformable shell is discussed. A simple analytical equation is applied for the energy of elastic repulsion of nanoparticles with arbitrary sizes and the elasticity moduli of self-healing polymer adsorption layers. The model is based on the representation of the absorption layer as a continuous medium that is elastically deformed upon the contact of nanoparticles. The major characteristic of this medium is the elasticity modulus. The magnitude of the elasticity modulus is determined from the condition of balance of the van der Waals attractive forces of nanoparticles and the elastic repulsion of their adsorption layers in the contact area, taking into account the temperature variations. We employed the kinetic approach to describe the dependence of the elasticity modulus on both the temperature and the rate of its change.
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