Персона: Писарев, Александр Александрович
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Институт лазерных и плазменных технологий
Стратегическая цель Института ЛаПлаз – стать ведущей научной школой и ядром развития инноваций по лазерным, плазменным, радиационным и ускорительным технологиям, с уникальными образовательными программами, востребованными на российском и мировом рынке образовательных услуг.
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- ПубликацияОткрытый доступInfluence of synthesis conditions on the crystal and local structures of WO3 powders(2019) Zubavichus, Y. V.; Svetogorov, R. D.; Shchetinin, I. V.; Zheleznyi, M. V.; Popov, V. V.; Menushenkov, A. P.; Pisarev, A. A.; Berdnikova, M. M.; Yaroslavtsev, A. A.; Gaynanov, B. R.; Попов, Виктор Владимирович; Менушенков, Алексей Павлович; Писарев, Александр Александрович; Бердникова, Мария Михайловна; Гайнанов, Булат Радикович© Published under licence by IOP Publishing Ltd.Influence of synthesis conditions on the crystal and local structures of WO3 powders prepared by thermal decomposition of ammonium paratungstate and precipitation of tungstates aqueous solutions in strong acid conditions has been investigated. Combination of X-ray powder diffraction, X-ray absorption fine structure spectroscopy, IR- and Raman-spectroscopy, and scanning electron microscopy was used. The calcination of all initial compounds at temperatures ≥ 500C led to formation of the monoclinic γ-WO3 single phase. It was concluded that the neutral octahedral complex [W=0(0H)4(H20)] can be a structural unit of the precursors prepared in acidic suspensions. The local structure of synthesized tungsten oxides consists of edge-shared and corner-shared distorted octahedral WO6 species linked together.
- ПубликацияТолько метаданныеEffects of synthesis conditions on the crystal and local structures of high-entropy oxides Ln2M2O7 (Ln = La-Yb, Y; M = Ti, Zr, Ce)(2024) Popov, V. V.; Menushenkov, A. P.; Yastrebtsev, A. A.; Gaynanov, B. R.; Ivanov, A. A.; Rudakov, S. G.; Berdnikova, M. M.; Pisarev, A. А.; Попов, Виктор Владимирович; Менушенков, Алексей Павлович; Ястребцев, Алексей Алексеевич; Гайнанов, Булат Радикович; Иванов, Андрей Анатольевич; Рудаков, Сергей Геннадьевич; Бердникова, Мария Михайловна; Писарев, Александр Александрович
- ПубликацияТолько метаданныеThe synthesis and studies of crystal/local structures and morphology of hydrated molybdenum oxides(2021) Khramov, E. V.; Zubavichus, Y. V.; Shchetinin, I. V.; Ponkratov, K. V.; Popov, V. V.; Menushenkov, A. P.; Yastrebtsev, A. A.; Molokova, A. Y.; Pisarev, A. A.; Попов, Виктор Владимирович; Менушенков, Алексей Павлович; Ястребцев, Алексей Алексеевич; Писарев, Александр Александрович© 2021 Elsevier Inc.The crystal/local structure and morphology of hydrated molybdenum oxides particles obtained by acidic precipitation of molybdates solutions were studied using X-ray diffraction, X-ray absorption spectroscopy, scanning electron microscopy, Raman and IR spectroscopy. The precipitation of ammonium heptamolybdate solutions (pH = 1.00) at room temperature result in the formation of poorly crystallized hydrated molybdenum oxides. At the same time, acidification of the sodium molybdate solutions does not lead to the appearance of precipitates for several days. Heating to 90 °C and aging the reaction suspension prepared from both ammonium heptamolybdate and sodium molybdate results in the formation of prismatic h-MoO3 particles with the hexagonal crystal structure. It was shown that distorted octahedra MoO6 are the basic structural units in the formed hydrated molybdenum oxides. Along with the presence of Mo[dbnd]O and Mo–O bonds, the presence of water molecules, hydroxyl ions, and NH4+ (or Na+) ions was detected in the structure of hydrated MoO3. The type of Mo salt and acid significantly affects the morphology of h-MoO3 particles. Large h-MoO3 particles are formed by aggregation of small ones and Ostwald ripening due to the “dissolution - precipitation” process.
- ПубликацияОткрытый доступInfluence of Synthesis Conditions on the Crystal, Local Atomic, Electronic Structure, and Catalytic Properties of (Pr1−xYbx)2Zr2O7 (0 ≤ x ≤ 1) Powders(2023) Popov, V. V.; Menushenkov, A. P.; Yastrebtsev, A. A.; Gaynanov, B. R.; Chernysheva, O. V.; Ivanov, A. A.; Rudakov, S. G.; Berdnikova, M. M.; Pisarev, A. A.; Попов, Виктор Владимирович; Менушенков, Алексей Павлович; Ястребцев, Алексей Алексеевич; Гайнанов, Булат Радикович; Чернышева, Ольга Викторовна; Иванов, Андрей Анатольевич; Рудаков, Сергей Геннадьевич; Бердникова, Мария Михайловна; Писарев, Александр АлександровичThe influence of Yb3+ cations substitution for Pr3+ on the structure and catalytic activity of (Pr1в€’xYbx)2Zr2O7 powders synthesized via coprecipitation followed by calcination is studied using a combination of long- (s-XRD), medium- (Raman, FT-IR, and SEM-EDS) and short-range (XAFS) sensitive methods, as well as adsorption and catalytic techniques. It is established that chemical composition and calcination temperature are the two major factors that govern the phase composition, crystallographic, and local-structure parameters of these polycrystalline materials. The crystallographic and local-structure parameters of (Pr1в€’xYbx)2Zr2O7 samples prepared at 1400 В°C/3 h demonstrate a tight correlation with their catalytic activity towards propane cracking. The progressive replacement of Pr3+ with Yb3+ cations gives rise to an increase in the catalytic activity. A mechanism of the catalytic cracking of propane is proposed, which considers the geometrical match between the metal–oxygen (Pr–O, Yb–O, and Zr–O) bond lengths within the active sites and the size of adsorbed propane molecule to be the decisive factor governing the reaction route.