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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ikonnikov D. A., Myslivets S. A., Arkhipkin V. G., Vyunishev A. M.
Заглавие : 3D optical vortex lattices
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [19-12-00203]
Место публикации : Ann. Phys.-Berlin. - 2021. - Vol. 533, Is. 7. - Ст.2100114. - ISSN 0003-3804, DOI 10.1002/andp.202100114. - ISSN 1521-3889(eISSN)
Примечания : Cited References: 29. - This work was supported by the Russian Science Foundation (Grant No. 19-12-00203).The surface grating was fabricated and characterized at the Center for Collective Use of the Krasnoyarsk Scientific Center, Siberian Branch, Russian Academy of Sciences. The authors thank M. N. Volochaev and A. I. Zaitsev for help
Предметные рубрики: MANIPULATION
PARTICLES
ARRAY
BEAMS
GENERATION
TRANSPORT
VORTICES
Аннотация: Fresnel diffraction of light beams with a topological charge on a 2D regular amplitude transparency mask is studied. Numerical predictions show that the 3D optical lattices of optical vortices can be formed using the Talbot effect, with these predictions confirmed by the experimental reconstruction of all 3D optical vortex lattices. The periodicity of the 3D optical vortex lattices is determined by the light wavelength and periodicity of a transparency mask. Furthermore, it is shown that the optical vortices are created and annihilated during light propagation behind the mask with the preservation of the total topological charge. The 3D optical vortex lattices are considered to be tolerant to the perturbations induced by trapped particles caused by the features of the Talbot effect. The 3D optical vortex lattices open new possibilities for light-matter interactions and the related applications.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Edelman I. S., Morozova T. P., Zabluda V. M., Kim T. A., Turpanov I. A., Betenkova A. Ya., Dynnik Y. A.
Заглавие : Dispersion of Faraday rotation in Co/SiO2 multilayer films
Место публикации : JETP Letters. - 1996. - Vol. 63, Is. 4. - P.273-277. - ISSN 0021-3640, DOI 10.1134/1.567015
Примечания : Cited References: 9
Предметные рубрики: PARTICLES
Аннотация: The Faraday rotation spectra of Co/SiO2 multilayer films were found to be substantially different from the well-known spectra of homogeneous Co films. The character of these changes was studied as a function of the thicknesses of the ferromagnetic metal and the nonmagnetic dielectric layers. (C) 1996 American Institute of Physics.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Slabko V. V., Tsipotan A. S. , Aleksandrovsky A. S., Slyusareva E. A.
Заглавие : Dynamics of self-organized aggregation of resonant nanoparticles in a laser field
Коллективы : Grant of the Ministry of Education and Science of the Russian Federation for Siberian Federal University; SB RAS Grant [24.31]; RFBR [14-02-00219 A]
Место публикации : Appl. Phys. B: Springer, 2014. - Vol. 117, Is. 1. - P.271-278. - ISSN 0946-2171, DOI 10.1007/s00340-014-5831-0. - ISSN 1432-0649
Примечания : Cited References: 30. - This research is partially supported by Grant of the Ministry of Education and Science of the Russian Federation for Siberian Federal University, by SB RAS Grant 24.31, and by RFBR Research Project No. 14-02-00219 A.
Предметные рубрики: PHOTOSTIMULATED AGGREGATION
SILVER
PRINCIPLES
PARTICLES
SPECTRA
SOLS
Аннотация: Self-organized aggregation of nanoparticles in external resonant laser field is considered using Brownian dynamics model. Formation probabilities are calculated for the pair of particles in dependence on laser wavelength and mutual orientation of particles. Times required for aggregation are calculated. Possibility of efficient aggregation using pulsed laser is deduced.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ershov A. E., Isaev I. L., Semina P. N., Markel V. A., Karpov S. V.
Заглавие : Effects of size polydispersity on the extinction spectra of colloidal nanoparticle aggregates
Место публикации : Phys. Rev. B: American Physical Society, 2012. - Vol. 85, Is. 4. - Ст.045421. - P. - ISSN 1098-0121, DOI 10.1103/PhysRevB.85.045421
Примечания : Cited References: 41. - This work was supported by grants from the following foundations of the Russian Federation: Presidium of RAS, OFN RAS, and SB RAS.
Предметные рубрики: METAL FRACTAL CLUSTERS
OPTICAL-PROPERTIES
ABSORPTION
NONLINEARITIES
COMPOSITES
SCATTERING
PARTICLES
SPHERES
GRAINS
Аннотация: We investigate the effect of particle polydispersity on the optical extinction spectra of colloidal aggregates of spherical metallic (silver) nanoparticles, taking into account the realistic interparticle gaps caused by layers of stabilizing polymer adsorbed on the metal surface (adlayers). The spectra of computer-generated aggregates are computed using two different methods. The coupled-multipole method is used in the quasistatic approximation and the coupled-dipole method beyond the quasistatics. The latter approach is applicable if the interparticle gaps are sufficiently wide relative to the particle radii. Simulations are performed for two different particle size distribution functions (bimodal and Gaussian), varying the number of particles per aggregate, and different distribution functions of the interparticle gap width. The strong influence of the latter factor on the spectra is demonstrated and investigated in detail.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F.
Заглавие : Enhancement of Rayleigh scattering in a two-dimensional Fabry-Perot resonator loaded with impurities
Коллективы : Russian Science Foundation (RSF) [14-12-00266]
Место публикации : J. Opt. Soc. Am. A: Optical Society of America, 2016. - Vol. 33, Is. 7. - P.1277-1282. - ISSN 1084-7529, DOI 10.1364/JOSAA.33.001277. - ISSN 1520-8532(eISSN)
Примечания : Cited References:32. - Russian Science Foundation (RSF) (14-12-00266)
Предметные рубрики: COUPLED-MODE THEORY
MULTIPLE-SCATTERING
NUCLEAR REACTIONS
UNIFIED THEORY
RANDOM-MEDIA
TRANSMISSION
PARTICLES
WAVES
LIGHT
STRIP
Аннотация: We study wave transmission through a Fabry-Perot resonator (FPR) loaded with point-like impurities. We show both analytically in the framework of the coupled mode theory and numerically that there are two different regimes for transmission dependent on the quality of the FPR mirrors. For low quality, we obtain transmittance very similar to the clean FPR with slightly shifted Lorentz peaks. However, for good quality, the transmittance peaks are strongly reduced and substituted with Gaussian peaks because of multiple scattering of waves by each impurity. As a side effect, we observe the angular (channel) conversion in the disordered FPR. We demonstrate that the resonant peaks are dependent on the concentration of impurities to pave a way for resonant measurement of the concentration. (C) 2016 Optical Society of America
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vorotynov A. M., Petrakovskii G. A., Sablina K. A., Bovina A. F., Vasil'ev A. D.
Заглавие : EPR study of the Jahn-Teller effect of Cu2+ ions in ZnGa2O4
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 11. - P2415-2418. - ISSN 1063-7834, DOI 10.1134/S1063783410110314
Примечания : Cited References: 12
Предметные рубрики: MAGNETIC-PROPERTIES
PARTICLES
CUFE2O4
Аннотация: The Jahn-Teller effect in the ZnGa2O4 spinel single crystal has been investigated using electron paramagnetic resonance of Cu2+ ions in the temperature range 110-560 K. It has been shown that copper ions occupy octahedral sites 16d in the ZnGa2O4 crystal with cubic symmetry O (h) (7) (Fd-3m). At T 560 K, the octahedra undergo tetragonal distortions (predominantly tension) and rotation around the fourfold axes by the angle theta a parts per thousand 2.6A degrees. The parameters of the spin Hamiltonian, which characterize the prolate (g (aEuro-)
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Fluctuations of orientational order in a uniaxial nematic liquid crystal with biaxial molecules and its response to an external field
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2003. - Vol. 45, Is. 5. - P990-1001. - ISSN 1063-7834, DOI 10.1134/1.1575350
Примечания : Cited References: 30
Предметные рубрики: PHASE-TRANSITION
SMECTIC-A
PARTICLES
SYSTEM
LANDAU
MODEL
Аннотация: Homogeneous thermal fluctuations of the orientational order parameters S and G of biaxial molecules in a uniaxial nematic liquid crystal are investigated in the framework of the molecular-statistical theory. It is demonstrated that the molecular biaxiality significantly affects the order parameters S and G, their temperature dependences in the nematic phase, the amplitude and the temperature dependence of the order parameter fluctuations in the nematic and isotropic phases, and the character of the transition from the nematic phase to the isotropic liquid phase. It is established that the fluctuations of the parameters S and G in the nematic phase are related to the temperature dependences of S and G and the susceptibilities chi(S) and chi(G) of the nematic liquid crystal to external fields, which leads to a change in the parameters S and G at a fixed director orientation. Explanations are offered for the known experimental data on the orientational ordering of biaxial molecules under the action of external fields in the isotropic phase of nematic liquid crystals. (C) 2003 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanova O. S., Ivantsov R. D., Edelman I. S., Petrakovskaja E. A., Velikanov D. A., Zubavichus Y. V., Zaikovskii V .I., Stepanov S. A.
Заглавие : Identification of ε-Fe2O3 nano-phase in borate glasses doped with Fe and Gd
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 401. - P.880-889. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2015.10.126
Примечания : Cited References: 40. - This work was supported partly by the Russian Foundation for Basic Research, Grants No 14-02-01211-a and by the President of Russia Grant No. NSh-2886.2014.2. Authors are grateful to G.A. Bukhtiyarova and U.N. Martyanov for the assistance in the ε-Fe2O3 nanoparticles prepared by a wet chemical pore filling impregnation method and for the discussion of the obtained results
Предметные рубрики: MAGNETIC-PROPERTIES
IRON-OXIDE
NANOPARTICLES
CERAMICS
CRYSTAL
PARTICLES
SURFACE
Ключевые слова (''Своб.индексиров.''): magnetic nanoparticles--ε-fe2o3--magnetic circular dichroism--electron magnetic resonance
Аннотация: A new type of magnetic nanoparticles was revealed in borate glasses co-doped with low contents of iron and gadolinium. Structure and magnetic properties of the particles differ essentially from that of the α-Fe2O3, γ-Fe2O3, or Fe3O4 nanoparticles which were detected earlier in similar glass matrices. Transmission electron microscopy including STEM-HAADF and EDX, synchrotron radiation-based XRD, static magnetic measurements, magnetic circular dichroism, and electron magnetic resonance studies allow referring the nanoparticles to the iron oxide phase-ε-Fe2O3. Analysis of the data set has shown that it is Gd atoms that govern the process of nanoparticles' nucleation and its incorporation into the particles in different proportions can be used to adjust their magnetic and magneto-optical characteristics. © 2015 Elsevier B.V.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Maksimov D. N.
Заглавие : Light guiding above the light line in arrays of dielectric nanospheres
Место публикации : Opt. Lett.: Optical Society of America, 2016. - Vol. 41, Is. 16. - P.3888-3891. - ISSN 01469592 (ISSN), DOI 10.1364/OL.41.003888
Примечания : Cited References: 46. - Russian Foundation for Basic Research (RFBR) (16-02-00314).
Предметные рубрики: SUBWAVELENGTH WAVE-GUIDES
OPTICAL MODES
NANOPARTICLES
CHAINS
RESONANCES
PARTICLES
SPHERES
Аннотация: We consider light propagation above the light line in arrays of spherical dielectric nanoparticles. It is demonstrated numerically that quasi-bound leaky modes of the array can propagate both stationary waves and light pulses to a distance of 60 wavelengths at the frequencies close to the bound states in the radiation continuum. A semi-analytical estimate for decay rates of the guided waves is found to match the numerical data to a good accuracy. © 2016 Optical Society of America.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Loiko V. A., Zyryanov V. Ya., Konkolovich A. V., Miskevich A. A.
Заглавие : Light transmission of polymer-dispersed liquid crystal layer composed of droplets with inhomogeneous surface anchoring
Место публикации : Opt. Spectrosc.: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 120, Is. 1. - P.143-152. - ISSN 0030-400X, DOI 10.1134/S0030400X16010112. - ISSN 1562-6911(eISSN)
Примечания : Cited References:43. - This work was supported by the National Academy of Sciences of Belarus and the Siberian Branch of the Russian Academy of Sciences (project no. 36) and the Belarusian Republican Foundation for Fundamental Research (project no. F15SO-039).
Предметные рубрики: NEMATIC DROPLETS
IONIC MODIFICATION
FIELD
TRANSITIONS
SCATTERING
PARTICLES
INTERFACE
DISPLAYS
Аннотация: We have developed a model and realized an algorithm for the calculation of the coefficient of coherent (direct) transmission of light through a layer of liquid crystal (LC) droplets in a polymer matrix. The model is based on the Hulst anomalous diffraction approximation for describing the scattering by an individual particle and the Foldy-Twersky approximation for a coherent field. It allows one to investigate polymer dispersed LC (PDLC) materials with homogeneous and inhomogeneous interphase surface anchoring on the droplet surface. In order to calculate the configuration of the field of the local director in the droplet, the relaxation method of solving the problem of minimization of the free energy volume density has been used. We have verified the model by comparison with experiment under the inverse regime of the ionic modification of the LC-polymer interphase boundary. The model makes it possible to solve problems of optimization of the optical response of PDLC films in relation to their thickness and optical characteristics of the polymer matrix, sizes, polydispersity, concentration, and anisometry parameters of droplets. Based on this model, we have proposed a technique for estimating the size of LC droplets from the data on the dependence of the transmission coefficient on the applied voltage.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Edelman I. S., Ivanova O. S., Ivantsov R. D., Velikanov D. A., Zabluda V. N., Zubavichus Y., Veligzhanin A. A., Zaikovskiy V. I., Stepanov S., Artemenko A., Curely J., Kliava J.
Заглавие : Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements
Место публикации : J. Appl. Phys.: American Institute of Physics, 2012. - Vol. 112, Is. 8. - Ст.84331. - P. - ISSN 0021-8979, DOI 10.1063/1.4759244
Примечания : Cited References: 65. - This work was partly supported by the Russian Foundation for Basic Research, Grant Nos. 07-02-92174 RFBR-CNRS and 11-02-00972, and President of Russia Federation Grant No NSh 1044.2012.2. A. Artemenko acknowledges financial support from the Marie Curie International Incoming Fellowship within the 7th European Community Framework Programme (EPREXINA, GA 255662). The synchrotron measurements were supported via the Russian federal Contract No. 16.552.11.7003. The authors thank K. P. Polyakova for the preparation of thin films.
Предметные рубрики: SUPERPARAMAGNETIC RESONANCE
FERROMAGNETIC-RESONANCE
TEMPERATURE-DEPENDENCE
FERRITE NANOPARTICLES
OXIDE NANOPARTICLES
FARADAY-ROTATION
CERAMICS
ANISOTROPY
PARTICLES
SPECTRA
Аннотация: A new type of nanoparticle-containing glasses based on borate glasses co-doped with low contents of iron and larger radius elements, Dy, Tb, Gd, Ho, Er, Y, and Bi, is studied. Heat treatment of these glasses results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: x-ray diffraction, extended x-ray absorption fine structure, x-ray absorption near-edge structure, and small-angle x-ray scattering, show a broad distribution of nanoparticle sizes with characteristics depending on the treatment regime; a crystalline structure of these nanoparticles is detected in heat treated samples. Magnetic circular dichroism (MCD) studies of samples subjected to heat treatment as well as of maghemite, magnetite, and iron garnet allow to unambiguously assign the nanoparticle structure to maghemite, independently of co-dopant nature and of heat treatment regime used. Different features observed in the MCD spectra are related to different electron transitions in Fe3+ ions gathered in the nanoparticles. The static magnetization in heat treated samples has non-linear dependence on the magnetizing field with hysteresis. Zero-field cooled magnetization curves show that at higher temperatures the nanoparticles occur in superparamagnetic state with blocking temperatures above 100 K. Below ca. 20 K, a considerable contribution to both zero field-cooled and field-cooled magnetizations occurs from diluted paramagnetic ions. Variable-temperature electron magnetic resonance (EMR) studies unambiguously show that in as-prepared glasses paramagnetic ions are in diluted state and confirm the formation of magnetic nanoparticles already at earlier stages of heat treatment. Computer simulations of the EMR spectra corroborate the broad distribution of nanoparticle sizes found by "direct" techniques as well as superparamagnetic nanoparticle behaviour demonstrated in the magnetization studies. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4759244]
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Krasikov A. A., Dubrovskiy A. A., Popkov S. I., Stolyar S. V., Bayukov O. A., Iskhakov R. S., Ladygina V. P., Yaroslavtsev R. N.
Заглавие : Magnetic properties of heat treated bacterial ferrihydrite nanoparticles
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 410. - P.171-180. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2016.02.059
Примечания : Cited References: 66. - TEM studies were performed on facility of Resource Sharing Center of Krasnoyarsk Scientific Center of Siberian Branch of Russian Academy of Sciences. Authors acknowledge to M.N. Volochaev for the TEM measurements.
Предметные рубрики: Hematite nanoparticles
NiO nanoparticles
Porous-glass
Ferritin
Particles
Temperature
Hysteresis
Transition
Anomalies
Mossbauer
Ключевые слова (''Своб.индексиров.''): ferrihydrite--nanoparticles--superparamagnetism
Аннотация: The magnetic properties of ferrihydrite nanoparticles, which are products of vital functions of Klebsiella oxitoca bacteria, have been studied. The initial powder containing the nanoparticles in an organic shell was subjected to low-temperature (T=160 °C) heat treatment for up to 240 h. The bacterial ferrihydrite particles exhibit a superparamagnetic behavior. Their characteristic blocking temperature increases from 26 to 80 K with the heat treatment. Analysis of the magnetization curves with regard to the magnetic moment distribution function and antiferromagnetic contribution shows that the low-temperature heat treatment enhances the average magnetic moment of a particle; i.e., the nanoparticles coarsen, probably due to their partial agglomeration during heat treatment. It was established that the blocking temperature nonlinearly depends on the particle volume. Therefore, a model was proposed that takes into account both the bulk and surface magnetic anisotropy. Using this model, the bulk and surface magnetic anisotropy constants KV≈1.7×105 erg/cm3 and KS≈0.055 erg/cm2 have been determined. The effect of the surface magnetic anisotropy of ferrihydrite nanoparticles on the observed magnetic hysteresis loops is discussed.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Frolov G. I., Bachina O. I., Zav'yalova M. M., Ravochkin S. I.
Заглавие : Magnetic properties of nanoparticles of 3d metals
Коллективы :
Место публикации : Tech. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 53, Is. 8. - P1059-1064. - ISSN 1063-7842, DOI 10.1134/S1063784208080136
Примечания : Cited References: 19. - This study was supported by the targeted program "Development of the Research Potential of Higher Education Institutions," grant no. RNP.2.1.1.7376.
Предметные рубрики: CLUSTERS
IRON
PARTICLES
Аннотация: The influence of size effects on the coercive force, magnetization, and Curie temperature in nanoparticles of 3d metals is considered. It is shown that experimental results obtained during the last two decades provide new information on peculiar magnetic properties of these particles.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lopatin V. N., Shepelevich N. V., Prostakova I. V.
Заглавие : Modelling optical properties of organic-mineral complexes in water ecosystems
Место публикации : J. Phys. D. - 2005. - Vol. 38, Is. 15. - P.2556-2563. - ISSN 0022-3727, DOI 10.1088/0022-3727/38/15/005
Примечания : Cited References: 22
Предметные рубрики: SCANNING FLOW-CYTOMETRY
LIGHT-SCATTERING
STRATIFIED SPHERE
PARTICLES
INDEX
Ключевые слова (''Своб.индексиров.''): approximation theory--ecosystems--inverse problems--light scattering--mathematical models--refractive index--suspensions (fluids)--water--generalization--integral light scattering indicatrix--organic-mineral complexes--spherical particles--complexation
Аннотация: Characteristics of organic-mineral complexes have been theoretically and experimentally studied in the paper, based on the method of integral light scattering indicatrix. Modelling of optical properties was realized using models of the coated spherical particles with a shell which is constant and changeable in the refractive index profile. General regularities have been revealed and generalized parameters for the method of integral light scattering indicatrix have been suggested.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Balaev D. A., Kirillov V. L., Bayukov O. A., Mart'yanov O. N.
Заглавие : Mossbauer spectroscopy study of the superparamagnetism of ultrasmall ε-Fe2O3 nanoparticles
Коллективы : Russian Science Foundation [17-12-01111]
Место публикации : JETP Letters. - 2018. - Vol. 108, Is. 8. - P.527-531. - ISSN 0021-3640, DOI 10.1134/S0021364018200092. - ISSN 1090-6487(eISSN)
Примечания : Cited References: 22. - This work was supported by the Russian Science Foundation (project no. 17-12-01111).
Предметные рубрики: High-temperature
Particles
ε-Fe2O3
Phase
Model
Аннотация: The superparamagnetism of an ensemble of ϵ-Fe2O3 nanoparticles with a mean size of 3.9 nm dispersed in a xerogel SiO2 matrix is studied by the Mössbauer spectroscopy method. It is shown that most nanoparticles at room temperature are in the superparamagnetic (unblocked) state. As the temperature decreases, the progressive blocking of the magnetic moments of the particles occurs, which is manifested in the Mössbauer spectra as the transformation of the quadrupole doublet into a Zeeman sextet. The analysis of the relative intensity of the superparamagnetic (quadrupole doublet) and magnetically split (sextets) spectral components in the range of 4–300 K provides the particle size distribution, which is in agreement with the transmission electron microscopy data. The values of the effective magnetic anisotropy constants (Keff) are determined, and the contribution of surface anisotropy (KS) is estimated for particles of various sizes. It is shown that the quantity Keff is inversely proportional to the particle size, which indicates the significant contribution of the surface to the magnetic state of the ϵ-Fe2O3 nanoparticles with the size of several nanometers.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Morozov E. V., Shabanova O. V., Falaleev O. V.
Заглавие : MRI Comparative Study of Container Geometry Impact on the PMMA Spheres Sedimentation
Место публикации : Appl. Magn. Reson. - 2013. - Vol. 44, Is. 5. - P.619-636. - ISSN 0937-9347, DOI 10.1007/s00723-012-0432-8
Примечания : Cited References: 31
Предметные рубрики: OPAL PHOTONIC CRYSTALS
SUSPENSIONS
PARTICLES
VELOCITY
Аннотация: Nuclear magnetic resonance (NMR) imaging results are presented for the comparative study of sedimentation of the polymethylmethacrylate colloidal suspensions with spherical particle diameters of 475, 350 and 255 nm. The time evolution of the particle volume fraction in the sedimenting system, velocity of the fluid/suspension interface, interface broadening, and sediment growth velocity are measured against the system concentration as well as the container geometry. Using the experimental data the hindered settling function is evaluated. The influence of the container geometry on the parameters defining the hindered settling function in different approaches is evaluated for the first time. The limiting value of the particle diameter is estimated at which the container geometry has no impact any longer. This effect can be explained by the microscale structure persisting at low Peclet numbers. In addition, the influence of the container geometry on interface broadening and sediment formation for different particle diameters and volume fractions is studied. Spontaneous sediment packing induced by a modified container geometry has been found. NMR imaging has proven to be a highly efficient research tool for studying sedimentation at low Peclet numbers.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rasskazov I. L., Karpov S. V., Panasyuk G. Y., Markel V. A.
Заглавие : Overcoming the adverse effects of substrate on the waveguiding properties of plasmonic nanoparticle chains
Место публикации : J. Appl. Phys.: American Institute of Physics, 2016. - Vol. 119, Is. 4. - Ст.043101. - ISSN 00218979 (ISSN), DOI 10.1063/1.4940415
Примечания : Cited References: 43. - This work has been carried out thanks to the support of the A*MIDEX project (No. ANR-11-IDEX-0001-02) funded by the “Investissements d'Avenir” French Government program, managed by the French National Research Agency (ANR) and was also supported in part by the U.S. National Science Foundation under Grant No. DMS1216970 and by the Ministry of Education and Science of the Russian Federation under Contract No. 1792.
Предметные рубрики: LINEAR-CHAINS
DISPERSION-RELATIONS
ARRAYS
RESONANCES
GUIDES
NANOSPHERES
MODES
FIELD
POLARITONS
PARTICLES
Аннотация: We have studied numerically the propagation of surface plasmon polaritons (SPPs) in linear periodic chains of plasmonic nanoparticles of different shapes. The chains are deposited on top of a thick dielectric substrate. While in many commonly considered cases the substrate tends to suppress the SPP propagation, we have found that this adverse effect is practically absent in the case when the nanoparticles have the shape of oblate spheroids with sufficiently small aspect ratio (e.g., nanodisks) whose axes of symmetry coincide with the axis of the chain. © 2016 AIP Publishing LLC.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kirillov V. L., Balaev D. A., Semenov S. V., Shaikhutdinov K. A., Martyanov O. N.
Заглавие : Size control in the formation of magnetite nanoparticles in the presence of citrate ions
Коллективы : Siberian Branch of the Russian Academy of Sciences
Место публикации : Mater. Chem. Phys.: Elsevier Science, 2014. - Vol. 145, Is. 1-2. - P.75-81. - ISSN 0254-0584, DOI 10.1016/j.matchemphys.2014.01.036. - ISSN 1879-3312
Примечания : Cited References: 46. - This work was supported by the Interdisciplinary Integration Project no. 45 of the Siberian Branch of the Russian Academy of Sciences for 2012-2014.
Предметные рубрики: OLEIC-ACID
CATALYST
HYPERTHERMIA
PARTICLES
OXIDATION
REMOVAL
CO
Ключевые слова (''Своб.индексиров.''): magnetic materials--magnetic properties--precipitation--electron paramagnetic resonance
Аннотация: A one-pot synthesis method for the controllable growth of magnetite nanoparticles directly during the process of co-precipitation using citrate ions was developed. The effects of the concentration of citrate ions and the solution pH on the characteristics of magnetite particles with sizes in the range of 4-10 nm synthesized by the method of co-precipitation were studied. The results showed that the specified concentration of citrate ions allowed the preparation of magnetite particles with a definite size that exhibited superparamagnetic behaviour in a particular temperature range. As the concentration ratio of citrate to iron ions was increased from 0 to 0.11, the average size of the prepared magnetite particles decreased from 10.5 to 4.4 nm. As a result, the superparamagnetic blocking temperature decreased from 300 to 20 K, the saturation magnetisation decreased from 50 to 20 emu g(-1), and the average magnetic moment decreased from 8000 mu(B) to 340 mu(B) (at T = 300 K). The obtained experimental data proved that the size effects of the magnetite nanoparticles can be attributed to the capping of the magnetite surface by adsorbed citrate ions. Thus, the suggested approach allows magnetite nanoparticles to be prepared with an optimum particle size around superparamagnetic threshold that prevents their irreversible agglomeration and simultaneously allows them to be removed from a solution at an acceptable rate. (C) 2014 Elsevier B.V. All rights reserved.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Li O. A., Lin C. -R., Chen H. -Y., Hsu, Hua-Shu, Shih K. -Y., Edelman I. S., Wu K. -W., Tseng Y. -T., Ovchinnikov S. G., Lee J. -S.
Заглавие : Size dependent magnetic and magneto-optical properties of Ni0.2Zn0.8Fe2O4 nanoparticles
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 408. - P.206-212. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2016.02.062
Примечания : Cited References: 51. - This work is supported by the Ministry of Science and Technology of Taiwan (MOST 103-2811-M-153 -001 and MOST 102-2112-M-153 -002 -MY3), and by the Russian Foundation for Basic Researches, grant No 14-02-01211.
Предметные рубрики: Zinc ferrite
Cation distribution
Sol-gel
Ni
ZnFe2O4
Spinel
Fe3O4
Particles
Spectra
State
Ключевые слова (''Своб.индексиров.''): nickel zinc ferrite--nanoparticles--magnetic properties--mcd
Аннотация: Ni0.2Zn0.8Fe2O4 spinel nanoparticles have been synthesized by combustion method. Average particles size varies from 15.5 to 50.0 nm depending on annealing temperature. Correlations between particles size and magnetic and magneto-optical properties are investigated. Magnetization dependences on temperature and external magnetic field correspond to the sum of paramagnetic and superparamagnetic response. Critical size of single-domain transition is found to be 15.9 nm. Magnetic circular dichroism (MCD) studies of nickel zinc spinel are presented here for the first time. The features in magnetic circular dichroism spectrum are assigned to the one-ion d-d transitions in Fe3+ and Ni2+ ions, as well to the intersublattice and intervalence charge transfer transitions. The MCD spectrum rearrangement was revealed with the change of the nanoparticles size. © 2016 Elsevier B.V. All rights reserved.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dubrovskiy A. A., Balaev A. D., Shaykhutdinov K. A., Bayukov O. A., Pletnev O. N., Yakushkin S. S., Bukhtiyarova G. A., Martyanov O. N.
Заглавие : Size effects in the magnetic properties of ε-Fe2O3 nanoparticles
Место публикации : J. Appl. Phys.: American Institute of Physics, 2015. - Vol. 118, Is. 21. - Ст.213901. - ISSN 00218979 (ISSN), DOI 10.1063/1.4936838
Примечания : Cited References: 41. - We are grateful to Professor Yu. L. Raikher for useful discussions and M. A. Kazakova for the help in sample preparationThis work was supported by Russian Federal Agency of Scientific Organizations (Project No. V.44.1.15) and scientific and educational center of energy-efficient catalysis of NSU
Предметные рубрики: FERROMAGNETIC-RESONANCE
OXIDE NANOPARTICLES
WAVE ABSORBER
IRON
TRANSITION
TEMPERATURE
PARTICLES
PHASE
FNANOWIRES
FIELD
Аннотация: We report the results of comparative analysis of magnetic properties of the systems based on ε-Fe2O3, nanoparticles with different average sizes (from ∼3 to 9 nm) and dispersions. The experimental data for nanoparticles higher than 6-8 nm in size are consistent with the available data, specifically, the transition to the magnetically ordered state occurs at a temperature of ∼500 K and the anomalies of magnetic properties observed in the range of 80-150 K correspond to the magnetic transition. At the same time, Mossbauer and ferromagnetic resonance spectroscopy data as well as the results of static magnetic measurements show that at room temperature all the investigated samples contain ε-Fe2O3 particles that exhibit the superparamagnetic behavior. It was established that the magnetic properties of nanoparticles significantly change with a decrease in their size to ∼6 nm. According to high-resolution electron microscopy and Mossbauer spectroscopy data, the particle structure can be attributed to the ε-modification of trivalent iron oxide; meanwhile, the temperature of the magnetic order onset in these particles is increased, the well-known magnetic transition in the range of 80-150 K does not occur, the crystallographic magnetic anisotropy constant is significantly reduced, and the surface magnetic anisotropy plays a decisive role. This is apparently due to redistribution of cations over crystallographic positions with decreasing particle size, which was established using Mössbauer spectra. As the particle size is decreased and the fraction of surface atoms is increased, the contribution of an additional magnetic subsystem formed in a shell of particles smaller than ∼4 nm becomes significant, which manifests itself in the static magnetic measurements as paramagnetic contribution. © 2015 AIP Publishing LLC.
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