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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) : Васильева, Наталья Дмитриевна, Софронова, Светлана Николаевна, Баринов В. В., Тайник А. В., Трушкина Т. В., Чуракова О. В.
Заглавие : Применение процессного моделирования для интерпретации вариации стабильных изотопов в годичных кольцах деревьев
Колич.характеристики :16 с
Коллективы : РусДендро-2023, Международная дендрохронологическая конференция
Место публикации : Лесотехнич. журн. - 2023. - Т. 13, № 4, Ч. 2. - С. 23-38. - ISSN 22227962 (ISSN), DOI 10.34220/issn.2222-7962/2023.4/15; Forest. Eng. J.
Примечания : Библиогр.: 33. - Исследование выполнено за счет гранта Российского научного фонда № 21-17-00006, (https://rscf.ru/en/project/21-17-00006/)
Аннотация: Ширина годичных колец деревьев и изотопный состав стабильных изотопов углерода (δ13C), кислорода (δ18O) и водорода (δ2H) в целлюлозе годичных колец широко используются для реконструкций условий окружающей среды. Применение моделей, способных описать вариацию стабильных изотопов в годичных кольцах деревьев, представляет собой набор инструментов для интерпретации изменений окружающей среды на экофизиологическом уровне. В данной работе хронологии с погодичным временным разрешением, полученные по стабильным изотопам δ13С, δ18O и δ2H в целлюлозе годичных колец хвойных для региона Дельта реки Маккензи в Канаде (68° 30′ с.ш., 133° 48′ з.д.) для периода с 1901 по 2009 гг., были сопоставлены с модельными расчетами для интерпретации экофизиологического сигнала. При помощи процессной модели (LPX) нам удалось смоделировать δ13С вариацию, значимо коррелирующую с измеренными данными (r = 0.29; p = 0.002) для периода с 1901 по 2009 гг. Модельные расчеты по кислороду и водороду требуют дальнейшего преобразования модельных блоков, в частности, требуют доработки включения источника воды, используемой деревьями, блока оттаивания и промерзания почвы с учетом вечной мерзлоты, а также экспериментальных данных по содержанию δ18O и δ2H в воде.Tree-ring width and stable isotopes (carbon, oxygen, and hydrogen) in tree-ring cellulose are widely used to reconstruct environmental conditions. The application of models capable to describe a variation of stable isotopes in annual tree rings can be a powerful tool for interpretation of environmental changes at the eco-physiological level. In this paper, we modelled carbon (δ13С), oxygen (δ18O), and hydrogen (δ2H) variations at the tree-ring level and compared results with measured data, obtained from the Mackenzie Delta River (68°30′ N, 133°48′ W) for the common period from 1901 to 2009. Using a process-based model (LPX), we were able to simulate carbon isotope values, which significantly (r = 0.29; p = 0.002) correlate with measured carbon isotope values. The model calculations for oxygen and hydrogen require further modifications and improvements, in particular the inclusion of the source of water used by the trees in the Canadian subarctic, as well as δ18O and δ2H in the water.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Верещагин, Сергей Николаевич, Дудников, Вячеслав Анатольевич, Орлов, Юрий Сергеевич
Заглавие : Применение ТГ/ДСК-анализа c программированным составом газовой фазы для изучения фазового перехода порядок-беспорядок в нестехиометрическом Sr-Dy-кобальтате
Место публикации : J. Sib. Fed. Univ. Chem. - 2018. - Vol. 11, Is. 4. - P.507-517. - ISSN 1998-2836, DOI 10.17516/1998-2836-0095; Журн. СФУ. Химия. - ISSN 2313-6049(eISSN)
Примечания : Библиогр.: 17. - Исследование выполнено при финансовой поддержке Российского фонда фундаментальных исследований, Правительства Красноярского края, Красноярского краевого фонда науки в рамках научного проекта No 18-42-243004 и проекта фундаментальных исследований СО РАН V.45.3.3.
Предметные рубрики: PEROVSKITE
OXYGEN
Ключевые слова (''Своб.индексиров.''): перовскит--порядок-беспорядок--фазовый переход--тг--дск--perovskite--order-disorder--phase transition--tg--dsc
Аннотация: Методом термического анализа (ТГ/ДСК) в условиях постоянного и программированного состава газовой фазы изучено влияние скорости закалки на полноту перехода кубического разупорядоченного нестехиометрического перовскита (I) Sr(0.8)Dy(0.2)CoO(3-d) в тетрагональную модификацию (II) с упорядоченным расположением катионов Sr/Dy и анионных вакансий, а также взаимосвязь степени превращения I в II с количеством мобильного кислорода и его энергетическими характеристиками. Показано, что фазовое превращение протекает как фазовый переход первого рода, процесс образования структуры II контролируется кинетическими факторами, а использование скоростей охлаждения 3-99 К/мин позволяет получить образцы, формально соответствующие 98-30 % превращению I в II; при этом как количество подвижного кислорода, так и энтальпия его удаления из образца нелинейно зависят от полноты перехода I в II.For the first time a method of TG/DSC analysis under constant and variable gas phase composition was applied to reveal interconnection between quenching ramp rates and degree of phase transformation of cubic nonstoichiometric disordered perovskite (I) Sr(0.8)Dy(0.2)CoO(3-d) to tetragonal structure (II) with ordered Sr/Dy cations and anion vacancies. It was shown that the transformation is a first order phase transition and the ordering process is kinetically controlled. Based on the experimental transition enthalpy it was found that a formal conversion degree of I to II was 98-30% under cooling ramp rates 3-99 K/min. Non-linear relationship between the completeness of I-to-II transformation and mobile oxygen characteristics (content and the enthalpy of O-removal) was demonstrated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Верещагин, Сергей Николаевич, Дудников, Вячеслав Анатольевич, Соловьев, Леонид Александрович
Заглавие : Изучение подвижного кислорода в упорядоченном/разупорядоченном нестехиометрическом кобальтате Sr-Gd методом синхронного термического анализа
Место публикации : Журн. СФУ. Химия. - 2017. - Т. 10, № 3. - С. 346-357. - ISSN 1998-2836, DOI 10.17516/1998-2836-0031; J. Sib. Fed. Univ. Chem. - 2017. - ISSN 2313-6049(eISSN)
Примечания : Библиогр.: 19
Ключевые слова (''Своб.индексиров.''): разупорядоченный перовскит--кобальтат--дск--тг--кристаллическая структура--подвижный кислород--disordered perovskite--cobaltate--dsc--tg--crystal structure--mobile oxygen
Аннотация: Методом синхронного термического анализа (ДСК/ТГ/масс-спектрометрия) при переменном парциальном давлении кислорода изучены разупорядоченная кубическая и упорядоченная по А-позициям тетрагональная фазы Sr-Gd-кобальтата (Sr/Gd=4). Показано, что упорядочение А-катионов приводит к снижению энтальпии отщепления О2, преимущественной локализации образовавшейся вакансии в одной из четырёх неэквивалентных позиций аниона О2- и снижению количества подвижного кислорода, удаляемого при изменении парциального давления О2. Наблюдаемые различия в свойствах мобильного кислорода и каталитической активности в реакции глубокого окисления метана для упорядоченной/разупорядоченной фазы перовскита обсуждены с позиций изменения доли анионов О2- с различным локальным окружением, содержащим от 0 до 4 катионов гадолиния.Simultaneous thermal analysis (DSC/TG/mass-spectroscopy) under variable pressure was applied to study properties of mobile oxygen in cubic disordered and tetragonal A-site ordered Sr-Gd-cobaltate (Sr/Gd=4). It was shown that A-site cation ordering results in a decrease of an enthalpy of oxygen elimination, predominant localization of created anion vacancies only at one of four unequivalent crystallographic O-sites and depletion of amount of mobile oxygen, which can be removed at a reduced pressure. The observed properties of mobile oxygen and catalytic activity in reaction of methane deep oxidation for ordered/disordered perovskite phases are discussed in connection with a local environment of O2- crystallographic sites with a different number of Gd3+ cations nearby.
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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) : Bataleva Yu. V., Palyanov Y .N., Sokol A. G., Borzdov Y. M., Bayukov O. A.
Заглавие : Wüstite stability in the presence of a CO2-fluid and a carbonate-silicate melt: Implications for the graphite/diamond formation and generation of Fe-rich mantle metasomatic agents
Место публикации : Lithos: Elsevier, 2016. - Vol. 244. - P.20-29. - ISSN 00244937 (ISSN), DOI 10.1016/j.lithos.2015.12.001
Примечания : Cited References: 68. - This work was supported by the Russian Science Foundation under grant no. 14-27-00054. The authors thank A. Moskalev for his assistance in the work preparation, A. Khokhryakov for useful suggestions throughout the study, and S. Ovchinnikov for his assistance in implementation of Mössbauer spectroscopy measurements. The authors thank editor M. Scambelluri, and two anonymous reviewers for their useful comments, which helped to profoundly improve the manuscript.
Предметные рубрики: EARTHS LOWER MANTLE
FERRIC IRON CONTENT
DIAMOND FORMATION
MINERAL INCLUSIONS
NATURAL DIAMOND
OXIDATION-STATE
DEEP MANTLECRUST
LITHOSPHERIC MANTLE
OXYGEN FUGACITY
OCEANIC-CRUST
Ключевые слова (''Своб.индексиров.''): wustite--co2-fluid--carbonate-silicate melt--decarbonation--graphite formation--hpht experiment
Аннотация: Experimental simulation of the interaction of wüstite with a CO2-rich fluid and a carbonate-silicate melt was performed using a multianvil high-pressure split-sphere apparatus in the FeO-MgO-CaO-SiO2-Al2O3-CO2 system at a pressure of 6.3GPa and temperatures in the range of 1150°C-1650°C and with run time of 20h. At relatively low temperatures, decarbonation reactions occur in the system to form iron-rich garnet (Alm75Prp17Grs8), magnesiowüstite (Mg#≤0.13), and CO2-rich fluid. Under these conditions, magnesiowüstite was found to be capable of partial reducing CO2 to C0 that leads to the formation of Fe3+-bearing magnesiowüstite, crystallization of magnetite and metastable graphite, and initial growth of diamond seeds. At T≥1450°C, an iron-rich carbonate-silicate melt (FeO~56wt.%, SiO2~12wt.%) forms in the system. Interaction between (Fe,Mg)O, SiO2, fluid and melt leads to oxidation of magnesiowüstite and crystallization of fayalite-magnetite spinel solid solution (1450°C) as well as to complete dissolution of magnesiowüstite in the carbonate-silicate melt (1550°C-1650°C). In the presence of both carbonate-silicate melt and CO2-rich fluid, dissolution (oxidation) of diamond and metastable graphite was found to occur. The study results demonstrate that under pressures of the lithospheric mantle in the presence of a CO2-rich fluid, wüstite/magnesiowüstite is stable only at relatively low temperatures when it is in the absolute excess relative to CO2-rich fluid. In this case, the redox reactions, which produce metastable graphite and diamond with concomitant partial oxidation of wüstite to magnetite, occur. Wüstite is unstable under high concentrations of a CO2-rich fluid as well as in the presence of a carbonate-silicate melt: it is either completely oxidized or dissolves in the melt or fluid phase, leading to the formation of Fe2+- and Fe3+-enriched carbonate-silicate melts, which are potential metasomatic agents in the lithospheric mantle. © 2015 Elsevier B.V.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kovel E. S., Kicheeva A. G., Vnukova N. G., Churilov G. N., Stepin E. A., Kudryasheva N. S.
Заглавие : Toxicity and antioxidant activity of fullerenol C60,70 with low number of oxygen substituents
Место публикации : Int. J. Mol. Sci. - 2021. - Vol. 22, Is. 12. - Ст.6382. - ISSN 16616596 (ISSN), DOI 10.3390/ijms22126382
Примечания : Cited References: 93. - This research was funded by RFBR, N18-29-19003; RFBR, Krasnoyarsk Territory and Krasnoyarsk Regional Fund of Science, N20-44-243001; and partly supported by the Program of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing, Fundamental Study 2020-2025 (Russian Federation)
Аннотация: Fullerene is a nanosized carbon structure with potential drug delivery applications. We studied the bioeffects of a water-soluble fullerene derivative, fullerenol, with 10-12 oxygen groups (F10-12); its structure was characterized by IR and XPS spectroscopy. A bioluminescent enzyme system was used to study toxic and antioxidant effects of F10-12 at the enzymatic level. Antioxidant characteristics of F10-12 were revealed in model solutions of organic and inorganic oxidizers. Low-concentration activation of bioluminescence was validated statistically in oxidizer solutions. Toxic and antioxidant characteristics of F10-12 were compared to those of homologous fullerenols with a higher number of oxygen groups:F24-28 and F40-42. No simple dependency was found between the toxic/antioxidant characteristics and the number of oxygen groups on the fullerene’s carbon cage. Lower toxicity and higher antioxidant activity of F24-28 were identified and presumptively attributed to its higher solubility. An active role of reactive oxygen species (ROS) in the bioeffects of F10-12 was demonstrated. Correlations between toxic/antioxidant characteristics of F10-12 and ROS content were evaluated. Toxic and antioxidant effects were related to the decrease in ROS content in the enzyme solutions. Our results reveal a complexity of ROS effects in the enzymatic assay system.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bataleva, Yu. V., Palyanov, Yu. N., Sokol A. G., Borzdov, Yu. M., Bayukov O. A.
Заглавие : The role of rocks saturated with metallic iron in the formation of ferric carbonate-silicate melts: experimental modeling under PT-conditions of lithospheric mantle
Коллективы : Siberian Branch of the Russian Academy of Sciences [31], Russian Foundation for Basic Research [12-05-00740]
Место публикации : Russ. Geol. Geophys.: Elsevier Science, 2015. - Vol. 56, Is. 1-2. - P.143-154. - ISSN 1068, DOI 10.1016/j.rgg.2015.01.008. - ISSN 1878030X(eISSN)
Примечания : Cited References:68. - This work was supported by Integration project 31 from the Siberian Branch of the Russian Academy of Sciences and by grant 12-05-00740 from the Russian Foundation for Basic Research.
Предметные рубрики: OXYGEN FUGACITY
DIAMOND FORMATION
OXIDATION-STATE
EARTHS MANTLE
Ключевые слова (''Своб.индексиров.''): carbonate-silicate melt--graphite--co2 fluid--iron carbide--garnet--redox gradient--high-pressure experiment
Аннотация: Experimental modeling of the processes of formation of ferric carbonate-silicate melts through the carbonate-oxide-metal interaction is performed in the (Mg,Ca)CO3-SiO2-Al2O3-Fe0 system at 6.3 and 7.5 GPa and within 1150-1650 °C, using a multianvil high-pressure apparatus of “split-sphere” type (BARS). Two parallel reactions run in the subsolidus region (1150-1450 °C): decarbonation, producing pyrope-almandine (Fe# = 0.40-0.75) and CO2 fluid, and redox interaction between carbonate and Fe0, resulting in the crystallization of iron carbide in assemblage with magnesiowustite (Fe# = 0.75-0.85). It is shown that the reduction of carbonate or CO2 fluid by iron carbide and parallel redox interaction of magnesiowustite with CO2 produce graphite in assemblage with Fe3 + -containing magnesiowustite. In the temperature range of 1450-1650 °C, generation of carbonate-silicate melts coexisting with pyrope-almandine, magnesiowustite, magnetite, ferrospinel, and graphite takes place. The composition of the produced melts is as follows: SiO2 - 10-15 wt.%, X(FeO + Fe2O3) = 36-43 wt.%, and Fe3+/XFe - 0.18-0.23. These Fe3 + -enriched carbonate-silicate melts/fluids are saturated with carbon and are the medium of graphite crystallization. Oxide and silicate phases (almandine, ferrospinel, and magnetite) coexisting with graphite are also characterized by high Fe3+/XFe values. It has been established that Fe3 + -enriched carbonate-silicate melts can result from the interaction of Fe0-containing rocks with carbonated rocks. In the reduced mantle (with the presence of iron carbides or oxides), melts of this composition can be the source of carbon and the medium of graphite crystallization at once. After separation and ascent, these ferric carbonate-silicate melts can favor oxidizing metasomatism in the lithospheric mantle.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Churilov G. N., Glushenko G. A., Tomashevich Ye. V., Nikolaev N. S., Vnukova N. G.
Заглавие : The role of oxygen in the formation of a continual metal shell strongly bonded to the carbon surface
Коллективы : "Functional materials", International conference, Крымский федеральный университет имени В.И. Вернадского
Место публикации : Ovchinnikov S. G. "Functional materials", International conference (2021 ; Oct. 4-8 ; Alushta, Russia) International conference "Functional materials": book of abstracts/ ed. V. N. Berzhansky ; org. com. S. G. Ovchinnikov [et al.]. - Simferopol, 2021. - P.244-245
Примечания : Библиогр.: 3
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10.

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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11.

Вид документа : Статья из сборника (выпуск продолж. издания)
Шифр издания :
Автор(ы) : Karpov I. V., Ushakov A. V., Lepeshev A. A., Fedorov L. Y., Dorozhkina E. A., Karpova O. N., Shaikhadinov A. A., Demin V. G., Bachurina E. P., Lichargin D. V., Abkaryan A. K., Zeer G. M., Zharkov S. M.
Заглавие : The investigation of the influence of oxygen concentration in the gas mixture on nanodispersed oxides synthesis
Коллективы : International Scientific Conference Reshetnev Readings
Место публикации : IOP Conf. Ser.: Mater. Sci. Eng. - 2017. - Vol. 255, Is. 1. - Ст.012008. - , DOI 10.1088/1757-899X/255/1/012008
Примечания : Cited References: 25
Ключевые слова (''Своб.индексиров.''): cathodes--electrodes--particle size--vacuum applications--average particle size--cathode process--discharge gaps--energy of ions--influence of oxygen--low pressure arc--oxides synthesis--superheated gas--gases
Аннотация: Thermal effects in cathode space of low-pressure arc discharge, which contribute to the synthesis of nanopowders with an average particle size of less than 10 nm, are considered. One of the most important parameters, characterizing the cathode processes of vacuum arc, is a voltage drop across the discharge gap. All the gases demonstrate a decrease of a voltage drop across the discharge gap under the condition ofincreasing the gas pressure in the range of p = 10-3 - 1 Pa. Dissipation of energy of ions and electrons on gas molecules causes abrupt heating of the gas. Heat, coming from gas plasma, has a significant impact on evaporating material of a cathode. It can be assumed that a microdrop fraction, formed as a result of a cathode spraying in a liquid phase, will further evaporate in a superheated gas.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Uschakov A. V., Karpov I. V., Lepeshev A. A., Zharkov S. M.
Заглавие : The influence of oxygen concentration on the formation of CuO and Cu2O crystalline phases during the synthesis in the plasma of low pressure arc discharge
Место публикации : Vacuum: Elsevier, 2016. - Vol. 128. - P.123-127. - ISSN 0042207X (ISSN), DOI 10.1016/j.vacuum.2016.03.025
Примечания : Cited References: 19. - This study was supported by the Russian Foundation for Basic Research. (Project No 15-08-02132).
Предметные рубрики: Nanoparticles
Oxide
Ключевые слова (''Своб.индексиров.''): oxides--vapor deposition--x-ray diffraction--transmission electron microscopy (tem)--catalytic properties
Аннотация: This paper describes the synthesis of copper oxide nanoparticles with different percentages of CuO and Cu2O phases. It was achieved by the control of the percentage of oxygen in the gas mixture (N2 + O2) in a plasma-chemical process of evaporation-condensation by means of low-pressure arc discharge. In all the experiments, the pressure in the plasma-chemical reactor remained constant at 60 Pa. By means of X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) it was found that the average particle size was 6 nm, and Cu2O phase content decreases with increasing oxygen content in the gas mixture. High photocatalytic properties of Cu2O powder were shown by the example of the reaction of the methyl orange dye decomposition in water solution. The problems, associated with the performance of this method and the formation of crystalline phases, are discussed.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shubin A. A., Kovalskii V. Y., Ruzankin S. P., Zilberberg I. L., Parmon V. N., Tomilin F. N., Avramov P. V.
Заглавие : The FeIV-O• oxyl unit as a key intermediate in water oxidation on the FeIII-hydroxide: DFT predictions
Место публикации : Int. J. Quantum Chem. - 2021. - Vol. 121, Is. 10. - Ст.e26610. - ISSN 00207608 (ISSN), DOI 10.1002/qua.26610
Примечания : Cited References: 21. - Aleksandr A. Shubin, Igor L. Zilberberg, and Valentin N. Parmon acknowledge the support of Russian Foundation for Basic Research under grant No. 15-29-01275. Viktor Yu. Kovalskii acknowledges the support of Russian Foundation for Basic Research under grant No. 18-33-00932. Calculations have been performed at the Siberian Supercomputer Centre SB RAS
Аннотация: The O-O coupling process in water oxidation on the gamma FeOOH hydroxide catalyst is simulated by means of density functional theory using model iron cubane cluster Fe4O4(OH)4. A key reactive intermediate is proposed to be the HO-FeIV-O• oxyl unit with terminal oxo radical. The “initial” vertex FeIII(OH) moiety forms this intermediate at the calculated overpotential of 0.93 V by adding one water molecule and withdrawing two proton–electron pairs. The O-O coupling goes via water nucleophilic attack on the oxyl oxygen to form the O-O bond with a remarkably low barrier of 11 kcal/mol. This process is far more effective than alternative scenario based on direct interaction of two ferryl FeIV-O sites (with estimated barrier of 36 kcal/mol) and is comparable with the coupling between terminal oxo center and three-coordinated lattice oxo center (12 kcal/mol barrier). The process of hydroxylation of terminal oxygen inhibits the O-O coupling. Nevertheless, being more effective for ferryl oxygen, the hydroxylation in fact enhances selectivity of the O-O coupling initiated by the oxyl oxygen.
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14.

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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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shakirova A. A., Tomilin F. N., Pomogaev V. A., Vnukova N. G., Churilov G. N., Kudryasheva N. S., Tchaikovskaya O. N., Ovchinnikov S. G., Avramov P. V.
Заглавие : Synthesis, mass spectroscopy detection, and density functional theory investigations of the Gd endohedral complexes of C82 fullerenols
Коллективы : RFBRRussian Foundation for Basic Research (RFBR) [18-29-19003 MK]; Russian Ministry of Science and EducationMinistry of Education and Science, Russian Federation [0721-2020-0033]; Collaborative NRF-RFBR grant (Korean) [NRF-2019K2A9A1A06100125]; Collaborative NRF-RFBR grant (Russian) [19-53-51005 NIFa RFFI-Korea]; NRF [2021R1A2C1010455]
Место публикации : Computation. - 2021. - Vol. 9, Is. 5. - Ст.58. - ISSN 2079-3197(eISSN), DOI 10.3390/computation9050058
Примечания : Cited References: 41. - The experimental results were funded by RFBR project No. 18-29-19003 MK. The quantum chemical study was funded by project 0721-2020-0033 of the Russian Ministry of Science and Education. The collaboration and coordination of Russian and Korean teams was supported by Collaborative NRF-RFBR grant (Korean ID: NRF-2019K2A9A1A06100125; Russian ID: Project No. 19-53-51005 NIFa RFFI-Korea) and NRF 2021R1A2C1010455 grant
Предметные рубрики: ZETA VALENCE QUALITY
BIOLOGICAL-ACTIVITY
BASIS-SETS
TOXICITY
Аннотация: Gd endohedral complexes of C82 fullerenols were synthesized and mass spectrometry analysis of their composition was carried out. It was established that the synthesis yields a series of fullerenols Gd@C82Ox(OH)y (x = 0, 3; y = 8, 16, 24, 36, 44). The atomic and electronic structure and properties of the synthesized fullerenols were investigated using the density functional theory calculations. It was shown that the presence of endohedral gadolinium increases the reactivity of fullerenols. It is proposed that the high-spin endohedral fullerenols are promising candidates for application in magnetic resonance imaging.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Denisenko, Yu. G., Sal'nikova E. I., Basova S. A., Molokeev M. S., Krylov A. S., Aleksandrovsky A. S., Oreshonkov A. S., Atuchin V. V., Volkova S. S., Khritokhin N. A., Andreev O. V.
Заглавие : Synthesis of samarium oxysulfate Sm2O2SO4 in the high-temperature oxidation reaction and its structural, thermal and luminescent properties
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [18-02-00754, 18-32-20011]; Russian Science FoundationRussian Science Foundation (RSF) [19-42-02003]
Место публикации : Molecules. - 2020. - Vol. 25, Is. 6. - Ст.1330. - ISSN 1420-3049(eISSN), DOI 10.3390/molecules25061330
Примечания : Cited References: 56. - This research was funded by the Russian Foundation for Basic Research (Grants 18-02-00754, 18-32-20011) and Russian Science Foundation (project 19-42-02003).
Предметные рубрики: RARE-EARTH SULFATES
SPECTROSCOPIC PROPERTIES
OXYGEN-STORAGE
LN
LA
Аннотация: The oxidation process of samariumoxysulfide was studied in the temperature range of 500–1000 °C. Our DTA investigation allowed for establishing the main thermodynamic (∆Hºexp = −654.6 kJ/mol) and kinetic characteristics of the process (Ea = 244 kJ/mol, A = 2 × 1010). The enthalpy value of samarium oxysulfate (ΔHºf (Sm2O2SO4(monocl)) = −2294.0 kJ/mol) formation was calculated. The calculated process enthalpy value coincides with the value determined in the experiment. It was established that samarium oxysulfate crystallizes in the monoclinic symmetry class and its crystal structure belongs to space group C2/c with unit cell parameters a = 13.7442 (2), b = 4.20178 (4) and c = 8.16711 (8)Å, β = 107.224 (1)°, V = 450.498 (9)Å3, Z = 4. The main elements of the crystalline structure are obtained and the cation coordination environment is analyzed in detail. Vibrational spectroscopy methods confirmed the structural model adequacy. The Sm2O2SO4 luminescence spectra exhibit three main bands easily assignable to the transitions from 4G5/2 state to 6H5/2, 6H7/2, and 6H9/2 multiplets.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnikov V. A., Vereshchagin S. N., Solov’ev L. A., Gavrilkin S. Y., Tsvetkov A. Y., Sitnikov M. V., Orlov Yu. S.
Заглавие : Structure of metastable Sr0.8Dy0.2Co3-δ phases and their electrical and magnetic properties
Место публикации : J. Exp. Theor. Phys. - 2022. - Vol. 134, Is. 3. - P.290-299. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776122030037
Примечания : Cited References: 40. - Investigation was supported by the Russian Foundation for Basic Research (grant no. 19-03-00017). Thermal and X-ray diffraction studies were conducted in the framework of State Task 0287-2021-0013 for the Institute of Chemistry and Chemical Technologies, Siberian Branch, Russian Academy of Sciences
Аннотация: Polycrystalline Sr0.8Dy0.2Co3-δ complex cobalt oxides with a different amount of oxygen (δ = 0.26, 0.44, 0.46) have been prepared by solid-state synthesis. An increase in oxygen deficiency causes the brownmillerite phase to appear in the perovskite structure, which significantly changes its properties. At δ = 0.46, the content of the brownmillerite phase reaches 38%. A comparative analysis of the magnetic and transport properties of synthesized samples has been carried out. The asymptotic Curie temperature changes sign from positive at δ = 0.26 to negative at δ = 0.46. The magnetoresistance of the sample with δ = 0.46 is negative and exceeds 40% at T = 10 K. The temperature dependence of resistivity is characteristic of semiconductors, and the absolute values for samples at low temperatures differ almost tenfold.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnikov V. A., Orlov Yu. S., Bushinsky M. V., Solovyov L. A., Vereshchagin S. N., Gavrilkin, S. Yu, Tsvetkov, A. Yu, Gorev M. V., Novikov S. V., Mantytskaya O. S., Ovchinnikov S. G.
Заглавие : Structural, magnetic, electronic, and dilatation properties of the ordered solid solutions Ln0.2Sr0.8CoO3-δ (Ln = Sm, Gd, Dy) with the same oxygen nonstoichiometry index δ
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [19-03-00017]; RFBRRussian Foundation for Basic Research (RFBR) [18-52-00017, F18R-119]; BRFFR [18-52-00017, F18R-119]; Russian Foundation for Basic Research, Government of Krasnoyarsk Territory [18-42-243004, SB RAS V.45.3.3]
Место публикации : J. Alloy. Compd. - 2020. - Vol. 830. - Ст.154629. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2020.154629. - ISSN 1873-4669(eISSN)
Примечания : Cited References: 44. - The work was financially supported by Russian Foundation for Basic Research (grant No. 19-03-00017); RFBR and BRFFR as a part of scientific project No. 18-52-00017 and project F18R-119; Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project: "New thermoelectric materials based on multi-scale spatially inhomogeneous substituted rare-earth cobalt oxides and the Ruddlesden-Popper phases " project No. 18-42-243004, Project of Basic Research SB RAS V.45.3.3.
Предметные рубрики: LN(1-X)SR(X)COO(3-DELTA) LN
COBALTATE PEROVSKITES
Аннотация: Single-phase samples of the layered perovskite-like cobalt oxides Ln0.2Sr0.8CoO3-δ (Ln = Sm, Gd, Dy) with the same oxygen nonstoichiometry index δ = 0.37 ± 0.01 were synthesized. All samples are characterized by a tetragonal unit cell with the space group I4/mmm. The structural, magnetic, electric transport and dilatation properties of the obtained samples are investigated. The studied samples are characterized by two anomalies in magnetic properties, a high-temperature maximum near Тm = 350 К with magnetic field hysteresis below Tm, and a diffuse peak in the intermediate temperature range, which shifts with ionic radius decrease of the rare-earth element to higher temperatures. The high-temperature maxima of the magnetic susceptibility correlate with anomalies in thermal expansion, heat capacity and the features in the temperature dependences of the electrical resistivity, pointing to a strong relationship between the structural, magnetic and electronic degrees of freedom. The given comparative analysis of the experimental data of various substituting rare-earth elements with the same oxygen nonstoichiometry has been carried out for the first time.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnikov V. A., Kazak N. V., Orlov Yu. S., Vereshchagin S. N., Gavrilkin, S. Yu., Tsvetkov, A. Yu., Gorev M. V., Veligzhanin A. A., Trigub A. L., Troyanchuk I. O., Ovchinnikov S. G.
Заглавие : Structural, Magnetic, and Thermodynamic Properties of Ordered and Disordered Cobaltite Gd0.1Sr0.9CoO3 – δ
Коллективы : Russian Foundation for Basic Research [17-02-00826, 16-02-00507, 18-52-00017 Bel_a]; Russian Federation [SP-1844.2016.1]; Ministry of Education and Science of the Russian Federation [RFMEFI61917X0007]
Место публикации : J. Exp. Theor. Phys. - 2019. - Vol. 128, Is. 4. - P.630-640. - ISSN 1063-7761, DOI 10.1134/S1063776119020171. - ISSN 1090-6509(eISSN)
Примечания : Cited References: 27. - This work was supported by the Russian Foundation for Basic Research (grant nos. 17-02-00826, 16-02-00507, and 18-52-00017 Bel_a) and by the Council on Grants of the President of the Russian Federation (SP-1844.2016.1). X-ray spectra were recorded using the equipment of a unique scientific facility Kurchatov Synchrotron Radiation Source financed by the Ministry of Education and Science of the Russian Federation (project ID RFMEFI61917X0007).
Предметные рубрики: PROFILE REFINEMENT
PHASE-TRANSITION
OXYGEN SORPTION
PEROVSKITE
Аннотация: The effect of cationic and anionic orderings on the crystal structure and magnetic properties of substituted rare-earth cobaltites Gd0.1Sr0.9CoO3 – δ was studied using X-ray diffraction, measurement of XANES spectra, and magnetic and thermodynamic characteristics. The effects of ordering cause a decrease in symmetry to tetragonal and a distortion of the coordination octahedra of CoO6. Anomalous magnetic and thermodynamic quantities are observed at 260 and 360 K, respectively, for disordered and ordered samples. The XANES spectra measured at the CoK edge did not reveal a noticeable shift in the absorption edge compared with the spectrum of original GdCoO3. This suggests that the charge compensation process is associated not only with a change in the electronic state of cobalt ions, but also with the emergence of holes in the 2p states of oxygen.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Janowitz C., Seidel U., Unger RST, Krapf A., Manzke R., Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Strong spin triplet contribution of the first removal state in the insulating regime of Bi2Sr2Ca1-xYxCu2O8+delta
Разночтения заглавия :авие SCOPUS: Strong spin triplet contribution of the first removal state in the insulating regime of Bi2Sr2Ca1-xY xCu2O8+δ
Место публикации : JETP Letters. - 2004. - Vol. 80, Is. 11. - P.692-696. - ISSN 0021-3640, DOI 10.1134/1.1862796
Примечания : Cited References: 18
Предметные рубрики: ELECTRONIC-STRUCTURE
APICAL OXYGEN
MODEL
SUPERCONDUCTIVITY
ONSET
Аннотация: The experimental dispersion of the first removal state in the insulating Bi2Sr2Ca1 - xYxCu2O8 + delta regime is found to differ significantly from that of other parent materials: oxyclorides and La2CuO4. For Y contents of 0.92 greater than or equal to x greater than or equal to 0.55 due to nonstoichiometric effects in the Bi-O layers, the hole concentration in the CuO2 layers is almost constant and, on the contrary, the crystal lattice parameters a, b, c change very strongly. This (a, b) parameter increase and c parameter decrease results in an unconventional three peak structure at (0, 0), (pi/2, pi/2), (pi, pi) for x = 0.92. We can describe the experimental data only beyond the framework of the three-band p-d-model involving the representations of a new triplet counterpart for the Zhang-Rice singlet state. (C) 2004 MAIK "Nauka/Interperiodica".
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