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114 results on '"Erenburg, S. B."'

1. XANES Pb LIII spectra of mixed-valence compound: Minium, Pb3O4

Author

Gabuda, S. P., Kozlova, S. G., Erenburg, S. B., and Bausk, N. V.

Subjects
Condensed Matter - Materials Science
Abstract

Mixed-valence compound Pb3O4 (minium) has been studied using X-ray absorption near-edge structure (XANES) spectroscopy and DFT calculations. In spite of presence of two valence states of lead [Pb(II) and Pb(IV)], the XANES spectrum of studied system is corresponding to apparently unified, an intermediate valence state of Pb. On the other hand, the 207Pb NMR spectra definitely show two different spectral bands corresponding to different Pb2+ and Pb4+ ions in Pb3O4 crystal structure. The explanation of this contradiction is related to the basics of XANES and NMR spectroscopy., Comment: Keywords: lead oxides, electronic structure, XANES, NMR

Published
2003

2. XANES spectroscopy study of Pb(Ti, Zr)O3 ferroelectric thin films

Author

Mandeljc, Mira, Kosec, Marija, Gabuda, S. P., Kozlova, S. G., Erenburg, S. B., and Bausk, N. V.

Subjects
Condensed Matter - Materials Science
Abstract

Thin films of zirconium-rich perovskites Pb1-3x/2 Lax Zr0.65 Ti0.35O3 (PLZT; x=0.095) were studied using X-ray absorption near-edge structure (XANES) spectroscopy. Is shown, that slow crystallization of the system is accompanied by partial reduction of lead oxides to a metal (Pb0) state. The same results were found in the samples of the same composition with addition of 30% mol of PbO. The evidence for stereo active 6s2 lone-pair is discussed., Comment: 8 pages, 6 figures

Published
2003

20. The Effect of Tin on the Formation and Properties of Pt/MgAl(Sn)Ox Catalysts for Dehydrogenation of Alkanes

Author

Belskaya, O. B., Stepanova, L. N., Nizovskii, A. I., Kalinkin, A. V., Erenburg, S. B., Trubina, S. V., Kvashnina, K. O., Leont’Eva, N. N., Gulyaeva, T. I., Trenikhin, M. V., Bukhtiyarov, V. I., Likholobov, V. A., Belskaya, O. B., Stepanova, L. N., Nizovskii, A. I., Kalinkin, A. V., Erenburg, S. B., Trubina, S. V., Kvashnina, K. O., Leont’Eva, N. N., Gulyaeva, T. I., Trenikhin, M. V., Bukhtiyarov, V. I., and Likholobov, V. A.

Abstract

The MgAl(Sn) layered double hydroxides (LDH) with the atomic ratios Mg/(Al+Sn) = 3 and Sn/(Sn+Al) = 0, 0.002, 0.005, 0.01, 0.05, 0.1, 0.3, 0.5, 0.7, 1.0 were synthesized and the ratio Sn/(Sn+Al) ≤ 0.1 was shown to provide the formation of systems with uniform phase composition. Mixed oxides derived from LDH retain the high specific surface area of 150-200 m2/g and the basic properties when some aluminium atoms are replaced with tin. It was found that the Sn-containing mixed oxides are able to restore the layered structure during rehydration and intercalate the anion precursors of platinum into the interlayer space of the formed LDH. The emerging platinum sites initiate the reduction of tin at temperatures below 723 K. TEM, EXAFS and XPS studies demonstrated that tin introduction in the support increases the dispersion of supported platinum. An extreme dependence of the activity of Pt/MgAl(Sn)Ox catalysts in propane and n-decane dehydrogenation on the tin content in the support was revealed. The active catalysts are characterized by the phase and elemental uniformity of the support, highly disperse state of Pt(0), and the absence of a noticeable amount of reduced tin and bimetallic particles.

Published
2019

21. Short-Range Order in Amorphous and Crystalline Ferroelectric Hf0.5Zr0.5O2

Author

Erenburg, S. B., Trubina, S. V., Kvashnina, K. O., Kruchinin, V. N., Gritsenko, V. V., Chernikova, A. G., and Markeev, A. M.

Abstract

The microstructures of amorphous and polycrystalline ferroelectric Hf0.5Zr0.5O2 films are studied by X-ray spectroscopy and ellipsometry. EXAFS spectra demonstrate that the amorphous film consists of an “incompletely mixed” solid solution of metallic oxides HfO2 and ZrO2. After rapid thermal annealing, the mixed Hf0.5Zr0.5O2 oxide films have a more ordered polycrystalline structure, and individual Hf and Zr monoxide islands form in the films. These islands are several nanometers in size and have a structure that is similar to the monoclinic structure of HfO2 and ZrO2. The presence of the HfO2 and ZrO2 phases in the Hf0.5Zr0.5O2 films is also detected by ellipsometry

Published
2018

22. Nanoscale Potential Fluctuations in Zirconium Oxide and the Flash Memory Based on Such Fluctuations

Author

Gritsenko, V. A., Perevalov, T. V., Kruchinin, V. N., Aliev, V. S., Gerasimova, A. K., Erenburg, S. B., Trubina, S. V., Kvashnina, K. O., and Prosvirin, I. P.

Abstract

X-ray photoelectron spectroscopy, EXAFS, XANES, spectral ellipsometry and quantum-chemistry calculations were used to examine the atomic and electronic structure of non-stoichiometric amorphous ZrOx slightly enriched with zirconium. The experimental data show that the ZrOx material consists of stoichiometric ZrO2, metallic Zr and zirconium suboxides ZrOy. The structure of ZrOx is analyzed using the Random Bonding and Random Mixture models. A model of nanoscale spatial potential fluctuations in ZrOx is substantiated. In this model, the potential fluctuations for electrons and holes arise due to the local fluctuations of bandgap energy in the range from 0 to 5.4 eV. A ZrOx-based flash memory element with giant retention time is proposed

Published
2018

24. Atomic and electronic structure of amorphous and crystalline hafnium oxide: X-ray photoelectron spectroscopy and density functional calculations.

Author

Perevalov, T. V., Gritsenko, V. A., Erenburg, S. B., Badalyan, A. M., Wong, Hei, and Kim, C. W.

Subjects
ATOMIC structure, ELECTRONIC structure, ATOMIC theory, HAFNIUM oxide, X-rays, PHOTOELECTRONS, SPECTRUM analysis
Abstract

The atomic structure of amorphous and crystalline hafnium oxide (HfO2) films was examined using x-ray diffractometry and Hf edge x-ray absorption spectroscopy. According to the x-ray photoelectron spectroscopy and band data calculated by the density functional method, we found that the valence band of HfO2 consists of three subbands separated by ionic gaps. The upper subband is formed by O 2p, Hf 4f, and Hf 5d states; the intermediate subband is formed by O 2s and Hf 4f states, whereas the lower narrow subband is mainly formed by Hf 5p states. The energy gap of amorphous HfO2 is 5.7 eV as determined by electron energy loss spectroscopy. The band calculation results indicate the existence of light (0.3m0) and heavy (8.3m0) holes in the HfO2 film and the effective mass of electron lies in the interval of 0.7m0–2.0m0. [ABSTRACT FROM AUTHOR]

Published
2007
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25. Zinc Influence on the Formation and Properties of Pt/Mg(Zn)AlO x Catalysts Synthesized From Layered Hydroxides

Author

Belskaya, O. B., Stepanova, L. N., Gulyaeva, T. I., Erenburg, S. B., Trubina, S. V., Kvashnina, K., Nizovskii, A. I., Kalinkin, A. V., Zaikovskii, V. I., Bukhtiyarov, V. I., and Likholobov, V. A.

Subjects
zinc containing layered double hydroxides, EXAFS, propane dehydrogenation, platinum catalysts, XPS
Abstract

Layered double hydroxides (LDH) containing Al3+, Mg2+ and Zn2+ cations in a ratio of Zn/(Mg+Zn) = 0, 0.05, 0.1, 0.2, 0.5, 0.7 and 1.0 were synthesized. The effect of zinc content on the phase composition of LDH and on the structural parameters, textural characteristics and acid-base properties of the corresponding mixed oxides were studied. This type of supports was used to obtain non-acid platinum catalysts Pt/Mg(Zn)AlOx. The formation of supported platinum particles, their composition, dispersion and electronic state were examined by means of TPR, TEM, XPS and EXAFS. The possibility to obtain bimetallic PtZn particles, whose structure and strength of interaction with the support depend on the zinc content of the support, was demonstrated. It was found that the presence of zinc atoms in the platinum environment decreases the particle size of active metal and stabilizes platinum in the active metallic state that ensures high activity of the catalyst in dehydrogenation of propane at a selectivity for propylene above 99%.

Published
2016

27. Bi(III) immobilization inside MIL-101: enhanced photocatalytic performance

Author

Kovalenko, K. A., Ruban, N. V., Adonin, S. A., Korneev, D. V., Erenburg, S. B., Trubina, S. V., Kvashnina, K., Sokolov, M. N., Fedin, V. P., Kovalenko, K. A., Ruban, N. V., Adonin, S. A., Korneev, D. V., Erenburg, S. B., Trubina, S. V., Kvashnina, K., Sokolov, M. N., and Fedin, V. P.

Abstract

A novel hybrid material Bi(III)@MIL-101 (Bi(III) = Bi-containing oxoclusters, MIL-101 = chromium(III) oxoterephthalate) has been obtained by the intra-pore hydrolysis of guest bismuth(III) chloride in ammonia solution. The compound was fully characterized by chemical analysis, PXRD, nitrogen sorption and TEM techniques. According to characterization techniques all Bi species are only inside matrix and elemental analysis reveals ca. 1 Bi atom per mesocage. The chemical structure of Bi(III)-containing clusters inside MIL-101 matrix has been suggested according to EXAFS study. The catalytic activity of Bi(III)@MIL-101 has been tested in photodegradation of methyl red (MR). An introduction of Bi(III)-species inside MIL-101 has significantly increased the photocatalytic performance in comparison with layered BiOCl which has been obtained in the same synthetic conditions without MIL-101.

Published
2017

32. Short-Range Order in Amorphous and Crystalline Ferroelectric Hf0.5Zr0.5O2.

Author

Erenburg, S. B., Trubina, S. V., Kvashnina, K. O., Kruchinin, V. N., Gritsenko, V. V., Chernikova, A. G., and Markeev, A. M.

Subjects
*AMORPHOUS alloys, *CRYSTALLINE polymers, *FERROELECTRIC crystals, *ELLIPSOMETRY, *OXIDE coating
Abstract

The microstructures of amorphous and polycrystalline ferroelectric Hf0.5Zr0.5O2 films are studied by X-ray spectroscopy and ellipsometry. EXAFS spectra demonstrate that the amorphous film consists of an “incompletely mixed” solid solution of metallic oxides HfO2 and ZrO2. After rapid thermal annealing, the mixed Hf0.5Zr0.5O2 oxide films have a more ordered polycrystalline structure, and individual Hf and Zr monoxide islands are formed in the films. These islands are several nanometers in size and have a structure that is similar to the monoclinic structure of HfO2 and ZrO2. The presence of the HfO2 and ZrO2 phases in the Hf0.5Zr0.5O2 films is also detected by ellipsometry. [ABSTRACT FROM AUTHOR]

Published
2018
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33. Short-Range Order in Amorphous and Crystalline Ferroelectric Hf0.5Zr0.5O2.

Author

Erenburg, S. B., Trubina, S. V., Kvashnina, K. O., Kruchinin, V. N., Gritsenko, V. V., Chernikova, A. G., and Markeev, A. M.

Subjects
AMORPHOUS alloys, CRYSTALLINE polymers, FERROELECTRIC crystals, ELLIPSOMETRY, OXIDE coating
Abstract

The microstructures of amorphous and polycrystalline ferroelectric Hf0.5Zr0.5O2 films are studied by X-ray spectroscopy and ellipsometry. EXAFS spectra demonstrate that the amorphous film consists of an “incompletely mixed” solid solution of metallic oxides HfO2 and ZrO2. After rapid thermal annealing, the mixed Hf0.5Zr0.5O2 oxide films have a more ordered polycrystalline structure, and individual Hf and Zr monoxide islands are formed in the films. These islands are several nanometers in size and have a structure that is similar to the monoclinic structure of HfO2 and ZrO2. The presence of the HfO2 and ZrO2 phases in the Hf0.5Zr0.5O2 films is also detected by ellipsometry. [ABSTRACT FROM AUTHOR]

Published
2018
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39. Developing XAFS Method Designed for Characterization of Materials Containing Nanostructures (Ge/Si Systems).

Author

Erenburg, S. B., Bausk, N. V., Mazalov, L. N., Nikiforov, A. I., and Yakimov, A. I.

Subjects
*EXTENDED X-ray absorption fine structure, *X-ray absorption near edge structure, *HETEROSTRUCTURES, *GERMANIUM, *SILICON
Abstract

Here we report the use of EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure) spectroscopy method to study the spatial and electronic structure of Ge/Si heterostructures. The pyramid-like Ge islands deposited on Si(001) substrate using molecular beam epitaxy at 300°C reveal quantum dots (QDs) properties. Measurements of X-ray absorption fine structure at germanium K edge (GeK XAFS measurements) have been performed using total electron yield and fluorescent detection mode. It is revealed that the pure Ge nanoclusters are covered by 1,2-monolayer film with 50% Si atom impurity caused by interface diffusion at 500°C. The Ge QDs are characterized by interatomic Ge-Ge distances of 2.41 Å which is 0.04 Å less than in bulk Ge. The influence of effective thickness of the germanium film, Ge nanocluster sizes and Ge, Si deposition temperature on the QDs microstructure parameters is revealed. The first attempt to extract from X-ray absorption spectra (XANES spectra) an information about the energy structure of the free states of the quantum dot was made. [ABSTRACT FROM AUTHOR]

Published
2003

45. XANES Spectroscopy Study of Pb(Ti, Zr)O3 Ferroelectric Thin Films.

Author

Mandeljc, Mira, Kosec, Marija, Gabuda, S. P., Kozlova, S. G., Erenburg, S. B., and Bausk, N. V.

Subjects
THIN films, SOLID state electronics, SPECTRUM analysis, CRYSTALLIZATION, ZIRCONIUM, TITANIUM group
Abstract

Thin films of zirconium-rich perovskites Pb1-3x/2LaxTi0.35Zr0.65O3(PLZT; x = 0.095) and PbTi0.7Zr0.3O3 were studied using X-ray absorption near-edge structure (XANES) spectroscopy. Is shown, that slow crystallization of the system is accompanied by essential change ot PbL(3)-edge fine structure indicating that perovskite thin film band structure is sensitive of Ti/Zr ratio. The same results were found in the samples of the same composition with addition of 30% mol of PbO. The evidence for stereo active 6s² lone-pair is discussed. [ABSTRACT FROM AUTHOR]

Published
2004
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