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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhlin Y. L., Borisov R. V., Vorobyev S. A., Tomashevich Y. V., Romanchenko A. S., Likhatski M. N., Karacharov A. A., Bayukov O. A., Knyazev Yu. V., Velikanov D. A., Zharkov S. M., Krylov A. S., Krylova S. N., Nemtsev I. V.
Заглавие : Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide
Место публикации : J. Mater. Chem. A. - 2022. - Vol. 10, Is. 17. - P.9621-9634. - ISSN 20507488 (ISSN), DOI 10.1039/d2ta00877g
Примечания : Cited References: 84. - This research was supported by the Russian Foundation for Basic Research, Krasnoyarsk Territory Administration and Krasnoyarsk Territory Science Foundation, project 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: We introduce here a multifunctional material composed of alternating atomic sulfide sheets close to the composition of CuFeS2 and Mg-based hydroxide ones (valleriite), which are assembled due to their electric charges of opposite sign. Valleriite particles 50-200 nm in lateral size and 10-20 nm in thickness were synthesized via a simple hydrothermal pathway using various concentrations of precursors and dopants, and examined with XRD, TEM, EDS, X-ray photoelectron spectroscopy, reflection electron energy loss spectroscopy (REELS), Mossbauer, Raman and UV-vis-NIR spectroscopies, and magnetization, dynamic light scattering, and zeta potential measurements. The electronic, magnetic and optical characteristics are found to be critically dependent on the charge (electron density) at the narrow-gap sulfide layers containing Cu+ and Fe3+ cations, and can be tuned via the composition of the hydroxide part. Particularly, substitution of Mg2+ with Al3+ increases the negative charge of the hydroxide layers and reduces the content of Fe3+-OH centers (10-45% of total iron); the effects of Cr and Co dopants entering both layers are more complicated. Mossbauer doublets of paramagnetic Fe3+ detected at room temperature transform into several Zeeman sextets at 4.2 K; the hyperfine fields up to 500 kOe and complex magnetic behavior, but not pure paramagnetism or antiferromagnetism, were observed for valleriites with the higher positive charge of the sulfide sheets, probably due to the depopulation of the minority-spin 3d states of S-bonded Fe3+ ions. Aqueous colloids of valleriite show optical absorption at 500-750 nm, which, along with the peaks at the same energies in REELS, may arise due to quasi-static dielectric resonance involving the vacant Fe 3d band and being dependent on the composition of both layers too. These and other findings call attention to valleriites as a new rich family of 2D materials for a variety of potential applications.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Draganyuk O. N.
Заглавие : The spin-state transition in ACo2O4 spinels (A = Be, Mg, Ca, Cd, Zn)
Место публикации : J. Magn. Magn. Mater. - 2022. - Vol. 552. - Ст.169206. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2022.169206
Примечания : Cited References: 51. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research projects № 19-42-240016: «Control of structural, magnetic, electronic, and optical properties by pressure and intercalation into functional compounds with a spinel structure containing 3d and 4f ions» and № 20-42-240004: “The effect of the composition, pressure, and dimension on the magnetic, electronic, optical, and elastic properties of the magnetic Mn+1AXn (M = Cr, Mn; Fe, A = Al, Ga, Si, Ge, P, In; X = C, N; n = 1-3) MAX-phases”. The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” (http://ckp.urcki.ru)
Аннотация: The magnetic and electronic properties of the Co-based spinel oxides ACo2O4 (A = Be, Mg, Ca, Zn, Cd) were studied within GGA + U approach. It was found that the Co3+ ion is in a low-spin state due to the effect of the crystal field of octahedral symmetry. It is shown that Co3+ ion undergoes a spin-state transition into the high-spin state under the critical pressure of P = −10 GPa – −20 GPa. This pressure-induced spin-state transition is caused by the redistribution of electrons between the t2g- and eg-orbitals arising with increasing interatomic distances. The role of interatomic distances between Co3+ ion and its ligands is discussed. Thin-film form also favors the appearance of a high-spin state of Co3+ ion. At the same critical pressure, there is a sharp increase in the majority spin bandgap and a sharp decrease in the minority spin bandgap. These findings allow manipulating the spin state of Co3+ ions and bandgap width through the pressure or strain arising in thin films.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Чурилов, Григорий Николаевич, Черепахин, Александр Владимирович, Осипова, Ирина Владимировна, Томашевич, Евгений Владимирович, Глущенко, Гарий Анатольевич, Федоров, Александр Семенович, Попов, Захар Иванович, Булина П. В., Верещагин С. П., Жижаев, Анатолий Михайлович
Заглавие : Гидрирование нанодисперсных порошков, образующихся в потоке углеродно-гелиевой плазмы при введении Ni и Mg
Место публикации : Журнал экспериментальной и теоретической физики. - Москва: Федеральное государственное унитарное предприятие Академический научно-издательский, производственно-полиграфический и книгораспространительский центр Наука, 2011. - Т. 140, № 6. - С. 1211-1217. - ISSN 0044-4510
Аннотация: Представлены как теоретические, так и экспериментальные исследования композитных наночастиц, состоящих из магния, никеля и углерода. Расчеты, выполненные в рамках теории формализма функционала плотности, показали, что частота перескоков атомов водорода внутри гидрида магния, содержащего никель, вблизи примесных атомов никеля существенно возрастает, в связи с чем увеличивается скорость абсорбции водорода магнием. Также показано, что никель на поверхности магния адсорбируется по механизму островкового роста. Экспериментально с помощью плазмохимического синтеза в потоке углеродно-гелиевой плазмы были получены композитные порошки составов: Mg-C, Ni-C, Mg-Ni-C. Водород вводился в камеру в процессе синтеза. Методами рентгеновской фотоэлектронной спектроскопии и термогравиметрического анализа было показано, что из трех рассмотренных композитов только Mg-Ni-C содержал магний в соединении Mgllj. Процесс такого «сверхбыстрого» гидрирования магния, происходящий за время образования наночастиц композита, можно объяснить каталитическим действием никеля, которое усиливается высокой температурой. В работе приведены фотографии, полученные на растровом электронном микроскопе, которые позволяют наблюдать динамику процесса дегидрирования частиц композита Mg-Ni-C при нагреве электронным пучком.
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4.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Churilov G. N., Osipova I. V., Novikov P.V., Grebennikova N.V., Chesnokov N.V.
Заглавие : Hydrogenation and properties of Pd-Mg-C and Pd-Al-C nanodispersion systems
Коллективы : "Hydrogen materials science and chemistry of carbon nanomaterials", International Conference
Место публикации : Hydrogen materials science and chemistry of carbon nanomaterials (ICHMS '2009): XI International Conference, Yalta - Crimea - UKRAINE, August 25-31, 2009. - 2009. - P.268-269
Примечания : Библиогр.: 9
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zou X., Zhang H., Li W., Zheng M., Molokeev M. S., Xia Z., Zheng Y., Li Q., Liu Y., Zhang X., Lei B.
Заглавие : Ultra-wide Vis–NIR Mg2Al4Si5O18:Eu2+,Cr3+ phosphor containing unusual NIR luminescence induced by Cr3+ occupying tetrahedral coordination for hyperspectral imaging
Место публикации : Adv. Opt. Mater. - 2022. - Vol. 10. Is. 19. - Ст.2200882. - ISSN 21951071 (ISSN), DOI 10.1002/adom.202200882
Примечания : Cited References: 48. - The work was supported from the National Natural Science Foundations of China (No. 21671070, 51802101), the Guangdong Basic and Applied Basic Research Foundation (No. 2021A1515012613), the Independent Research and Development Projects of Maoming Laboratory (No. 2021ZZ004), the Key Realm R&D Program of Guangdong Province (No. 2021B0707010003), the Guangdong Provincial Science & Technology Project (No. 2020A1414010046), the Guangzhou Science & Technology Project (No. 202007020005, 202103000059, and 202102020410), the Project of GDUPS (2018) for Prof. Bingfu LEI, the Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams (No. 2021KJ122), and the Natural Science Foundation of Guangdong Province (No. 2022A1515010229, 2018A030310217)
Аннотация: Cr3+-activated broadband near-infrared (NIR) phosphors, featured by the octahedral coordination preference and strong absorption in visible (Vis) region, have great potential application in nondestructive assessment. It is still a challenge to develop Cr3+-doped phosphors with the tetrahedrally coordinated Cr3+ NIR emission behavior and ultra-wide Vis–NIR luminescence. Herein, an unusual NIR-emitting Mg2Al4Si5O18:Cr3+ phosphor offers emission peak at 867 nm with full-width at half-maximum of 237 nm due to preferential occupation of the AlO4 tetrahedra by Cr3+ as demonstrated by structural and optical properties studies. Eu2+–Cr3+ energy transfer is proposed to induce ultra-wide Vis–NIR Mg2Al4Si5O18:Eu2+,Cr3+ phosphors with more efficient NIR emission and lower thermal quenching behavior of Cr3+. The fabricated Vis–NIR phosphor-converted light-emitting diode is expected to be an alternative to halogen lamp in hyperspectral imaging. This work reveals the luminescence behavior of Cr3+ in tetrahedra and demonstrates the application of Mg2Al4Si5O18:Eu2+,Cr3+ phosphor in hyperspectral imaging, which will facilitate further research on NIR and Vis–NIR phosphors.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Павлов, Вячеслав Фролович, Линейцев А. В., Павлов И. В., Шабанов, Василий Филиппович
Заглавие : Кристаллизация рентгеноаморфных cA-mG-алюмосиликатных материалов
Место публикации : Физика и химия стекла. - 2009. - Т. 35, № 5. - С. 725. - ISSN 0132-6651
ГРНТИ : 31
Ключевые слова (''Своб.индексиров.''): расплавы оксидов--самораспространяющаяся кристаллизация
Аннотация: Рассмотрен механизм процесса кристаллизации рентгеноаморфных материалов, полученных охлаждением силикатных расплавов шихт на основе дунита и известняка, а также на основе оксидов MgO, CaO, SiO 2, после глубокого восстановительного плавления и удаления металлической части расплава, содержащего железо. Показаны особенности зарождения центров тепловой волны самораспространяющейся кристаллизации и возможность их визуализации. Приведены значения выделяемого тепла кристаллизации и изменения температуры фронта тепловой волны, определена скорость его распространения.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Eremina R. M., Moshkina E. M., Gavrilova T. P., Muftakhutdinov A. R., Gilmutdinov I. F.
Заглавие : Investigation of the Magnetic Properties of Warwickite Mn0.89Mg1.11BO4
Место публикации : Bull. Russ. Acad. Sci. Phys. - 2019. - Vol. 83, Is. 7. - P.792-794. - ISSN 10628738 (ISSN), DOI 10.3103/S106287381907013X
Примечания : Cited References: 3. - This work was supported by the Russian Foundation for Basic Research; the Administration of Krasnoyarsk Krai; and the Krasnoyarsk Krai Science Foundation, project no. 18-42-243007.
Аннотация: The temperature dependences of the magnetic susceptibility in magnetic fields applied parallel and perpendicular to axis с of a Mn0.89Mg1.11BO4 single crystal were measured. Spin ordering typical of an antiferromagnetic with an easy magnetization axis was observed below 16 K. The Dzyaloshinskii–Moriya interaction between spins of manganese ions in Mn0.89Mg1.11BO4 was estimated by analyzing the EPR linewidth. © 2019, Allerton Press, Inc.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Xing G., Feng Y., Pan M., Wei Y., Li G., Dang P., Liang S., Molokeev M. S., Cheng Z., Lin J.
Заглавие : Photoluminescence tuning in a novel Bi3+/Mn4+ co-doped La2ATiO6:(A = Mg, Zn) double perovskite structure: Phase transition and energy transfer
Место публикации : J. Mater. Chem. C. - 2018. - Vol. 6, Is. 48. - P.13136-13147. - ISSN 20507534 (ISSN), DOI 10.1039/c8tc05171b
Примечания : Cited References: 60. - This work was supported by the National Natural Science Foundation of China (Grant No. 51672259, 51672265, 21521092, 51750110511), the Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences (Wuhan) (No. NGM2016KF002), the Key Research Program of Frontier Sciences, CAS (Grant No. YZDYSSW-JSC018), and the projects for science and technology development plan of Jilin province (20170414003GH), the Program for Jiangmen Innovative Research Team (No. [2017]385), and the major program of basic research and applied research of Guangdong Province (2017KZDXM083).
Ключевые слова (''Своб.индексиров.''): crystal symmetry--energy transfer--light--luminescence--perovskite--phosphors--rietveld refinement
Аннотация: Red-emitting phosphors are indispensable compounds which are used to achieve a warm white light in phosphor-converted white light emitting diodes (pc-WLEDs). However, the luminous efficiency and stability of red phosphors are still big challenges. In this work, we developed red-emitting double perovskite phosphors La2ATiO6:Bi3+,Mn4+ (A = Mg, Zn) (LAT:Bi3+,Mn4+) and discuss the relationship between the double perovskite phosphor structure and the luminescence performance in detail. According to the Rietveld refinement results for the La2Mg(1−w)ZnwTiO6:Bi3+,Mn4+ (0 ≤ w ≤ 1) (LM(1−w)ZwT:Bi3+,Mn4+) solid solution, the proposed mechanism of the spectral adjustment is ascribed to the appearance of the phase transition, which results in a lower local structural symmetry of the [LaO12] polyhedron and the variation of the crystal field environment for Mn4+. Notably, this is the first time that the influence of the local structure variation on the luminescence tuning in double perovskite structure phosphors has been revealed, and this could offer guidance for the development of new phosphor system. By designing Mg2+/Zn2+ cation substitution, the internal quantum efficiency (IQE) is remarkably enhanced beyond 20%. In addition, we succeeded in achieving a Bi3+/Mn4+ co-doped energy transfer in the double perovskite structure phosphors. Owing to the Bi3+ → Mn4+ energy transfer in LAT, the red emission of the Mn4+ ions could be dramatically enhanced. The energy transfer efficiency of LAT:Bi3+,Mn4+ eventually exceeded 90%. The IQE and the thermal stability were all enhanced by around 30% compared to the non-co-doped samples, respectively. These results indicate that the Bi3+ → Mn4+ energy transfer strategy could play a pivotal role in the development of highly efficient red-emitting phosphors. The performance of the fabricated pc-WLEDs devices indicates that LAT:Bi3+,Mn4+ could be a promising red phosphor for near ultraviolet (n-UV) based warm pc-WLEDs.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ji W., Xia Z., Liu K., Ali Khan S., Hao L., Xu X., Yin L., Molokeev M. S., Agathopoulos S., Yang W., Ma X., Sun K., Da Silva I.
Заглавие : The crystal structure and luminescence properties of a novel green-yellow emitting Ca1.5Mg0.5Si1-xLixO4- δ:Ce3+ phosphor with high quantum efficiency and thermal stability
Место публикации : Dalton Trans. - 2018. - Vol. 47, Is. 29. - P.9834-9844. - ISSN 14779226 (ISSN), DOI 10.1039/c8dt02241k
Примечания : Cited References: 42
Аннотация: A novel green-yellow emitting Ca1.5Mg0.5Si1−xLixO4−δ:Ce3+ phosphor with high quantum efficiency and thermal stability was discovered for applications in near ultraviolet pumped white light-emitting diodes. Its crystal structure was determined with a single-particle diagnosis approach. The Si sites in the SiO4 tetrahedra are reported for the first time to accommodate Li+ ions. This substitution, confirmed by 6Li solid-state NMR and T.O.F. neutron powder diffraction, causes a disordered occupation of Ca/Mg in the Ca3MgSi2O8 host and favors a phase transformation at ∼330 °C, which results in the formation of the novel phosphor. The produced phosphor was efficiently excited by near UV light peaking at 365 and 410 nm and produced broad green-yellow emission with peaks at 500 and 560 nm, respectively. Its quantum efficiency reached 88.4% (internal) and 55.7% (external) under excitation at 365 nm, and 80.5% (internal) and 42.7% (external) under excitation at 410 nm, while the decrease of luminescence intensity at 200 °C was small (∼26%). A WLED lamp with a high color rendering index of Ra = 92.8 was produced with the combination of a 365 nm emitting chip with blue emitting BaMgAl10O17:Eu2+, green-yellow emitting CMSL:0.01Ce, and red emitting Sr2Si5N8:Eu2+ phosphors.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Churilov G. N., Nikolaev N. S., Elesina V. I., Glushenko G. A., Isakova V. G., Tomashevich Y. V.
Заглавие : Obtaining particles with the structure Mg@C and (Mg@C)@Pd, their properties and stability in the hydrogenation/dehydrogenation processes
Место публикации : Int. J. Hydrogen Energy. - 2022. - Vol. 47. Is. 11. - P.7299-7309. - ISSN 03603199 (ISSN), DOI 10.1016/j.ijhydene.2021.03.042
Примечания : Cited References: 46
Аннотация: In this work, we studied the change in the properties of powders with a core (magnesium) – shell structure (carbon and carbon/palladium) in the process of hydrogenation/dehydrogenation with hydrogen (99.995 wt%). Magnesium powders were obtained by plasma chemical synthesis in an atmosphere of argon containing a small amount of hydrogen (2–3 at.%) and nitrogen (8–9 at.%), when performing a low-frequency arc discharge between a tungsten electrode and a magnesium melt. The shell (carbon and carbon/palladium) was deposited in a plasma generator with vortex and magnetic stabilization. For all samples, a decrease in the sorption capacity of hydrogen was observed as a result of successive cycles of sorption and desorption reactions. It was found that the reason for this fall is associated with the formation of the MgO and Mg(OH)2 phase, which prevents the diffusion of hydrogen. The carbon shell provides a more complete hydrogenation of the magnesium particles, and an additional palladium shell increases the resistance to cyclic hydrogenation/dehydrogenation and reduces the temperature of these processes. According to the data obtained, powders with particles (Mg@C)@Pd can absorb the largest amount of hydrogen (6.9 wt%) for the duration of 5 cycles, after which the protective shell of the particles begins to collapse and a loss of sorption capacity is observed.
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