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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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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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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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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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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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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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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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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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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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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Михалева Н. С., Кузубов, Александр Александрович, Попов, Захар Иванович, Еремина А. Д., Высотин, Максим Александрович
Заглавие : Теоретическое исследование внедрения атомов лития в кремний
Место публикации : Вестник СибГАУ. - Красноярск: СибГАУ, 2015. - Т. 16, № 2. - С. 456-463. - ISSN 1816-9724
Примечания : Библиогр.: 55
Ключевые слова (''Своб.индексиров.''): диффузия--литий--кремний--dft--diffusion--lithium--silicon
Аннотация: Рассматривается процесс диффузии атомов лития в приповерхностные слои кремния (001). Расчеты выполнялись в рамках теории функционала плотности. Показано, что при малой концентрации лития на реконструированной поверхности кремния (001) энергия связи в подповерхностном слое ниже, чем на поверхности, что препятствует диффузии лития внутрь кристалла. Подобная ситуация существенно не меняется при увеличении температуры. Анализ частот перескока одиночных атомов лития с поверхности в приповерхностные слои показал, что в случае малых концентраций миграция атомарного Li будет осуществляться практически по одному пути реакции (из положения L-состояния, в котором литий находится в канале между димерами). При концентрации лития в два монослоя, наоборот, диффузия в подповерхностные слои становится более предпочтительна. Поскольку при достижении концентрации в один монослой происходит изменение симметрии димеров, диффузия лития внутрь кристалла также облегчается вследствие увеличения плотности положений в каналах между димерами. Таким образом, результат моделирования позволил объяснить причину экспериментального факта затруднения диффузии лития при прохождении через данную поверхность и определить пути возможной модификации поверхности, которая должна увеличить энергию связи атомов лития в приповерхностных состояниях при низких степенях заполнения им поверхности.The article deals with a theoretical investigation of lithium diffusion through silicon (001) surface within density functional theory formalism. It was shown that it is more energetically favorable for dilute lithium atoms to stay atop fully-relaxed silicon (001) surface than beneath it. This fact hampers the diffusion into the silicon crystal and the situation doesn't change significantly with increase in temperature. The frequencies of lithium atom hopping from the surface to the subsurface layers of silicon crystal were estimated. The analysis of frequencies for different transition paths indicates that in the case of dilute concentration Li atoms are likely to migrate through the surface from one type of sites (site L-located in channels between silicon dimers). With increasing of lithium concentration up to 1 monolayer and further, the silicon (001) surface swaps the asymmetric dimers reconstruction model for symmetric, leading to doubling of number of the sites in between silicon dimers. After the concentration reaches 2 monolayers, the binding energy of Li atoms on the surface becomes less than binding energy beneath the surface, so the diffusion turns to be thermodynamically allowed. As a result of the investigation, the ab-initio modeling puts light on the cause of experimentally observed decelerated lithium diffusion through silicon (001) surface and delivers an opportunity to determine possible techniques for surface modification, which will increase lithium atom binding energies in sites beneath silicon surface at low lithium concentrations.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Кузубов, Александр Александрович, Михалева Н. С., Попов, Захар Иванович, Краснов, Павел Олегович, Николаева К. М.
Заглавие : Теоретическое исследование влияния допирования поверхности Si (100) на сорбцию и диффузию лития
Место публикации : Вестник СибГАУ. - Красноярск, 2015. - Т. 16, № 3. - С. 743-749. - ISSN 1816-9724
Примечания : Библиогр.: 56. - Исследование выполнено при финансовой поддержке РФФИ в рамках научных проектов No 14-02-31071, 14-02-31309. Авторы выражают благодарность информационно-вычислительному центру (ИВЦ) Новосибирского государственного университета (Новосибирск), Институту компьютерного моделирования СО РАН (Красноярск), Межведомственному суперкомпьютерному центру РАН (Москва), компьютерному центру СФУ, а также НИВЦ МГУ «Лаборатории параллельных информационных технологий» (система СКИФ МГУ «Ломоносов») за предоставление возможности использования вычислительных кластеров, на которых были проведены все расчеты.
Ключевые слова (''Своб.индексиров.''): диффузия--литий--кремний--кремний--допирование--метод функционала плотности (dft)--diffusion--lithium--silicon--doping--dft
Аннотация: В настоящее время перспективным анодным материалом нового поколения считается кремний, поскольку он имеет самую высокую теоретическую удельную емкость (4200 мАч/г). Однако одной из проблем, препятствующих широкому использованию данного материала, является медленная диффузия лития с поверхности кремния в объем, которая может быть решена с помощью модификации поверхности кремния. Проведено моделирование поверхностных процессов сорбции и диффузии лития в допированной поверхности Si (100) с помощью метода функционала плотности. В ходе исследования допирования Si (100) одиночными атомами B, Ga, Ge выявлено, что для всех выбранных нами допантов наиболее выгодны положения замещения кремния, а не адсорбции. Энергия связи допанта с пластиной кремния ослабевает в ряду от германия к галлию. Найдено, что атом бора замещает атом третьего слоя кремния, а германий и галлий занимают положение в первом слое. Тенденция первоначальной сорбции атомов лития в канале между димерами по сравнению с чистым материалом сохраняется и при допировании одиночными атомами B, Ga, Ge. Наблюдается значительное снижение (в случае бора) и увеличение (для галия и германия) энергетических барьеров перехода атома лития по поверхности кремниевой пластины. Величины энергетических барьеров перехода L-U с поверхности в приповерхностные слои при допировании возрастают на 0,05 эВ, что свидетельствует о замедлении данной стадии. В результате работы было обнаружено, что допирование бором, галлием и германием (концентрация составляет 0,3 атомных %) поверхности Si (100) не оказывает значительного влияния на сорбционные и диффузионные параметры.Currently, silicon is the most promising anode material for a new generation of lithium-ion batteries due to its very high theoretical specific capacity (4200 mAh/g). However, one of the problems hindering the wider use of this material is the slow diffusion of lithium from silicon surface into volume that can be solved by modifying silicon surface. The simulation of surface processes of sorption and diffusion of lithium in doped Si (100) was carried out by using the density functional method. In the study Si (100) doped with single atoms B, Ga, Ge, found that the silicon replacement compared to adsorption are more profitable for all dopants. The binding energy of dopant to silicon decreases from germanium to gallium. It was found that boron atom substitutes for the third layer of silicon, germanium and gallium occupy positions in the first layer. In comparison with the pure material the trend of initial lithium sorption in the channel between silicon dimmers retain for Si (100) doped with single atoms of B, Ga, Ge. Energy barriers of lithium transition on silicon surface substantially reduce (in the case of boron) and increase (in the case of gallium and germanium). The energy barrier of transition from surface to surface layers L-U during the doping increases by 0.05 eV, this shows a moderation of the stage. According to the study, Si (100) doping with boron, gallium and germanium (concentration of 0.3 atomic %) has not significant influence on sorption and diffusion parameters.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuklin A. V., Kuzubov A. A., Krasnov P. O., Lykhin A. O., Tikhonova L. V.
Заглавие : Ni-doping effect of Mg(0 0 0 1) surface to use it as a hydrogen storage material
Место публикации : J. Alloys Compd.: Elsevier Science, 2014. - Vol. 609. - P.93-99. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2014.04.160. - ISSN 1873-4669
Примечания : Cited References: 38
Предметные рубрики: INITIO MOLECULAR-DYNAMICS
AUGMENTED-WAVE METHOD
MINIMUM ENERGY PATHS
ELASTIC BAND METHOD
METAL-HYDRIDES
SADDLE-POINTS
MAGNESIUM
Mg
TRANSITION
Pd
Ключевые слова (''Своб.индексиров.''): hydrogen absorbing materials--intermetallics--diffusion--dft--mg-based hydride
Аннотация: A detailed study of Ni-doped Mg(0 0 0 1) surface performed by PAW method and the gradient corrected density functional GGA-PBE within the framework of generalized Kohn–Sham density functional theory (DFT) is presented in this work. Structural and electronic properties of magnesium surface interaction with nickel for the purpose of such compounds use for creation of hydrogen storage matrixes were investigated here. Choice of the PBE functional was caused by the good accordance of its prediction of the cell parameters with experimental results. It was shown that Ni atoms prefer to substitute for Mg atoms. Using NEB method, the diffusion barrier was calculated, and the most probable reaction path was established. In particular, when the Ni atom dopes the magnesium surface, it can migrate to the bulk and substitute for Mg in subsurface layers. Also a possibility of nickel cluster formation on clean surface of magnesium was examined. The kinetic factors hinder the movement of the nickel atoms to each other and make problematic the formation of clusters. The studies presented here showed that the diffusion barriers of the nickel atom migration from the cluster on the surface to the bulk of magnesium are 1.179 eV and 1.211 eV for the forward and reverse reactions, respectively. Therefore an improvement of the hydrogenation properties of Ni-doped magnesium surface depends on deposition not of the individual atoms, but their clusters. Hydrogenation of Ni cluster doping the magnesium surface was investigated. Initially Kubas complexes arise on the Ni cluster with hydrogen–hydrogen bond lengths equal to 0.80–0.87 Å. Next the cluster needs to be saturated by hydrogen atoms to allow them later to migrate from cluster to magnesium.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Zhigalov V. S., Matsynin A. A., Bykova L. E., Mikhlin Y. L., Bondarenko G. N., Patrin G. S., Yurkin G. Yu.
Заглавие : Formation of ferromagnetic germanides by solid-state reactions in 20Ge/80Mn films
Место публикации : Thin Solid Films: Elsevier Science, 2014. - Vol. 552. - P.86-91. - ISSN 0040-6090, DOI 10.1016/j.tsf.2013.12.029
Примечания : Cited References: 53
Предметные рубрики: PHASE-FORMATION
MAGNETIC-PROPERTIES
Mn5Ge3 FILMS
X-RAY
Ge(111)
TRANSFORMATIONS
DIFFUSION
SPECTRA
SYSTEM
LAYERS
Ключевые слова (''Своб.индексиров.''): manganite-germanium--solid state reaction--first phase--mn5ge3 alloy--carbon impurity--oxygen impurity--annealing--magnetic anisotropy
Аннотация: Solid state reactions between Ge and Mn films are systematically examined using X-ray diffraction, photoelectron spectroscopy, and magnetic and electrical measurements. The films have a nominal atomic ratio Ge:Mn = 20:80 and are investigated at temperatures from 50 to 500 °C. It is established that after annealing at ~ 120°C, the ferromagnetic Mn5Ge3 phase is the first phase to form at the 20Ge/80Mn interface. As the annealing temperature increases to 300°C, the weak magnetic Mn5Ge 2 + Mn3Ge phases simultaneously begin to grow and they become dominant at 400°C. Increasing the annealing temperature to 500°C leads to the formation of the ferromagnetic phase with a Curie temperature TC ~ 350-360 K and magnetization 14-25 kA/m at room temperature. The X-ray diffraction study of the samples shows the reflections from the Mn 5Ge3 phase, and the photoelectron spectra contain the oxygen and carbon peaks. The homogeneous distribution of oxygen and carbon over the sample thickness suggests that the increased Curie temperature and magnetization are related to the migration of C and O atoms into the Mn 5Ge3 lattice and the formation of the Nowotny phase Mn5Ge3CxOy. The initiation temperature (~ 120 C) is the same in the Mn5Ge3 phase with the solid-state reactions in the Ge/Mn films as well as in the phase separation in the GexMn1 - x diluted semiconductors. Thus, we conclude that the synthesis of the Mn5Ge3 phase is the moving force for the spinodal decomposition of the GexMn 1 - x diluted semiconductors.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Bayukov O. A., Mikhlin Y. L., Zhigalov V. S., Bykova L. E., Bondarenko G. N.
Заглавие : Long-range chemical interactions in solid-state reactions: effect of an inert Ag interlayer on the formation of L10-FePd in epitaxial Pd(0 0 1)/Ag(0 0 1)/Fe(0 0 1) and Fe(0 0 1)/Ag(0 0 1)/Pd(0 0 1) trilayers
Место публикации : Philos. Mag.: Taylor & Francis, 2014. - Vol. 94, Is. 23. - P.2595-2622. - ISSN 1478-6435, DOI 10.1080/14786435.2014.926037. - ISSN 1478-6443
Примечания : Cited References: 117
Предметные рубрики: HIGH-TEMPERATURE SYNTHESIS
THIN-FILMS
PHASE-FORMATION
MAGNETIC-PROPERTIES
X-RAY
MARTENSITIC TRANSFORMATIONS
PHOTOELECTRON-SPECTROSCOPY
STRUCTURAL CHARACTERISTICS
CASIMIR FORCE
GOLD-FILMS
Ключевые слова (''Своб.индексиров.''): fe-pd system--epitaxial thin film--inert ag buffer layer--diffusion--solid-state reactions--l1(0)--long-range chemical interactions
Аннотация: The effect of 0, 0.5, and 1 μm-thick Ag interlayers on the chemical interaction between Pd and Fe in epitaxial Pd(0 0 1)/Ag(0 0 1)/Fe(0 0 1)/MgO(0 0 1) and Fe(0 0 1)/Ag(0 0 1)/Pd(0 0 1)/MgO(0 0 1) trilayers has been studied using X-ray diffraction, 57Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy, and magnetic structural measurements. No mixing of Pd and Fe occurs via the chemically inert Ag layer at annealing temperatures up to 400 °C. As the annealing temperature is increased above 400 °C, a solid-state synthesis of an ordered L10-FePd phase begins in the Pd(0 0 1)/Ag(0 0 1)/Fe(0 0 1) and Fe(0 0 1)/Ag(0 0 1)/Pd(0 0 1) film trilayers regardless of the thickness of the buffer Ag layer. In all samples, annealing above 500 °C leads to the formation of a disordered FexPd1−x(0 0 1) phase; however, in samples lacking the Ag layer, the synthesis of FexPd1−x is preceded by the formation of an ordered L12-FePd3 phase. An analysis of the X-ray photoelectron spectroscopy results shows that Pd is the dominant moving species in the reaction between Pd and Fe. According to the preliminary results, the 2.2 μm-thick Ag film does not prevent the synthesis of the L10-FePd phase and only slightly increases the phase’s initiation temperature. Data showing the ultra-fast transport of Pd atoms via thick inert Ag layers are interpreted as direct evidence of the long-range character of the chemical interaction between Pd and Fe. Thus, in the reaction state, Pd and Fe interact chemically even though the distance between them is about 104 times greater than an ordinary chemical bond length.
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16.

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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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Kuzubov A. A., Eliseeva N. S., Popov Z. I., Visotin M. A., Galkin N. G.
Заглавие : Theoretical study of the lithium diffusion in the crystalline and amorphous silicon as well as on its surface
Коллективы : Asian School-Conference on Physics and Technology of Nanostructured Materials, Азиатская школа-конференция по физике и технологии наноструктурированных материалов
Место публикации : Solid State Phenom.: Selected, peer reviewed papers/ ed. N. Galkin: Trans Tech Publications, 2014. - Vol. 213: Physics and Technology of Nanostructured Materials II. - P.29-34. - ISSN 1662-9779, DOI 10.4028/www.scientific.net/SSP.213.29. - ISSN 978-3-03785-970-4
Примечания : Cited References: 21
Ключевые слова (''Своб.индексиров.''): ab initio calculations--diffusion--lithium-ion accumulators--silicon
Аннотация: Using the PAW DFT-GGA method and numerical solving of master equation the diffusion rates of lithium atoms inside both crystal and amorphous silicon of LixSi (x= 0.0.5) composition have been calculated for different temperatures. It is shown the diffusion rate for amorphous silicon is ~10 times greater than that for the crystal silicon. For both structures the rate is increased by 1.5-2 orders of magnitude while the lithium concentration is increased up to 0.5 value. This should result in that the LixSi/Si interface will be sharp. This fact has been further confirmed using molecular dynamic calculations based on Angular Dependent Potential (ADP) model. Also binding energies of Li atoms lying on different sites of Si (001) surface as well as the potential barriers for the atom jumps both along the surface and in the subsurface layers have been calculated. The data show the Li atoms move along the surface very easily but their jumps into subsurface layers are very difficult due to the high potential barrier values. В© (2014) Trans Tech Publications, Switzerland.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Eliseeva N. S., Popov Z. I., Fedorov A. S., Serzhantova M. V., Denisov V. M., Tomilin F. N.
Заглавие : Theoretical study of sorption and diffusion of lithium atoms on the surface of crystalline silicon and inside it
Место публикации : JETP Letters. - 2013. - Vol. 97, Is. 11. - P.634-638. - ISSN 0021-3640, DOI 10.1134/S0021364013110088
Аннотация: The energy of the sorption and diffusion of lithium atoms on the reconstructed (4 ? 2) (100) silicon surface in the process of their transport into near-surface layers, as well as inside crystalline silicon, at various lithium concentrations have been investigated within the density functional theory. It has been shown that single lithium atoms easily migrate on the (100) surface and gradually fill the surface states (T3 and L) located in channels between silicon dimers. The diffusion of lithium into near-surface silicon layers is hampered because of high potential barriers of the transition (1.22 eV). The dependences of the binding energy, potential barriers, and diffusion coefficient inside silicon on distances to the nearest lithium atoms have also been examined. It has been shown that an increase in the concentration of lithium to the Li0.5Si composition significantly reduces the transition energy (from 0.90 to 0.36 eV) and strongly increases (by one to three orders of magnitude) the lithium diffusion rate. В© 2013 Pleiades Publishing, Ltd.
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19.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Fedorov A. S., Kuzubov A. A., Eliseeva N. S., Popov Z. I.
Заглавие : Theoretical study of the lithium diffusion in the crystalline and amorphous silicon, as well as on its surface at different lithium concentrations
Коллективы : Asian School-Conference on Physics and Technology of Nanostructured Materials, Азиатская школа-конференция по физике и технологии наноструктурированных материалов
Место публикации : Asian School-Conference on Physics and Technology of Nanostructured Materials. - 2013. - P.133-134
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Кузубов, Александр Александрович, Елисеева, Наталья Сергеевна, Попов, Захар Иванович, Федоров, Александр Семенович, Сержантова, Мария Викторовна, Денисов, Виктор Михайлович, Томилин, Феликс Николаевич
Заглавие : Теоретическое исследование сорбции и диффузии атомов лития на поверхности и внутри кристаллического кремния
Место публикации : Письма в Журн. эксперим. и теор. физ. - 2013. - Т. 97, Вып. 11. - С. 732-736. - DOI 10.7868/S0370274X13110064
Аннотация: В рамках теории функционала плотности изучены энергия сорбции и диффузия атомов лития по реконструированной (4× 2) поверхности (100) кремния при их переходе в подповерхностные слои, а также внутри кристаллического кремния при различной концентрации лития. Показано, что одиночные атомы лития легко мигрируют по поверхности (100), постепенно заполняя поверхностные состояния (Т3 и L), расположенные в каналах между димерами кремния. Диффузия лития в подповерхностные слои кремния затруднена в связи с высокими потенциальными барьерами перехода (1.22 эВ). Также исследованы зависимости энергии связи, потенциальных барьеров и коэффициента диффузии атомов лития внутри кремния от расстояний до ближайших атомов лития. Показано, что увеличение его концентрации до состава Li0.5Si существенно снижает энергию перехода (с 0.90 до 0.36 эВ) и вызывает значительное (на 1-3 порядка) увеличение скорости диффузии лития.
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