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Попов, Виктор Владимирович

Организационные подразделения

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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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Попов

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Виктор Владимирович

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Теперь показываю 1 - 10 из 23

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Influence 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.
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Formation of ultrathin MoS2 films using laser-based methods
(2019) Fominski, V. Y.; Romanov, R. I.; Nevolin, V. N.; Fominski, D. V.; Komleva, O. V.; Popov, V. V.; Фоминский, Вячеслав Юрьевич; Романов, Роман Иванович; Неволин, Владимир Николаевич; Фоминский, Дмитрий Вячеславович; Попов, Виктор Владимирович
© Published under licence by IOP Publishing Ltd.A comparative analysis of the abilities of several novel methods to produce ultrathin molybdenum disulphide (MoS2) films containing from 1 to 10 molecular layers was carried out. To deposit MoSx films and MoOx precursor films, the atomic flux was formed by laser ablation of Mo, MoS2, and MoO3 targets. Saturation with sulphur of the deposited layers was performed using a reactive gas (hydrogen sulphide) or by thermally activated treatment of thin-film precursors in a sulphur vapor. It has been established that the use of hydrogen sulphide makes it possible to obtain ultrathin MoS2 films at relatively low temperatures ∼ 350 C. However, these films contained local defects which were absent in the films prepared by the treatment of thin film MoOx precursors in sulphur vapours at higher temperatures (≥ 650C).
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Comparative neutron and X-ray diffraction analysis of anionic and cationic ordering in rare-earth zirconates (Ln = La, Nd, Tb, Yb, Y)
(2020) Beskrovnyi, A. I.; Neov, D. S.; Shchetinin, I. V.; Ponkratov, K. V.; Yastrebtsev, A. A.; Popov, V. V.; Menushenkov, A. P.; Ястребцев, Алексей Алексеевич; Попов, Виктор Владимирович; Менушенков, Алексей Павлович
© 2020 Elsevier B.V.The influence of the cation radii ratio (γ = 1.37–1.61) and temperature of the isothermal annealing on the specific features of fluorite – pyrochlore phase transition in Ln2O3: ZrO2 = 1:2 (Ln = La, Nd, Tb, Yb, and Y) systems was investigated by means of Neutron (NPD) and X-ray (XRD) powder diffractions as well as Raman spectroscopy. It was shown that with a decrease in the radius of the Ln cation in the La → Nd → Tb → Y → Yb series, the following sequence of phase transitions is observed: the pyrochlore structure → the structure of defect fluorite → the rhombohedral δ-phase. Significant advantages of NPD over XRD are demonstrated for determining the structural features of the anion sublattice. A detailed description of the parameters of the vibrational modes in Raman spectra for samples with a pyrochlore type of ordering is given, depending on the refined structural parameters.
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Effect of the Chemical and Phase Composition of Nanocrystalline Gadolinium Complex Oxides on the Propane Cracking Process
(2020) Markova, E. B.; Kovtun, S. O.; Tereshina, T. A.; Shchetinin, I. V.; Popov, V. V.; Menushenkov, A. P.; Yastrebtsev, A. A.; Molokova, A. Y.; Попов, Виктор Владимирович; Менушенков, Алексей Павлович; Ястребцев, Алексей Алексеевич
© 2020, Pleiades Publishing, Ltd.Abstract: Effect of the chemical composition and crystal structure type of gadolinium complex oxides on their catalytic activity is studied. It is shown that nanocrystalline powders Gd2Ti2O7, Gd2Zr2O7, and Gd2Hf2O7 form highly symmetrical face-centered сubic crystal structures having localized (in Gd2Ti2O7) and delocalized (in Gd2Zr2O7 and Gd2Hf2O7) oxygen vacancies. At the same time, low-symmetrical crystal structures are formed in Gd2(WO4)3 (the monoclinic structure) and Gd2(МоO4)3 (a mixture of monoclinic and rhombic structures). Catalytic runs show that formation of the cubic structure contributes to an increase in the degree of conversion of propane and causes a shift in cracking temperatures to lower values. Formation of this type of nanocrystalline oxides facilitates the dehydrogenation reaction with propylene selectivity up to 80% at temperatures up to 700 К. Formation of the mixture of monoclinic and rhombic structures in Gd2(МоO4)3 leads to a shift in the degree of conversion to the catalytic temperature range of 700–900 К, in which the dehydrogenation reaction predominates (80%). In the case of the monoclinic structure of Gd2(WO4)3 in the same cracking temperature ranges the process of degradation occurs in parallel; this decreases propylene selectivity to 50% and promotes an increase in the yield of ethylene to 30%.
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Magnetic susceptibility of pyrochlores R2Ti2O7: R = Gd, Dy, Tb
(2020) Kuznetsov, A. V.; Churkin, O. A.; Ivanov, A. A.; Popov, V. V.; Alekseev, P. A.; Menushenkov, A. P.; Кузнецов, Алексей Владимирович; Чуркин, Олег Алексеевич; Иванов, Андрей Анатольевич; Попов, Виктор Владимирович; Алексеев, Павел Александрович; Менушенков, Алексей Павлович
© 2019We present the study of magnetic susceptibility of pyrochlores Gd2Ti2O7, Dy2Ti2O7 and Tb2Ti2O7 which belong to frustrated magnets. The temperature dependence of the susceptibility χ(T) of powder samples was measured in the temperature range from 4.2 to 300 K and analyzed in the framework of mean field approximation taking into account both crystal field effects and anisotropy of the exchange interaction. We developed a simple approach allowing us to estimate interaction energies of magnetic ions from χ(T) dependences and data on wave functions of the crystal-field states of the ions using a minimum number of fitting parameters. We revealed a strong anisotropy of the exchange interaction in the paramagnetic state of Gd2Ti2O7 and obtained nearest-neighbor effective bond energies of the magnetic ions in Tb2Ti2O7 and Dy2Ti2O7 which are in good agreement with the temperatures of formation of the spin-ice state in these compounds.
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Rearrangement in the local, electronic and crystal structure of europium titanates under reduction and oxidation
(2020) Khramov, E. V.; Svetogorov, R. D.; Kurilkin, V. V.; Murzin, V. Y.; Popov, V. V.; Menushenkov, A. P.; Molokova, A. Y.; Ivanov, A. A.; Rudakov, S. G.; Boyko, N. V.; Yastrebtsev, A. A.; Попов, Виктор Владимирович; Менушенков, Алексей Павлович; Иванов, Андрей Анатольевич; Рудаков, Сергей Геннадьевич; Бойко, Надежда Владимировна; Ястребцев, Алексей Алексеевич
© 2020 Elsevier B.V.We studied powder samples of europium titanates Eu1−x 2+Eux 3+TiO3+x/2 prepared by sol-gel and coprecipitation methods with subsequent thermal treatment of precursors at different conditions (reducing or oxidizing atmosphere, temperature, exposure time). We have revealed a radical rearrangement in the local, electronic and crystal structure of europium titanates depending on synthesis conditions. The combination of synchrotron X-ray diffraction (s-XRD), X-ray absorption (XANES and EXAFS), infrared and Raman spectroscopies supplemented by photoluminescence and simultaneous thermal analysis was used in our study. It is shown that the combined XANES and thermogravimetric analysis gives clear evidence of a change in the oxidation state of europium cations from Eu2+ to Eu3+. The comparison of s-XRD, XANES, and EXAFS data allowed us to explain the local structure rearrangement during the phase transition from cubic perovskite Eu2+TiO3 (space group Pm3¯m) to pyrochlore phase Eu2 3+Ti2O7 (space group Fd3¯m) through intermediate layered perovskite Eu2 3+Ti2O7 with monoclinic structure (space group P21) under annealing in oxidizing atmosphere. The Raman spectroscopy study pointed to significant changes in the local structure of the anionic sublattice upon the observed phase transitions. The analysis of luminescence spectra has shown that Eu3+ cations occupy positions with low local site symmetry in all synthesized compounds regardless of the type of the crystal structure.
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A XAFS investigation of amorphous-to-crystalline and fluorite-to-pyrochlore phase transitions in Ln2M2O7 (Ln = Gd, Tb, Dy; M = Ti, Zr)
(2020) d'Acapito, F.; Puri, A.; Popov, V. V.; Menushenkov, A. P.; Ivanov, A. A.; Yastrebtsev, A. A.; Gaynanov, B. R.; Попов, Виктор Владимирович; Менушенков, Алексей Павлович; Иванов, Андрей Анатольевич; Ястребцев, Алексей Алексеевич; Гайнанов, Булат Радикович
© 2019 Elsevier LtdAmorphous-to-crystalline and fluorite-to-pyrochlore phase transitions in complex oxides Ln2M2O7 (Ln = Gd, Tb, Dy; M = Ti, Zr) prepared by sol-gel and coprecipitation methods were studied using x-ray absorption spectroscopy in combination with x-ray diffraction and Raman spectroscopy. The Ln titanates crystallize directly from the amorphous state to the pyrochlore structure, while the Ln zirconates form the intermediate fluorite phase first. We have found that both XANES and EXAFS data reflect the considerable difference between the crystallization processes of Ln titanates and zirconates. In particular the evolution of the K–Ti pre-edge features is a good indicator of the phase transition from amorphous to crystalline state. The splitting of the first Ln-O shell in the FT modulus of L3-Ln edge EXAFS spectra in Ln titanates can be regarded as a fingerprint of the ordered pyrochlore structure formation which is accompanied also by specific changes in the main features of the XANES spectra. For the Ln zirconates these features are less pronounced.
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Magnetization of Crystalline and Amorphous Phases of R(2)Ti(2)O(7)and R2Zr2O7(R = Gd, Dy, Tb)
(2020) Kuznetsov, A. V.; Churkin, O. A.; Popov, V. V.; Shchetinin, I. V.; Ivanov, A. A.; Yaroslavtsev, A. A.; Gaynanov, B. R.; Yastrebtsev, A. A.; Chernysheva, O. V.; Alekseev, P. A.; Menushenkov, A. P.; Кузнецов, Алексей Владимирович; Чуркин, Олег Алексеевич; Попов, Виктор Владимирович; Иванов, Андрей Анатольевич; Гайнанов, Булат Радикович; Ястребцев, Алексей Алексеевич; Чернышева, Ольга Викторовна; Алексеев, Павел Александрович; Менушенков, Алексей Павлович
We present the study of frustrated magnets R2M2O7, where R = Gd, Dy, Tb and M = Ti, Zr. Magnetic susceptibility chi and low-temperature magnetization of perfectly ordered pyrochlores R2Ti2O7, partially disordered fluorites R2Zr2O7, and their completely disordered amorphous phases were measured and analyzed. We have found that structural disorder weakens the exchange interaction of the rare-earth ions. Magnetic moments of dysprosium and terbium, obtained from nearly saturated magnetization, are slightly affected by the disorder while the gadolinium moment is completely independent of it. The local structure of the compounds, including oxygen environment of the rare-earth ions, is discussed in terms of the influence of the crystal electric field on the magnetic properties of R2M2O7.
Открытый доступ
Материалы и процессы получения теплозащитных покрытий
(НИЯУ МИФИ, 2016) Попов, В. В.; Писарев, А. А.; Попов, Виктор Владимирович; Писарев, Александр Александрович
Рассмотрены основные вопросы, связанные с созданием современных теплозащитных покрытий. Выполнен анализ используемых и перспективных керамических оксидных материалов для теплозащитных покрытий, методов их синтеза, способов нанесения теплозащитных покрытий, а также возможных механизмов их разрушения. Монография предназначена для широкого круга специалистов, аспирантов и студентов, занимающихся изучением материалов теплозащитных покрытий и созданием самих теплозащитных покрытий.
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Crystalline structure formation and phase transitions in complex oxides Ln2Me2O7 (Ln = La - Lu; Me = Ti, Zr, Hf)
(2019) Tsarenko, N. A.; Popov, V. V.; Yastrebtsev, A. A.; Menushenkov, A. P.; Попов, Виктор Владимирович; Ястребцев, Алексей Алексеевич; Менушенков, Алексей Павлович
© 2019 Komarov Botanical Institute of the Russian Academy of Sciences. All rights reserved.Using X-ray diffraction and Raman spectroscopy, the authors of this paper investigated the formation and evolution of crystalline structure in complex oxides Ln2Me2O7 (Ln = La - Lu; Me = Ti, Zr, Hf), which occur as a result of calcination of amorphous precursors synthesized through coprecipitation from metal salt solutions. It is shown that the crystallization parameters and further phase transformations are largely governed by the cation radius ratio = rLn3+/rMe4+. In the case of zirconates and hafnates of rare earth elements (REE), nanocrystalline powders with fcc fluorite are initially formed during amorphous precursor crystallization. Further increase of the annealing temperature to _1,000 oC in the case of Ln = La - Dy leads to the phase transition fluorite → pyrochlore, the temperature of which rises and the intensity decreases as the REE radius gets smaller. The powders containing REEs with smaller cation radii retain their fluorite structure within the entire tempe rature range studied. For Yb2Zr2O7, it was found that _-phase was formed. In the case of rare earth titanates (Ln = Sm - Yb), crystallization of amorphous precursors directly resulted in a pyrochlore structure. For titanates of REEs with big cation radii (Ln = La - Nd), generation of layered perovskites was observed. Crystallite growth activation energies were calculated for the above mentioned types of phase transitions, which helped explain the sequence of structural transformations (amorphous phase → fluorite → pyrochlore) observed in rare earth zirconates and hafnates from the energy point of view. A good correlation was found between the X-ray diffraction and Raman spectroscopy data. It was concluded that Raman spectroscopy provides a more sensitive technique (versus X-ray diffraction) for studying the phase transitions occurring in complex rare earth oxides.