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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Myagkov V. G., Zhigalov V. S., Bykova L. E., Bondarenko G. N.
Заглавие : Invar effect and solid-state synthesis in Ni/Fe(001)/MgO(001) thin films: structural and magnetic studies
Место публикации : Байкальская международная конференция”Магнитные материалы: Новые технологии”, Россия, Иркутск, 2008, С.56
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bukhanov E. R., Shikhov V. N., Velichko V. V., Lipshin A. G., Surin N. A.
Заглавие : Influence of growth environment on structural and optical characteristics of higher plants
Колич.характеристики :5 с
Коллективы : International Advances in Applied Physics and Materials Science Congress and Exhibition
Место публикации : AIP Conf. Proc. - 2024. - Vol. 2924: Proceedings of the 3rd International Advances in Applied Physics and Materials Science Congress & Exhibition, Is. 1. - Ст.040003. - ISSN 0094243X (ISSN), DOI 10.1063/5.0181655. - ISSN 15517616 (eISSN). - ISSN 978-073544852-0 (ISBN)
Примечания : Cited References: 26
Аннотация: Two barley samples were taken for the study – one grown in the field and the other in a special chamber under intensive light. Chloroplasts structure was obtained during electron microscopy process. The results showed that the maximum quantum yield of photosystem II in both samples was in the range of values typical for normal physiological state of plants. At the same time, electron transport speed comparison shows that electrons are transferred 1.7 times faster in the vegetation chamber compared to field environment. Such difference is confirmed by the results of microscopy performed with flag leaves tissue samples of barley grown under intensive light in a chamber and in the field. A grana structure significantly denser and better organized was observed in chloroplasts of barley grown in chamber. This study shows a clear connection between the environment, the ordering of thylakoid structures and fluorescent indicators of photosynthesis.
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Вид документа : Статья из журнала
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Автор(ы) : Flerov I. N., Gorev M. V., Bogdanov E. V., Laptash N. M.
Заглавие : Chemical pressure as an effective tool for tuning the structural disordering and barocaloric efficiency of complex fluorides (NH4)3MF7 (M: Sn, Ti, Ge, Si)
Колич.характеристики :18 с
Место публикации : J. Phys. D: Appl. Phys. - 2024. - Vol. 57, Is. 17. - Ст.175301. - ISSN 00223727 (ISSN), DOI 10.1088/1361-6463/ad211b. - ISSN 13616463 (eISSN)
Примечания : Cited References: 39. - The study was supported by a Grant from the Russian Science Foundation No. 23-22-00115, https://rscf.ru/project/23-22-00115/
Аннотация: Double fluoride salts (NH4)3M4+F7 (M4+: Sn, Ti, Ge, Si) demonstrate a high efficiency of using chemical pressure as a tool for control and tuning structural ordering/disordering, sensitivity to hydrostatic pressure, successions of the phase transitions, etc and, as a result, for purposeful variation within a wide range of parameters of barocaloric effect (BCE). The conventional and inverse BCEs near the triple points were found on the T − p phase diagrams, combination of which can be used to construct original cooling cycle in narrow temperature and pressure ranges. Reconstructive transformation between two cubic phases, Pm3-m ↔ Pa3-, realized in (NH4)3SnF7 at atmospheric pressure and in (NH4)3TiF7 at p ˃ 0.4 GPa are characterized by rather low thermal hysteresis, δT0 = 1 K, and a great entropy change, ΔSBCE = 110–152 J (kg · K)−1, depending on the size of the central atom. At above 300–350 K, a contribution to BCE associated with the regular thermal expansion of the crystal lattice becomes comparable to entropy and temperature changes under pressure in the region of the phase transitions. An analysis of the absolute, relative and integral barocaloric characteristics of (NH4)3M4+F7 compounds showed their high competitiveness with respect to other barocaloric materials considered as promising solid-state refrigerants.
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Вид документа : Статья из журнала
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Автор(ы) : Banerjee S., Saikia S., Molokeev M. S., Nag A.
Заглавие : Unveiling temperature-induced structural phase transition and luminescence in Mn2+-doped Cs2NaBiCl6 double perovskite
Колич.характеристики :8 с
Место публикации : Chem. Mater. - 2024. - Vol. 36, Is. 9. - P.4750-4757. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.4c00514. - ISSN 15205002 (eISSN)
Примечания : Cited References: 49. - Authors acknowledge Dr. Arup Rath’s lab NCL Pune and SAIF-IIT Bombay for diffuse reflectance spectroscopy and ICP-AES measurements, respectively. A.N. acknowledges Science & Engineering Research Board, India, for Swarnajayanti Fellowship (SB/SJF/2020-21/02), and BRICS grant (e-27558) of the Department of Science and Technology, India. Authors acknowledge the Department of Science and Technology India (FIST program, SR/FST/CS-II/2019/105) for temperature-dependent powder XRD and EPR data. S.B. is grateful to IISER Pune for a research fellowship. S.S. acknowledges Prime Minister’s Research Fellowship (PMRF), Ministry of Education, India. M.M. acknowledges the Russian Science Foundation, grant 24-43-00006
Аннотация: Halide double perovskites like Cs2NaBiCl6 are good host materials for luminescent dopants like Mn2+. The nature of photoluminescence (PL) depends on the local structure around the dopant ion, and doping may sometimes influence the global structure of the host. Here, we unveil the correlation between the temperature-induced (global) structural phase transition of Mn2+-doped Cs2NaBiCl6 with the local structure and PL of the Mn2+ dopant. X-ray diffraction analysis shows Mn2+-doped Cs2NaBiCl6 is in a cubic (Fm3m) phase between 300 and 110 K, below which the phase changes to tetragonal (I4/mmm), which persists at least until 15 K. The small (∼1%) doping amount does not alter the phase transition behavior of Cs2NaBiCl6. Importantly, the phase transition does not influence the Mn2+ d-electron PL. The PL peak energy, intensity, spectral width, and lifetime do not show any signature of the phase transition between 300–6 K. The hyperfine splitting in temperature-dependent electron paramagnetic spectra of Mn2+ ions also remain unchanged across the phase transition. These results suggest that the global structural phase transition of the host does not influence the local structure and emission property of the dopant Mn2+ ion. This structure–property insight might be explored for other transition-metal- and lanthanide-doped halide double perovskites as well. The stability of dopant emission regardless of the structural phase transition bodes well for their potential applications in phosphor-converted light emitting diodes.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Oreshonkov A. S., Aleksandrovsky A. S., Chimitova O.D., Pankin D.V., Popov Z.I., Sukhanova E.V., Molokeev M. S., Adichtchev S.V., Pugachev A.M., Nemtsev I. V.
Заглавие : Solid state synthesis, structural, DFT and spectroscopic analysis of EuAl3(BO3)4
Колич.характеристики :10 с
Место публикации : Mater. Chem. Phys. - 2024. - Vol. 320. - Ст.129400. - ISSN 02540584 (ISSN), DOI 10.1016/j.matchemphys.2024.129400. - ISSN 18793312 (eISSN)
Примечания : Cited References: 55. - The work was carried out within the state assignment No FWES-2024-0003 of Kirensky Institute of Physics. This work was partially supported by the state order of BINM SB RAS (0273-2021-0008). The samples for this research were synthesized using equipment of the CCU BINM SB RAS. The reflectance spectrum was obtained at the Center for Optical and Laser Materials Research of Research park of St. Petersburg State University. The SEM measurements were performed at Krasnoyarsk Regional Center of Research Equipment of Federal Research Center "Krasnoyarsk Science Center SB RAS"
Аннотация: Huntite-like borates are versatile and promising materials with wide range of applications in frequency conversion, UV light generation, lighting, displays, quantum information storage, and more, demonstrated by their various properties and uses in scientific research. In this work, EuAl3(BO3)4 powder was prepared through multi-stage solid-state reaction method using high-purity starting reagents: Eu2O3, Al2O3 and H3BO3, considering a 20 wt% excess of H3BO3 to compensate for B2O3 volatilization. Obtained samples undergo several treatments at varying temperatures and their phase purity is subsequently verified through powder X-ray diffraction analysis. The scanning electron microscopy reveals that resulting EuAl3(BO3)4 powder consists of granules exhibiting irregular morphologies with dimensions of 0.5–8 μm. The electronic band structure of EuAl3(BO3)4, calculated using the GGA PBE method, reveals f-states of Eu near 4 eV. These states do not produce emphasized peaks on simulated absorbance spectra. Using of DFT + U for the f-states of Eu pushed up f-bands above 6 eV and the charge transfer from p-O to d-Eu was obtained (Egdirect = 5.63 eV, Egindirect = 5.37 eV using Ueff = 4 eV). The variation of Ueff has a weak influence on the position of the bottom of the conduction band. The experimental bandgaps of EuAl3(BO3)4 crystalline powder, both direct and indirect, are found to be 3.96 and 3.67 eV, correspondingly. These values are lower than theoretical values what is associated with limitations of DFT calculations involving f electrons. The Raman spectrum of EuAl3(BO3)4 powder is discussed, detailing the contributions of different ions to specific spectral bands. Investigation of high-resolution luminescence spectra shows the possibility to estimate the content of defects by the testing the violation of the prohibition of ultranarrow 5D0 → 7F0 line that is forbidden in the ideal crystalline structure of trigonal EuAl3(BO3)4.
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Вид документа : Статья из журнала
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Автор(ы) : Ma Y., Liao W., Quan B., Kong Z., Molokeev M. S., Zolotov A., Cheng M., Chen X., Zhou Zh., Xia M.
Заглавие : Solid solution structural engineering enhances the luminescence of SrMgAl10O17:Cr3+ for agricultural lighting
Колич.характеристики :7 с
Место публикации : J. Lumin. - 2024. - Vol. 270. - Ст.120553. - ISSN 00222313 (ISSN), DOI 10.1016/j.jlumin.2024.120553. - ISSN 18727883 (eISSN)
Примечания : Cited References: 46. - The authors would like to gratefully acknowledge funds from the Key R & D Projects in Hunan Province (2021SK2047, 2022NK2044), the Wangcheng Science and Technology Plan (KJ221017), the Science and Technology Innovation Program of Hunan Province (2022WZ1022). The work was supported by the Ministry of Science and Higher Education of the Russian Federation as part of the World-class Research Center program: ‘‘Advanced Digital Technologies’’, contract no. 075-15-2020-935. Research Foundation of Education Bureau of Hunan Province, China (22B0211)
Аннотация: Lead-free non-rare earth oxide phosphors have attracted wide attention due to their environmental protection, sustainability, and potential to replace halides and fluorides in the field of plant lighting. Among them, the Cr3+-excited aluminate phosphor exhibits high brightness, high thermal stability, and far red to near-infrared (NIR) emission due to the influence of the crystal field strength (CFS). This property gives rise to a variety of strategies used to modulate the CFS, for example, single ion substitution, chemical unit co-substitution, etc. Here, we chose the substitution of a single ion, with [BaO6] gradually replacing [SrO6] to form a solid solution. Their structural characteristics and the local structure of Cr3+ are studied and discussed. The device is packaged to evaluate the feasibility of the material for practical application. The prepared phosphor had a bright far-red light emission of 693 nm under blue light excitation, and this spectrum strongly matched the absorption of plant phytochrome PFR. This work provides the design principle of far red light emission activated by Cr3+ aluminate solid solution, which can inspire further research on pc-LED lights for plant lighting.
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Вид документа : Статья из журнала
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Автор(ы) : Shchapova, Yuliya V., Krylov A. S., Votyakov, Sergei L.
Заглавие : Structural characteristics of radiation-amorphized ZrSiO4:U,Th according to Raman spectroscopy of Boson peak
Место публикации : J. Raman. Spectrosc. - 2023. - Vol. 54, Is. 6. - P.662-673. - ISSN 03770486 (ISSN), DOI 10.1002/jrs.6526. - ISSN 10974555 (eISSN)
Примечания : Cited References: 66. - The study was carried out within IGG UB RAS State assignment, registration number 123011800012-9 (YVS and SLV). The authors thank Dmitry Zamyatin for performing electron probe microanalysis of zircon chemical composition. The authors are grateful to Olga Galakhova for X-ray diffraction measurements. The equipment of the «Geoanalitik» shared research facilities of the IGG UB RAS was used, the re-equipment and comprehensive development of which is financially supported by the grant of the Ministry of Science and Higher Education of the Russian Federation, Agreement No. 075-15-2021-680 (YVS and SLV). The temperature Raman experiments were performed in the Krasnoyarsk Regional Center of Research Equipment of Federal Research Center ‘Krasnoyarsk Science Center SB RAS’
Аннотация: The structure of the amorphous fraction and the tensile-compressive stressesin amorphous-crystalline radiation-damaged zircon ZrSiO:U,Th depending on radiation dose and temperature (8–350 K) are investigated according to Raman spectroscopy of Boson peak for the first time. The Boson peak at 60–70 cm-1 associated with localized phonon states in the amorphous fraction (fa) is recorded at low temperatures (T ˂ 100 K) for samples with fa ˂ 30% and over the entire temperature range 8–350 K for fa ˃ 70%. The wider localized states distribution in the latter case is considered as a sign of the amorphous phase structure evolution with an increase in radiation dose. The estimates of anatomic correlation radius based on the Ioffe–Regel criterion are similar to those in glasses, Rc2:0 – 2:3 nm. The monotonic increase in Rc value during heating of zircon with fa ˃ 70% is governed by thermal expansion of the percolating amorphous fraction. The nonmonotonic variations of the Rc value in zircon with fa ˂ 30% is determined by the stresses in the amorphous fraction due to the mismatch in thermal expansion coefficient (CTE) and elastic moduli of the amorphous and crystalline phases depending on temperature; a change in the sign of the crystalline fraction CTE at 30 K is assumed. The Boson peak disappearance at 100 K in zircon with fa ˂ 30% during heating conforms to with the violation of the phonon localization as a consequence of amorphous fraction contraction and partial ordering. The data obtained are important for predicting the thermal and mechanical properties of heterogeneous radiation-damaged materials and nanocomposites.
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Вид документа : Статья из журнала
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Автор(ы) : Аверьянов, Евгений Михайлович
Заглавие : Молекулярно-оптическая и структурная анизотропия одноосных монодоменных/полидоменных пленок сопряженного полимера F8BT с аксиальной/плоскостной ориентацией макромолекул
Место публикации : Жидк. крист. и их практич. использ. - 2023. - Т. 23, № 1. - С. 68-77. - ISSN 19913966 (ISSN), DOI 10.18083/LCAppl.2023.1.68; Liq. Cryst. Appl. - ISSN 24999644 (eISSN)
Примечания : Библиогр.: 14
Аннотация: На практике используются одноосные полимерные пленки двух типов: монодоменные пленки на ориентирующих подложках с аксиальной ориентацией макромолекул относительно оптической оси пленки n, параллельной плоскости подложки (тип ОА); полидоменные пленки на изотропных подложках с плоскостной ориентацией макромолекул и оптической осью n, нормальной к подложке (тип ОP). Молекулярно-оптическая анизотропия пленки определяется средней по ансамблю анизотропией δγ = γ|| – γ⊥ компонент поляризуемости γj мономерных звеньев полимерных цепей для поляризаций световой волны вдоль (j = ||) и нормально (j = ⊥) оси n. Структурную анизотропию пленки описывают параметры ориентационного порядка U дипольных моментов m электронных (колебательных) переходов в мономерных звеньях макромолекул относительно оси n. Для пленок одного полимера значения параметров Rδ(λ) = δγА/δγP и RU = UA/UP характеризует степень близости полидоменной пленки к идеальному двумерному поликристаллу. В данной работе исследованы зависимость Rδ(λ) от длины световой волны λ в видимой области прозрачности и параметры порядка UA(P) для дипольного момента длинноволнового электронного перехода в монодоменных и полидоменных пленках сопряженного полимера F8BT. Значения Rδ(λ) получены из показателей преломления пленок nj(λ) с учетом компонент fj(λ) = 1 + Lj[nj2(λ) – 1] тензора локального поля. Компоненты Lj тензора Лорентца определены с использованием зависимостей nj(λ). Значения Rδ(λ) согласуются с Rδ = –2 для двумерного поликристалла, состоящего из одноосных кристаллитов. Параметры UA(P) определены с использованием фоновых величин nbj и максимальных значений kjmax компонент комплексного показателя преломления Nj(λ) = nj(λ) + ikj(λ) пленок в области длинноволновой полосы электронного поглощения при учете фоновых значений fbj = 1 + Lj(nbj2 – 1). Экспериментальное значение RU отличается от RU = –2 для двумерного поликристалла, что показывает чувствительность параметра UP к ориентационному беспорядку мономерных звеньев макромолекул в междоменных областях полидоменных пленок.Two types of uniaxial polymer films are used in practice. The first type is singledomain film on orienting substrate with axial orientation of macromolecules with respect to the optical axis of the film n which is parallel to the substrate plane (type ОА). The second type is polydomain film on isotropic substrate with in-plane orientation of macromolecules and the optical axis of the film n which is perpendicular to the substrate plane (type ОP). The molecular-optical anisotropy of a film is defined by the ensemble-averaged anisotropy δγ = γ|| – γ⊥ of the components γj of the polarizability of the monomer units of a polymer for the light-wave polarizations along (j = ||) and across (j = ⊥) the optical axis n. The structural anisotropy of the film is described by the orientation order parameters U of the dipole moments m of the electronic (oscillatory) transitions in monomer units of macromolecule with respect to axis n. For films of the same polymer, the values of Rδ(λ) = δγА/δγP and RU = UA/UP characterize the closeness degree of the polydomain film to the ideal twodimensional polycrystal. In this work, the dependence Rδ(λ) on the light-wavelength λ in the visible range and the order parameters UA(P) for the dipole moment of the long-wavelength electronic transition in single-domain and polydomain films of the conjugated polymer F8BT were studied. The values Rδ(λ) were determined from the refractive indices nj(λ) of the films with the local-field tensor components fj(λ) = 1 + Lj[nj2(λ) – 1]. The Lorentz-tensor components Lj were obtained using the dependences nj(λ). The values Rδ(λ) are in agreement with Rδ = –2 for two-dimensional polycrystal consisted of the uniaxial crystallites. The parameters UA(P) were determined with the use of the background values nbj and maximal values kjmax of the components of the complex refractive indices Nj(λ) = nj(λ) + ikj(λ) of the films in the region of their long-wavelength electronic absorption band, taking into account the background values fbj = 1 + Lj(nbj2 – 1). The experimental value RU differs from RU = –2 for two-dimensional polycrystal. This difference reveals the sensitivity of the parameter UP to the orientation disorder of the monomer units of macromolecules in interdomain regions of polydomain films.
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Вид документа : Статья из журнала
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Автор(ы) : Udod L. V., Aplesnin S. S., Sitnikov M. N., Eremin E. V., Molokeev M. S., Shabanov A. V., Romanova O. B., Kharkov A. M.
Заглавие : Structural and magnetic transitions in the Bi2Fe4O9/BiFeO3 composite
Место публикации : J. Alloys Compd. - 2023. - Vol. 958. - Ст.170445. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2023.170445. - ISSN 18734669 (eISSN)
Примечания : Cited References: 51
Аннотация: A Bi2Fe4O9/BiFeO3 composite with a percentage ratio of 67/33 has been synthesized, its morphological analysis has been carried out. The average crystallite sizes for each phase have been determined. The magnetization hysteresis has been established and the temperature of its disappearance has been found. Using the infrared absorption spectra, temperatures of the magnetic phase transitions in each phase have been determined from the magnetic susceptibility, magnetostriction constant, ultrasound damping coefficient, and phonon mode softening. The change of magnetostriction constant sign observed in the vicinity of the spin reorientation transition and antiferromagnetic transition in mullite has been attributed to the change of the sign of the magnetoelastic constants. The interaction between the phases in the composite and the correlation of its structural and magnetic properties have been established.
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Вид документа : Статья из журнала
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Автор(ы) : Kirik N., Krylov A. S., Boronin A., Koshcheev S., Solovyov L., Rabchevskii E., Shishkina N., Anshits A.
Заглавие : The relationship between the structural characteristics of α-Fe2O3 catalysts and their lattice oxygen reactivity regarding hydrogen
Место публикации : Materials. - 2023. - Vol. 16, Is. 12: The 15th Anniversary of Materials — Recent Advances in Catalytic Materials. - Ст.4466. - ISSN 19961944 (eISSN), DOI 10.3390/ma16124466
Примечания : Cited References: 63. - This work was conducted within the framework of the budget project for the Institute of Chemistry and Chemical Technology of the Siberian Branch of the Russian Academy of Sciences, Federal Research Center KSC SB RAS, No. FWES–2021–0013
Аннотация: In this paper, the relationship between the structural features of hematite samples calcined in the interval of 800–1100 °C and their reactivity regarding hydrogen studied in the temperature-programmed reaction (TPR-H2) was studied. The oxygen reactivity of the samples decreases with the increasing calcination temperature. The study of calcined hematite samples used X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), and Raman spectroscopy, and their textural characteristics were studied also. According to XRD results, hematite samples calcined in the temperature range under study are monophase, represented by the α-Fe2O3 phase, in which crystal density increases with increasing calcination temperature. The Raman spectroscopy results also register only the α-Fe2O3 phase; the samples consist of large, well-crystallized particles with smaller particles on their surface, having a significantly lower degree of crystallinity, and their proportion decreases with increasing calcination temperature. XPS results show the α-Fe2O3 surface enriched with Fe2+ ions, whose proportion increases with increasing calcination temperature, which leads to an increase in the lattice oxygen binding energy and a decrease in the α-Fe2O3 reactivity regarding hydrogen.
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11.

Вид документа : Статья из журнала
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Автор(ы) : Moshkina E. M., Belskaya N. A., Molokeev M. S., Bovina A. F., Shabanova K. A., Kokh D., Seretkin Yu. V., Velikanov D. A., Eremin E. V., Krylov A. S., Bezmaternykh L. N.
Заглавие : Growth conditions and the structural and magnetic properties of Cu2MBO5 (M = Cr, Fe, Mn) oxyborates with a ludwigite structure
Коллективы : Eurasian Symposium “Trends in Magnetism”
Место публикации : J. Exp. Theor. Phys. - 2023. - Vol. 136, Is. 1. - P.17-25. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776123010144. - ISSN 10906509 (eISSN)
Примечания : Cited References: 23. - The study was supported by the Russian Science Foundation (grant no. 22-12-20019) and Krasnoyarsk Regional Science Foundation
Аннотация: Copper oxyborate single crystals with a ludwigite structure, Cu2MBO5 (M = Cr, Fe, Mn), containing different substitutes in the trivalent subsystem have been grown from Bi2O3–MoO3–Na2O–B2O3 fluxes. The structural properties of grown compounds have been compared in detail using X-ray diffraction and Raman spectroscopy methods. In addition, these methods have been used to determine the degree of cationic ordering in these ludwigites. The temperature and field dependences of the Cu2MBO5 (M = Cr, Fe, Mn) ludwigite magnetization are presented.
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12.

Вид документа : Статья из журнала
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Автор(ы) : Grossman V., Atuchin V. V., Bazarov B. G., Aleksandrovsky A. S., Eremin E. V., Krylov A. S., Kuratieva N., Bazarova J. G., Maximov N., Molokeev M. S., Oreshonkov A. S., Pervukhina N., Shestakov N. P.
Заглавие : Structural, spectroscopic, electric and magnetic properties of new trigonal K5FeHf(MoO4)6 orthomolybdate
Место публикации : Molecules. - 2023. - Vol. 28, Is. 4. - Ст.1629. - ISSN 14203049 (eISSN), DOI 10.3390/molecules28041629
Примечания : Cited References: 82. - This work was supported by the state order of BINM SB RAS (0273-2021-0008), IIC (121031700318-8), ISP (FWGW-2022-0006) and the Russian Science Foundation (21-19-00046). The research was granted by the Government of the Russian Federation (075-15-2022-1132)
Аннотация: A new multicationic structurally disordered K5FeHf(MoO4)6 crystal belonging to the molybdate family is synthesized by the two-stage solid state reaction method. The characterization of the electronic and vibrational properties of the K5FeHf(MoO4)6 was performed using density functional theory calculations, group theory, Raman and infrared spectroscopy. The vibrational spectra are dominated by vibrations of the MoO4 tetrahedra, while the lattice modes are observed in a low-wavenumber part of the spectra. The experimental gap in the phonon spectra between 450 and 700 cm−1 is in a good agreement with the simulated phonon density of the states. K5FeHf(MoO4)6 is a paramagnetic down to 4.2 K. The negative Curie–Weiss temperature of −6.7 K indicates dominant antiferromagnetic interactions in the compound. The direct and indirect optical bandgaps of K5FeHf(MoO4)6 are 2.97 and 3.21 eV, respectively. The K5FeHf(MoO4)6 bandgap narrowing, with respect to the variety of known molybdates and the ab initio calculations, is explained by the presence of Mott-Hubbard optical excitation in the system of Fe3+ ions.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhu, Yingze, Wang, Xuesong, Qiao, Jianwei, Molokeev M. S., Swart, Hendrik C., Ning, Lixin, Xia, Zhiguo
Заглавие : Regulating Eu2+ multisite occupation through structural disorder toward broadband near-infrared emission
Место публикации : Chem. Mater. - 2023. - Vol. 35, Is. 3. - P.1432-1439. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.2c03631. - ISSN 15205002 (eISSN)
Примечания : Cited References: 33. - This research was supported by the National Key Research and Development Program of China (2021YFB3500400 and 2021YFE0105700), the National Natural Science Foundations of China (Grant Nos. 51972118, 11974022, and 52102169), the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01X137), the China Postdoctoral Science Foundation (2021M691053), and the Young Elite Scientists Sponsorship Program by China Association for Science and Technology (No. YESS20200053)
Аннотация: To promote the development of near-infrared (NIR) light sources in optoelectronic and biomedical applications, the discovery of NIR-emitting phosphor materials and their design principles are essential. Herein, we report a novel Eu2+-activated broadband NIR-emitting phosphor, BaSrGa4O8:Eu2+, which features multisite occupation due to Ba/Sr and oxygen site occupancy disorder. With an increase in the Ba/Sr atomic ratio from 1:1 to 1.7:0.3, the Eu2+ emission band maximum red-shifts from 670 to 775 nm, along with an enlargement of the full width at half-maximum (FWHM) from 140 to 230 nm. The underlying mechanism for the structure–property relationship is elucidated using density functional theory calculations. The application of the NIR phosphor-converted light-emitting diodes (pc-LEDs) is demonstrated, showing their potential in night-vision technology. Our results can initiate further exploitation of the host structural disorder toward Eu2+ broadband NIR luminescence for applications in pc-LEDs.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lim, Chang S., Aleksandrovsky A. S., Molokeev M. S., Oreshonkov A. S., Atuchin V.
Заглавие : Structural and spectroscopic effects of Li+ substitution for Na+ in LixNa1–xCaLa0.5Er0.05Yb0.45(MoO4)3 upconversion scheelite-type phosphors
Место публикации : Crystals. - 2023. - Vol. 13, Is. 2. - Ст.362. - ISSN 20734352 (eISSN), DOI 10.3390/cryst13020362
Примечания : Cited References: 63. - This study was funded by the Research Program through the Campus Research Foundation funded by Hanseo University in 2022 (2022046)
Аннотация: New triple molybdates LixNa1−xCaLa0.5(MoO4)3:Er3+0.05/Yb3+0.45 (x = 0, 0.05, 0.1, 0.2, 0.3) were manufactured successfully using the microwave-assisted sol-gel-based technique (MAS). Their room-temperature crystal structures were determined in space group I41/a by Rietveld analysis. The compounds were found to have a scheelite-type structure. In Li-substituted samples, the sites of big cations were occupied by a mixture of (Li, Na, La, Er, Yb) ions, which provided a linear cell volume decrease with the Li content increase. The increased upconversion (UC) efficiency and Raman spectroscopic properties of the phosphors were discussed in detail. The mechanism of optimization of upconversion luminescence upon Li content variation was shown to be due to the control of excitation/energy transfer channel, while the control of luminescence channels played a minor role. The UC luminescence maximized at lithium content x = 0.05. The mechanism of UC optimization was shown to be due to the control of excitation/energy transfer channel, while the control of luminescence channels played a minor role. Over the whole spectral range, the Raman spectra of LixNa1−xCaLa0.5(MoO4)3 doped with Er3+ and Yb3+ ions were totally superimposed with the luminescence signal of Er3+ ions, and increasing the Li+ content resulted in the difference of Er3+ multiple intensity. The density functional theory calculations with the account for the structural disorder in the system of Li, Na, Ca, La, Er and Yb ions revealed the bandgap variation from 3.99 to 4.137 eV due to the changing of Li content. It was found that the direct electronic transition energy was close to the indirect one for all compounds. The determined chromaticity points (ICP) of the LiNaCaLa(MoO4)3:Er3+,Yb3+ phosphors were in good relation to the equal-energy point in the standard CIE (Commission Internationale de L’Eclairage) coordinates.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Romanova O. B., Aplesnin S. S., Sitnikov M. N., Udod L. V., Zelenov F. V.
Заглавие : Phase transitions in a polycrystalline compound Ho0.1Mn0.9S
Колич.характеристики :6 с
Место публикации : Solid State Commun. - 2023. - Vol. 364. - Ст.115134. - ISSN 00381098 (ISSN), DOI 10.1016/j.ssc.2023.115134. - ISSN 18792766 (eISSN)
Примечания : Cited References: 35. - The investigation of microstructural properties of the samples was carried out using equipment's (SEM) the Krasnoyarsk Regional Center of Research Equipment of Federal Research Center « Krasnoyarsk Science Center SB RAS». This work was supported by the Russian Science Foundation, the Government of the Krasnoyarsk Territory, and the Krasnoyarsk Science Foundation project no. 23-22-10016 «The colossal Nernst-Ettingshausen effect in manganese chalcogenides with rare earth substitution»
Аннотация: Sequence of structural transitions in the magnetically ordered region and a displacement-type structural transition at T = 220 K accompanied by the variation in the thermal expansion coefficient, ultrasound attenuation coefficient, g factor, and polarization current in the polycrystalline compound Ho0.1Mn0.9S was found. The electronic transitions above room temperature were established on the basis of the measurements of the conductivity, ultrasound attenuation maxima, and IR spectra.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Bykova L. E., Zhigalov V. S., Matsynin A. A., Zharkov S. M., Ivanenko A. A., Bondarenko G. N., Velikanov D. A.
Заглавие : Solid-state synthesis, magnetic and structural properties of epitaxial D03-Fe3Rh(001) thin films
Место публикации : Intermetallics. - 2023. - Vol. 157. - Ст.107871. - ISSN 09669795 (ISSN), DOI 10.1016/j.intermet.2023.107871. - ISSN 18790216 (eISSN)
Примечания : Cited References: 27. - The authors are grateful to L.A. Solovyov for carrying out the XRD φ-scan experiments and I.V. Nemtsev for the measurements of the sample composition. The work is partially based upon the experiments performed at Krasnoyarsk Regional Center of Research Equipment of Federal Research Center « Krasnoyarsk Science Center SB RAS». This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors
Аннотация: Here we first report on the formation of epitaxial D03-Fe3Rh(001) films grown during solid-state reaction in Rh/Fe(001) bilayers on MgO(001) substrates. Samples of the Fe68Rh32 composition above 400 °C showed the formation of a new ordered phase, in addition to the ordered B2–FeRh phase (space group Pm-3m, lattice constant a = 0.2993 nm), which becomes the dominant phase in Fe76Rh24 samples. These results and the results of the asymmetrical XRD φ-scan prove that the new ordered phase is the ordered D03-Fe3Rh(001) phase (space group Fm-3m, lattice constant a = 0.5888 nm), forming a cube-on-cube orientation relationship with respect to the MgO(001) substrate. The D03-Fe3Rh sample is a soft magnetic material with high saturation magnetization.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Thakur, Atul, Verma, Ritesh, Wan, Fayu, Ravelo, Fayu, Edelman I. S., Ovchinnikov S. G., Thakur, Preeti
Заглавие : Investigation of structural, elastic and magnetic properties of Cu2+ ions substituted cobalt nano ferrites
Место публикации : J. Magn. Magn. Mater. - 2023. - Vol. 581. - Ст.170980. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2023.170980. - ISSN 18734766 (eISSN)
Примечания : Cited References: 47. - This research work was supported by the National Key Research and Development Program of China (2022YFE010707). The author(s) would like to acknowledge the support provided under the DST-FIST Grant No. SR/FST/PS-I/2018/48 of Govt. of India. PT is thankful to DST-SERB TARE fellowship vide Sanction Order No TAR/2022/000414
Аннотация: In the present work, we synthesized the Cu-doped CoFe2O4 (Co1-xCuxFe2O4) nanoparticles with x = 0.0, 0.2, 0.4 and 0.6, by employing the citrate precursor method. The X-ray Diffraction (XRD) pattern confirmed the pure cubic structure formation with the Fd-3m space group. To know the structural purity of each sample as well as the distribution of cations, Rietveld refinement was carried out. The crystallite size increases from 39.55 nm to 41.80 nm upto x = 0.2 and with further doping of Cu2+ ions it decreases to 36.27 nm. Similar variation is observed in the lattice parameter where the value of ‘a’ first increases from 8.378 Å to 8.381 Å and then decreases to 8.377 Å. The development of a non-uniform grain is seen using scanning electron microscope (SEM), which reveals the reduction in grain size. Fourier Transform Infrared Spectroscopy (FTIR) showed the two peaks ν1 and ν2 for all the samples around 541 cm−1 and 408 cm−1, respectively, which further decreases to 532.5 cm−1 and 402.5 cm−1 as the dopant ion concentration increases. The Stiffness constant, and Elastic modulus decrease with doping whereas, the Poisson’s ratio and Pugh’s ratio show a constant value of around 0.249 and 1.660, respectively. Vibrating Sample Magnetometer (VSM) analysis shows a decrease in saturation magnetization (σs) value from 76.85 emu/g to 43.62 emu/g. The net magnetic moment (nB) decreases from 3.29 μB to 1.85 μB and the effective anisotropy constant value decreases from 10.672erg/g to 4.461erg/g. Thus, the prepared nanoparticles provide a way forward for their industrial applications.
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18.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Kazak N. V., Gokhfeld Yu. S., Belskaya N. A., Molokeev M. S., Gudim I. A., Eremin E. V., Knyazev Yu. V., Velikanov D. A., Ovchinnikov S. G.
Заглавие : Structural disorder, heat capacity, and magnetic transitions in Cu2FeBO5
Коллективы : Samarkand International Symposium on Magnetism, Samarkand State University
Место публикации : Book of abstacts of Samarkand International Symposium on Magnetism (SISM-2023)/ int. adv. com. S. G. Ovchinnikov [et al.]. - 2023. - Ст.3PO-L9-7. - P.208. - ISBN 978-5-00202-320-2
Примечания : Cited References: 3. - РФФИ № 21-52-12033
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Drokina T. V., Molokeev M. S., Velikanov D. A., Bayukov O. A., Vorotynov A. M., Friedman A. L., Petrakovsky G. A.
Заглавие : Synthesis, structural and magnetic properties NaZnFe2(VO4)3
Колич.характеристики :9 с
Место публикации : Phys. Solid State. - 2023. - Vol. 65, Is. 8. - P.1278-1286. - ISSN 10637834 (ISSN), DOI 10.21883/PSS.2023.08.56572.134. - ISSN 10906460 (eISSN)
Примечания : Cited References: 15
Аннотация: A new magnetic compound NaZnFe2(VO4)3 obtained by solid-phase synthesis has been studied using X-ray diffraction, Mossbauer spectroscopy, electron paramagnetic resonance, measurement of the temperature dependence of the dielectric permeability, and magnetometry. The crystalline structure of NaZnFe2(VO4)3 is described by a triclinic spatial group of symmetry P1 with the parameters of an elementary crystalline chain: a=6.74318 (7) Å, b= 8.1729 (1) Å, c=9.8421 (1) Å, α= 106.2611 (9)°, β=104.55 (1)°, γ= 102.337 (1)°, V=479.88 (1) Å3, Z=2. Magnetic Fe3+ cations in the cell occupy six positions populated together with diamagnetic Zn2+ cations, which leads to states of magnetic inhomogeneity and local violation of charge neutrality. Data from resonance and magnetic studies of NaZnFe2(VO4)3 confirm the main role of high-spin Fe3+ iron cations in the formation of magnetism with competing exchange magnetic interactions and a high value of the frustration index. It is shown that the magnetic subsystem of a sample with a negative asymptotic Neel temperature undergoes a magnetic transition from the paramagnetic state to the magnetic state of the spin glass when the temperature decreases.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kostikov D. A., Krakhalev M. N., Prishchepa O. O., Zyryanov V. Ya.
Заглавие : Electrically induced structural transformations of a chiral nematic under tangential-conical boundary conditions
Колич.характеристики :10 с
Место публикации : Molecules. - 2023. - Vol. 28, Is. 23. - Ст.7842. - ISSN 14203049 (eISSN), DOI 10.3390/molecules28237842
Примечания : Cited References: 30
Аннотация: In this study, structural transformations induced by an electric field in the chiral nematic under tangential-conical boundary conditions have been considered. The composition influence of the orienting polymer films on the director tilt angles, the formation of orientational structures in the LC layer, as well as the electro-optical response and relaxation processes have been studied. It has been shown that the poly(tert-butyl methacrylate) concentration change in the orienting polymer mixture allows for smoothly controlling the director tilt angle without fixing its azimuthal orientation rigidly.
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