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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Юмашев, Владимир Витальевич, Кирик, Надежда Павловна, Шишкина, Нина Николаевна, Князев, Юрий Владимирович, Жижаев, Анатолий Михайлович, Соловьев, Леонид Александрович
Заглавие : Состав, структура и реакционная способность при восстановлении водородом композиционных материалов системы α-Fe2O3–CaFe2O4
Место публикации : Журнал СФУ. Химия. - 2019. - Т. 12, Вып. 1. - С. 54-72. - ISSN 1998-2836, DOI 10.17516/1998-2836-0108; J. Sib. Fed. Univ. Chem. - ISSN 2313-6049(eISSN)
Примечания : Библиогр.: 37
Предметные рубрики: CHEMICAL LOOPING GASIFICATION
OXYGEN CARRIER
PARTIAL OXIDATION
Аннотация: В работе изучены композиционные материалы системы α-Fe2O3-CaFe2O4, полученные методом высокотемпературного твердофазного синтеза из оксидов Са и Fe(III) с вариацией мольного отношения СаО/Fe2O3 от 0.15 до 1.00. Материалы охарактеризованы методами рентгеновской дифракции (РФА), сканирующей электронной микроскопии с системой энергодисперсионного микроанализа (СЭМ-ЭДС) и синхронного термического анализа (СТА) в режиме термопрограммируемого восстановления водородом (H2-ТПВ). СЭМ-ЭДС - исследование образцов выявило формирование сложной микроструктуры материала по типу «ядро-оболочка» с фазой гематита в качестве «ядра». H2-ТПВ образцов позволило установить, что с увеличением содержания фазы CaFe2O4 (от 33.4 до 97.5 мас. %) наблюдается снижение вклада низкотемпературных форм решеточного кислорода в областях 350-510 °С (до 2.6 раза) и 510-650 °С (до 1.7 раза) и рост вклада высокотемпературной формы кислорода в интервале 650-900 °С (до 2 раз). На основе оценки подвижности решеточного кислорода высказано предположение о перспективности использования полученных композиционных материалов с содержанием фазы CaFe2O4 более 55.2 мас. % в качестве носителей кислорода в химических циклических процессах получения синтез-газа.In this paper, α-Fe2O3–CaFe2O4 composite materials obtained by high-temperature solid-phase synthesis from Ca and Fe (III) oxides with varying molar ratio CaO/Fe2O3 in the range 0.15-1.00 were investigated. The materials are characterized by Х-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray microanalysis (SEM-EDS) and simultaneous thermal analysis (STA) in the hydrogen temperature-programmed reduction mode (H2-TPR). SEM-EDS studies of the specimens were revealed a formation of the “core-shell” type complex microstructure of material with the hematite phase as the “core”. H2-TPR of the specimens allowed to establish a decrease of the contribution of low-temperature forms of lattice oxygen in areas of 350-510 °С (up to 2.6 times) and 510-650 °С (up to 1.7 times), and the growth of the contribution of the high-temperature oxygen form in the range of 650-900 °С (up to 2 times) with an increase in the content of the phase CaFe2O4 from 33.4 to 97.5 wt. %. Relying on the assessment of lattice oxygen mobility, it was suggested, that the samples with content of CaFe2O4 phase more than 55.4 wt. % are promising for use as oxygen carriers in chemical looping processes of syngas production.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Platunov M. S., Knyazev Yu. V., Moshkina E. M., Solovyov L. A., Vereshchagin S. N., Mikhlin, Yu. L., Veligzhanin A. A., Trigub A. L., Ovchinnikov S. G.
Заглавие : Study of mixed-valence Mn2BO4 using XRD, XPS and XAFS spectroscopies
Коллективы : Russian Foundation for Basic Research [17-02-00826, 16-32-60049]
Место публикации : Physica B. - 2019. - Vol. 560. - P.228-235. - ISSN 0921-4526, DOI 10.1016/j.physb.2019.02.019. - ISSN 1873-2135(eISSN)
Примечания : Cited References: 39. - This work has been financed by Russian Foundation for Basic Research (17-02-00826 and 16-32-60049 grant numbers).
Предметные рубрики: SPIN-GLASS BEHAVIOR
MAGNETIC-PROPERTIES
PROFILE REFINEMENT
Аннотация: The valence states and local structure around Mn atoms in mixed-valence Mn2BO4 have been studied by temperature dependent X-ray powder diffraction (XRPD), X-ray photoelectron (XPS) and Mn K-edge X-ray absorption (XAFS) spectroscopies measurements. X-ray absorption near-edge structure (XANES) and XPS have been used to measure the average oxidation state of Mn in bulk and near-surface of the material. The edge position, peak shapes and pre-edge features of Mn K-edge XANES spectra have been discussed. The pronounced temperature dependence of the Debye-Waller (DW) factor corresponding to the MnO coordination shell has been found from the extended x-ray absorption fine structure (EXAFS) analysis and has been associated with variations in the local distortions in MnO6 octahedra and emergence of short-range magnetic correlations at low temperatures. The XRPD measurements have been carried out at 298, 523 and 773 K. The monoclinic symmetry (P21/n) was found to persist up to highest temperature measured. The BVS calculations have revealed large valence difference between two manganese sites that strongly supports the presence of charge ordering up to high temperatures.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuznetsov B. N., Vasil'eva N. Yu., Levdansky A. V., Karacharov A. A., Krylov A. S., Mazurova E. V., Bondarenko G. N., Levdansky V. A., Kazachenko A. S.
Заглавие : The Raman spectroscopy, XRD, SEM, and AFM study of arabinogalactan sulfates obtained using sulfamic acid
Место публикации : Russ. J. Bioorgan. Chem. - 2017. - Vol. 43, No. 7. - P.32-36. - ISSN 1068-1620, DOI 10.1134/S106816201707010X
Примечания : Cited References: 9. - The work was financially supported by the Russian Foundation for Basic Research and the Government of the Krasnoyarsk krai (project no. 16-43-242083).
Ключевые слова (''Своб.индексиров.''): physicochemical investigation--sulfated arabinogalactan--«green» synthesis--sulfamic acid--urea
Аннотация: The structure of sodium salts of sulfated arabinogalactan (AG), obtained by sulfation of larch wood AG with sulfamic acid – urea mixture in the medium of 1,4-dioxane was investigated with the use of Raman spectroscopy, X-ray diffraction (XRD), scaning electron microscopy (SEM) and aromatic force microscopy (AFM) methods. The introduction of sulfate groups into the structure of AG was confirmed by appearance in Raman spectra new absorption bands characteristic for the deformation vibrations of d (SO3) at 420 cm-1 and d (O=S=O) at 588 cm-1, stretching vibrations n (C–O–S) at 822 cm-1, symmetric stretching vibrations ns (O=S=O) at 1076 cm-1, asymmetric stretching vibrations nas (О=S=O) at 1269 cm-1. According to XRD data the amorphization of arabinogalactan structure take place during it`s sulfation. The difference in the morphology of initial and sulfated arabinogalactans was established by SEM method. Initial arabinigalactan consists of particles of globular shape with size of 10–90 µm, but sulfates of AG – from particles of different shapes and sizes of 1–8 µm. According to AFM data the surface of film of arabinogalactan sulfates is formed by the rather homogeneous spherical particles with sizes near 70 nm. The mean-square value of the surface rounghness is equal to 33 nm.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vereshchagin S., Dudnikov V. A., Orlov Yu. S., Solovyov L.
Заглавие : Tetragonal to cubic transition of Sr0.8Dy0.2CoO3-δ and oxygen mobility: TG-DSC-XRD study
Место публикации : J. Alloys Compd. - 2021. - Vol. 860. - Ст.158257. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2020.158257
Примечания : Cited References: 35. - This work was conducted within the framework of the budget project (Project No. АААА-А17-117021310222-4) for Institute of Chemistry and Chemical Technology SB RAS using the equipment of Krasnoyarsk Regional Research Equipment Centre of SB RAS and in part was funded by Russian Foundation for Basic Research (projects 19-03-00017), RFBR and BRFBR (project 18-52-00017), Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science (project 18-42-243004)
Аннотация: Processes of ordering (d-o) and disordering (o-d) of Sr2+/Dy3+ cations in a single-phase Sr0.8Dy0.2CoO3-δ was investigated by TG-DSC and XRD as a function of heating/cooling rate (β = 2,10,20,50,99 K min−1 and ~50 K/s) in 20% O2-Ar flow. According to DSC data the interconversion of disordered cubic (c) and ordered tetragonal (t) structure appears at 1276–1328 K as a first-order phase transition; the temperature and enthalpy of o-d transformation have only slight dependence on β whereas the characteristics of reversed d-o process vary greatly with cooling rate. XRD powder patterns of all samples showed no indications of a simultaneous presence of c+t domains, pointing to a single phase composition (c or t). It was suggested that the observed behavior is a consequence of two simultaneous interconnected processes of A-sublattice melting and cation/ (anion vacancy) ordering. A rarely used novel TG-DSC method based on variable gas phase composition was utilized to study properties of mobile oxygen over Sr0.8Dy0.2CoO3-δ samples. It was shown that the appearance of tetragonal phase reduces both oxygen mobility and its bonding energy, the latter decreasing substantially only at high degree of Sr2+/Dy3+ ordering.
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Вид документа : Статья из журнала
Шифр издания :
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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Azarapin N. O., Khritokhin N. A., Atuchin V. V., Gubin A. A., Molokeev M. S., Mukherjee S., Andreev O. V.
Заглавие : Kinetics and mechanism of BaLaCuS3 oxidation
Место публикации : Crystals. - 2023. - Vol. 13, Is. 6. - Ст.903. - ISSN 20734352 (eISSN), DOI 10.3390/cryst13060903
Примечания : Cited References: 65. - The work was partially carried out using the resources of the Research Resource Center “Natural Resources Management and Physico-Chemical Research” (Tyumen University) with financial support from the Ministry of Science and Higher Education of the Russian Federation (contract No. 05.594.21.0019., Unique identification number RFMEFI59420X0019). M.S. Molokeev was supported by the Tyumen Oblast Government, as part of the West-Siberian Interregional Science and Education Center’s project No. 89-DON (3)The authors would like to thank the staff of the Engineering Center of the Tyumen State University (special Alexej V. Matigorov) for their help in carrying out physical and chemical tests
Аннотация: The oxidation reactions of BaLaCuS3 in the artificial air atmosphere were studied at different heating rates in the temperature range of 50–1200 °C. The oxidation stages were determined by DSC-TG, XRD and IR–vis methods. The kinetic characteristics of the proceeding reactions were obtained with the use of the Kissinger model in a linearized form. Compound BaLaCuS3 was stable in the air up to 280 °C. Upon further heating up to 1200 °C, this complex sulfide underwent three main oxidation stages. The first stage is the formation of BaSO4 and CuLaS2. The second stage is the oxidation of CuLaS2 to La2O2SO4 and copper oxides. The third stage is the destruction of La2O2SO4. The final result of the high-temperature treatment in the artificial air atmosphere was a mixture of barium sulfate, copper (II) oxide and La2CuO4. The mechanism and stages of BaLaCuS3 oxidation and further interactions of the components were discussed.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Vereshchagin S.N., Vereshchagina T.A., Solovyov L.A., Shishkina N.N., Vasilieva N.G., Anshits A.G.
Заглавие : Solid-phase transformation of Cs+- and Sr2+-bearing zeolite sorbents derived from cenospheres to mineral-like forms
Место публикации : Materials Research Society Symposium Proceedings. - 2009. - Vol. 1193: 32nd Symposium on Scientific Basis for Nuclear Waste Management (24 May 2009 through 29 May 2009, St. Petersburg, ) Conference code: 79940. - С. 87-94. - ISBN 02729172 (ISSN); 9781605111667 (ISBN)
Ключевые слова (''Своб.индексиров.''): apparent activation energy--cenospheres--crystalline minerals--crystalline phasis--crystallization temperature--higher temperatures--long-term disposal--multi phase systems--pollucites--principal components--solid-phase transformation--temperature range--thermal treatment--thermochemical transformations--transformation temperatures--xrd analysis--activation energy--atmospheric pressure--cesium--crystalline materials--crystallization--fly ash--metallic glass--radioactive waste disposal--radioactive wastes--silicate minerals--sodium--sorbents--sorption--strontium--synthesis (chemical)--waste management--atmospheric temperature
Аннотация: The paper describes the studies of the transformation of Cs+- and Sr2+-containing zeolite sorbents synthesized from fly ash cenospheres to crystalline mineral composition, suitable for the long-term disposal. Series of Cs+- and Sr2+-exchanged NaP1-containing sorbents were subjected to the thermochemical transformation in the temperature range 40-1100°C at atmospheric pressure in air and the progress of reaction was monitored by DSC and XRD analysis. It was shown that initial sodium zeolite undergoes two-step transformation at 736-785°C and 892-982°C forming nepheline as the principle product, with the conversion temperatures being dependant on the heating rate. The thermal treatment of Cs+-bearing zeolite sorbent led to formation of a complex multiphase system, the principal components of which were nepheline and pollucite. Increasing cesium content in the samples led to a monotonous shift of crystallization peak to the higher temperature range (1005-1006°C). A more complicated behavior was observed for Sr2+-containing samples, for which the crystallization temperature tends to increase (compared with NaP1) at lower Sr contents, but it starts decreasing parallel to the Sr2+ content at Sr2+ loadings 10 mg/g. The principal crystalline phases in Sr-NaP1 sample conversion were nepheline and Sr2+- containing feldspar, the quantity of which increased parallel to the increase of strontium content in zeolite. Apparent activation energies of thermochemical transformations were calculated and possible approaches to reduce transformation temperature are discussed and experimentally illustrated. © 2009 Materials Research Society.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Верещагин С. Н., Дудников, Вячеслав Анатольевич, Соловьев, Леонид Александрович
Заглавие : Изучение фазового перехода порядок-беспорядок в нестехиометрическом Sr-Gd-кобальтате методами ДСК, ТГ и РСА
Место публикации : Журн. СФУ. Сер. "Химия". - 2016. - Т. 9, № 3. - С. 326-336. - ISSN 1998-2836, DOI 10.17516/1998-2836-2016-9-3-326-336; J. Sib. Fed. Univ. Chem. - ISSN 2313-6049(eISSN)
Примечания : Библиогр.: 26. - Исследование выполнено при финансовой поддержке Российского фонда фундаментальных исследований, Правительства Красноярского края, Красноярского краевого фонда поддержки научной и научно-технической деятельности в рамках научного проекта 16-43-240505 «р_а».
Предметные рубрики: PEROVSKITE-TYPE OXIDES
PHASE-TRANSITION
OXYGEN SORPTION
PERFORMANCE
Ключевые слова (''Своб.индексиров.''): perovskite--order-disorder--phase transition--dsc--перовскит--порядок-беспорядок--фазовый переход--дск
Аннотация: Методами термического и рентгеноструктурного анализа в интервале температур 11001473 К изучен процесс взаимопревращения тетрагонального перовскита Sr ( 0.8 ) Gd ( 0.2 ) CoO ( 3-d ) с упорядоченным расположением катионов Sr/Gd и анионных вакансий в кубическую разупорядоченную модификацию. Показано, что фазовое превращение протекает как размытый фазовый переход первого рода. Процесс разупорядочения не зависит от скорости нагрева и контролируется термодинамическими характеристиками процессов в кристалле, тогда как процесс образования упорядоченной тетрагональной структуры контролируется кинетическими факторами. Проведен количественный анализ температурной зависимости теплоемкости на основе размытых фазовых переходов.Process of interconversion of tetragonal Sr(0.8) Gd(0.2) CoO(3-d) (with ordered Sr/Gd cations and anion vacancies) to cubic one (with disordered structure) was studied by X-ray structural and thermal analysis at 1100-1473 K. It was shown that the transformation is a first order diffuse phase transition. The ramp rate does not affect cation and anion vacancies disordering which is controlled by thermodynamic parameters of the processes in the solid whereas cubic to tetragonal transition is kinetically controlled. A theory of diffuse phase transition was applied to quantitatively analyze heat capacity temperature dependence.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lim, Chang Sung, Aleksandrovsky A. S., Molokeev M. S., Oreshonkov A. S., Atuchin V. V.
Заглавие : Microwave sol–gel synthesis and upconversion photoluminescence properties of CaGd2(WO4)4:Er3+/Yb3+ phosphors with incommensurately modulated structure
Место публикации : J. Solid State Chem. - 2015. - Vol. 228. - P.160-166. - ISSN 0022, DOI 10.1016/j.jssc.2015.04.032. - ISSN 1095726X(eISSN)
Примечания : Cited References:70. - This study was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2014-046024). VVA, ASA and ASO are partially supported by the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: CORE-LEVEL SPECTROSCOPY
LUMINESCENCE PROPERTIES
WHITE-LIGHT
Ключевые слова (''Своб.индексиров.''): double tungstate--microwave sol-gel--upconversion--xrd refinement--raman
Аннотация: CaGd2−x(WO4)4:Er3+/Yb3+ phosphors with the doping concentrations of Er3+ and Yb3+ (x=Er3++Yb3+, Er3+=0.05, 0.1, 0.2 and Yb3+=0.2, 0.45) have been successfully synthesized by the microwave sol–gel method. The crystal structure of CaGd2−x(WO4)4:Er3+/Yb3+ tungstates have been refined, and upconversion photoluminescence properties have been investigated. The synthesized particles, being formed after the heat-treatment at 900 °C for 16 h, showed a well crystallized morphology. Under the excitation at 980 nm, CaGd2(WO4)4:Er3+/Yb3+ particles exhibited a strong 525-nm and a weak 550-nm emission bands in the green region and a very weak 655-nm emission band in the red region. The Raman spectrum of undoped CaGd2(WO4)4 revealed about 12 narrow lines. The strongest band observed at 903 cm−1 was assigned to the ν1 symmetric stretching vibration of WO4 tetrahedrons. The spectra of the samples doped with Er and Yb obtained under the 514.5 nm excitation were dominated by Er3+ luminescence preventing the recording of these samples Raman spectra. Concentration quenching of the erbium luminescence at 2H11/2→4I15/2 transition is weak in the range of erbium doping level xEr=0.05–0.2, while, for transition 4S3/2→4I15/2, the signs of concentration quenching become pronounced at xEr=0.2.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Gavrilova T. A., Kesler V. G., Molokeev M. S., Aleksandrov K. S.
Заглавие : Low-temperature synthesis and structural properties of ferroelectric K 3WO3F3 elpasolite
Место публикации : Chem. Phys. Lett. - 2010. - Vol. 493, Is. 1-3. - P.83-86. - ISSN 0009-2614, DOI 10.1016/j.cplett.2010.05.023
Примечания : Cited References: 37
Предметные рубрики: PEROVSKITE-LIKE OXYFLUORIDES
CORE-LEVEL SPECTROSCOPY
PHASE-TRANSITIONS
SOLID-STATE
ELECTRON-DIFFRACTION
DIFFUSE-SCATTERING
RHEED ANALYSIS
POLAR
BEHAVIOR
(NH4)(3)TIOF5
Ключевые слова (''Своб.индексиров.''): chemical synthesis--elpasolite--ferroelectric phase transition--fluorine atoms--low temperature synthesis--low temperatures--oxyfluorides--partial ordering--room temperature--sem--space groups--structure parameter--xrd--chemical properties--ferroelectric materials--ferroelectricity--fluorine--oxygen--phase transitions--rietveld method--single crystals--synthesis (chemical)--x ray photoelectron spectroscopy--x ray powder diffraction--scanning electron microscopy
Аннотация: Low-temperature ferroelectric G2 polymorph of K3WO 3F3 has been prepared by chemical synthesis. Structural and chemical properties of the final product have been evaluated with X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Structure parameters of G2-K 3WO3F3 are refined by the Rietveld method from XRD data measured at room temperature (space group Cm, Z = 2, a = 8.7350(3), b = 8.6808(5), c = 6.1581(3), ? = 135.124(3), V = 329.46(3) 3; RB = 2.47%). Partial ordering of oxygen and fluorine atoms has been found over anion positions. Mechanism of ferroelectric phase transition in A2BMO3F3 oxyfluorides is discussed. В© 2010 Elsevier B.V. All rights reserved.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Goryainov S. V., Krylov A. S., Likhacheva A.Yu., Vtyurin A. N.
Заглавие : Raman investigation of fibrous zeolites of the natrolite group at high pressures of an aqueous medium
Место публикации : Bull. Russ. Acad. Sci.: Phys. - 2012. - Vol. 76, Is. 7. - P.804-807. - ISSN 1062-8738, DOI 10.3103/S1062873812070143
Примечания : Cited References: 7
Ключевые слова (''Своб.индексиров.''): aqueous medium--high pressure--intermediate phase--intermediate phasis--raman bands--raman investigations--water molecule--xrd--raman spectroscopy--silicon--zeolites
Аннотация: The intermediate phases preceding overhydration are observed by Raman spectroscopy both in scolecite Ca[Al2Si3O10] вЂў 3H2O and in thomsonite NaCa2[Al5Si 5O20] вЂў 6H2O upon compression in an aque-ous medium. The first intermediate phase of scolecite is attributed to a phase precursor revealed earlier using XRD at pressure of ~1 GPa. The widening of the Raman bands of O-H vibrations caused by the disordering of H 2O, which appears after additional water molecules are embedded in the zeolite channels, is typical of this intermediate phase. It is assumed on the basis of the Raman spectroscopy data that scolecite contains sec-ond overhydrated and second intermediate phases. В© 2012 Allerton Press, Inc.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lim C. S., Atuchin V. V., Aleksandrovsky A. S., Molokeev M. S.
Заглавие : Preparation of NaSrLa(WO4)3:Ho3+/Yb3+ ternary tungstates and their upconversion photoluminescence properties
Место публикации : Mater. Lett.: Elsevier, 2016. - Vol. 181. - P.38-41. - ISSN 0167577X (ISSN), DOI 10.1016/j.matlet.2016.05.121
Примечания : Cited References: 24. - This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2015-058813), SB RAS Program No.II.2P (No. 0358-2015-0012) and Russian Foundation for Basic Research (15-52-53080).
Предметные рубрики: VIBRATIONAL PROPERTIES
LUMINESCENCE PROPERTIES
MODULATED STRUCTURE
PHOSPHORS
CRYSTAL
RED
Ключевые слова (''Своб.индексиров.''): tungstate--phosphor--sol-gel preparation--luminescence--raman spectroscopy--xrd
Аннотация: NaSrLa1-x(WO4)3:Ho3+/Yb3+ ternary tungstates were synthesized via microwave sol-gel route. Well-crystallized particles with particle sizes of 2-5 ?m were obtained after heat-treatment at 900 °C for 16 h. Under the excitation at 980 nm, the particles showed yellow emissions based on the strong 545 and 655 nm emission bands. The preferable Yb3+:Ho3+ ratio was obtained to be 9:1. Raman spectra of the doped particles indicated the presence of strong Ho3+ luminescence lines. The pump power dependence and Commission Internationale de L'Eclairage chromaticity of the upconversion emission intensity were evaluated. © 2016 Published by Elsevier B.V.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lim C. S., Atuchin V. V., Aleksandrovsky A. S., Molokeev M. S., Oreshonkov A. S.
Заглавие : Incommensurately modulated structure and spectroscopic properties of CaGd2(MoO4)4:Ho3+/Yb3+ phosphors for up-conversion applications
Место публикации : J. Alloys Compd.: Elsevier, 2017. - Vol. 695. - P.737-746. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2016.06.134
Примечания : Cited References: 60. - This research was supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education (2015-058813) and the Russian Foundation for Basic Research (15-52-53080). VVA, ASA and ASO were partially supported by the Ministry of Education and Science of the Russian Federation.
Ключевые слова (''Своб.индексиров.''): modulation--molybdate--raman--sol-gel synthesis--upconversion--xrd
Аннотация: CaGd2(MoO4)4:Ho3+/Yb3+ phosphors doped by Ho3+ and Yb3+ (Ho3+ = 0 and 0.05, and Yb3+ = 0, 0.35, 0.40, 0.45 and 0.50) were successfully synthesized by the microwave sol-gel method. The synthesized particles, being formed after heat-treatment at 900 °C for 16 h, showed a well crystallized morphology. All compounds are (3 + 2)D incommensurately modulated with superspace group I41/a(α,β,0)00(-β,α,0)00. It was found that parameter (α2 + β2)1/2 is proportional to cell parameter a for all studied compositions and, therefore, modulation vector k is the same for all known CaRE2(MoO4)4 compounds. The modulation vector invariance is a specific and valuable feature of this type of the structure. Under the excitation at 980 nm, the doped particles exhibited the yellow emission composed of green (545-nm) and red (655-nm) emission bands due to frequency upconversion (UC). The pump power dependence and CIE chromaticity of the UC emission were evaluated. The shape of UC bands in CaGd2(MoO4)4:Ho3+/Yb3+ is dependent on the Yb content due to the influence of the crystal field affecting a holmium ion. 13 Raman-active modes of the CaGd2(MoO4)4 lattice were identified via a comparison of experimental Raman spectra and the lattice dynamics simulation results. Four additional Raman lines were found in the region of stretching vibrations and, at least, two additional modes are present in the bending mode region. These additional modes are ascribed to incommensurate crystal lattice modulation. Luminescence bands of Ho ions are severely broadened due to a statistical disorder in the CaGd2−xYby (MoO4)4 lattice.
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14.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Kazak N. V., Platunov M. S., Knyazev Yu. V., Bezmaternykh L. N., Veligzhanin A. A., Zubavichus Y. V., Trigub A., Solovyov L. A., Ovchinnikov S. G.
Заглавие : Charge ordering in Mn2BO4: XRD and XANES studies
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.I10.6. - P.432. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 3. - This work has been financed by the Council for Grants of the President of the Russian Federation (SP-938.2015.5), the RFBR (№ 16-32-60049 mol_a_dk, № 16-32-00206 mol_a), SB RAS program № II.2P contract 0358-2015-0005 and by «UMNIK» program.
Ключевые слова (''Своб.индексиров.''): charge ordering--x-ray spectroscopy--x-ray diffraction--phase transitions
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fokina V. D., Flerov I. N., Molokeev M. S., Pogoreltsev E. I., Bogdanov E. V., Krylov A. S., Bovina A. F., Voronov V. N., Laptash N. M.
Заглавие : Heat capacity, p-T phase diagram, and structure of Rb2KTiOF5
Коллективы :
Разночтения заглавия :авие SCOPUS: Heat capacity, p-T phase diagram, and structure of Rb2KTiOF 5
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 11. - P2175-2183. - ISSN 1063-7834, DOI 10.1134/S1063783408110280
Примечания : Cited References: 23. - This work was supported by the Russian Foundation for Basic Research, project no. 06-02-16102.
Предметные рубрики: ELECTRON-DIFFRACTION
TRANSITIONS
OXYFLUORIDES
(NH4)(2)KWO3F3
TEMPERATURE
XRD
CS
Ключевые слова (''Своб.индексиров.''): 61--50--ks--65--40--ba--65--40--gd--78--30--hv--81--30--dz
Аннотация: Elpasolite Rb2KTiOF5 (space group, Fm was synthesized using a solid-phase reaction method. The temperature dependences of the heat capacity, the unit cell parameters, the structure, the permittivity, the response to an external pressure, and the Raman spectra were studied. A nonferroelectric phase transition was revealed at T (0) = 215 K; the transition is accompanied by a tetragonal distortion of the unit cell (space group I4/m, Z = 10) and a change in the entropy (S (0) = Rln8), which is anomalously large for perovskite-like oxyfluorides with atomic cations. The specific features of the mechanism of structure distortion are discussed in combination with the previous experimental data obtained for cryolite (NH4)(3)TiOF5 and elpasolite Rb2KGaF6.
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