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1.

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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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Zelenov F. V., Semenov S. V., Bayukov O. A.
Заглавие : Anomalies in the magnetic properties of bismuth-substituted diluted yttrium iron garnet
Колич.характеристики :9 с
Место публикации : J. Magn. Magn. Mater. - 2023. - Vol. 582. - Ст.171030. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2023.171030. - ISSN 18734766 (eISSN)
Примечания : Cited References: 61. - The authors are grateful to T. N. Tarasenko for providing samples for magnetic measurements
Аннотация: The magnetic properties and Mossbauer spectra of the Y1.8Bi1.2Fe3.5Ga1.5O12 compound were investigated. A linear temperature dependence of the saturation magnetization, hysteresis, and stability of the coercive field in the magnetically ordered state were found. Using the Mossbauer measurements, the distribution of iron ions over octahedral and tetrahedral sites and the concentration of paramagnetic iron ions were determined. Two critical temperatures – the sublattice magnetization compensation temperature and the ferrimagnet–paramagnet transition temperature – were established. The disappear of the phonon mode in the vicinity of the magnetic transition was observed. The experimental data have been interpreted in terms of the spin–lattice interaction model.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev A. D., Bayukov O. A., Savitskii A. F.
Заглавие : Magnetic and mossbauer studies of magnesium-chromium ferrites
Место публикации : Phys. Status Solidi B. - 1989. - Vol. 152, Is. 2. - P.639-644. - ISSN 0370-1972, DOI 10.1002/pssb.2221520226
Примечания : Cited References: 10
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bayukov O. A., IKONNIKOV V. P., SAVITSKII A. F.
Заглавие : Magnetic and mossbauer studies of anion-substituted nickel ferrites
Место публикации : Phys. Status Solidi B. - 1989. - Vol. 151, Is. 1. - P.269-274. - ISSN 0370-1972, DOI 10.1002/pssb.2221510131
Примечания : Cited References: 14
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5.

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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6.

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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7.

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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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fomenko E. V., Akimochkina G. V., Knyazev Yu. V., Semenov S. V., Yumashev V. V., Solovyov L. A., Anshits A. G.
Заглавие : Characterization and magnetic properties of sintered glass-ceramics from dispersed fly ash microspheres
Место публикации : Magnetochemistry. - 2023. - Vol. 9, Is. 7. - Ст.177. - ISSN 23127481 (eISSN), DOI 10.3390/magnetochemistry9070177
Примечания : Cited References: 50. - Russian Science Foundation and the Krasnoyarsk Regional Science Foundation, grant number 22-27-20039, https://rscf.ru/project/22-27-20039/ (accessed on 15 March 2023)
Аннотация: The recycling of hazardous industrial waste into high-tech materials with desired properties is of considerable interest since it provides optimal alternatives for its final disposal. Coal fly ash, the major waste generated by coal-fired power plants, contains significant quantities of dispersed microspheres with a diameter smaller than 10 μm, which are anthropogenic atmospheric pollutants PM10. Due to their composition and fine-grained powder morphology, they can be converted into sintered products. In this study, dispersed microspheres from class C fly ash were directly sintered without any additive to form high-strength glass-ceramics with magnetic properties. The optimum processing conditions were achieved at a temperature of 1200 °C, at which samples with a compressive strength of 100.6 MPa were obtained. Sintering reduces the quantity of the glass phase and promotes the formation of larnite, Fe-spinel, ye’elimite, and ternesite. Mössbauer measurements show that the relative concentration of the magnetic phase compared to the paramagnetic one rises almost in order. The sintered sample demonstrates a narrower distribution of the hyperfine magnetic field and a significantly lower value of the coercive field of 25 Oe, which allows proposing such materials as soft magnetic materials. The presented results demonstrate promising industrial applications of hazardous PM10 to minimize solid waste pollution.
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9.

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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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Smirnova E. S., Alekseeva O. A., Dudka A. P., Khmelenin D. N., Frolov K. V., Lyubutina M. V., Gudim I. A., Lyubutin I. S.
Заглавие : Crystal structure and structural phase transition in bis­muth-containing HoFe3(BO3)4 in the temperature range 11–500 K
Место публикации : Acta Crystallogr. B. - 2019. - Vol. 75. - P.954-968. - ISSN 20525192 (ISSN), DOI 10.1107/S2052520619010473
Примечания : Cited References: 37. - The authors are grateful to D. Yu. Chernyshov (SNBL, ESRF, Grenoble) for his assistance in obtaining the experimental data. This work was performed using the equipment of the Shared Research Center FSRC ‘Crystallography and Photonics’ RAS and was supported by the Russian Ministry of Education and Science (project RFMEFI62119X0035)This work was supported by the Ministry of Science and Higher Education within the State assignment FSRC ‘Crystallography and Photonics’ RAS and partially by the Russian Foundation for Basic Research (grant No. 17-02-00766)
Аннотация: An accurate single-crystal X-ray diffraction study of bis­muth-containing HoFe3(BO3)4 between 11 and 500 K has revealed structural phase transition at Tstr = 365 K. The Bi atoms enter the composition from Bi2Mo3O12-based flux during crystal growth and significantly affect Tstr. The content of Bi was estimated by two independent methods, establishing the composition as (Ho0.96Bi0.04)Fe3(BO3)4. In the low-temperature (LT) phase below Tstr the (Ho0.96Bi0.04)Fe3(BO3)4 crystal symmetry is trigonal, of space group P3121, whereas at high temperature (HT) above 365 K the symmetry increases to space group R32. There is a sharp jump of oxygen O1 (LT) and O2 (LT) atomic displacement parameters (ADP) at Tstr. O1 and O2 ADP ellipsoids are the most elongated over 90–500 K. In space group R32 specific distances decrease steadily or do not change with decreasing temperature. In space group P3121 the distortion of the polyhedra Ho(Bi)O6, Fe1O6 and Fe2O6, B2O3 and B3O3 increases with decreasing temperature, whereas the triangles B1O3 remain almost equilateral. All BO3 triangles deviate from the ab plane with decreasing temperature. Fe–Fe distances in Fe1 chains decrease, while distances in Fe2 chains increase with decreasing temperature. The Mössbauer study confirms that the FeO6 octahedra undergo complex dynamic distortions. However, all observed distortions are rather small, and the general change in symmetry during the structural phase transition has very little influence on the local environment of iron in oxygen octahedra. The Mössbauer spectra do not distinguish two structurally different Fe1 and Fe2 positions in the LT phase. The characteristic temperatures of cation thermal vibrations were calculated using X-ray diffraction and Mössbauer data.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Alekseeva O. A., Smirnova E. S., Frolov K. V., Lyubutina M. V., Lyubutin I. S., Gudim I. A.
Заглавие : Crystal structure dynamics of RFe3(BO3)4 single crystals in the temperature range 25–500 K
Место публикации : Crystals. - 2022. - Vol. 12, Is. 9. - Ст.1203. - ISSN 20734352 (ISSN), DOI 10.3390/cryst12091203
Примечания : Cited References: 67. - This research was funded by the Ministry of Science and Higher Education within the State assignment FSRC ‘Crystallography and Photonics’ RAS 075-01025-22-00
Аннотация: The multiferroic RFe3(BO3)4 family is characterized by diverse magnetic, magnetoelectric, and magnetoelastic properties, the fundamental aspects of which are essential for modern electronics. The present research, using single-crystal X-ray diffraction (XRD) and Mossbauer spectroscopy (MS) in the temperature range of 25–500 K, aimed to analyze the influence of local atomic coordination on magnetoelectric properties and exchange and super-exchange interactions in RFe3(BO3)4. Low-temperature, single-crystal XRD data of the magnetically ordered phase of RFe3(BO3)4 at 25 K, which were obtained for the first time, were supplemented with data obtained at higher temperatures, making it possible to draw conclusions about the mechanism of the structural dynamics. It was shown that, in structures with R = Gd, Ho, and Y (low-temperature space group P3121), a shift in oxygen atoms (O2, second coordination sphere of R atoms) was accompanied by rotation of the B2O3 triangle toward R atoms at low temperatures, and by different rearrangements in iron chains of two types, in contrast to Nd and Sm iron borates (space group R32). These rearrangements in the structures of space group P3121 affected the exchange and super-exchange paths at low temperatures. The MS results confirm the influence of the distant environment of atoms on the magnetoelectric properties of rare-earth iron borates at low temperatures.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Smirnova E. S., Alekseeva O. A., Dudka A. P., Verin I. A., Artemov V. V., Lyubutina M. V., Gudim I. A., Frolov K. V., Lyubutin I. S.
Заглавие : Crystal structure of bis­muth-containing NdFe3(BO3)4 in the temperature range 20–500 K
Коллективы : Russian Ministry of Science and Higher Education; Ministry of Science and Higher Education within the State assignment FSRC 'Crystallography and Photonics' RAS
Место публикации : Acta Crystallogr. B. - 2022. - Vol. 78, Pt. 1. - P.1-13. - ISSN 2052-5206(eISSN), DOI 10.1107/S205252062101180X
Примечания : Cited References: 44. - This work was performed using the equipment of the Shared Research Center FSRC `Crystallography and Photonics' RAS supported by the Russian Ministry of Science and Higher Education. This work was supported by the Ministry of Science and Higher Education within the State assignment FSRC `Crystallography and Photonics' RAS
Предметные рубрики: MAGNETIC PHASE-TRANSITIONS
UNIT-CELL PARAMETERS
DIFFRACTION
Аннотация: Neodymium iron bor­ate NdFe3(BO3)4 is an intensively studied multiferroic with high electric polarization values controlled by a magnetic field. It is char­ac­ter­ized by a large quadratic magnetoelectric effect, rigidity in the base plane and a rather strong piezoelectric effect. In this work, the atomic structure of (Nd0.91Bi0.09)Fe3(BO3)4 was studied by single-crystal X-ray diffraction in the tem­per­ature range 20–500 K (space group R32, Z = 3). The Bi atoms found in the com­position partially substitute the Nd atoms in the 3a position; they entered the structure due to the growth conditions in the presence of Bi2Mo3O12. It was shown that in the tem­per­ature range 20–500 K there is no structural phase transition R32→P3121, which occurs in rare-earth iron bor­ates (RE = Eu–Er, Y) with an effective rare-earth cation radius smaller than that of Nd. The tem­per­ature dependence of the unit-cell c parameter reveals a slight increase on cooling below 90 K, which is similar to the results obtained previously for iron bor­ates of Gd, Y and Ho. The atomic distances (Nd,Bi)—O, (Nd,Bi)—B, (Nd,Bi)—Fe, Fe—O, Fe—B and Fe—Fe in the iron chains and between chains decrease steadily with decreasing tem­per­ature from 500 to 90 K, whereas the B1(3b)—O distance does not change and the average B2(9e)—O distance increases slightly. There is a uniform decrease in the atomic displacement parameters with decreasing tem­per­ature, with a more pronounced decrease for the Nd(3a) and O2(9e) atoms. The O2(9e) atoms are characterized by the maximum atomic displacement parameters and the most elongated atomic displacement ellipsoids. The characteristic Debye and Einstein tem­per­atures, and the static com­ponent in the atomic displacements were determined for cations using multi-tem­per­ature diffraction data. It was shown that the Nd cations have the weakest bonds with the surrounding atoms and the B cations have the strongest.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Smirnova E. S., Alekseeva O. A., Dudka A. P., Sorokin T. A., Khmelenin D. N., Yapaskurt V. O., Lyubutina M. V., Frolov K. V., Lyubutin I. S., Gudim I. A.
Заглавие : Crystal structure, absolute configuration and characteristic temperatures of SmFe3(BO3)4 in the temperature range 11-400 K
Место публикации : Acta Crystallogr. B. - 2022. - Vol. 78, Is. 3-2, Pt. 1. - P.546-556. - ISSN 20525206 (ISSN), DOI 10.1107/S2052520622003948
Примечания : Cited References: 43. - The authors are grateful to D. Yu. Chernyshov (SNBL, ESRF, Grenoble) for assistance in obtaining the experimental data. This work was performed using the equipment of the Shared Research Center FSRC ‘Crystallography and Photonics’ RAS supported by the Russian Ministry of Science and Higher Education. This work was supported by the Ministry of Science and Higher Education within the State assignment FSRC ‘Crystallography and Photonics’ RAS
Аннотация: The crystal structure of samarium iron borate was analyzed with regard to growth conditions and temperature. The inclusion of about 7% Bi atoms in the crystals grown using the Bi2Mo3O12-based flux was discovered and there were no impurities in the crystals grown using the Li2WO4-based flux. No pronounced structural features associated with Bi inclusion were observed. The different absolute configurations of the samples grown using both fluxes were demonstrated. Below 80 K, a negative thermal expansion of the c unit-cell parameter was found. The structure of (Sm0.93Bi0.07)Fe3(BO3)4 belongs to the trigonal space group R32 in the temperature range 90–400 K. A decrease in the (Sm,Bi)—O, Sm—B, Sm—Fe, Fe—O, Fe—B and Fe—Fe distances is observed with a lowering of the temperature, B1—O does not change, B2—O increases slightly and the B2O3 triangles deviate from the ab plane. The strongest decrease in the equivalent isotropic atomic displacement parameters (Ueq) with decreasing temperature is observed for atoms Sm and O2, and the weakest is observed for B1. The O2 atoms have the highest Ueq values, the most elongated atomic displacement ellipsoids of all the atoms and the smallest number of allowed vibrational modes of all the O atoms. The largest number of allowed vibrational modes and the strongest interactions with neighbouring atoms is seen for the B atoms, and the opposite is seen for the Sm atoms. The quadrupole splitting Δ(T) of the paramagnetic Mössbauer spectra increases linearly with cooling. The Néel temperature [TN = 31.93 (5) K] was determined from the temperature dependence of the hyperfine magnetic field Bhf(T), which has a non-Brillouin character. The easy-plane long-range magnetic ordering below TN was confirmed.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Frolov K. V., Lyubutin I. S., Alekseeva O. A., Smirnova E. S., Verin I. A., Temerov V. L., Bezmaternykh L. N., Gudim I. A., Artemov V. V., Dmitrieva T. V.
Заглавие : Dynamics of structural and magnetic phase transitions in ferroborate YFe3(BO3)4
Место публикации : J. Alloys Compd. - 2018. - Vol. 748. - P.989-994. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2018.03.243
Примечания : Cited References: 58. - We thank Dr. A.P. Dudka for help in the low temperature XRD measurements and Dr. D.Yu. Chernyshov for help in the synchrotron XRD measurements. This study was supported by the Federal Agency of Scientific Organizations (Agreement No 007-ГЗ/Ч3363/26 ) in parts of energy-dispersive X-ray microanalysis, high-temperature XRD, and Mossbauer measurements, by the Russian Foundation for Basic Research (project #17-02-00766а ) in parts of low-temperature XRD and Mossbauer measurements, Russian Ministry of Education and Science and performed using the equipment of the Shared Research Center of the Shubnikov Institute of Crystallography of FSRC “Crystallography and Photonics” RAS.
Ключевые слова (''Своб.индексиров.''): multiferroics--rare-earth compounds--x-ray diffraction--mossbauer spectroscopy--crystal structure
Аннотация: X-ray analysis of the YFe3(BO3)4 single crystal revealed different behavior of parameters of the crystal cell with an increase in temperature from 25 to 500 K. The parameters a and b initially increase monotonically and then rise sharply in the range between 360 and 380 K, which corresponds to the structural phase transition. The parameter c initially decreases linearly upon heating and then begins to increase, passing through a minimum at 90 K. In the interval of 200–500 K the parameter c grows linearly and does not undergo anomalies at the structural phase transition. The results of Mössbauer measurements at 57Fe nuclei in the paramagnetic phase of YFe3(BO3)4 correlate well with the XRD data, but they do not separate the two structural states of iron ions Fe1 and Fe2 arising in the P3121 phase during the structural phase transition. The temperature of the magnetic phase transition TN = 39.42(16) K is established, below which the iron ions form a 3D magnetic order of the Heisenberg type. The calculated “Mössbauer” Debye temperature ΘM = 340(2) K turned out to be three times lower than the Debye temperature of the entire crystal lattice TD = 1020 K. Mössbauer data indicate a weak bonding between the helicoidal chains of iron and the rest of the crystal lattice.Рентгеновский анализ монокристалла YFe3(bo3-серии)4 выявил различие в поведении параметров кристаллической ячейки с увеличением температуры от 25 до 500 к. Параметры a и b сначала монотонно возрастают, а затем резко поднимется в диапазон между 360 и 380 К, что соответствует структурному фазовому переходу. Параметр c сначала линейно уменьшается при нагревании, а затем начинает возрастать, проходя через минимум при 90 K. В интервале 200-500 K параметр c растет линейно и не претерпевает аномалий при структурном фазовом переходе. Результаты Мёсбауэровской спектроскопии ядер 57Fe в парамагнитной фазе в YFe3(BO3)4 коррелируют с РСА, но они не разделяют двух структурных состояний ионов железа Fe1 и Fe2, возникающие в фазе P3121 в процессе структурного перехода. Установили температуру магнитного фазового перехода TN= 39.42(16) К, в результате которого ионы железа образуют 3D магнитный порядок типа Гейзенберга. Рассчитанная по Мёссбауэру Дебаевская температура QM= 340(2) K оказалась в три раза ниже температуры Дебая внутри кристаллической решетки TD= 1020 K. Данные Мёсбауэра указывают на слабую связь между геликоидальными цепочками железной и остальных кристаллических решеток.
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15.

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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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Frolov G. I., Bayukov O. A., Zhigalov V. S., Kveglis L. I., Myagkov V. G.
Заглавие : Electron-microscopy and mossbauer study of superlattices in iron films
Место публикации : JETP Letters. - 1995. - Vol. 61, Is. 1. - P.63-67. - ISSN 0021-3640
Примечания : Cited References: 6
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17.

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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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yakushkin S. S., Balaev D. A., Dubrovskiy A. A., Semenov S. V., Shaikhutdinov K. A., Kazakova M. A., Bukhtiyarova G. A., Martyanov O. N., Bayukov O. A.
Заглавие : Evolution of the Fe3+ ion local environment during the phase transition ε-Fe2O3 → α-Fe2O3
Место публикации : J. Supercond. Nov. Magn. - 2018. - Vol. 31, Is. 4. - P.1209–1217. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-017-4307-y
Примечания : Cited References: 37. - The work was supported by the Russian Science Foundation (Grant No. 17-12-01111).
Ключевые слова (''Своб.индексиров.''): ε−fe2o3 iron oxide nanoparticles--phase transition--structure size effect--magnetic properties--mossbauer spectroscopy
Аннотация: Evolution of the local environment of Fe3+ ions in deposited Fe2O3/SiO2 nanoparticles formed in samples with different iron contents was investigated in order to establish the conditions for obtaining the stable ε-Fe2O3/SiO2 samples without impurities of other iron oxide polymorphs. Microstructure of the samples with an iron content of up to 16% is studied by high-resolution transmission electron microscopy, X-ray diffraction analysis, and Mössbauer spectroscopy, and their magnetic properties are examined. At iron concentrations below 6%, calcinations of iron-containing precursor nanoparticles in a silica gel matrix lead to the formation of the ε-Fe2O3 iron oxide polymorphic modification without foreign phase impurities, while at the iron concentration in the range of 6–12%, the hematite phase forms in the sample in the fraction of no more than 5%. It is concluded on the basis of the data obtained that the spatial stabilization of iron-containing particles is one of the main factors facilitating the formation of the ε-Fe2O3 phase in a silica gel matrix without other iron oxide polymorphs. It is demonstrated that the increase in the iron content leads to the formation of larger particles in the sample and gradual changes of the Fe3+ ion local environment during the phase transition ε-Fe2O3 → α-Fe2O3.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Ivanova N. B., Bayukov O. A., Kazak N. V., Bezmaternykh L. N., Vasiliev A. D.
Заглавие : Evolution of the mossbauer spectra of ludwigite Co3-xFexO2BO3 with substitution of iron for cobalt
Место публикации : Phys. Solid State. - 2013. - Vol. 55, Is. 6. - P.1175-1179. - ISSN 1063-7834, DOI 10.1134/S1063783413060176
Аннотация: A concentration series of single crystals of iron-cobalt ludwigites Co3-xFexO2BO3 (x = 0.0125, 0.025, 0.050, 0.10, 1.0) has been synthesized. The structure has been studied using X-ray diffraction and Mossbauer effect. A preferred occupation of nonequivalent crystallographic positions by iron in the ludwigite structure has been revealed. It has been found that the valence of substituting iron ions is three. It has been revealed that the structure of the ?-resonance spectrum of Co2FeO2BO3 is complicated due to a composition disorder in the system. В© 2013 Pleiades Publishing, Ltd.
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20.

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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