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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Platunov M. S., Fedorova N. A., Pyastolova Yu. V., Laptash N. M., Knyazev Yu. V., Tomilin F. N., Dubrovskiy A. A.
Заглавие : Unraveling dynamic Jahn-Teller effect and magnetism in FeTiF6×6H2O single crystal
Колич.характеристики :9 с
Место публикации : J. Alloys Compd. - 2024. - Vol. 999. - Ст.175104. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2024.175104. - ISSN 18734669 (eISSN)
Примечания : Cited References: 51. - The authors thank the Joint Supercomputer Center (JSCC) of the Russian Academy of Sciences. The authors would like to express their sincere gratitude to the ID12 beamline staff their exceptional dedication and professionalism in performing the synchrotron experiment during the challenging circumstances of the COVID-pandemic. We are particularly grateful to the postdocs, scientists, and technicians who took part in the experiment, ensuring its successful completion. We also gratefully acknowledge the provision of beamtime (Proposal HC-4375) by the European Synchrotron Radiation Facility (ESRF). The access to this world-class facility was instrumental in obtaining the high-quality data that formed the basis of our research. We are deeply appreciative of the contributions of all involved, and we extend our heartfelt thanks to each and every one of them
Аннотация: Hydrated iron fluoridotitanate (FeTiF6 × 6 H2O) single crystals are fascinating magnetic materials with unique properties. To understand the underlying mechanisms, this study combines X-ray absorption near-edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) techniques, complemented by density functional theory (DFT) calculations. Polarization-dependent X-ray absorption spectroscopy, encompassing XANES and XMCD, is a powerful technique for probing the local structures and magnetic properties of materials. It is element-selective, bulk-sensitive, and compatible with a wide range of experimental conditions. In this study, we used XANES and XMCD spectroscopies to investigate the local structures and magnetic properties of Fe and Ti in FeTiF6 × 6 H2O single crystals. XANES analysis revealed distinct local environments around Fe and Ti, providing insights into their coordination environments. Element-selective magnetization measurement at the Fe K-edge demonstrated that iron sites in the oxidation state Fe2+ have an unambiguous paramagnetic contribution to the magnetization along the b-axis. Notably, the absence of an XMCD signal at the Ti K-edge confirmed the absence of a magnetic moment in Ti atoms within the crystal. DFT calculations corroborate the experimental findings and provide insights into the electronic structure and magnetic interactions. The combined results provide a comprehensive understanding of the dynamic Jahn-Teller effect in FeTiF6 × 6 H2O single crystals, highlighting the significance of polarization-dependent X-ray absorption spectroscopy in unraveling the intricate magnetic behavior of such materials. This study contributes to the fundamental understanding of magnetism in these materials and paves the way for the development of novel magnetic materials with tailored properties.
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2.

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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3.

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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4.

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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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhlin Y. L., Likhatski M. N., Romanchenko A. S., Vorobyev S. A., Tomashevich Y. V., Fetisova O. Yu., Bayukov O. A., Knyazev Yu. V., Nemtsev I. V., Karasev S. V., Karacharov A. A., Borisov R. V.
Заглавие : Valleriite-containing ore from Kingash deposit (Siberia, Russia): Mossbauer and X-ray photoelectron spectroscopy characterization, thermal and interfacial properties
Место публикации : J. Sib. Fed. Univ. Chem. - 2022. - Vol. 15, Is. 3. - P.303-317. - ISSN 19982836 (ISSN), DOI 10.17516/1998-2836-0294; Журн. СФУ. Химия
Примечания : Cited References: 25. - This research was funded by the Russian Foundation for Basic Research, Krasnoyarsk Territory Science Foundation and Krasnoyarsk Territory Administration, grant number 20-43-242903. Facilities of the Krasnoyarsk Regional Center of Research Equipment of Federal Research Center «Krasnoyarsk Science Center SB RAS» were employed in the work
Аннотация: Valleriite, (Cu,Fe)S2×n(Mg,Al,Fe)(OH)2, and related layered minerals are of interest due to their unusual two-dimensional structure, formation mechanisms, physical and chemical properties, and potential involvement into mineral processing and materials science applications. Here, we have studied Kingash Cu-Ni ore samples containing 10-25% of valleriite in association with serpentines (lizardite and chrysotile) and magnetite using scanning electron microscopy and electron microprobe analysis, Mössbauer spectroscopy, X-ray photoelectron spectroscopy (XPS), thermal analysis and zeta potential measurement. The data are compared with those for Al-doped valleriite synthesized via a hydrothermal route. It was found that the Kingash valleriite contains excessive iron relative to CuFeS2 stoichiometry, which mainly occurs, leaving aside magnetite, as Fe3+-OH species in hydroxide layers of valleriite and minor Fe centers in serpentines. Thermal dehydroxylation of hydroxide layers of valleriites occurs near 500oC in inert atmosphere; in air, sulfide sheets oxidize with an exothermal peak at 447oC, and sulfur oxides don't volatilize but react with hydroxide groups of valleriite rather than serpentines. Zeta potential measurements of coarse ore particles using the flow potential technique suggested that the surface of valleriite is negatively charged in a wide pH range while the positive values at low pHs for fine particles are inflicted by serpentine. The findings demonstrate close resemblance of the natural and synthetic Al-doped valleriites, and the key role of valleriite, despite its moderate content, for the interfacial characteristics of the valleriite-bearing ores.Валлериит, (Cu, Fe)S2×n(Mg, Al, Fe)(OH)2 и родственные ему слоистые минералы представляют интерес в связи с их необычной двумерной структурой, механизмами образования, физическими и химическими свойствами и возможностью применения в процессах переработки полезных ископаемых и материаловедения. В настоящей работе с помощью сканирующей электронной микроскопии и электронного микрозондового анализа, мессбауэровской спектроскопии, рентгеновской фотоэлектронной спектроскопии (РФЭС), термического анализа и измерения дзета-потенциала нами были изучены образцы медно-никелевых руд Кингашского месторождения, содержащие 10–25 % валлериита в ассоциации с серпентинами (лизардит и хризотил) и магнетитом. Было проведено сравнение полученных данных с результатами измерений легированного алюминием валлериита, синтезированного гидротермальным способом. Установлено, что валлериит Кингашского месторождения содержит избыточное железо по отношению к стехиометрии CuFeS2, которое представлено в основном, не считая магнетита, в виде центров Fe3+-OH, расположенных в гидроксидных слоях валлериита и небольшого числа примесей Fe в серпентинах. Термическое дигидроксилирование гидроксидных слоев валлериитов происходит около 500 °C в инертной атмосфере; на воздухе сульфидные слои окисляются с экзотермическим пиком при 447 °C, а оксиды серы не улетучиваются, а реагируют скорее с гидроксидными группами валлериита, чем с серпентинами. Измерения дзета-потенциала крупных частиц руды с использованием метода потенциала протекания показали, что поверхность валлериита отрицательно заряжена в широком диапазоне рН, в то время как положительные показатели при низких значениях рН для более мелких частиц обусловлены присутствием серпентина. Полученные данные демонстрируют близкое сходство природного и синтетического валлериитов, легированного алюминием, и его ключевую роль для межфазных характеристик валлериитсодержащих руд, даже при его умеренном содержании.
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6.

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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7.

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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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Balaev D. A., Stolyar S. V., Krasikov A. A., Bayukov O. A., Volochaev M. N., Yaroslavtsev R. N., Ladygina V. P., Velikanov D. A., Iskhakov R. S.
Заглавие : Interparticle magnetic interactions in synthetic ferrihydrite: Mossbauer spectroscopy and magnetometry study of the dynamic and static manifestations
Место публикации : J. Alloys Compd. - 2022. - Vol. 889. - Ст.161623. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2021.161623
Примечания : Cited References: 84. - This study was supported by the Russian Foundation for Basic Research, the Government of the Krasnoyarsk Territory, and the Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project no. 19–42–240012 R-A “Magnetic Resonance in Ferrihydrite Nanoparticles: Effects Related to the Core-Shell Structure”
Аннотация: Samples of synthetic ferrihydrite with an average nanoparticle size of 2.7 nm have been examined by magnetometry and Mossbauer spectroscopy. Ferrihydrite is characterized by the antiferromagnetic interactions between the magnetic moments of iron atoms. In ferrihydrite nanoparticles, as in any other antiferromagnetic ones, structural defects induce the formation of an uncompensated magnetic moment, which determines the magnetic properties typical of single-domain ferro- and ferrimagnetic particles. The manifestation of the magnetic interactions between ferrihydrite nanoparticles in the magnetic properties of the material and in the temperature evolution of Mossbauer spectra has been in focus. The results obtained on synthetic ferrihydrite have been compared with the data for the biogenic ferrihydrite sample with a similar average size of particles surrounded by a polysaccharide shell, which weakens and screens the interparticle magnetic interactions. A clear manifestation of the effect of the interparticle magnetic interactions on the transition to the blocked state is the presence of a significant contribution of the relaxation component in the Mossbauer spectra at temperatures of the transition from the superparamagnetic to blocked state. The temperature dependence of the particle relaxation time obtained from the Mossbauer spectra points out the collective effect of freezing of the magnetic moments of particles due to the magnetic interactions between them.
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9.

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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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Omelyanchik A., Kamzin A. S., Valiullin A. A., Semenov V. G., Vereshchagin S. N., Volochaev M. N., Dubrovskiy A. A., Sviridova T., Kozenkov I., Dolan E., Peddis D., Sokolov A. Е., Rodionova V.
Заглавие : Iron oxide nanoparticles synthesized by a glycine-modified coprecipitation method: Structure and magnetic properties
Место публикации : Colloids Surf. A Physicochem. Eng. Asp. - 2022. - Vol. 647. - Ст.129090. - ISSN 09277757 (ISSN), DOI 10.1016/j.colsurfa.2022.129090
Примечания : Cited References: 80. - This work was supported by the Russian Science Foundation grant No. 21-72-20158 . The study of the structure was carried out on the equipment of the Center Collective Use " Materials Science and Metallurgy " which was purchased with the financial support of the Russian Federation represented by the Ministry of Education and Science (No. 075-15-2021-696)
Аннотация: Iron oxide magnetic nanoparticles (MNPs) are of interest in biomedicine and research owing to their moderate cytotoxicity and advanced properties, such as extensive surface-to-volume ratio and possibilities for tailoring their functionality through surface chemistry. To date, various approaches have been used for the synthesis of MNPs with controllable structural properties and various coatings to enhance their stability and functionality. This study describes a modified one-step method of coprecipitation in the presence of glycine allowing the production of particles with controllable size and in situ surface decoration. The effect of different glycine concentrations on the morphostructural and magnetic properties of iron oxide MNPs is studied. The particle size is reduced from 10.2 ± 0.3 to 7.2 ± 0.5 nm by increasing the glycine concentration from 0.06 up to 0.60 mol. The magnetic properties of obtained particles were tracked by SQUID magnetometry and Mossbauer spectroscopy. All samples of glycine capped iron oxide MNPs showed superparamagnetic behaviour at room temperature with maximal value of the saturation magnetization of 69 ± 4 Am2/kg. The results show the optimal concentration range of glycine which can be used in this method: a lower concertation than 0.15 mol does not affect the properties of obtained particles while higher concentrations than 0.3 mol lead to the reduction of magnetic properties (the saturation magnetisation reduces to 59 ± 3 Am2/kg when glycine concentration was 0.6 mol). The proposed economic and environment-friendly approach can be utilized to synthesise –NH2 functionalised MNPs for biomedical or wastewater treatment.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Frolov K. V., Lyubutin I. S., Alekseeva O. A., Smirnova E. S., Dudka A. P., Verin I. A., Temerov V. L., Gudim I. A.
Заглавие : Magnetic properties and structural anomalies observed in multiferroic NdFe3(BO3)4 by 57Fe Mossbauer spectroscopy
Место публикации : J. Alloys Compd. - 2022. - Vol. 909. - Ст.164747. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2022.164747
Примечания : Cited References: 61. - This work was supported by the Russian Ministry of Science and Higher Education within the State assignment FSRC "Crystallography and Photonics" RAS and performed using the equipment of the Shared Research Center "Structural diagnostics of materials" of FSRC "Crystallography and Photonics" RAS
Аннотация: The results of studies of the NdFe3(BO3)4 by 57Fe Mossbauer spectroscopy in comparison with the data of single crystal X-ray diffraction measurements are presented. Scanning of the crystal cell parameters in a wide temperature range T = 15–500 K revealed a negative thermal expansion along the c axis and structural anomalies. The temperature dependences of the Mössbauer parameters of hyperfine interaction in the paramagnetic state of NdFe3(BO3)4 correlate well with the behavior of crystal cell parameters obtained by X-ray diffraction data. The temperature of the magnetic phase transition TN = 32.54(4) K is established, below which the iron ions form a 3D magnetic order of the Izing type. The magnetic transition of the iron subsystem from a commensurate to an incommensurate structure at a temperature of about T ≈ 15 K is discussed. The "Mössbauer" Debye temperature ΘM was estimated to be 485(2) K.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhlin Y. L., Likhatski M. N., Bayukov O. A., Knyazev Yu. V., Velikanov D. A., Tomashevich Y. V., Romanchenko A. S., Vorobyev S. A., Volochaev M. N., Zharkov S. M., Meira D. M.
Заглавие : Valleriite, a natural two-dimensional composite: X-ray absorption, photoelectron, and Mossbauer spectroscopy, and magnetic characterization
Место публикации : ACS Omega. - 2021. - Vol. 6, Is. 11. - P.7533-7543. - ISSN 24701343 (ISSN), DOI 10.1021/acsomega.0c06052
Примечания : Cited References: 92. - This research was supported by the Russian Science Foundation, project 18-17-00135. The authors thank Dr. Y. Laptev for providing valleriite samples, the ESRF for allocating beamtime and the BM23 staff for their help during the experiments. Facilities of the Krasnoyarsk Regional Research Equipment Centre of SB RAS were employed in the work
Аннотация: Valleriite is of interest as a mineral source of basic and precious metals and as an unusual material composed of two-dimensional (2D) Fe-Cu sulfide and magnesium hydroxide layers, whose characteristics are still very poorly understood. Here, the mineral samples of two types with about 50% of valleriites from Noril'sk ore provenance, Russia, were examined using Cu K- and Fe K-edge X-ray absorption fine structure (XAFS) spectroscopy, X-ray photoelectron spectroscopy (XPS), 57Fe Mossbauer spectroscopy, and magnetic measurements. The Cu K X-ray absorption near-edge structures (XANES) spectra resemble those of chalcopyrite, however, with a higher electron density at Cu+ centers and essentially differ from those of bornite Cu5FeS4; the Fe K-edge was less informative because of accompanying oxidized Fe-containing phases. The post-edge XANES and extended XAFS (EXAFS) analysis reveal differences in the bond lengths, e.g., additional metal-metal distances in valleriites as compared with chalcopyrite. The XPS spectra confirmed the Cu+ and Fe3+ state in the sulfide sheets and suggest that they are in electron equilibrium with (Mg, Al) hydroxide layers. Mossbauer spectra measured at room temperature comprise central doublets of paramagnetic Fe3+, which decreased at 78 K and almost disappeared at 4.2 K, producing a series of hyperfine Zeeman sextets due to internal magnetic fields arising in valleriites. Magnetic measurements do not reveal antiferromagnetic transitions known for bornite. The specific structure and properties of valleriite are discussed in particular as a platform for composites of the 2D transition metal sulfide and hydroxide (mono)layers stacked by the electrical charges, promising for a variety of applications.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Smirnova E., Alekseeva O. A., Dudka A. P., Verin I. A., Artemov V. V., Khmelenin D. N., Gudim I. A., Frolov K. V., Lyubutin I. S.
Заглавие : Structural peculiarities of bismuth-containing RFe3(BO3)4 (R = Ho, Y, Sm, Nd)
Коллективы : Congress of the International Union of Crystallography , Ministry of Science and Higher Education within the State assignment FSRC 'Crystallography and Photonics' RAS
Место публикации : Acta Crystallogr. A. - 2021. - Vol. 77, Supplement. - P.C1237-C1237. - ISSN 2053-2733, DOI 10.1107/S0108767321084749
Примечания : Cited References: 4. - This work was performed using the equipment of the Shared Research Center FSRC 'Crystallography and Photonics' RAS and was supported by the Ministry of Science and Higher Education within the State assignment FSRC 'Crystallography and Photonics' RAS
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Abramova G. M., Knyazev Yu. V., Bayukov O. A., Kubrin S. P.
Заглавие : Magnetic states of Fe2+ ions in FexMn1–xS induced by chemical pressure
Место публикации : Phys. Solid State. - 2021. - Vol. 63, Is. 1. - P.68-74. - ISSN 10637834 (ISSN), DOI 10.1134/S1063783421010029
Примечания : Cited References: 25. - The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (state contract in the sphere of scientific activities, Southern Federal University, 2020)
Аннотация: Influence of the chemical pressure (x) in single crystals of FexMn1 – xS (0.12 ≤ x ≤ 0.29) on the spin state of iron ions was studied by Mössbauer spectroscopy in the temperature range from 4.2 to 300 K. Peculiarities of formation of the paramagnetic and antiferromagnetic phases of solid solutions were found. Substitution of Fe2+ cations in the high-spin state for Mn2+ was found to occur in FexMn1 – xS as x changes. A decrease in the distance between the ions in FexMn1 – xS induces changes in the state of the Fe2+ ions in the samples with x = 0.25 and 0.29. The asymmetry parameter of the electric field gradient (EFG) tensor and the angle between the directions of the magnetic moment and the principal axis of the electric field gradient were found to change in the magnetically ordered phase at 4.2 K; the angle between the magnetic moment and the electric field gradient axis changes from 21° in the sample with x = 0.12 to 33° when x = 0.29.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivantsov R. D., Lin C. -R., Ivanova O. S., Altunin R. R., Knyazev Yu. V., Molokeev M. S., Zharkov S. M., Chen Y. -Z., Lin E. -S., Chen B. -Y., Shestakov N. P., Edelman I. S.
Заглавие : Mossbauer and MCD spectroscopy of the Fe3S4 nanoparticles synthesized by the thermal decomposition method with two different surfactants
Место публикации : Curr. Appl. Phys. - 2021. - Vol. 25. - P.55-61. - ISSN 15671739 (ISSN), DOI 10.1016/j.cap.2021.02.013
Примечания : Cited References: 30. - The reported study was funded by Joint Research Project of Russian Foundation for Basic Research № 19-52-52002 and Ministry of Science and Technology, Taiwan MOST № 108-2923-M-153-001-MY3 and № 106-2112-M-153-001-MY3 , and by Russian Foundation for Basic Research with Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science , the research project number 19-42-240005 : “Features of the electronic structure, magnetic properties and optical excitations in nanocrystals of the multifunctional magnetic chalcogenides Fe3S4 and FeSe”. The electron microscopy and electron diffraction investigations were conducted in the SFU Joint Scientific Center supported by the State assignment (#FSRZ-2020-0011) of the Ministry of Science and Higher Education of the Russian Federation. The thermal-gravity measurements were carried out with the differential Scanning Calorimeter DSC 204 F-1 Phoenix (NETZSCH) in the Krasnoyarsk Regional Center of Research Equipment of Federal Research Center «Krasnoyarsk Science Center SB RAS»
Аннотация: Greigite (Fe3S4) nanoparticles (NPs) were fabricated by the thermal decomposition method using two different surfactants: oleylamine (OLA) and 1-hexadecylamine (HDA). In both cases, the synthesized NPs were characterized as the Fe3S4 nanocrystals with minor inclusions of Fe9S11 phase. FT-IR spectroscopy and thermo-gravimetric analysis allow concluding about OLA or HDA shells covering magnetic core of NPs. Mossbauer spectra has revealed deviations of iron ions distribution among crystal positions from that presented in literature for pure greigite. In accordance with these deviations, the pronounce changes are observed in the magnetic circular dichroism (MCD) spectra which manifest themselves as the spectrum shift to higher energies of electromagnetic waves and redistribution of the MCD maximum intensities. These effects are associated with a change in the density of electronic states in the samples due to the redistribution of iron ions between octahedral and tetrahedral positions in nanocrystals under the influence of surfactants.
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16.

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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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Chumakov A. I., Dubrovskiy A. A., Semenov S. V., Sergueev I., Yakushkin S. S., Kirillov V. L., Martyanov O. N., Balaev D. A.
Заглавие : Nuclear forward scattering application to the spiral magnetic structure study in epsilon-Fe2O3
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [17-12-01111, SC-4708]
Место публикации : Phys. Rev. B. - 2020. - Vol. 101, Is. 9. - Ст.094408. - ISSN 2469-9950, DOI 10.1103/PhysRevB.101.094408. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 44. - We thank Dr. Natalia Kazak for assistance with the NFS measurements. This study was supported by the Russian Science Foundation, Project No. 17-12-01111. We thank the European Synchrotron Radiation Facility for provision of the synchrotron radiation facilities at the beamline ID18 (Exp. No. SC-4708)
Предметные рубрики: INCOMMENSURATE STRUCTURES
MOSSBAUER-SPECTROSCOPY
HIGH-TEMPERATURE
Аннотация: The ε−Fe2O3 magnetic structure has been analyzed using the synchrotron radiation source. Time spectra of nuclear forward scattering for isolated nanoparticles with an average size of 8 nm immobilized in a xerogel matrix have been recorded in the temperature range of 4–300K in applied magnetic fields of 0–4T in the longitudinal direction at the European Synchrotron Radiation Facility (ESRF, Grenoble, France). It has been found that the external magnetic field does not qualitatively change the Hhf(T) behavior, but makes a strong opposite impact on the hyperfine fields in the nonequivalent iron sites, leading to the divergence of Hhf polar angle dependences below 80 K. A complete diagram of the ε−Fe2O3 magnetic structure in the temperature range of 4–300K is proposed. At 300 K, the ε−Fe2O3 compound is confirmed to be a collinear ferrimagnet. The experimental results show that the magnetic transition at 150–80K leads to the formation of a noncollinear magnetic structure. Furthermore, in the range of the 80–4 K, the ground state of a magnetic spiral is established. The experimental results are supplemented by the analysis of the exchange interactions and temperature dependence of the magnetization in a magnetic field of 7 T.
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18.

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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19.

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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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Plotnikova A. A., Bragin V. I., Knyazev Yu. V.
Заглавие : Structural Characteristics and Processability of Sphalerite in Lead-Zinc Ore of the Gorevka Deposit
Место публикации : J. Min. Sci. - 2019. - Vol. 55, Is. 6. - P.995-1006. - ISSN 1062-7391, DOI 10.1134/S1062739119066381. - ISSN 1573-8736(eISSN)
Примечания : Cited References: 33
Аннотация: The theoretical and experimental substantiation of the behavior of ferrous sphalerite in magnetic separation is given in terms of the Gorevka deposit ore. In sphalerite of this deposit, the content of isomorphous iron ranges as 4-9%. The Mossbauer spectroscopy showed the singlet and two doublet lines of iron, demonstrating separate arrays of iron atoms in sphalerite lattice, with formation of Fe-Fe pairs and clusters of three or more iron atoms. It is found that distribution of iron in sphalerite into three forms coincides for magnetic and nonmagnetic products of zinc concentrate separation. It is determined that magnetic separation undivides sphalerite grains by the isomorphous iron content but is governed by the genetic features of the deposit formation-association of sphalerite with magnetic minerals (pyrrhotine and siderite) and the absence of such associations in galena.
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