Персона:
Менушенков, Алексей Павлович

Организационные подразделения

Организационная единица

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.

Фамилия

Менушенков

Имя

Алексей Павлович

Полная страница элемента

Результаты поиска

Теперь показываю 1 - 10 из 38

Только метаданные
Reversible Valence Transition Eu-3+ ? Eu-2+ ? Eu-3+ in EuxEux Ox (2)+ (3)+ (M = Ti, Zr, Hf) 1-MO3+x /2 : An Analysis of XAFS and XRD Data
(2022) Menushenkov, A. P.; Popov, V. V.; Kuznetsov, A. V.; Molokova, A. Y.; Yastrebtsev, A. A.; Gaynanov, B. R.; Rudakov, S. G.; Менушенков, Алексей Павлович; Попов, Виктор Владимирович; Кузнецов, Алексей Владимирович; Ястребцев, Алексей Алексеевич; Гайнанов, Булат Радикович; Рудаков, Сергей Геннадьевич
The regularities of completely reversible valence transition Eu3+. Eu2+. Eu3+ in complex europium oxides have been investigated using a combination of X-ray diffraction (XRD) and X-ray absorption spectroscopy (XANES + EXAFS) synchrotron methods. The influence of the type of M4+ cations on the reduction and oxidation, as well as the formation and evolution of the crystalline and local structure of the (M = Ti, Zr, Hf) compounds is established. It is shown that oxidation of initially reduced Eu2+MO3 samples leads to the formation of mixed-valence (MV) state Eu2+/Eu3+ with inhomogeneous charge distribution, causing a phase transition with formation of partially amophized intermediate metastable phases Eu3+MO3.5 having a monoclinic structure (sp. gr..1211). An increase in the oxidative annealing temperature to 1000 degrees. facilitates further phase transition with the formation of stable cubic phases Eu M2O7.
Только метаданные
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.
Только метаданные
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%.
Только метаданные
Coherence properties of the high-energy fourth-generation X-ray synchrotron sources
(2019) Khubbutdinov, R.; Vartanyants, I. A.; Menushenkov, A. P.; Менушенков, Алексей Павлович
open access.An analysis of the coherence properties of the fourth-generation high-energy storage rings with emittance values of 10 pm rad is performed. It is presently expected that a storage ring with these low emittance values will reach diffraction limit at hard X-rays. Simulations of coherence properties were performed with the XRT software and an analytical approach for different photon energies from 500 eV to 50 keV. It was demonstrated that a minimum photon emittance (diffraction limit) reached at such storage rings is λ/2π. Using mode decomposition it is shown that, for the parameters of the storage ring considered in this work, the diffraction limit will be reached for soft X-ray energies of 500 eV. About ten modes will contribute to the radiation field at 12 keV photon energy and even more modes give a contribution at higher photon energies. Energy spread effects of the electron beam in a low-emittance storage ring were analysed in detail. Simulations were performed at different relative energy spread values from zero to 2 × 10-3. A decrease of the degree of coherence with an increase of the relative energy spread value was observed. This analysis shows that, to reach the diffraction limit for high photon energies, electron beam emittance should go down to 1 pm rad and below.
Только метаданные
Unconventional magnetic behavior of Lao.4Ce0.6Co2P2
(2019) Roth, J.; Kovnir, K.; Tan, X. Y.; Yaroslavtsev, A.; Menushenkov, A.; Менушенков, Алексей Павлович
Открытый доступ
Electronic, local atomic structure of lutetium tetraphenylporfyrin: XPS and XAFS spectroscopy stadies
(2019) Mozhchil, R. N.; Ionov, A. M.; Bozhko, S. I.; Bozhko, V. S.; Menushenkov, A. P.; Менушенков, Алексей Павлович
© Published under licence by IOP Publishing Ltd.The electronic and local atomic structure of lutetium metalloporphyrins Lu(acac)TPP and precursor tetraphenylporphyrin (TPP) have been studied by X-ray photoelectron spectroscopy (XPS) and absorption spectroscopy (XAFS). The XPS spectroscopy data show changes in the electronic structure of tetraphenylporphyrins under incorporation of the lutetium atom: a redistribution of the electron density between the nitrogen atoms of the pyrrole- and aza- group and appearance of one broadened peak of the N1s state. The integer trivalent state of the rare-earth metal (Lu3+) in metalloporphyrins has been confirmed by both XPS and XAFS methods.
Открытый доступ
Influence 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 Александрович
The 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 metalвЂ“oxygen (PrвЂ“O, YbвЂ“O, and ZrвЂ“O) bond lengths within the active sites and the size of adsorbed propane molecule to be the decisive factor governing the reaction route.
Только метаданные
Comparative analysis of long- and short-range structures features in titanates Ln 2 Ti 2 O 7 and zirconates Ln 2 Zr 2 O 7 (Ln = Gd, Tb, Dy) upon the crystallization process
(2019) d'Acapito, F.; Puri, A.; Castro, G. R.; Shchetinin, I. V.; Popov, V. V.; Menushenkov, A. P.; Ivanov, A. A.; Gaynanov, B. R.; Yastrebtsev, A. A.; Попов, Виктор Владимирович; Менушенков, Алексей Павлович; Иванов, Андрей Анатольевич; Гайнанов, Булат Радикович; Ястребцев, Алексей Алексеевич
© 2019 Elsevier Ltd We report a comparative study of Ln 2 M 2 O 7 (Ln = Gd, Tb, Dy; M = Ti, Zr) synthesized by combination of the sol-gel and coprecipitation methods followed by calcination at elevated temperatures. The long-range average crystal as well as short-range local structure in the samples were analyzed using X-ray diffraction, X-ray absorption spectroscopy (XAFS) and Raman spectroscopy. It has been found that Ln-Ti precursors crystallize directly to pyrochlore phase, whereas crystallization of Ln-Zr precursors to pyrochlore phase goes through intermediate fluorite phase. We have shown that X-ray absorption data make possible to detect the crystallization and phase transition features in Ln 2 M 2 O 7 such as splitting of Ln-O coordination shells and changes of the symmetry in local environment.
Только метаданные
Multiscale study on the formation and evolution of the crystal and local structures in lanthanide tungstates Ln2(WO4)3
(2022) Svetogorov, R. D.; Khramov, E. V.; Zubavichus, Y. V.; Tsarenko, N. A.; Popov, V. V.; Menushenkov, A. P.; Yastrebtsev, A. A.; Rudakov, S. G.; Ivanov, A. A.; Gaynanov, B. R.; Molokova, A. Y.; Попов, Виктор Владимирович; Менушенков, Алексей Павлович; Ястребцев, Алексей Алексеевич; Рудаков, Сергей Геннадьевич; Иванов, Андрей Анатольевич; Гайнанов, Булат Радикович
© 2022 Elsevier B.V.The influence exerted by the specific type of the lanthanide cation and calcination temperature on the crystal and local structures of Ln2(WO4)3 tungstates (Ln = La–Dy) prepared by a coprecipitation is studied using synchrotron X-ray diffraction, X-ray absorption fine structure (XAFS) spectroscopy, Fourier transform infrared (FT-IR) and Raman spectroscopies, photoluminescence, simultaneous thermal analysis, and inductively coupled plasma atomic emission spectroscopy. The combination of these experimental techniques enabled a structural insight into Ln tungstates at multiple characteristic scales, i.e. short-range of metal atom coordination (XAFS), medium-range of the network of chemical bonds (FT-IR and Raman spectroscopies), and long-range or 3D periodicity within crystallites (XRD). It is found that the onset of amorphous precursor crystallization is observed at 575–600 ∘C/3 h and leads to the formation of Ln2(WO4)3 nanocrystalline powders with a monoclinic (sp. gr. C12/c1 (15)) structure. An increase in the calcination temperature leads to the growth of crystallite size and a decrease in microstrains. In the case of Dy2(WO4)3 an additional orthorhombic phase emerges (sp. gr. Pbcn(60)) at 1000 ∘C. It is shown that the local structure of all well-crystallized compounds being studied contains lanthanide ions in the form of Ln3+ and tungsten ions in the form of WO42− tetrahedra. The local structure in the monoclinic phase can be represented as a superposition of two non-equivalent tungstate tetrahedra: W(1)O4 (C2 site symmetry) and W(2)O4 (C1 site symmetry). The LnO8 polyhedra are strongly irregular, and the Ln3+ cations occupy low-symmetry sites.
Только метаданные
The influence of BaSnO3and BaZrO3nanoinclusions on the critical current and local structure of HTS coated conductors
(2022) Kaul, A. R.; Chepikov, V. N.; Mathon, O.; Monteseguro, V.; Menushenkov, A. P.; Ivanov, A. A.; Chernysheva, O. V.; Rudnev, I. A.; Osipov, M. A.; Менушенков, Алексей Павлович; Иванов, Андрей Анатольевич; Чернышева, Ольга Викторовна; Руднев, Игорь Анатольевич; Осипов, Максим Андреевич
© 2022 IOP Publishing Ltd.We studied the effect of artificial pinning centers in the form of nanoinclusions of stannate BaSnO3 (BSO) and zirconate BaZrO3 (BZO) barium on the critical current of high-temperature superconducting tapes of the second generation (2G) based on YBa2Cu3O 7-δ films (YBCO). It has been found that the introduction of BaZrO3 nanoinclusions increases the critical current at 77 K for the magnetic field direction parallel and normal to the tape surface, while the introduction of BaSnO3 nanoinclusions decreases the critical current in both cases. To elucidate the origin of a different impact of nanoinclusions we examined the local structure of the YBCO-matrix using x-ray absorption spectroscopy (EXAFS and XANES). The spectra were collected at K-edges of Cu, Sn, and Zr at the European Synchrotron (ESRF). It was revealed that the introduction of BaZrO3 nanoinclusions increases the stiffness of copper-oxygen bonds in superconducting CuO2 plane and minimizes their static disorder in the YBCO matrix, while the introduction of BaSnO3 nanoinclusions leads to a significant increase in static disorder with a relatively weak effect on the stiffness of Cu-O bonds. These changes in the local structure become decisive for changing the macroscopic properties of high-temperature superconductor-tapes.