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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Frolov G. I., Zhigalov V. S., Bayukov O. A.
Заглавие : Phase composition of nanocrystalline iron films deposited in a nitrogen atmosphere
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 1999. - Vol. 41, Is. 10. - P1669-1671. - ISSN 1063-7834, DOI 10.1134/1.1131050
Примечания : Cited References: 14
Предметные рубрики: ELECTRON-MICROSCOPY
MOSSBAUER
Аннотация: The phase composition of iron films prepared by pulsed-plasma deposition in a controlled nitrogen atmosphere is investigated by Mossbauer spectroscopy. The observed changes in the phase composition are dictated by the nanocrystalline structure of the samples and the dynamics of the substrate temperature during film deposition. (C) 1999 American Institute of Physics. [S1063-7834(99)02110-3].
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Abramova G. M., Petrakovskiy G. A., Zuberek R., Nabialek A., Boem M., Sokolov V. V., Bovina A. F.
Заглавие : Magnetostriction of FexMn1-xS (x=0.27) Crystals
Коллективы : Siberian Branch, Russian Academy of Sciences; INTAS [06-1000013-9002]
Разночтения заглавия :авие SCOPUS: Magnetostriction of FexMn1 - xS (x = 0.27) crystals
Место публикации : JETP Letters. - 2009. - Vol. 90, Is. 3. - P.207-210. - ISSN 0021-3640, DOI 10.1134/S0021364009150107
Примечания : Cited References: 19. - This work was supported by the Siberian Branch, Russian Academy of Sciences, and INTAS, joint project no. 06-1000013-9002.
Предметные рубрики: ALPHA-MNS
SINGLE-CRYSTALS
TRANSITION
MOSSBAUER
Аннотация: The magnetostriction of FexMn1-xS (x = 0.27) single crystals in strong magnetic fields up to 120 kOe has been investigated. It has been found that the magnetostriction reaches colossal values (+/-3 x 10(-4)) atypical of compounds of 3d elements. It has been found that the magnetostriction changes sign when varying temperature and magnetic field; this behavior indicates an important role of the spin-phonon interactions in the formation of the magnetic order in solid solutions of iron-manganese sulfides.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Ovchinnikov S. G., Abd-Elmeguid M. M., Ivanova N. B.
Заглавие : Electronic properties of Fe1-xVxBO3 at ambient conditions and at high pressure
Разночтения заглавия :авие SCOPUS: Electronic properties of Fe1-xVx-BO3 at ambient conditions and at high pressure
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2005. - Vol. 17: 2nd International Symposium on Physics of Solids Under High Pressure Using Nuclear Probes (JUL 20-24, 2004, Cologne, GERMANY), Is. 11. - P.S795-S800. - ISSN 0953-8984, DOI 10.1088/0953-8984/17/11/008
Примечания : Cited References: 16
Предметные рубрики: FEBO3 SINGLE-CRYSTALS
SOLID-SOLUTIONS
BAND-STRUCTURE
TRANSITION
MOSSBAUER
MAGNETIZATION
MODEL
VBO3
Ключевые слова (''Своб.индексиров.''): electronic properties--ferrimagnetic materials--high pressure effects--high temperature superconductors--metal insulator transition--single crystals--superconductivity--thermal effects--carrier localization--correlation effects--critical pressure--semiconducting behavior--oxide superconductors
Аннотация: We present the results of an in-plane resistivity study of the solid solutions Fe1-xVxBO3. The measurements were made on single crystals with concentration x = 0.02, 0.13, 0.18, 0.3, 0.95, 1.0 in the temperature range 220-600 K. Semiconducting behaviour for samples with x = 0.13 was found. Mott variable-range-hopping transport rho(T) = rho(0)exp(T*/T)(alpha) has been observed with alpha = 1/4 at T 290 K, suggesting carrier localization. Above this temperature the activation-type conductivity, with activation energies, E-a, about 1 eV for all samples, is observed. The possible electronic states and band structure of Fe1-xVx BO3 crystals are discussed in the different pressure ranges: P P-c(Fe), p(c)(Fe) p p(c)(V) P P-c(V) where p(c)(Fe) P-c(V) are the critical pressure values for FeBO3 and VBO3, respectively.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanova N. B., Kazak N. V., Markov V. V., Ovchinnikov S. G., Rudenko V. V., Abd-Elmeguid M. M.
Заглавие : Analysis of the electrical and optical properties of VBO3 single crystals and Fe1-xVxBO3 solid solutions on the basis of a many-electron model of energy band structure
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2004. - Vol. 46, Is. 8. - P1462-1468. - ISSN 1063-7834, DOI 10.1134/1.1788779
Примечания : Cited References: 32. - One of the authors (M.M.A.) would like to thank the Deutsche Forschungsgemeinschaft (SFB608) for financial support. This study was supported by the Russian Foundation for Basic Research (project no. 03-02-16286), the program "Integration" (project no. B0017), and the program of the Division of Physical Sciences of the Russian Academy of Sciences "Strongly Correlated Electrons"
Предметные рубрики: MAGNETIC-PROPERTIES
CALCITE STRUCTURE
PHASE-TRANSITION
FERRIC BORATE
HIGH-PRESSURE
FEBO3
FE1-XCRXBO3
FERROMAGNET
MOSSBAUER
SPECTRA
Аннотация: A many-electron model of the energy band structure of VBO3 and of Fe1 - xVxBO3 solid solutions is proposed with strong electron correlations taken into account. Experimental optical absorption spectra and data on the resistivity are discussed in the framework of the suggested model. Variation in the magnetic and electronic properties of VBO3 and Fe1 - xVxBO3 under high pressure is predicted. For VBO3, a Mott-Hubbard (insulator-metal) transition is expected in the high-pressure phase. In Fe1 - xVxBO3 solid solutions, a nontrivial variation in the properties is predicted, leading to the appearance of a different magnetic state. (C) 2004 MAIK "Nauka / Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Anshits A. G., Bayukov O. A., Kondratenko E. V., Anshits N. N., Pletnev O. N., Rabchevskii E. V., Solovyov L. A.
Заглавие : Catalytic properties and nature of active centers of ferrospheres in oxidative coupling of methane
Коллективы : Russian Science Foundation [14-13-00289]
Место публикации : Appl. Catal. A-Gen.: Elsevier Science, 2016. - Vol. 524. - P.192-199. - ISSN 0926-860X, DOI 10.1016/j.apcata.2016.06.032. - ISSN 1873-3875(eISSN)
Примечания : Cited References:47. - This study was supported by the Russian Science Foundation (project no. 14-13-00289).
Предметные рубрики: GLASS CRYSTAL CATALYSTS
MAGNETIC-PROPERTIES
PROFILE REFINEMENT
FLY-ASH
MOSSBAUER
MICROSPHERES
PERFORMANCE
CONVERSION
ETHYLENE
OXIDE
Ключевые слова (''Своб.индексиров.''): methane coupling--active center--ferrospinel--mossbauer spectroscopy
Аннотация: Ferrospheres with the Fe2O3 content in the range from 76 to 97 wt% were applied as catalysts for the oxidative coupling of methane (OCM). To identify their phase composition and distribution of iron sites, the ferrospheres were characterized by X-ray powder diffraction and Mossbauer spectroscopy before and after the OCM reaction. Magnetite-based ferrite spinel, hematite and aluminosilicate glasses were established to be the main phases. The ferrospinel of all ferrospheres partially oxidized to hematite after the OCM reaction. It was established that the yield of C-2-hydrocarbons sharply increased at the ferrospheres with Fe2O3 content higher than 89 wt% The spinel phase of these ferrospheres includes Fevv3+(B) sites with a Ca2+ tetrahedral cation and an octahedral cation vacancy among the nearest neighbors. A linear correlation between the yield of C-2-hydrocarbons (ethane and ethylene) and the content of such sites was established, thus indicating that their electrophilic oxygen species participate in selective CH4 conversion to C2H6. (C) 2016 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kremneva A. M., Fedorov A. V., Bulavchenko O. A., Knyazev Yu. V., Saraev A. A., Yakovlev V. A., Kaichev V. V.
Заглавие : Effect of calcination temperature on activity of Fe2O3-Al2O3 nanocomposite catalysts in CO oxidation
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [17-73-20157]; National center of investigation of catalysts" at Boreskov Institute of Catalysis
Место публикации : Catal. Lett. - 2020. - Vol. 150. - P.3377-3385. - ISSN 1011-372X, DOI 10.1007/s10562-020-03250-8. - ISSN 1572-879X(eISSN)
Примечания : Cited References: 31. - This work was supported by the Russian Science Foundation (Grant No. 17-73-20157). The experiments were performed using facilities of the shared research center "National center of investigation of catalysts" at Boreskov Institute of Catalysis. The authors thank A.Yu. Gladky for the TPR measurements and Z.S. Vinokurov for the XRD measurements.
Предметные рубрики: MOSSBAUER
SPECTROSCOPY
CHEMISTRY
IRON
XPS
ADSORPTION
OXYGEN
FE
Аннотация: Nanocomposite Fe–Al oxide catalysts were prepared by the melting of iron and aluminum nitrates with the subsequent calcination in air at different temperatures. It was found that the catalysts calcined at 450 °C are more active in the oxidation of CO than the catalysts calcined at 700 °C. X-ray diffraction and X-ray photoelectron spectroscopy showed that all the catalysts consist of hematite, α-Fe2O3 nanoparticles, and Al2O3 in an amorphous state. Iron oxide is the active component, which provides the oxidation of CO, while alumina is a texture promoter. The increase in the calcination temperature leads to a minor increase in the average size of hematite nanoparticles and an insignificant decrease in the specific surface area. Kinetic measurements showed that the oxidation of CO over the Fe–Al catalysts calcined at 450 and 700 °C proceeds with the activation energy of 61–69 and 91 kJ/mol, respectively. This means that the low-temperature and high-temperature catalysts contain different active species. Temperature-programmed reduction with CO indicated that the decrease in the calcination temperature improves the reducibility of the Fe-Al nanocomposites. According to 57Fe Mössbauer spectroscopy, the low-temperature catalysts contain hydrated iron oxides (acagenite and ferrihydrite) and a significant amount of highly defective hematite, which is absent in the high-temperature catalyst. These species can provide the enhanced activity of the low-temperature catalysts in the oxidation of CO.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Cazacu, Nicoleta, Chilom, Claudia G., Iftimie, Sorina, Balasoiu, Maria, Ladygina, Valentina P., Stolyar S. V., Orelovich, Oleg L., Kovalev, Yuriy S., Rogachev, Andrey V.
Заглавие : Biogenic ferrihydrite nanoparticles produced by Klebsiella oxytoca: Characterization, physicochemical properties and bovine serum albumin interactions
Место публикации : Nanomaterials. - 2022. - Vol. 12, Is. 2. - Ст.249. - ISSN 2079-4991(eISSN), DOI 10.3390/nano12020249
Примечания : Cited References: 59. - This research was funded by JINR Themes 02-1-1107-2011/2021, 04-5-1131-2017/2021 and 04-4-1133-2018/2023 and with the financial support of the RO-JINR Projects Nos. 366/11.05.2021 (items 7, 86, 97) and 365/11.05.2021 (items 8, 87 and 98). This work also benefited from the use of the SasView application, originally developed under NSF Award DMR-0520547. SasView also contains the code developed with funding from the EU Horizon 2020 program under the SINE2020 project Grant No 654000. The APC was funded by JINR Theme 02-1-1107-2011/2021, Project No. 366/11.05.2021, item 7. This study used the infrastructure of the Applied Genetics Resource Facility of MIPT (Suport Grant 075-15-2021-684)
Предметные рубрики: MAGNETIC-PROPERTIES
REDUCTION
MOSSBAUER
FERRITIN
DOCKING
BINDING
Аннотация: The synthesis of nanoparticles inside microorganisms is an economical alternative to chemical and physical methods of nanoparticle synthesis. In this study, ferrihydrite nanoparticles synthesized by Klebsiella oxytoca bacterium in special conditions were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), small-angle X-ray (SAXS), UV-Vis spectroscopy, fluorescence, fluorescence resonance energy transfer (FRET), and molecular docking. The morphology and the structure of the particles were characterized by means of SEM and SAXS. The elemental content was determined by means of the EDS method. The absorption properties of the ferrihydrite nanoparticles were investigated by UV-Vis spectroscopy. The binding mechanism of the biogenic ferrihydrite nanoparticles to Bovine Serum Albumin (BSA) protein, studied by fluorescence, showed a static and weak process, combined with FRET. Protein denaturation by temperature and urea in the presence of the ferrihydrite nanoparticles demonstrated their influence on the unfolding process. The AutoDock Vina and UCSF Chimera programs were used to predict the optimal binding site of the ferrihydrite to BSA and to find the location of the hydrophobic cavities in the sub-domain IIA of the BSA structure.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Krasikov A. A., Stolyar S. V., Iskhakov R. S., Ladygina V. P., Yaroslavtsev R. N., Bayukov O. A., Vorotynov A. M., Volochaev M. N., Dubrovskiy A. A.
Заглавие : Change in the magnetic properties of nanoferrihydrite with an increase in the volume of nanoparticles during low-temperature annealing
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 58, Is. 9. - P.1782-1791. - ISSN 10637834 (ISSN), DOI 10.1134/S1063783416090092
Примечания : Cited References: 32. - This study was supported by the Ministry of Education and Science of the Russian Federation within the State Task for 2014-2016.
Предметные рубрики: FERRIHYDRITE NANOPARTICLES
BACTERIAL FERRIHYDRITE
FERRITIN
HYSTERESIS
MOSSBAUER
ORIGIN
Аннотация: The results of the investigation into the effect of low-temperature annealing of a powder of nanoparticles of bacterial ferrihydrite on its magnetic properties have been presented. It has been found that an increase in the time (up to 240 h) and temperature (in the range from 150 to 200°C) of annealing leads to a monotonic increase in the superparamagnetic blocking temperature, the coercive force, and the threshold field of the opening of the magnetic hysteresis loop (at liquid-helium temperatures), as well as to an increase in the magnetic resonance line width at low temperatures and in the magnetic susceptibility at room temperature. At the same time, according to the results of the analysis of the Mossbauer spectra, the annealing of ferrihydrite does not lead to the formation of new iron oxide phases. Most of these features are well consistent with the fact that the low-temperature annealing of ferrihydrite causes an increase in the size of nanoparticles, which is confirmed by the results of transmission electron microscopy studies. © 2016, Pleiades Publishing, Ltd.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Semenov S. V., Dubrovskii A. A., Krasikov A. A., Popkov S. I., Yakushkin S. S., Kirillov V. L., Mart'yanov O. N.
Заглавие : Synthesis and magnetic properties of the core-shell Fe3O4/CoFe2O4 nanoparticles
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [17-12-01111]
Место публикации : Phys. Solid State. - 2020. - Vol. 62, Is. 2. - P.285-290. - ISSN 1063-7834, DOI 10.1134/S1063783420020043. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 37. - This study was supported by the Russian Science Foundation, project no. 17-12-01111.
Предметные рубрики: MOSSBAUER
ENSEMBLE
Аннотация: The Fe3O4/CoFe2O4 nanoparticles with a core-shell structure with an average size of 5 nm have been obtained by codeposition from the iron and cobalt chloride solutions. An analysis of the magnetic properties of the obtained system and their comparison with the data for single-phase Fe3O4 (4 nm) and CoFe2O4 (6 nm) nanoparticles has led to the conclusion about a noticeable interaction between the soft magnetic (Fe3O4) and hard magnetic (CoFe2O4) phases forming the core and shell of hybrid particles.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Edelman I. S., Ivanova O., Polyakova K., Polyakov V., Bayukov O. A.
Заглавие : Evolution of the structure and magneto-optical properties of Mn (x) Fe3-x O-4 films prepared by solid-state reactions
Коллективы :
Разночтения заглавия :авие SCOPUS: Evolution of the structure and magneto-optical properties of Mn x Fe3 - X O4 films prepared by solid-state reactions
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 12. - P2289-2294. - ISSN 1063-7834, DOI 10.1134/S106378340812010X
Примечания : Cited References: 13. - We are grateful to G.N. Bondarenko for x-ray diffraction measurements.This study was supported by the Russian Foundation for Basic Research (project no. 07-02-92174_ NTsNI) and the Program "Development of the Scientific Potential of the Higher Education School."
Предметные рубрики: MOSSBAUER
Аннотация: This paper reports on the results of investigations into the structure and the magnetic and magnetooptical properties of thin films Mn (x) Fe3 - x O-4 prepared by solid-state reactions: isothermal annealing, self-propagating high-temperature synthesis, and a combination of these two regimes. The regimes favorable for the formation of films close in composition and structure to the stoichiometric compounds MnFe2O4 or Fe3O4 are established. The features observed in the spectral response of the magneto-optical Faraday effect and of the magnetic circular dichroism of the MnFe2O4 films are considered in terms of the electronic transitions in magnetic ions, primarily Fe3+, which occupy octahedral positions in the spinel structure.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Krasikov A. A., Dubrovskii A. A., Bayukov O. A., Stolyar S. V., Iskhakov R. S., Ladygina V. P., Yaroslavtsev R. N.
Заглавие : The effect of low-temperature heat treatment on the magnetic properties of biogenic ferrihydrite nanoparticles
Коллективы : Ministry of Education and Science of the Russian Federation
Место публикации : Tech. Phys. Lett.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 41, Is. 7. - P.705-709. - ISSN 1063-7850, DOI 10.1134/S1063785015070172
Примечания : Cited References: 12. - This study was supported in part by the Ministry of Education and Science of the Russian Federation in the framework of a federal program for 2014-2016.
Предметные рубрики: BACTERIAL FERRIHYDRITE
MOSSBAUER
Аннотация: We have studied the influence of low-temperature heat treatment (annealing) on the magnetic properties of superparamagnetic nanoparticles of biogenic ferrihydrite. It is established that the proposed treatment leads to an increase in the blocking temperature and magnetic susceptibility of samples. After subsequent exposure in aqueous medium, the magnetic properties of annealed sol remain constant. The character of changes in the magnetic properties of samples studied shows that low-temperature heat treatment allows nanoparticle dimensions to be increased in a controlled way. © 2015, Pleiades Publishing, Ltd.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Anshits A. G., Bayukov O. A., Anshits N. N., Pletnev O. N., Rabchevskii E. V., Vereshchagin S. N., Kondratenko E. V.
Заглавие : Nature of the active sites of ferrospheres in the oxidative condensation of methane
Коллективы : Russian Science Foundation [4-13-00289], Russian Congress on Catalysis (2; 2014 ; Oct. ; 2–5; Samara)
Место публикации : Kinet. Catal.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 56, Is. 4. - P.523-531. - ISSN 0023, DOI 10.1134/S0023158415040023. - ISSN 16083210(eISSN)
Примечания : Cited References:37. - This work was supported by the Russian Science Foundation (grant no. 14-13-00289).
Предметные рубрики: GLASS CRYSTAL CATALYSTS
HIGH-TEMPERATURE
MOSSBAUER
MAGNETITES
MICROSPHERES
SELECTIVITY
CONVERSION
FERRITES
ASHES
IRON
Ключевые слова (''Своб.индексиров.''): oxidative condensation of methane--ferrospheres--iron spinel--mossbauer spectroscopy--structural defects
Аннотация: The catalytic properties of ferrospheres containing 76–97 wt % Fe2O3 in the oxidative condensation of methane were compared with their phase composition and the distribution of iron cations over the crystallographic positions of iron-containing phases in a steady state. It was established that the reaction route of methane oxidation changed at a Fe2O3 content of 89 wt %. Deep oxidation was the main reaction route on ferrospheres with a Fe2O3 content of 88.8 wt %. At a Fe2O3 content of ≥89 wt %, the yield of C2 hydrocarbons sharply increased and the contribution of deep oxidation decreased. The yield of C2 hydrocarbons correlated with the amount of defects in the structure of iron spinel, which are iron ions with the tetrahedral cation of Ca2+ and the octahedral cation vacancy among the nearest neighbors.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Raevski I. P., Titov V. V., Malitskaya M. A., Eremin E. V., Kubrin S. P., Blazhevich A. V., Chen H., Chou C.-C., Raevskaya S. I., Zakharchenko I. N., Sarychev D. A., Shevtsova S. I.
Заглавие : Studies of ferroelectric and magnetic phase transitions in multiferroic PbFe0.5Ta0.5O3-PbTiO3 solid solution ceramics
Коллективы : Russian Foundation for Basic Research (RFBR) [12-08-00887_a]; Research Committee of the University of Macau
Место публикации : J. Mater. Sci.: Springer, 2014. - Vol. 49, Is. 18. - P.6459-6466. - ISSN 0022-2461, DOI 10.1007/s10853-014-8376-z. - ISSN 1573-4803
Примечания : Cited References: 35. - This study is partially supported by the Russian Foundation for Basic Research (RFBR) Project 12-08-00887_a and Research Committee of the University of Macau under Research and Development Grant for Chair Professor.
Предметные рубрики: MOSSBAUER
CRYSTALS
BEHAVIOR
NIOBATE
Аннотация: Dielectric, X-ray, Mossbauer and magnetization studies of (1 − x)PbFe0.5Ta0.5O3–(x)PbTiO3 ceramics with 0 ≤ x ≤ 0.3 have been carried out to determine the compositional evolution of ferroelectric and magnetic phase transition temperatures. Addition of PbTiO3 to PbFe0.5Ta0.5O3 increases the temperature T m of the dielectric permittivity maximum, decreases both the diffusion of this maximum and its frequency dependence. However, the Curie–Weiss temperature exceeds T m for all the compositions studied, indicating that the phase transition still remains diffused. Dilution of the (Fe, Ta)-sublattice by Ti lowers the Neel temperature T N but above a certain compositional threshold (x ≈ 0.1) fast lowering of T N stops and a new magnetic state stable in a rather wide compositional range appears. Large difference between the zero-field-cooled (ZFC) and FC magnetization–temperature curves as well as between the temperatures of magnetic phase transition determined from Mossbauer and magnetization studies for compositions with x 0.1 implies that this state is a spin-glass phase.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Krasikov A. A., Dubrovskii A. A., Semenov S. V., Bayukov O. A., Stolyar S. V., Iskhakov R. S., Ladygina V. P., Ishchenko L. A.
Заглавие : Magnetic properties and the mechanism of formation of the uncompensated magnetic moment of antiferromagnetic ferrihydrite nanoparticles of a bacterial origin
Коллективы : Ministry of Education and Science of the Russian Federation; Siberian Branch of the Russian Academy of Sciences
Место публикации : J. Exp. Theor. Phys.: Pleiades Publishing, 2014. - Vol. 119, Is. 3. - P.479-487. - ISSN 1063-7761, DOI 10.1134/S1063776114080044. - ISSN 1090-6509
Примечания : Cited References: 42. - This work was supported by the Ministry of Education and Science of the Russian Federation (state contract in 2014-2016) and a program of the Siberian Branch of the Russian Academy of Sciences.
Предметные рубрики: NIO NANOPARTICLES
EXCHANGE BIAS
HYSTERESIS ANOMALIES
FERRITIN
SURFACE
MOSSBAUER
ORDER
SIZE
Аннотация: The magnetic properties of the superparamagnetic ferrihydrite nanoparticles that form as a result of the vital activity of Klebsiella oxytoca bacteria are studied. Both an initial powder with an average number of iron atoms N Fe ∼ 2000–2500 in a particle and this powder after annealing at 140°C for 3 h in air are investigated. The following substantial modifications of the magnetic properties of the ferrihydrite nanoparticles are detected after annealing: the superparamagnetic blocking temperature increases from 23 to 49.5 K, and the average magnetic moment of a particle increases (as follows from the results of processing of magnetization curves). The particles have antiferromagnetic ordering, and the magnetic moment resulting in the superparamagnetism of the system appears due to random spin decompensation inside the particle. For this mechanism, the number of uncompensated spins is proportional to the number of magnetically active atoms raised to the one-half power, and this relation holds true for the samples under study at a good accuracy. The possible causes of the detected shift of magnetic hysteresis loops at low temperatures upon field cooling are discussed.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bataleva, Yu. V., Palyanov, Yu. N., Borzdov, Yu. M., Bayukov O. A., Sobolev N. V.
Заглавие : Conditions for diamond and graphite formation from iron carbide at the P-T parameters of lithospheric mantle
Коллективы : Russian Science Foundation [14-27-00054]
Место публикации : Russ. Geol. Geophys.: Elsevier Science, 2016. - Vol. 57, Is. 1: Tectonics, geodynamics, and petrology of earth’s lithosphere and mantle (to the 80th birthday of Academician Nikolai Leontievich Dobretsov). - P.176-189. - ISSN 1068-7971, DOI 10.1016/j.rgg.2016.01.012. - ISSN 1878-030X(eISSN)
Примечания : Cited References:55. - This work was supported by the Russian Science Foundation under Grant No. 14-27-00054.
Предметные рубрики: DEEP CARBON-CYCLE
EARTHS MANTLE
MINERAL INCLUSIONS
HIGH-PRESSURE
KOKCHETAV MASSI
SUBDUCTION ZONES
REDOX BUDGET
FERRIC IRON
MOSSBAUER
METAL
Ключевые слова (''Своб.индексиров.''): iron carbide--wusite--graphite--diamond--oxides--olivine--subduction--redox interaction--lithospheric mantle--high-pressure experiment
Аннотация: To estimate conditions for the stability of iron carbide under oxidation conditions and to assess the possibility of formation of elemental carbon by interaction between iron carbide and oxides, experimental modeling of redox interaction in the systems Fe3C-Fe2O3 and Fe3C-Fe2O3-MgO-SiO2 was carried out on a split-sphere high-pressure multianvil apparatus at 6.3 GPa and 900-1600 degrees C for 18-20 h. During carbide-oxide interaction in the system Fe3C-Fe2O3, graphite crystallizes in assemblage with Fe3+-containing wusite. Graphite forms from carbide carbon mainly by cohenite oxidation: Fe3C + 3Fe(2)O(3) - 9FeO + C-0 and FeO + Fe3C - (Fe2+, Fe3+)O + C-0. At above-solidus temperatures (= 1400 degrees C), when metal-carbon melt is oxidized by wusite, graphite and diamond crystallize by the redox mechanism and form the Fe3+-containing wstite + graphite/diamond assemblage. Interaction in the system Fe3C-Fe2O3-MgO-SiO2 results in the formation of Fe3+-containing mannesiowusite-olivine-graphite assemblage. At = 1500 degrees C, two melts with contrasting f(O2) values are generated: metal-carbon and silicate-oxide; their redox interaction leads to graphite crystallization and diamond growth. Under oxidation conditions, iron carbide is unstable in the presence of iron, silicon, and magnesium oxides, even at low temperatures. Iron carbide-oxide interaction at the mantle temperatures and pressures leads to the formation of elemental carbon; graphite is produced from carbide carbon mainly by redox reactions of cohenite (or metal-carbon melt) with Fe2O3 and FeO as well as by interaction between metal-carbon and silicate-oxide melts. The results obtained suggest that cohenite can be a potential source of carbon during graphite (diamond) formation in the lithospheric mantle and the interaction of iron carbide with iron, silicon, and magnesium oxides, during which carbon is extracted can be regarded as a process of the global carbon cycle. (C) 2016, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bartolome J., Arauzo A., Kazak N. V., Ivanova N. B., Ovchinnikov S. G., Knyazev Yu. V., Lyubutin I. S.
Заглавие : Uniaxial magnetic anisotropy in Co2.25Fe0.75O2BO3 compared to Co3O2BO3 and Fe3O2BO ludwigites
Разночтения заглавия :авие SCOPUS: Uniaxial magnetic anisotropy in Co2.25Fe0.75O 2BO3 compared to Co3O2BO3 and Fe3O2BO ludwigites
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2011. - Vol. 83, Is. 14. - Ст.144426. - ISSN 1098-0121, DOI 10.1103/PhysRevB.83.144426
Примечания : Cited References: 25. - The authors acknowledge V. V. Rudenko for the oxyborate samples they made and O. A. Bayukov for fruitful discussion. The financial support of Spanish MINCYT, Grant No. MAT08/1077, and the Aragonese E-34 project are acknowledged. Fruitful discussions with F. Bartolome and P. Bordet are acknowledged. The latter is thanked for providing the FeINF3/INFOINF2/INFBOINF3/INF single crystal. Also this study was supported by the Russian Foundation for Basic Research (Project No. 09-02-00171-a), the Federal Agency for Science and Innovation (Rosnauka) (Project No. MK-5632.2010.2), and the Physical Division of the Russian Academy of Science (Program "Strongly Correlated Electrons," Project No. 2.3.1).
Предметные рубрики: CRYSTAL-STRUCTURE
MOSSBAUER
CO3BO5
Аннотация: Magnetic and Mossbauer spectroscopy (MS) measurements have been performed on a single crystal of Co2.25Fe0.75O2BO3 with ludwigite structure. Two magnetic transitions (T-N = 115 K and T-C = 70 K) were traced from the ac susceptibility temperature dependence. The MS spectra as a function of temperature clearly show the onset of magnetic ordering below 115 K. Magnetization measurements on the parent Co3O2BO3 and Fe3O2BO3 compounds have been done for comparison. In Fe3O2BO3 the anisotropy of the different phases has been determined, showing that the anisotropy axis changes from the a to the b axis in the low-temperature antiferromagnetic phase. High magnetic uniaxial anisotropy has been detected for both Co3O2BO3 and Co2.25Fe0.75O2BO3. From the angle-dependent magnetization measurements it is found that in both compounds the easy axis of magnetization is the b [010] axis, where an antiferromagnetic component is superimposed on the main ferromagnetic component. In the c direction the behavior is purely antiferromagnetic. In Co2.25Fe0.75O2BO3 a strong reduction of the remanent magnetization and a very strong increase in coercive field along the b axis with respect to those found in Co3O2BO3 were observed from magnetic hysteresis cycles measured below T-C. The increase of coercive field is caused by the increase of defects upon Co substitution by Fe.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bukhtiyarova G. A., Mart'yanov O. N., Yakushkin S. S., Shuvaeva M. A., Bayukov O. A.
Заглавие : State of iron in nanoparticles prepared by impregnation of silica gel and aluminum oxide with FeSO4 solutions
Коллективы :
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 4. - P826-837. - ISSN 1063-7834, DOI 10.1134/S1063783410040268
Примечания : Cited References: 27. - This study was supported by the Presidium of the Russian Academy of Sciences within the framework of the Program no. 27 "Principles of Basic Research of Nanotechnologies and Nanomaterials," Project no. 46 "Magnetically Ordered Nanoparticles in Catalytic Systems: Synthesis, Evolution, and Physicochemical Properties."
Предметные рубрики: THERMAL-DECOMPOSITION
BETA-FEOOH
MOSSBAUER
FERRIHYDRITE
EPSILON-FE2O3
FE-2(SO4)(3)
SULFATE
FE-57
Аннотация: The state of iron in nanoparticles prepared by impregnating silica gel and aluminum oxide with iron(II) sulfate solutions has been investigated using Mossbauer spectroscopy. It has been revealed that the state of iron depends on the nature of the support. Iron(III) hydroxysulfate and iron(III) oxysulfate nanoparticles are formed on the surface of silica gel, and iron oxide nanoparticles are formed on the surface of aluminum oxide. An increase in the concentration of iron ions or in the size of iron-containing particles leads to hydration of the nanoparticle surface. The calcination of the samples results in the formation of E -Fe2O3 oxide in a strongly disordered or amorphous state in iron-containing particles on the surface of silica gel.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Flerov I. N., Tressaud A., Bogdanov E. V., Kartashev A. V., Bayukov O. A., Eremin E. V., Krylov A. S.
Заглавие : Heat capacity and magnetic properties of fluoride CsFe2+Fe3+F6 with defect pyrochlore structure
Место публикации : J. Solid State Chem. - 2016. - Vol. 237. - P.330-335. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2016.02.045
Примечания : Cited References: 19. - This study was partially supported by the Grant NSh-924.2014.2 of the President of the Russian Federation for the Support of Leading Scientific Schools.
Предметные рубрики: Crystal-structure
Mossbauer
CsFe2F6
Spectra
Ключевые слова (''Своб.индексиров.''): pyrochlore structure--phase transition--magnetic properties--thermal properties
Аннотация: Heat capacity, Mossbauer and Raman spectra as well as magnetic properties of fluoride CsFe2F6 with defect pyrochlore structure were studied. In addition to recently found above room temperature three successive structural transformations Pnma-Imma-I41amd-Fd-3m, phase transition of antiferromagnetic nature with the 13.7 K Neel temperature and a broad heat capacity anomaly with a maximum at about 30 K were observed. The room temperature symmetry Pnma is unchanged at least down to 7 K. Simple model of indirect bond used to estimate the exchange interactions and to propose a magnetic structure model. © 2016 Elsevier Inc. All rights reserved.
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19.

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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