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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Safronov A. P., Beketov I. V., Komogortsev S. V., Kurlyandskaya G. V., Medvedev A. I., Leiman D. V., Larranaga A., Bhagat S. M.
Заглавие : Spherical magnetic nanoparticles fabricated by laser target evaporation
Место публикации : AIP Adv.: American Institute of Physics, 2013. - Vol. 3, Is. 5. - Ст.052135. - P. - ISSN 2158-3226, DOI 10.1063/1.4808368
Примечания : Cited References: 47. - This work was supported by the RFBR 10-02-96015 and 12-02-31385 projects, UrFU 215, Spanish MEC MAT2011-27573-C04 grants, Universidad del Pais Vasco UPV/EHU under UFI11/53 action and Physics Department of the University of Maryland visiting grant. Selected measurements were performed at SGIker service of UPV-EHU. We thank O.M. Samatov, Dr. A.M. Murzakayev, Dr. I. Orue, and A.A. Svalova for special support.
Предметные рубрики: IRON-OXIDE NANOPOWDERS
CO2-LASER EVAPORATION
FE3O4 NANOPARTICLES
FINITE-SIZE
TEMPERATURE
FERROMAGNETS
FERROFLUIDS
DEPENDENCE
EXPLOSION
PARTICLES
Аннотация: Magnetic nanoparticles of iron oxide (MNPs) were prepared by the laser target evaporation technique (LTE). The main focus was on the fabrication of de-aggregated spherical maghemite MNPs with a narrow size distribution and enhanced effective magnetization. X-ray diffraction, transmission electron microscopy, magnetization and microwave absorption measurements were comparatively analyzed. The shape of the MNPs (mean diameter of 9 nm) was very close to being spherical. The lattice constant of the crystalline phase was substantially smaller than that of stoichiometric magnetite but larger than the lattice constant of maghemite. High value of M-s up to 300 K was established. The 300 K ferromagnetic resonance signal is a single line located at a field expected from spherical magnetic particles with negligible magnetic anisotropy. The maximum obtained concentration of water based ferrofluid was as high as 10g/l of magnetic material. In order to understand the temperature and field dependence of MNPs magnetization, we invoke the core-shell model. The nanoparticles is said to have a ferrimagnetic core (roughly 70 percent of the caliper size) while the shell consists of surface layers in which the spins are frozen having no long range magnetic order. The core-shell interactions were estimated in frame of random anisotropy model. The obtained assembly of de-aggregated nanoparticles is an example of magnetic nanofluid stable under ambient conditions even without an electrostatic stabilizer. (C) 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Efremov D. V., Mar'enko M. S., Val'kov V. V.
Заглавие : Superconductivity in repulsive fermi-systems at low density
Коллективы : RFBR [11-02-00741]
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2013. - Vol. 26, Is. 9. - P.2809-2815. - ISSN 1557-1939, DOI 10.1007/s10948-013-2262-9
Примечания : Cited References: 57. - The authors acknowledge helpful discussions with A. V. Chubukov, A. S. Alexandrov, V. V. Kabanov, K. I. Kugel, Yu. V. Kopaev, N.M. Plakida, N.V. Prokof'ev, M. M. Korovushkin, M. A. Mitskan. M. Yu. K. work was supported by RFBR grant No. 11-02-00741.
Предметные рубрики: T-J MODEL
SUPERFLUID TRANSITION-TEMPERATURE
FRACTIONAL-STATISTICS
PHASE-SEPARATION
HUBBARD-MODEL
GAS
ENHANCEMENT
MECHANISM
EXCHANGE
PARTICLES
Ключевые слова (''Своб.индексиров.''): anomalous superconductivity--p-wave and d-wave pairings--kohn-luttinger mechanism--shubin-vonsovsky--hubbard and t-j models
Аннотация: In the large variety of models such as 3D and 2D Fermi-gas model with hard-core repulsion, 3D and 2D Hubbard model, and the Shubin-Vonsovsky model, we demonstrate the possibility of triplet p-wave pairing at low electron density. We show that the critical temperature of the p-wave pairing can be strongly increased in a spin-polarized case or in a two-band situation already at low density and reach experimentally feasible values of (1-5) K. We also discuss briefly d-wave pairing and high-T-C superconductivity with T-C similar to 100 K, which arises in the 2D t-J model in the range of parameters realistic for cuprates.
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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) : Karpov S. V., Semina P. N., Gavrilyuk A. P.
Заглавие : The role of the electron tunneling effect in the coagulation kinetics of polydisperse metal nanocolloids
Место публикации : Colloid J.: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 74, Is. 3. - P.305-312. - ISSN 1061-933X, DOI 10.1134/S1061933X12030052
Примечания : Cited References: 16. - Authors are thankful to G. A. Chiganova for discussions and helpful comments. Studies were carried out with the support of grants: the Presidium of RAS No 29 and No 31, OFN RAS III.9.5, IP SB RAS No 43, IP SB RAS (and SFU) No 101.
Предметные рубрики: PARTICLES
Аннотация: The energy of pair interactions between metal nanoparticles of different sizes is shown to be able to increase upon coagulation due to the additional electrostatic effect resulting from mutual heteropolar charging of the particles. The tunnel electron transfer occurring upon the collisions between particles of different sizes may be the reason for the charging. The transfer is caused by the dependence of the electron work function on the particle size. The electron transfer through the interparticle gap equalizes the Fermi levels in particles of different sizes and is associated with this dependence. Using the example of bimodal silver nanocolloids, it is shown that mutual heteropolar charging of particles with different sizes may accelerate the coagulation of polydisperse colloidal systems by an order of magnitude or more as compared with monodisperse systems, in which this effect is absent.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Bekenev V. L., Chimitova O. D., Molokeev M. S., Bazarov B. G., Bazarova J. G., Khuzhum O. Y., Lim C. S.
Заглавие : Synthesis and electronic properties of β-RbNd(MoO4)2
Место публикации : Asian J. Chem. - 2014. - Vol. 26, No. 5. - P.1284-1286. - ISSN 0970-7077, DOI 10.14233/ajchem.2014.17209
Примечания : Cited References: 26. - This study is partly supported by by the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: UP-CONVERSION PHOTOLUMINESCENCE
VIBRATIONAL PROPERTIES
CRYSTAL-STRUCTURE
PARTICLES
MOLYBDATE
SPECTROSCOPY
SYSTEM
ER3+
Ключевые слова (''Своб.индексиров.''): β-rbnd(moo4)2--electronic structure--ab initio calculations--x-ray photoelectron spectroscopy
Аннотация: The electronic structure of β-RbNd(MoO4)2 has been evaluated from experimental and theoretical points of view. For the molybdate, X-ray photoelectron valence-band spectra have been measured. The total and partial densities of states of the constituent atoms of β-RbNd(MoO4)2 have been calculated using the FP-LAPW method. The FP-LAPW data reveal that main contributors in the valence-band region of β-RbNd(MoO4)2 are the Rb 4p-, Nd 4f-, Mo 4d- and O 2p-like states.
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pankrats A. I., Vorotynov A. M., Tugarinov V. I., Zharkov S. M., Velikanov D. A., Abramova G. M., Zeer G. M., Ramasamy K., Gupta A.
Заглавие : Structural and magnetic resonance investigations of CuCr2S4 nanoclusters and nanocrystals
Коллективы : Grant CRDF-SB RAS "New Nano-size and Layered Cu-containing Sulphides for Electronics" [RUP1-7054-KR-11, 16854]; Ministry of education and science of the Russian Federation
Место публикации : J. Appl. Phys.: American Institute of Physics, 2014. - Vol. 116, Is. 5. - Ст.54302. - ISSN 0021-8979, DOI 10.1063/1.4891993. - ISSN 1089-7550
Примечания : Cited References: 26. - The work was supported by a Grant CRDF-SB RAS "New Nano-size and Layered Cu-containing Sulphides for Electronics" RUP1-7054-KR-11, N 16854. S.M.Z. acknowledges support from the Ministry of education and science of the Russian Federation (in the framework of the state assignment for SFU for 2014).
Предметные рубрики: SUPERPARAMAGNETIC RESONANCE
NANOPARTICLES
GLASS
BIOMEDICINE
PARTICLES
SPINELS
Аннотация: Nanoclusters and nanocrystals of the room temperature magnetic spinel CuCr2S4 synthesized using a facile solution-based method have been examined by transmission electron microscopy, magnetic measurements, and magnetic resonance over a wide frequency range 9.6–80 GHz and at temperatures down to 4.2 K. Decreasing of the resonance field and broadening of the resonance lines below 50 K for both samples are due to the freezing of magnetic moments of nanocubes and nanocrystalline particles constituting nanoclusters. The effective fields of averaged magnetic anisotropy (HA)≌2.4 kOe are similar for both nanopowder samples as estimated from resonance measurements at T = 4.2 K. An additional blocking temperature T b ≅ 300 K appears in nanoclusters due to freezing of the magnetic moment of the entire cluster as a whole. Below this blocking temperature, the magnetic dipolar field acting in boundary areas of interacting constituent nanocrystals is responsible for the additional low-field resonance line observed in the resonance spectra of nanoclusters at X-band.
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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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10.

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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11.

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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12.

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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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Zhigalov V. S., Bykova L. E., Zharkov S. M., Matsynin A. A., Volochaev M. N., Tambasov I. A., Bondarenko G. N.
Заглавие : Thermite synthesis and characterization of Co-ZrO2 ferromagnetic nanocomposite thin films
Место публикации : J. Alloys Compd.: Elsevier, 2016. - Vol. 665. - P.197-203. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2015.12.257
Примечания : Cited References: 56. - This study was partially supported by the Russian Foundation for Basic Research (grants ##15-02-00948, 14-03-00515), by the Council for Grants of the President of the Russian Federation (SP-317.2015.1), and by the program of the Foundation for Assistance to Small Innovative Enterprises in Science and Technology (“UMNIK” program). The TEM studies were carried out using the facilities of Electron Microscopy Laboratory of Siberian Federal University and the Performance Service at Krasnoyarsk Scientific Center.
Предметные рубрики: SOLID-STATE SYNTHESIS
PHASE-FORMATION
ZrO2
NANOPARTICLES
TRANSPORT
OXIDE
MICROSTRUCTURE
NANOTHERMITE
FABRICATION
PARTICLES
Ключевые слова (''Своб.индексиров.''): thermite reactions--reactive films--ferromagnetic nanocomposite films--zro2
Аннотация: Co-ZrO2 ferromagnetic nanocomposite thin films were successfully synthesized using a new thermite reaction between Zr and Co3O4 in layer geometry. The initial Zr/Co3O4 bilayers were obtained by the deposition of Zr layers onto Co3O4 films at room temperature. The process of mixing at the Zr/Co3O4 interface and synthesis of fine-crystalline Co and amorphous ZrO2 phases started at a temperature above the initiation temperature Tin ∼250 °C which did not depend on the bilayer thickness. For the bilayer thickness more than 300 nm high-temperature fcc-Co and cubic c-ZrO2 (or tetragonal t-ZrO2) phases were formed. For the bilayer thickness less than ∼50 nm stable low-temperature hexagonal hcp-Co and monoclinic m-ZrO2 phases were also present in the reaction product. A partial transformation from Co3O4 to CoO occurred after annealing at 300 °C. The secondary reaction between CoO and Zr started soon after Co3O4 had been converted to the CoO phase. After annealing at 500 °C more than 80% of Co was reduced and the final product contained Co nanoparticles above and below the superparamagnetic critical size embedded into a dielectric ZrO2 matrix. The synthesized Co-ZrO2 nanocomposite films possessed soft magnetic behavior, high magnetization and good chemical stability.
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14.

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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15.

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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16.

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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17.

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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18.

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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19.

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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20.

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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