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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Morozov E. V., Voronin A. S., Kniga, S., V, Buznik V. M.
Заглавие : Nuclear magnetic resonance study of ice-based composite materials reinforced with nanodisperse aluminum oxide fibers
Коллективы : Institute of Chemistry and Chemical Technology (Siberian Branch, Russian Academy of Sciences) [0287-2021-0012]; Russian Science FoundationRussian Science Foundation (RSF) [18-1300392]
Место публикации : Inorg. Mater. Appl. Res. - 2022. - Vol. 13, Is. 1. - P.217-224. - ISSN 2075-1133, DOI 10.1134/S2075113322010270. - ISSN 2075-115X(eISSN)
Примечания : Cited References: 21. - This work was performed within the scope of state contract no. 0287-2021-0012 of the Institute of Chemistry and Chemical Technology (Siberian Branch, Russian Academy of Sciences) in the part of developing the MRI methods for studying composite materials; also the work was supported by the Russian Science Foundation (project no. 18-1300392) in the part of the study of the processes of water crystallization and ice melting in ice-based composite materials
Предметные рубрики: SELF-DIFFUSION
WATER
Аннотация: Pulsed-field gradient NMR spectroscopy and magnetic resonance imaging methods were used to investigate water suspensions of nanosized fibers of aluminum oxide and ice composite materials based on these fibers. Introduction of the nanofibers was shown to have no noticeable structural effect in the suspensions in the Al2O3 concentration range of 1-10 wt %. High content of the filler was found to change the morphology and texture of the ice matrix in the composites remarkably: it becomes more homogeneous and acquires a higher degree of continuity; the melting front does not visualize internal melting zones or integrity defects in the composite. At the same time, addition of the nanofibers to the ice composites weakly influences the quantitative dynamics of the heat transfer, which is manifested in close values of the propagation speeds of the freezing/melting front in the samples at similar temperatures.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Morozov E. V., Nizovtseva P. V., Martyanov O. N.
Заглавие : From components to phase-dependent dynamics of diffusivity in wax solutions subjected to fluid-solid phase transition: Insights from Pulsed Field Gradient NMR
Место публикации : Energy Fuels. - 2022. - Vol. 36, Is. 24. - P.14696-14709. - ISSN 08870624 (ISSN), DOI 10.1021/acs.energyfuels.2c02943. - ISSN 15205029 (eISSN)
Примечания : Cited References: 76. - The present research was performed with the financial support of the Russian Science Foundation (project no. 21-13-00171, http://rscf.ru/project/21-13-00171/)
Аннотация: The evolution of solvent and solute diffusivity during fluid-solid phase transition was studied in model wax in n-dodecane solutions in a wide concentration range. Studied systems were characterized using viscosity measurements to provide supplementary information related to wax precipitation onset, while diffusion coefficients of n-dodecane and paraffin molecules were quantified using Pulsed Field Gradient (PFG) NMR. It was revealed that above the wax appearance temperature (WAT), the Hayduk-Minhas equation adequately predicts the solute and solvent diffusivity. At lower temperatures (below the WAT), three distinct diffusive components appear, which no longer originate from individual molecular components but correspond to a liquid phase differing in terms of association to the wax crystal network. These diffusion components were concluded to contain dodecane and the residual dissolved wax; the major components among them correspond to fluid, which relatively freely diffuses between the wax microcrystals and experiences the hindrance due to the wax gel network, and the minor components correspond to the fluid closely associated with the wax crystals. Unlike at high temperatures, the Hayduk-Minhas equation was found to be unable to predict adequately the diffusivity below the WAT. Using Singh's approach, the aspect ratio of wax crystals was calculated for different temperatures and concentrations and its complex nonlinear behavior was observed. It turned out that none of the models available differentiate the fluids with respect to the wax crystal network that leaves out of modeling the diffusion components with reduced mobility. The results indicate that the intuitive paradigm of component-dependent dynamics of solvent and solute diffusivity should be changed to phase-dependent dynamics once the system turns into wax gel since the diffusion of separate components becomes the diffusion of separate phases. This understanding shows a new route to improving the wax deposition modeling, which will facilitate an increase of effectiveness of the remedial strategies in the petroleum industry.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Moiseenko E. T., Zharkov S. M., Altunin R. R., Belousov O. V., Solovyov L. A., Yumashev V. V., Volochaev M. N., Zeer G. M.
Заглавие : Peculiarities of Intermetallic Phase Formation in the Process of a Solid State Reaction in (Al/Cu)n Multilayer Thin Films
Место публикации : JOM. - 2021. - Vol. 73, Is. 2. - P.580-588. - ISSN 10474838 (ISSN), DOI 10.1007/s11837-020-04522-9
Примечания : Cited References: 44. - This work was supported by the Russian Science Foundation under Grant #18-13-00080. The electron microscopy investigations were conducted in the SFU Joint Scientific Center whose infrastructure was supported by the State assignment (#FSRZ-2020-0011) of the Ministry of Science and Higher Education of the Russian Federation. The preparation of cross-section samples for TEM investigations was conducted in the Krasnoyarsk Regional Center of Research Equipment of Federal Research Center “Krasnoyarsk Science Center SB RAS”
Аннотация: Phase formation in a solid state reaction in Al/Cu bilayer and multilayer thin films was studied by the methods of in situ transmission electron microscopy, electron diffraction, simultaneous thermal analysis and x-ray diffraction. It was established that the phase formation sequences in the (Al/Cu)n (n = 2, 15) multilayer thin films (θ-Al2Cu → γ1-Al4Cu9 → η2-AlCu) and Al/Cu bilayer thin films (θ-Al2Cu → η2-AlCu → γ1-Al4Cu9) were different. It was assumed that the phase formation process in the thin films was strongly affected by a number of copper/aluminum interfaces due to the changes of aluminum and copper diffusion current.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bykov A. A., Gokhfeld D. M., Terent'ev K. Yu., Volochaev M. N., Petrov M. I.
Заглавие : Diffusion of strontium in the intergranular boundaries of La2–xSrxCuO4
Место публикации : Russ. J. Phys. Chem. A. - 2021. - Vol. 95, Is. 6. - P.1165-1168. - ISSN 00360244 (ISSN), DOI 10.1134/S0036024421060066
Примечания : Cited References: 11. - This work was supported by the Russian Science Foundation, project no. 17-72-10067
Аннотация: Energy dispersive X-ray spectroscopy and scanning electron microscopy are used to study La2CuO4–La1.56Sr0.44CuO4 composites with different annealing times. Maps of the strontium distribution for such systems are calculated and compared to experimental data obtained for the area of contact between two dissimilar granules. The coefficient of lattice diffusion of strontium is found. At the areas of contact between La2CuO4 and La1.56Sr0.44CuO4 granules, the strontium concentration corresponds to superconducting phase La2−xSrxCuO4 with x = 0.05–0.25. The technological parameters of synthesis affect the size and number of superconducting and normal regions. Prolonged annealing lowers the gradient of the strontium concentration, which halts the increase in the size of the superconducting regions. This saturation confirms the diffusion front model.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Altunin R. R., Moiseenko E. T., Zharkov S. M.
Заглавие : Effect of the structural properties on the electrical resistivity of the Al/Ag thin films during the solid-state reaction
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [18-13-00080]
Место публикации : Phys. Solid State. - 2020. - Vol. 62, Is. 4. - P.708-713. - ISSN 1063-7834, DOI 10.1134/S1063783420040034. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 43. - This study was supported by the Russian Science Foundation, project no. 18-13-00080.
Предметные рубрики: LIGHT-EMITTING-DIODES
PHASE-FORMATION
AG
AL
DIFFUSION
SUPPRESSION
INTERFACE
SURFACE
GROWTH
HEAT
Аннотация: Based on the results of in situ electron diffraction study of the solid-state reaction and electrical resistivity measurements on the Al/Ag thin films with an atomic ratio of Al : Ag = 1 : 3, the temperature of the reaction onset has been established and a model of the structural phase transitions has been proposed. The solid-state reaction begins at 70°C with the formation of the Al–Ag solid solution at the interface between the aluminum and silver nanolayers. It has been found that, in the course of the reaction, the intermetallic compounds γ-Ag2Al → μ-Ag3Al are successively formed. It is shown that the possibility of the formation of the μ‑Ag3Al phase during the solid-state reaction in the Al/Ag thin films depends on the aluminum-to-silver ratio, while the formation of the μ-Ag3Al phase begins only after all fcc aluminum has reacted.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Maximova O. A., Lyashchenko S. A., Varnakov S. N., Ovchinnikov S. G.
Заглавие : Multilayered ferromagnetic nanostructures study: Processing data from magneto-ellipsometry measurements
Коллективы : Asian School-Conference on Physics and Technology of Nanostructured Materials, Азиатская школа-конференция по физике и технологии наноструктурированных материалов
Место публикации : Defect Diffus. Forum. - 2018. - Vol. 386 DDF. - P.131-136. - ISSN 10120386, DOI 10.4028/www.scientific.net/DDF.386.131
Примечания : Cited References: 15
Ключевые слова (''Своб.индексиров.''): ellipsometry--ferromagnetic--thin layered films--transverse magneto-optical kerr effect
Аннотация: Nowadays, the magneto-ellipsometry technique is considered as a promising tool for studying nanostructures. It leads to a great demand of both designing set-ups for conducting experiments and developing approaches to data processing. The later one is a problem in framework of in situ analysis as it would be useful to have an approach to data analysis which is reliable, quick and reasonably easy. This work continues our previous study of layered nanostructures by means of magneto-ellipsometry technique and logically generalizes the approach to magneto-ellipsometry data analysis for the multi-layered model use. As a result, the algorithm with detailed description of necessary formulae is presented.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Bykova L. E., Matsynin A. A., Volochaev M. N., Zhigalov V. S., Tambasov I. A., Mikhlin Y. L., Velikanov D. A., Bondarenko G. N.
Заглавие : Solid state synthesis of Mn5Ge3 in Ge/Ag/Mn trilayers: Structural and magnetic studies
Место публикации : J. Solid State Chem. - 2017. - Vol. 246. - P.379-387. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2016.12.010
Примечания : Cited References: 64. - This study was supported by the Russian Foundation for Basic Research (RFBR) (Grants # 15-02-00948-a, # 16-03-00069-a), by the Council for Grants of the President of the Russian Federation (SP-1373.2016.3), and by the program of Foundation for Promotion of Small Enterprises in Science and Technology (“UMNIK” program) # 6650GU/2015. The reported study was funded by RFBR and Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund to the research project #, 16-42-243006. The XPS and TEM studies were carried out using the facilities of the Performance Service at Krasnoyarsk Scientific Center.
Ключевые слова (''Своб.индексиров.''): long-range atomic transfer--mn-ge system--thin-film solid-state reaction--diffusion barrier--dominant diffusing species--first phase--mn5ge3 alloy
Аннотация: The thin-film solid-state reaction between elemental Ge and Mn across chemically inert Ag layers with thicknesses of (0, 0.3, 1 and 2.2 µm) in Ge/Ag/Mn trilayers was studied for the first time. The initial samples were annealed at temperatures between 50 and 500 °C at 50 °C intervals for 1 h. The initiation temperature of the reaction for Ge/Mn (without a Ag barrier layer) was ~ 120 °C and increased slightly up to ~ 250 °C when the Ag barrier layer thickness increased up to 2.2 µm. In spite of the Ag layer, only the ferromagnetic Mn5Ge3 compound and the Nowotny phase were observed in the initial stage of the reaction after annealing at 500 °C. The cross-sectional studies show that during Mn5Ge3 formation the Ge is the sole diffusing species. The magnetic and cross-sectional transmission electron microscopy (TEM) studies show an almost complete transfer of Ge atoms from the Ge film, via a 2.2 µm Ag barrier layer, into the Mn layer. We attribute the driving force of the long-range transfer to the long-range chemical interactions between reacting Mn and Ge atoms. © 2016 Elsevier Inc.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bouznik V. M., Morozov E. V., Avilova I. A., Volkov V. I.
Заглавие : NMR applications for polymer composite materials moisture uptake investigation
Место публикации : Appl. Magn. Reson.: Springer, 2016. - Vol. 47, Is. 3. - P.321-334. - ISSN 09379347 (ISSN), DOI 10.1007/s00723-015-0748-2
Примечания : Cited References: 41. - This research was performed with the financial support of Russian Foundation for Basic Research (project no. 14-29-10178 ofi_m).
Предметные рубрики: FIELD GRADIENT NMR
REINFORCED EPOXY COMPOSITES
WATER SELF-DIFFUSION
TRANSPORT
GLASS
SYSTEM
SPECTROSCOPY
TEMPERATURE
ABSORPTION
ADHESIVE
Аннотация: The 1H nuclear magnetic resonance (NMR) spectroscopy, NMR imaging, and pulsed field gradient NMR (PFG NMR) were applied for comparative study of moisture–polymer composite materials (PCM) interaction. The water uptake in PCM reinforced by aramid and carbon fibers was measured by NMR spectroscopy techniques. The aramid fiber-reinforced PCM absorbs water more intensively compared with PCM reinforced by carbon fiber, but both of them are retaining water inside of pores without formation of chemical bonds. Using NMR imaging the spatial distribution of water absorbed was visualized; preferable water pathways and influence of surface treatment on water-resistant properties were revealed. It was found that the surface rough treatment sufficiently improves the water absorption, but penetration of water molecules is still occurring only through the surfaces and it happens within a thin layer. PFG NMR technique revealed influence of pore structure on moisture–PCM interaction; it was found that additionally to strong hydrophobic properties of carbon fiber, the smaller total volume of pores sufficiently decrease the water uptake. Results achieved in this work demonstrate efficiency of NMR methods applied all together for investigation of PCM, and information obtained is practically important when designing advanced PCM with required properties. © 2016, Springer-Verlag Wien.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Morozov E. V., Falaleev O. V., Martyanov O. N.
Заглавие : New insight into the wax precipitation process: in situ NMR imaging study in a cold finger cell
Место публикации : Energy Fuels: American Chemical Society, 2016. - Vol. 30, Is. 11. - P.9003-9013. - ISSN 08870624 (ISSN), DOI 10.1021/acs.energyfuels.6b01535
Примечания : Cited References: 69. - This research was performed with the financial support of the Russian Science Foundation (Project No. 15-19-00119).
Ключевые слова (''Своб.индексиров.''): cells--crude oil--cytology--deposits--diffusion--gelation--magnetic resonance imaging--ostwald ripening--phase separation--polymer blends--deposit formation--deposit structures--diffusion controlled growth--dominant mechanism--lower temperatures--morphology and dynamics--phase-separation process--temperature regimes--image processing
Аннотация: A cold finger cell intended for the wax deposition measurements was fabricated and integrated into an NMR imaging probe for the noninvasive study of wax precipitation processes in situ. The cell was first tested with a model system; then, a series of experiments with different thermal gradients applied to the cell were performed for a waxy crude oil. NMR imaging of the operating cell revealed the formation of a deposit with the morphology and dynamics strongly correlating with the temperature regime. At higher temperatures of cold finger, the incipient wax gel ages uniformly, giving rise to the hard and thin inner layer of deposit accompanied by a branched loosely consolidated outer layer. Conversely, the lower temperatures facilitate formation of a thick deposit which no longer ages uniformly and slow down the diffusion-controlled growth of the branched deposit structure. The results obtained are consistent with the majority of the data previously reported. Thus, gelation of the wax at temperatures below the cloud point and subsequent thermal-driven diffusion processes are considered to be the dominant mechanisms of the deposit formation. The counter diffusion and Ostwald ripening aging concepts were found to be relevant in the case of the cold finger study and account for the phenomena observed in this work. The information obtained via NMR imaging is highly complementary to the results obtained by other techniques that can aid in understanding the essential processes behind the wax precipitation phenomena. The approach developed can be effectively extended to study any thermal-driven phase separation process. © 2016 American Chemical Society.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhaleva N. S., Visotin M. A., Popov Z. I., Kuzubov A. A., Fedorov A. S.
Заглавие : Ab initio and empirical modeling of lithium atoms penetration into silicon
Место публикации : Comput. Mater. Sci.: Elsevier, 2015. - Vol. 109. - P.76-83. - ISSN 0927-0256, DOI 10.1016/j.commatsci.2015.06.024
Примечания : Cited References: 69. - The authors would like to thank the Institute of Computational Modeling SB RAS, Krasnoyarsk, Information Technology Centre Novosibirsk State University, for providing access to their computational resources. The reported study was supported by RFBR, research project No. 14-02-31071, 14-02-31309, 12-02-00640, by the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (project No. NSh-2886.2014.2), Increase Competitiveness Program of NUST "MISiS" (No. K2-2015-033). The authors also would like to thank Prof. Stephan Irle and L.R. Moskvina for fruitful discussions and helpful ideas.
Предметные рубрики: LONG CYCLE LIFE
CORE-LEVEL SPECTROSCOPY
CARBON-COATED SILICON
AUGMENTED-WAVE METHOD
ION BATTERIES
MOLECULAR-DYNAMICS
INTERATOMIC POTENTIALS
ELECTRONIC-STRUCTURE
CRYSTALLINE SILICON
SI(100)2X1 SURFACE
Ключевые слова (''Своб.индексиров.''): li-ion batteries--silicon--surface diffusion--li diffusion--density functional theory--molecular dynamics
Аннотация: A process of lithium atoms penetration into silicon (1 0 0) subsurface layers was investigated with the help of DFT method. It was shown that, while the concentration of lithium adatoms on reconstructed (1 0 0) silicon surface is low, the bonding energy of lithium atoms in the subsurface layers is smaller than the bonding energy on the surface, so lithium atoms are unlikely to migrate into the crystal. When the (1 0 0) silicon surface is covered by 2 layers of lithium, migration into the subsurface layer becomes favorable. In addition to this, the reconstruction of the surface changes to the form with symmetric dimers as the concentration increases. Thus, all possible lithium migration paths become energy-wise equal, so the rate of lithium atom transfer into silicon crystal rises. In addition to the ab initio calculations, an ad-hoc empirical interatomic potential was developed and the kinetics of lithium diffusion into silicon were studied. It was shown that lithium penetration proceeds in a layer-by-layer way with a sharp border between undoped and lithiated silicon. This is accounted for the fact that, once a tetrahedral interstice is occupied by a lithium atom, the migration barriers between the adjacent interstices become lower and the rate of diffusion increases. © 2015 Elsevier B.V. All rights reserved.
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