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1. International Conference on Low Temperature Chemistry (6th) Held in Chernogolovka, Russia on 27 August - 1 September 2006

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF PROBLEMS OF CHEMICAL PHYSICS and RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF PROBLEMS OF CHEMICAL PHYSICS

Abstract

The Final Proceedings for Sixth International Conference on Low Temperature Chemistry 29 August - 2 September 2006. This conference will cover the following sections: Section 1: Cryosynthesis structure and properties of chemical compounds with unusual chemical bonding. Topics: (a) novel cryogenic media clusters and nanostructures; (b) noble gas containing compounds; (b) active intermediate structures reactivity and spectroscopy. Section 2: Novel reaction pathways in cryogenic solids. Topics: (a) reactions in quantum media: liquids crystals nanodroplets; (b) cooled biomolecules and cryo-pharmacology; (c) astro- and stratospheric chemistry. Section 3: Quantum phenomena and reaction dynamics. Topics: (a) coherence and ultrafast dynamics; (b) tunneling and transport processes., The original document contains color images.

Published
2006

2. Vacancy Generation During Grain Boundary Migration

Author

Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, 48109-2136, USA, Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow distr, 142432, Russia; Institut f??r Metallkunde und Metallphysik, RWTH Aachen, 52 56, Aachen, Germany, Institut f??r Metallkunde und Metallphysik, RWTH Aachen, 52 56, Aachen, Germany, Ann Arbor, Upmanyu, Moneesh, Srolovitz, David J., Shvindlerman, L.S., Gottstein, G., Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, 48109-2136, USA, Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow distr, 142432, Russia; Institut f??r Metallkunde und Metallphysik, RWTH Aachen, 52 56, Aachen, Germany, Institut f??r Metallkunde und Metallphysik, RWTH Aachen, 52 56, Aachen, Germany, Ann Arbor, Upmanyu, Moneesh, Srolovitz, David J., Shvindlerman, L.S., and Gottstein, G.

Abstract

We present a molecular dynamics simulation study of vacancy generation and emission from grain boundaries during curvature-driven grain boundary migration. The U-shaped half-loop bicrystal geometry is employed in order to maintain a constant driving force during boundary migration. Nonlinearities in plots of half-loop grain area versus time indicate the onset of non-steady-state behavior and vacancy formation. Such events appear much more frequently at elevated temperature than at low temperature. Detailed observation of the atomic configurations in the vicinity of the grain boundary before and after these events clearly demonstrate that these non-linearities are associated with the generation and subsequent emission of vacancies. The excess volume associated with the grain boundaries in conjunction with the loss in grain boundary area during curvature-driven migration accounts for the generation of these vacancies. This description is used to predict the rate of vacancy emission, which represents an upper bound on the observed emission rates.

Published
2006

3. Fluorinated??-aminophosphonates???a new type of irreversible inhibitors of serine hydrolases

Author

EHS Department, Toxicology Program, University of Michigan, 48109, Ann Arbor, USA, Institute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka, 142432, Moscow oblast, Russia, Ann Arbor, Malygin, V.V., Rasdolsky, A.N., Makhaeva, G.F., Sokolov, V.B., Richardson, Rudy J., Martynov, I.V., Aksinenko, A. Yu., Strakhova, N.N., EHS Department, Toxicology Program, University of Michigan, 48109, Ann Arbor, USA, Institute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka, 142432, Moscow oblast, Russia, Ann Arbor, Malygin, V.V., Rasdolsky, A.N., Makhaeva, G.F., Sokolov, V.B., Richardson, Rudy J., Martynov, I.V., Aksinenko, A. Yu., and Strakhova, N.N.

Published
2006

4. Unmonotonous Variation of Oscillation Threshold with In-Plane Magnetic Field in Resonant-Tunneling Diode

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Popov, V. G., Dubrovskii, Yu. V., Dubonos, S. V., Eaves, L., Henini, M., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Popov, V. G., Dubrovskii, Yu. V., Dubonos, S. V., Eaves, L., and Henini, M.

Abstract

Current oscillations in the negative differential conductance region of resonant tunneling diodes with different lateral pattern and size versus perpendicular to the tunneling current magnetic field have been studied. It is revealed that the value of the critical negative differential conductance or oscillations threshold that is the value of conductance when the oscillations in measurement circuit are arisen, unmonotonically depends on magnetic field. The relation of the observed dependence with inhomogeneous distribution of the tunneling current is discussed., This article is from ADA408025 Nanostructures: Physics and Technology International Symposium (9th), St. Petersburg, Russia, June 18-22, 2001 Proceedings

Published
2001

5. Multiple Polariton Scattering in Semiconductor Microcavities

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF SOLID STATE PHYSICS, Krizhanovskii, D. N., Tartakovskii, A. I., Kulakovskii, V. D., Skolnick, M. S., Roberts, J. S., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF SOLID STATE PHYSICS, Krizhanovskii, D. N., Tartakovskii, A. I., Kulakovskii, V. D., Skolnick, M. S., and Roberts, J. S.

Abstract

This article is from ADA408025 Nanostructures: Physics and Technology International Symposium (9th), St. Petersburg, Russia, June 18-22, 2001 Proceedings

Published
2001

6. Resonant Tunnelling via States of the X-Related Donors Located at Different Atomic Layer in AlAs Barrier

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF MICROELECTRONICS AND HIGH PURITY MATERIALS, Khanin, Yu. N., Vdovin, E. E., Dubrovskii, Yu. V., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF MICROELECTRONICS AND HIGH PURITY MATERIALS, Khanin, Yu. N., Vdovin, E. E., and Dubrovskii, Yu. V.

Abstract

We report an electrical transport and magnetotransport study of GaAs/AlAs/ GaAs single- barrier heterostructures incorporating unintentional donors in the barrier. Resonant tunneling was observed both through the quasiconfined states in the AlAs layer originated from the X(xy) and X(z) conduction band minima and through two distinct states of the donors bound to the X(xy) and X(z) valleys. Furthermore we observed an additional oscillatory like fine structure of the donor resonances that we attribute to difference in binding energies of donors located at different position of the AlAs layer. Magnetic field behaviour of the fine structure demonstrated that the binding energy of X-related donors has an essential dependence on both magnetic field and donor position in the barrier., This article is from ADA408025 Nanostructures: Physics and Technology International Symposium (9th), St. Petersburg, Russia, June 18-22, 2001 Proceedings

Published
2001

7. Nonlinear Effects in Dense Two-Dimensional Exciton-Polariton System

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF SOLID STATE PHYSICS, Kulakovskii, V. D., Tartakovskii, A. I., Krizhanovskii, D. N., Gippius, N. A., Skolnick, M. S., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF SOLID STATE PHYSICS, Kulakovskii, V. D., Tartakovskii, A. I., Krizhanovskii, D. N., Gippius, N. A., and Skolnick, M. S.

Abstract

Angle resolved emission spectra of MCs with quantum wells embedded in the active layer have been investigated under conditions of resonant excitation into the lower polariton (LP) branch. The conditions have been found at which macroscopic filling at the LP branch bottom is reached in the strong coupling regime. Under these conditions strong nonlinear effects in the intensity and the degree of polarization of polariton emission have been observed and investigated. The experimental dispersion of renormalized cavity mode and its strong narrowing have been explained using an interacting polariton model predicting that the coupling between the LP mode E(LP)(k) and the mode E*(k)= 2hw - E(LP)(k +2k(excitation) is qualitatively different from that of exciton and photon., This article is from ADA408025 Nanostructures: Physics and Technology International Symposium (9th), St. Petersburg, Russia, June 18-22, 2001 Proceedings

Published
2001

8. Peculiarities in Equilibrium Tunneling Between Disordered Two-Dimensional Electron Systems: From Fermi Edge Singularity to Linear Gap in High Magnetic Field

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Dubrovskii, Yu. V., Hill, R., Volkov, V. A., Popov, V. G., Vdovin, E. E., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Dubrovskii, Yu. V., Hill, R., Volkov, V. A., Popov, V. G., and Vdovin, E. E.

Abstract

We have investigated equilibrium tunneling between disordered two-dimensional electron systems at temperature below 0.3 K and in a wide range of magnetic field normal to the electron layers. Observed transformation of a narrow conductance peak of about I mV width at zero bias into the narrow dip with magnetic field is discussed in the frame of many-electron interaction effects in tunnel phenomena., This article is from ADA408025 Nanostructures: Physics and Technology International Symposium (9th), St. Petersburg, Russia, June 18-22, 2001 Proceedings

Published
2001

9. Normal-to-Plane Magnetoresistance of Single Crystalline Refractory Metal Nanostructures

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Mikhailov, G. M., Malikov, I. V., Chernykh, A. V., Fomin, L. A., Joyez, P., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Mikhailov, G. M., Malikov, I. V., Chernykh, A. V., Fomin, L. A., and Joyez, P.

Abstract

We have performed normal-to-plane magneto transport measurements in single crystalline (100) W and Mo nanostructures down to 1.5 K. Fabricated nanostructures possess large mean free path due to their bulk crystalline perfection and low surface roughness. Under these conditions electrons scatter only on the boundaries of nanostructures and may travel long distance without scattering. We found that in this regime the normal-to-plane magnetoresistance of planar metallic nanostructures exhibit specific for ballistic transport attributes such as transverse magnetic focusing suppression of Hall resistance (quenching Hall effect) and negative bend resistance at moderate magnetic fields., This article is from ADA408025 Nanostructures: Physics and Technology International Symposium (9th), St. Petersburg, Russia, June 18-22, 2001 Proceedings

Published
2001

10. Unconventional Landan States in the Quantum Well with Embedded Self-Arranged Quantum Dots

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Dubrovskii, Yu. V., Volkov, V. A., Vdovin, E. E., Eaves, L., Main, P. C., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Dubrovskii, Yu. V., Volkov, V. A., Vdovin, E. E., Eaves, L., and Main, P. C.

Abstract

It have been found that the presence of InA self-arranged quantum dots strongly modify the structure of Landau levels in a host GaAs quantum well., This article is from ADA408025 Nanostructures: Physics and Technology International Symposium (9th), St. Petersburg, Russia, June 18-22, 2001 Proceedings

Published
2001

11. Magneto-Tunnelling Spectroscopy of Localised and Extended States in a Quantum Well Containing Quantum Dots

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Dubrovskii, Yu. V., Patane, A., Brounkov, P. N., Vdovin, E. E., Larkin, I. A., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Dubrovskii, Yu. V., Patane, A., Brounkov, P. N., Vdovin, E. E., and Larkin, I. A.

Abstract

We investigate resonant tunneling in GaAs/(AlGa)As double-barrier resonant-tunneling diodes (RTDs) in which a single layer of InAs self-assembled quantum dots (SAQDs) is embedded in the center of the GaAs quantum well. The dots provide a well-defined and controllable source of disorder in the well and we use resonant tunneling for studying the effect of disorder on the electronic properties of the well., This article is from ADA408025 Nanostructures: Physics and Technology International Symposium (9th), St. Petersburg, Russia, June 18-22, 2001 Proceedings

Published
2001

12. Spatial Mapping of the Electron Eigenfunctions in InAs Self-Assembled Quantum Dots by Magnetotunneling

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Vdovin, E. E., Levin, A., Patane, A., Eaves, L., Main, P. C., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Vdovin, E. E., Levin, A., Patane, A., Eaves, L., and Main, P. C.

Abstract

We use magnetotunnelling spectroscopy as a non-invasive probe to produce two-dimensional spatial images of the probability density of an electron confined in a self-assembled semiconductor quantum dot. The images reveal clearly the elliptical symmetry of the ground state and the characteristic lobes of the higher energy states., This article is from ADA408025 Nanostructures: Physics and Technology International Symposium (9th), St. Petersburg, Russia, June 18-22, 2001 Proceedings

Published
2001

13. High Magnetic Field Dependence of the Edge and Bulk State Electron Transport in Single-Crystalline Tungsten Nanostructures

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF MICROELECTRONICS AND HIGH PURITY MATERIALS, Mikhailov, G. M., Chernykh, A. V., Maan, J. C., Lok, J. G., Geim, A. K., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF MICROELECTRONICS AND HIGH PURITY MATERIALS, Mikhailov, G. M., Chernykh, A. V., Maan, J. C., Lok, J. G., and Geim, A. K.

Abstract

Electron conductivity of single crystalline nanostructures both of bridge- and cross- type has been investigated at 4.2 K. It shows strong dependence in magnetic field and also exhibits anisotropy against magnetic field direction. It was found new reentrance effect in ballistic properties of multi-terminal cross-type nanostructure. where ballistic properties are suppressed in moderate magnetic field and restored again at higher field., This article is from Nanostructures: Physics and Technology Intl Symposium (8th), p. 520-523 This article is from ADA407315 Nanostructures: Physics and Technology International Symposium (8th) Held in St. Petersburg, Russia on June 19-23, 2000 Proceedings

Published
2000

14. Collective Behavior of the Interwell Excitons in Biased GaAs/AlGaAs Double Quantum Wells

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF SOLID STATE PHYSICS, Timofeev, V. B., Larionov, A. V., Hvam, J. M., Soerensen, C. B., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF SOLID STATE PHYSICS, Timofeev, V. B., Larionov, A. V., Hvam, J. M., and Soerensen, C. B.

Abstract

Described phenomena are associated with the creation of a collective excitonic phase. Dielectric excitonic nature of this new phase is confirmed by its diamagnetic behavior and by Zeeman splittings in magnetic field parallel to the structure growth direction (Faraday geometry). Space coherence of collective excitonic phase is investigated and discussed., Pres: 8th Int Symp Nanostructures: Physics and Technology, St Petersburg, Russia, 19-23 Jun 2000, p1. This article is from ADA407315 Nanostructures: Physics and Technology International Symposium (8th) Held in St. Petersburg, Russia on June 19-23, 2000 Proceedings

Published
2000

15. Current Instabilities in Negative Differential Resistance Region of a Large Area Resonant Tunneling Diode

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Popov, V. G., Dubrovskii, Yu. V., Wang, K. L., Eaves, L., Maan, J. C., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Popov, V. G., Dubrovskii, Yu. V., Wang, K. L., Eaves, L., and Maan, J. C.

Abstract

The current instabilities in the negative differential conductance region of the resonance tunneling diode have been thoroughly studied at different parameters of the external circuit. The instabilities were dealt with an excitement of the current oscillations in the circuit. In a homogeneous approximation two small signal equivalent circuits of the resonant tunneling diode were used to describe the observed instabilities. Some revealed effects were out of the approximation., This article is from Nanostructures: Physics and Technology Intl Symposium (8th), p. 347-350 This article is from ADA407315 Nanostructures: Physics and Technology International Symposium (8th) Held in St. Petersburg, Russia on June 19-23, 2000 Proceedings

Published
2000

16. Deformation and Viscouse Flow in Nano-Imprinting

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Chukalina, M. V., Matveev, V. N., Sirotkin, V. V., Svintsov, A. A., Zaitsev, S. SI., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Chukalina, M. V., Matveev, V. N., Sirotkin, V. V., Svintsov, A. A., and Zaitsev, S. SI.

Abstract

The paper is concentrated on the theoretical consideration of imprinting process and of polymer flow during embossing of the master. Another activity was related to development of experimental techniques for performing imprinting., Pres: 8th Int Symp Nanostructures: Physics and Technology, St Petersburg, Russia, 19-23 Jun 2000, p121-124. This article is from ADA407315 Nanostructures: Physics and Technology International Symposium (8th) Held in St. Petersburg, Russia on June 19-23, 2000 Proceedings

Published
2000

17. The Influence of Anticrossing of Exciton States on Exciton Relaxation in GaAs/A1GaAs Double Single Quantum Wells

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Litvinenko, K. L., Lyssenko, V. G., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Litvinenko, K. L., and Lyssenko, V. G.

Abstract

It was found that the dephasing time T2 of direct light hole excitons is decreased in 5 times by mixing its wave function with indirect heavy hole exciton wave function. The decreasing and restoring of light hole exciton dephasing time takes place two times for the values of external steady electric field from 1 V to 3 V. We hope this effect will be useful for the designing of new electro-optic devises., Pres: 7th Int Symp Nanostructures: Physics and Technology; St Petersburg, Russia. p420-422. This article is from ADA407055 Nanostructures: Physics and Technology. 7th International Symposium. St. Petersburg, Russia, June 14-18, 1999 Proceedings

Published
1999

18. Tunneling Between Strongly Localized Two-Dimensional Electron Systems

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Dubrovskii, Yu V., Vdovin, E. E., Khanin, Yu N., Popov, V. G., Ivanov, D. Y., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY, Dubrovskii, Yu V., Vdovin, E. E., Khanin, Yu N., Popov, V. G., and Ivanov, D. Y.

Abstract

This article have investigated equilibrium tunneling between strongly localized 2D electron systems in a high magnetic field in the structure with pure vertical transport. High magnetic field suppresses equilibrium tunneling creating a gap in the tunneling density of states which depends linearly on magnetic field., Pres: 7th Int Symp Nanostructures: Physics and Technology, St Petersburg, Russia. 14-18 Jun 1999. p266-268. This article is from ADA407055 Nanostructures: Physics and Technology. 7th International Symposium. St. Petersburg, Russia, June 14-18, 1999 Proceedings

Published
1999

19. Fabrication of SiGe Quantum Wires by Self-Assembled Local Molecular Beam Growth

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF MICROELECTRONICS AND HIGH PURITY MATERIALS, Avrutin, V. S., Izumskaya, N. F., Vyatkin, A. F., Yunkin, V. A., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF MICROELECTRONICS AND HIGH PURITY MATERIALS, Avrutin, V. S., Izumskaya, N. F., Vyatkin, A. F., and Yunkin, V. A.

Abstract

One-dimensional SiGe structures were grown by molecular beam epitaxy on mesa-patterned Si (100) and (111) substrates. The effect of temperature and deposition rate on faceting of local epitaxial Si and SiGe structures was studied in temperature range from 45O C to 900 C. Scanning electron microscopy revealed that the increase of growth temperature and/or the decrease of deposition rate result in faceting of the growing structures. Epitaxial structures with Si(.75)Ge(.25) quantum wires 4 nm in thickness and 30-50 nm in width separated by 30-nm Si barriers were grown. Low-temperature luminescence spectra of these structures were obtained., Pres: 6th Int Symp Nanostructures: Physics and Technology, St Petersburg, Russia. 22-26 Jun 1998. p481-482. This article is from ADA406591 Nanostructures: Physics and Technology International Symposium (6th) held in St. Petersburg, Russia on June 22-26, 1998 Proceedings

Published
1998

20. Fabrication and Electron Transport Properties of Superconducting-Normal Metal (Ballistic) Nanostructures

Author

RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF MICROELECTRONICS AND HIGH PURITY MATERIALS, Mikhailov, G. M., Malikov, I. V., RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF MICROELECTRONICS AND HIGH PURITY MATERIALS, Mikhailov, G. M., and Malikov, I. V.

Abstract

Experiments with ballistic weak link, where coherent Andreev's reflection may taken place, are of great interest. Recently, such type expenments were carried out using high electron rnobllity 2 DEG of semiconductor heterostructures contacted to the superconductors. Developing of monocrystalline metallic nanostructure fabrication capable ballistic electron transport makes it possible to fabricate superconductor normal metal (ballistic) structures, including also heteroepitaxial multilayered nanostructures. In this report we present for the first time the experimental realization of that and also the first results on electron transport investigation of S-N nanostructures fabricated., Pres: 6th Int Symposium Nanostructures: Physics and Technology, St Petersburg, Russia. 22-26 Jun 1998. p82-85. This article is from ADA406591 Nanostructures: Physics and Technology International Symposium (6th) held in St. Petersburg, Russia on June 22-26, 1998 Proceedings

Published
1998

21. Numerical Assessment of Morphological and Hydraulic Properties of Moss, Lichen and Peat from a Permafrost Peatland

Author

Simon Cazaurang, Manuel Marcoux, Oleg S. Pokrovsky, Sergey V. Loiko, Artem G. Lim, Stéphane Audry, Liudmila S. Shirokova, Laurent Orgogozo, Institut de mécanique des fluides de Toulouse (IMFT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Tomsk State University [Tomsk], N. Laverov Federal Center for Integrated Arctic Research of the Ural Branch (FECIAR UrB RAS ), Russian Academy of Sciences - Chernogolovka, and ANR-19-CE46-0003,HiPerBorea,Calul haute performance pour la quantification des impacts du changement climatique sur les régions boréales(2019)

Subjects
[PHYS]Physics [physics], Peatland, [SDU]Sciences of the Universe [physics], Hydraulic conductivity, [SDE]Environmental Sciences, Porous media, Permafrost, General Earth and Planetary Sciences, Lichen, [INFO]Computer Science [cs], Computational fluid dynamics, Moss, General Environmental Science
Abstract

Due to its insulating and draining role, assessing ground vegetation cover properties is important for high-resolution hydrological modeling of permafrost regions. In this study, morphological and effective hydraulic properties of Western Siberian Lowland ground vegetation samples (lichens, Sphagnum mosses, peat) are numerically studied based on tomography scans. Porosity is estimated through a void voxels counting algorithm, showing the existence of representative elementary volumes (REVs) of porosity for most samples. Then, two methods are used to estimate hydraulic conductivity depending on the sample's homogeneity. For homogeneous samples, direct numerical simulations of a single-phase flow are performed, leading to a definition of hydraulic conductivity related to a REV, which is larger than those obtained for porosity. For heterogeneous samples, no adequate REV may be defined. To bypass this issue, a pore network representation is created from computerized scans. Morphological and hydraulic properties are then estimated through this simplified representation. Both methods converged on similar results for porosity. Some discrepancies are observed for a specific surface area. Hydraulic conductivity fluctuates by 2 orders of magnitude, depending on the method used. Porosity values are in line with previous values found in the literature, showing that arctic cryptogamic cover can be considered an open and well-connected porous medium (over 99 % of overall porosity is open porosity). Meanwhile, digitally estimated hydraulic conductivity is higher compared to previously obtained results based on field and laboratory experiments. However, the uncertainty is less than in experimental studies available in the literature. Therefore, biological and sampling artifacts are predominant over numerical biases. This could be related to compressibility effects occurring during field or laboratory measurements. These numerical methods lay a solid foundation for interpreting the homogeneity of any type of sample and processing some quantitative properties' assessment, either with image processing or with a pore network model. The main observed limitation is the input data quality (e.g., the tomographic scans' resolution) and its pre-processing scheme. Thus, some supplementary studies are compulsory for assessing syn-sampling and syn-measurement perturbations in experimentally estimated, effective hydraulic properties of such a biological porous medium.

Published
2022

22. Luminescence of zinc oxide nanorods

Author

I. A. Karpov, E. E. Yakimov, A. N. Red’kin, A. B. Kulakov, Carlos Barthou, G. A. Emel’chenko, A. N. Gruzintsev, É. N. Samarov, Institute of Solid State Physics of the Russian Academy of Sciences, Russian Academy of Sciences - Chernogolovka, Institute of Microelectronics Technology and High Purity Materials, Russian Academy of Sciences, Chernogolovka 142432 Moscow Region, Russia., Institut des Nanosciences de Paris (INSP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Institute of Solid State Physics, Russian Academy of Sciences [Moscow] (RAS), and Institut of Microelectronics Technology and High Purity Materials

Subjects
Materials science, Physics::Optics, chemistry.chemical_element, 02 engineering and technology, Chemical vapor deposition, Zinc, 01 natural sciences, Condensed Matter::Materials Science, 0103 physical sciences, Stimulated emission, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], ComputingMilieux_MISCELLANEOUS, Power density, 010302 applied physics, business.industry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, chemistry, Optoelectronics, Nanorod, Nitrogen laser, 0210 nano-technology, Luminescence, business, Lasing threshold
Abstract

International audience; The spectra of spontaneous and stimulated emission of ZnO nanorods grown by two low-temperature procedures are studied. Stimulated emission at 385 nm is observed at room temperature in CVD ZnO nanocrystals pumped by the nitrogen laser radiation at the wavelength 337 nm. The threshold pumping power density for lasing exitonic recombination is similar to 600 kW/cm(2).

Published
2007

23. Nanomaterials by severe plastic deformation: review of historical developments and recent advances

Author

Kaveh Edalati, Andrea Bachmaier, Victor A. Beloshenko, Yan Beygelzimer, Vladimir D. Blank, Walter J. Botta, Krzysztof Bryła, Jakub Čížek, Sergiy Divinski, Nariman A. Enikeev, Yuri Estrin, Ghader Faraji, Roberto B. Figueiredo, Masayoshi Fuji, Tadahiko Furuta, Thierry Grosdidier, Jenő Gubicza, Anton Hohenwarter, Zenji Horita, Jacques Huot, Yoshifumi Ikoma, Miloš Janeček, Megumi Kawasaki, Petr Král, Shigeru Kuramoto, Terence G. Langdon, Daniel R. Leiva, Valery I. Levitas, Andrey Mazilkin, Masaki Mito, Hiroyuki Miyamoto, Terukazu Nishizaki, Reinhard Pippan, Vladimir V. Popov, Elena N. Popova, Gencaga Purcek, Oliver Renk, Ádám Révész, Xavier Sauvage, Vaclav Sklenicka, Werner Skrotzki, Boris B. Straumal, Satyam Suwas, Laszlo S. Toth, Nobuhiro Tsuji, Ruslan Z. Valiev, Gerhard Wilde, Michael J. Zehetbauer, Xinkun Zhu, International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Erich Schmid Institute of Materials Science (ESI), Austrian Academy of Sciences (OeAW), Donetsk Institute for Physics and Engineering named after A.A. Galkin, National Academy of Sciences of Ukraine (NASU), Technological Institute for Superhard and Novel Carbon Materials, Departamento de Engenharia de Materiais (DEMa), Universidade Federal de São Carlos [São Carlos] (UFSCar), Cracow University of Technology, CHARLES UNIVERSITY IN PRAGUE FACULTY OF MATHEMATICS AND PHYSICS PRAGUE CZE, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Westfälische Wilhelms-Universität Münster = University of Münster (WWU), Ufa State Aviation Technical University (USATU), Monash University [Clayton], University of Tehran, School of Chemical Engineering, College of Engineering, Universidade Federal de Minas Gerais = Federal University of Minas Gerais [Belo Horizonte, Brazil] (UFMG), Advanced Ceramics Research Center, Nagoya Institute of Technology, Tajimi, Data-Driven Material Processing Research-Domain, Toyota Central R&D Laboratories Inc., Nagakute, Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux (LEM3), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Arts et Métiers Sciences et Technologies, HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM), Labex DAMAS, Université de Lorraine (UL), Eötvös Loránd University (ELTE), Montanuniversität Leoben (MUL), Université du Québec à Trois-Rivières, Oregon State University, Corvallis, USA, IMP Academy of Sciences of the Czech Republic, Ibaraki University, University of Southampton, Ames Laboratory [Ames, USA], Iowa State University (ISU)-U.S. Department of Energy [Washington] (DOE), Institute of Nanotechnology [Karlsruhe] (INT), Karlsruhe Institute of Technology (KIT), Russian Academy of Sciences - Chernogolovka, Kyushu Institute of Technology (Kyutech), Doshisha University [Kyoto], Kyushu Sangyo University, M.N. Mikheev Institute of Metal Physics (IMP), Ural Branch of Russian Academy of Sciences (UB RAS), KARADENIZ TECHNICAL UNIVERSITY FACULTY OF FORESTRY TRABZON TUR, Groupe de physique des matériaux (GPM), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), University of Technology Dresden, Indian Institute of Science [Bangalore] (IISc Bangalore), Center for Elements Strategy Initiative for Structure Materials (ESISM), Kyoto University, University of Vienna [Vienna], Kunming University of Science and Technology (KMUST), and ANR-17-CE08-0049,DIPLOX,Couplage diffusion-plasticité au cours de l'oxydation sélective d'alliages métalliques(2017)

Subjects
Technology, functional properties, ultrafine-grained (UFG) materials, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], severe plastic deformation (SPD), General Materials Science, surface severe plastic deformation, mechanical properties, ddc:600
Abstract

Severe plastic deformation (SPD) is effective in producing bulk ultrafine-grained and nanostructured materials with large densities of lattice defects. This field, also known as NanoSPD, experienced a significant progress within the past two decades. Beside classic SPD methods such as high-pressure torsion, equal-channel angular pressing, accumulative roll-bonding, twist extrusion, and multi-directional forging, various continuous techniques were introduced to produce upscaled samples. Moreover, numerous alloys, glasses, semiconductors, ceramics, polymers, and their composites were processed. The SPD methods were used to synthesize new materials or to stabilize metastable phases with advanced mechanical and functional properties. High strength combined with high ductility, low/room-temperature superplasticity, creep resistance, hydrogen storage, photocatalytic hydrogen production, photocatalytic CO 2 conversion, superconductivity, thermoelectric performance, radiation resistance, corrosion resistance, and biocompatibility are some highlighted properties of SPD-processed materials. This article reviews recent advances in the NanoSPD field and provides a brief history regarding its progress from the ancient times to modernity. Abbreviations: ARB: Accumulative Roll-Bonding; BCC: Body-Centered Cubic; DAC: Diamond Anvil Cell; EBSD: Electron Backscatter Diffraction; ECAP: Equal-Channel Angular Pressing (Extrusion); FCC: Face-Centered Cubic; FEM: Finite Element Method; FSP: Friction Stir Processing; HCP: Hexagonal Close-Packed; HPT: High-Pressure Torsion; HPTT: High-Pressure Tube Twisting; MDF: Multi-Directional (-Axial) Forging; NanoSPD: Nanomaterials by Severe Plastic Deformation; SDAC: Shear (Rotational) Diamond Anvil Cell; SEM: Scanning Electron Microscopy; SMAT: Surface Mechanical Attrition Treatment; SPD: Severe Plastic Deformation; TE: Twist Extrusion; TEM: Transmission Electron Microscopy; UFG: Ultrafine Grained.

Published
2022

24. Prepared for submission to npj Materials Degradation as an invited paper Weak impact of microorganisms on Ca, Mg-bearing silicate weathering

Author

Pokrovsky, Oleg, Shirokova, Liudmila, Zabelina, Svetlana, Jordan, Guntram, Bénézeth, Pascale, Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Tomsk State University [Tomsk], N. Laverov Federal Center for Integrated Arctic Research of the Ural Branch (FECIAR UrB RAS ), Russian Academy of Sciences - Chernogolovka, and Ludwig-Maximilians-Universität München (LMU)

Subjects
[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry
Abstract

International audience; Assessment of the microbial impact on mineral dissolution is crucial for a predictive understanding of basic (Ca, Mg-bearing) silicate weathering and the associated CO2 consumption, bioerosion and CO2 storage in basaltic rocks. However, there are controversies about the mechanism of microbial effect, which ranges from inhibiting via nil to accelerating. Here we studied diopside interaction with the heterotrophic bacterium Pseudomonas reactants and the soil fungus Chaetomium brasiliense using a combination of mixed-flow and batch reactors and in-situ (AFM) and ex-situ (SEM) microscopy. The results provide new nano-level insights into the degree to which microorganisms modify silicate dissolution. Taking into account negligible effects of organic ligands on diopside dissolution as reported earlier, we conclude that the microbial effect on Ca-Mg silicates is weak and the acceleration of dissolution of "basic" silicate rocks in the presence of soil biota is solely due to pH decrease in porewaters.

Published
2021

31. Isoprene Formation from Isoamyl Alcohol in Microchannels of a Converter Modified with Nanoscale Catalytic Iron–Chromium-Containing Systems

Author

D. O. Antonov, V. I. Uvarov, Franck Dumeignil, Svetlana Heyte, A. S. Fedotov, Sébastien Paul, M. V. Tsodikov, ENSCL, CNRS, Centrale Lille, Univ. Artois, Université de Lille, A.V. Topchiev Institute of Petrochemical Synthesis [TIPS], Unité de Catalyse et Chimie du Solide - UMR 8181 [UCCS], A.V. Topchiev Institute of Petrochemical Synthesis (TIPS), Russian Academy of Sciences [Moscow] (RAS), Russian Academy of Sciences - Chernogolovka, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille, and Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
010405 organic chemistry, General Chemical Engineering, Energy Engineering and Power Technology, chemistry.chemical_element, [CHIM.CATA]Chemical Sciences/Catalysis, General Chemistry, 010402 general chemistry, Isoamyl alcohol, 01 natural sciences, 0104 chemical sciences, Catalysis, chemistry.chemical_compound, Chromium, Fuel Technology, chemistry, Chemical engineering, Geochemistry and Petrology, Yield (chemistry), Dehydrogenation, Selectivity, Bimetallic strip, Isoprene
Abstract

International audience; A two-stage process for producing isoprene from isoamyl alcohol has been developed through the successive implementation of the steps of dehydration of isoamyl alcohol and dehydrogenation of resulting isoamylenes using porous ceramic converters obtained by self-propagating high-temperature synthesis, with the converter pores bearing Fe–Cr systems synthesized by the sol–gel technique and containing subnanosized iron and chromium particles. It has been shown that the bimetallic catalytic system obtained by separate deposition of Fe and Cr has the highest activity toward the isoamylenes studied in the dehydrogenation reaction; on this catalyst system using 24-fold dilution with water and a temperature of 600°C, the isoprene yield is up to ~10%, selectivity is ~23%, and productivity is ~0.13 Lisoprene/(h gact.comp). The conversion of the isoamylene fraction is 46%.

Published
2019

32. Advances in 3D imaging and volumetric reconstruction of fluid and melt inclusions by high resolution X-ray computed tomography

Author

Vanessa Dyja-Person, Laura Créon, Jacques Pironon, Isabella Pignatelli, Gaston Giuliani, Svetlana Pentelei, Nicolas Beaudoin, Vladimir S. Balistky, Hélène Legros, Antonin Richard, Jérôme Sterpenich, Christophe Morlot, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), Centro de Geociencias [Queretaro], Universidad Nacional Autónoma de México (UNAM), Le Mans Université (UM), Laboratoire des Fluides Complexes et leurs Réservoirs (LFCR), TOTAL FINA ELF-Université de Pau et des Pays de l'Adour (UPPA)-Centre National de la Recherche Scientifique (CNRS), School of Geographical and Earth Sciences [Univ Glasgow], University of Glasgow, Department of Civil and Environmental Engineering [Glasgow], University of Strathclyde [Glasgow], Russian Academy of Sciences - Chernogolovka, Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), ANR-10-LABX-0021,RESSOURCES21,Strategic metal resources of the 21st century(2010), Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
High resolution X-ray computed tomography, 010504 meteorology & atmospheric sciences, Mineralogy, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Crystal, chemistry.chemical_compound, Geochemistry and Petrology, Phase (matter), Fluid inclusions, [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology, Quartz, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Melt inclusions, Volume, Spinel, Shape, Geology, Silicate, TA, chemistry, Phase, engineering, Inclusion (mineral)
Abstract

Fluid and melt inclusions are tiny pockets of fluid and melt trapped in natural and synthetic minerals. Characterizing the 3D distribution of fluid and melt inclusions within minerals, their shape and the volume fraction of their different phases is crucial for determining the conditions of crystal growth and paleostress analysis. However, their relatively small size (typically 5 to 100 mu m), complex shape, heterogeneous content, the opaque nature of some host minerals and projection bias frequently hamper accurate imaging and volumetric reconstruction using conventional microscopic techniques. High resolution X-ray computed tomography (HRXCT) is a non-destructive method which uses contrasts of X-ray attenuation in a series of contiguous radiographs with different view angles to reconstruct the 3D distribution of areas of different densities within a large variety of materials. In this work, we show the capabilities of HRXCT for: (i) imaging the 3D distribution of aqueous and hydrocarbon-bearing fluid inclusions and silicate melt inclusions in a crystal; (ii) characterizing the shape of fluid and melt inclusions and (iii) reconstructing the total volume and the volume of the different phases (liquid, glass, crystal, vapor) of fluid and melt inclusions. We have used a variety of hand specimens and chips of transparent and opaque minerals (olivine, quartz, feldspar, garnet, emerald, wolframite), that we analyzed using three different HRXCT setups. When a resolution of similar to 1 mu m(3)/voxel is achieved, HRXCT allows identifying > 5 mu m fluid inclusions, and the identification and volumetric reconstruction of the different phases can be carried out with reasonable confidence for relatively large (> 25 mu m) inclusions. Density contrasts are high enough to properly identify: (i) a silicate melt inclusion, and its different phases (glass, vapor and crystals such as clinopyroxene and spinel) in an olivine crystal; (ii) aqueous monophase (liquid) and two-phase (liquid + vapor) fluid inclusions in transparent and opaque minerals (quartz, garnet, emerald, wolframite). In the case of hydrocarbon-bearing fluid inclusions containing a vapor phase and two liquid phases (oil and aqueous solution), the two liquid phases could not be distinguished from each other. Volumetric reconstruction of liquid and vapor phases of aqueous and hydrocarbon-bearing fluid inclusions show compatible results with independent calculations using known pressure, temperature, molar volume and composition (P-T-V-x) conditions of trapping or imaging using confocal laser scanning microscopy respectively. Collectively, our results show that HRXCT is a promising tool for non-destructive characterization of fluid and melt inclusions.

Published
2019

34. Thermal behavior of Mg−Ni‐phyllosilicate nanoscrolls and performance of the resulting composites in hexene‐1 and acetone hydrogenation

Author

Valery L. Ugolkov, Sergey A. Lermontov, Alexandre Nominé, D. A. Kozlov, A. A. Krasilin, Stéphanie Bruyère, E. A. Straumal, E. K. Khrapova, Thierry Belmonte, Tatyana S. Kunkel, Vasily A. Lebedev, Jaafar Ghanbaja, A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences [Moscow] (RAS), Grebenshchikov Institute of Silicate Chemistry, Russian Academy of Sciences, Institute of Physiologically Active Compounds, Russian Academy of Sciences - Chernogolovka, Bernal Institute [Limerick, Ireland], University of Limerick (UL), Lomonosov Moscow State University (MSU), Moscow Institute of Physics and Technology [Moscow] (MIPT), ITMO University [Russia], Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Russian Science Foundation, and French Ministry of Higher Education

Subjects
Materials science, metal, Energy Engineering and Power Technology, reduction, 02 engineering and technology, 010402 general chemistry, Heterogeneous catalysis, 7. Clean energy, 01 natural sciences, nanotubes, Biomaterials, Metal, chemistry.chemical_compound, Thermal, Materials Chemistry, Acetone, Hydrothermal synthesis, Renewable Energy, Sustainability and the Environment, [CHIM.ORGA]Chemical Sciences/Organic chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, [CHIM.CATA]Chemical Sciences/Catalysis, 021001 nanoscience & nanotechnology, 0104 chemical sciences, hydrothermal synthesis, heterogeneous catalysis, chemistry, Chemical engineering, Hexene, METAL, visual_art, visual_art.visual_art_medium, nanoparticles, 0210 nano-technology
Abstract

peer-reviewed The full text of this article will not be available in ULIR until the embargo expires on the 05/11/2021 Here we report on the thermal properties of Mg−Ni‐phyllosilicate nanoscrolls as a promising precursor for production of Ni/silicate composite catalysts. Spontaneous scrolling of the phyllosilicate layer originating from size difference between metal‐oxygen and silica sheets provides high surface area of the catalyst. Metal nanoparticles can be obtained directly from the matrix by H2 reduction. The phyllosilicate structure passed through a number of transformations including partial dehydroxylation with formation of sepiolite‐like phase followed by silicate or oxide crystallization. Temperature ranges of these transitions overlapped with the reduction process sophisticating the H2 consumption profiles. In particular, some amount of Ni2+ got sealed up by the sepiolite structural features, that opened a path for the tuning of Ni0 : Ni2+ ratio of the catalyst. An increase of Ni content in the system yielded a decrease in the metal nanoparticles sizes due to both high intensity of nucleation and type of residual matrix. Ni nanoparticles size distribution and specific surface area of the composite catalysts governed conversion rate of hexene‐1 and acetone hydrogenation. In the view of the turnover frequency MgNi2Si2O5(OH)4 precursors were slightly more preferable than pure Ni3Si2O5(OH)4.

Published
2021

35. Pressure dependent half-metallic ferromagnetism in inverse Heusler alloy Fe 2 CoAl: a DFT+U calculations

Author

I. V. Malikov, Madhav Prasad Ghimire, Lalrinkima, Adlane Sayede, L. A. Fomin, Raj Kumar Thapa, Lalhriatzuala, Lalthakimi Zadeng, D. P. Rai, Physical Sciences Research Center, Department of Physics, Pachhunga University College, Institute of Microelectronics Technology and High Purity Materials, Russian Academy of Sciences, Chernogolovka 142432 Moscow Region, Russia., Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille, Central Department of Physics, Tribhuvan University, Mizoram University, Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Tribhuvan University, CNRS, Centrale Lille, ENSCL, Univ. Artois, Université de Lille, and Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181

Subjects
010302 applied physics, Materials science, Condensed matter physics, Magnetic moment, Band gap, Orbital hybridisation, General Chemical Engineering, 02 engineering and technology, General Chemistry, Electronic structure, [CHIM.MATE]Chemical Sciences/Material chemistry, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Ferromagnetism, Mean field theory, 0103 physical sciences, Curie temperature, 0210 nano-technology, Spin (physics)
Abstract

International audience; We report the electronic and magnetic properties along with the Curie temperature (TC) of the inverse full Heusler alloy (HA) Fe2CoAl obtained by using the first-principles computational method. Our calculations suggests that Fe2CoAl is a magnetic metal when treated within PBE-GGA under the applied compressive pressures. However, the implementation of electron–electron (U) (i.e., GGA+U) with varying compressive pressure (P) drastically changes the profile of the electronic structure. The application of GGA+U along with pressure induces ferromagnetic half-metallicity with an integer value of total magnetic moment ∼4.0 μB per unit cell. The integer value is in accordance with the Slater–Pauling's rule. Here, we demonstrate the variation of semiconducting gap in the spin down channel. The band gap increases from 0.0 eV to 0.72 eV when increasing the pressure from 0 to 30 GPa. Beyond 30 GPa, the electronic band gap decreases, and it is completely diminished at 60 GPa, exhibiting metallic behaviour. The analysis of the computed results shows that the treatment of electron–electron interactions within GGA+U and the application of compressive pressure in Fe2CoAl enables d–d orbital hybridization giving rise to a half-metal ferromagnet. The TC calculated from mean field approximation (MFA) decreases up to 30 GPa and then increases linearly up to 60 GPa.

Published
2020

41. Strong magnetocaloric effect induced by spin reorientation transitions in epitaxial Ho thin films

Author

O. Koplak, Stéphane Mangin, Rajasekhar Medapalli, R. B. Morgunov, Eric E. Fullerton, Institute of Problems of Chemical Physics, Russian Academy of Sciences - Chernogolovka, Center for Memory and Recording Research, University of California [San Diego] (UC San Diego), University of California-University of California, National Institute of Technology Andhra Pradesh, Partenaires INRAE, Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), IMPACT N4S, and ANR-15-IDEX-0004,LUE,Isite LUE(2015)

Subjects
Physics, [PHYS]Physics [physics], Condensed matter physics, Spin transition, chemistry.chemical_element, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Magnetic field, Orientation (vector space), Magnetization, chemistry, 0103 physical sciences, Magnetic refrigeration, Antiferromagnetism, 010306 general physics, 0210 nano-technology, Holmium, Spin-½
Abstract

Magnetocaloric effect (MCE) in an antiferromagnetic holmium (Ho) film is studied near the spin reorientation temperatures. A series of magnetization isotherms from 60 to 150 K around the N\'eel temperature, ${T}_{N}\ensuremath{\approx}130\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ were recorded for both in-plane and out-of-plane magnetic field orientations. A change in entropy, $\mathrm{\ensuremath{\Delta}}{S}_{M}$ of $\text{--}5\phantom{\rule{0.28em}{0ex}}\mathrm{J}/\mathrm{kg}\mathrm{K}$ was found near ${T}_{N}$ for an in-plane field orientation. A large change in $\mathrm{\ensuremath{\Delta}}{S}_{M}$ of \ensuremath{-}11.8 J/kg K due to a fan-helix spin transition at $T=90\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ is observed for an in-plane field orientation. Spin transition at both ${T}_{N}$ and at the fan-helix transition exhibit larger MCE in the in-plane field orientations in comparison with the perpendicular orientation. The value of the refrigerant capacity extracted from the temperature dependence of $\mathrm{\ensuremath{\Delta}}{S}_{M}(T)$ is found to be larger for the ``in- plane'' orientation by a factor of two.

Published
2020

42. On the Ohm law in dilute colloidal polyelectrolytes

Author

Chikina, I., Shikin, V., Varlamov, Andrey, Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire (LIONS), Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Energie (ex SIS2M) (NIMBE UMR 3685), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Russian Academy of Sciences - Chernogolovka, SPIN-CNR [Rome], Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Condensed Matter::Soft Condensed Matter, endocrine system, digestive, oral, and skin physiology, 73.21.-b, 65.40.gd, Soft Condensed Matter (cond-mat.soft), FOS: Physical sciences, Condensed Matter - Soft Condensed Matter, complex mixtures
Abstract

We discuss the peculiarities of the Ohm law in dilute polyelectrolytes containing a relatively low concentration of the multiply-charged colloidal particles. It is demonstrated that in this conditions, the effective conductivity of polyelectrolyte is the linear function of colloidal particles concentration. This happens due to the change of electric field in the polyelectrolyte under the effect of colloidal particle polarization. Such mechanism gives grounds to propose the alternative scenario for the phenomenon observed experimentally., 6 pages, 2 figures

Published
2020

43. Solvent extraction of intra-lanthanides using a mixture of TBP and TODGA in ionic liquid

Author

Maria Boltoeva, Alexander N. Turanov, Vasilii K. Karandashev, Russian Academy of Sciences - Chernogolovka, National University of Science and Technology (MISIS), Département Recherches Subatomiques (DRS-IPHC), Institut Pluridisciplinaire Hubert Curien (IPHC), and Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Lanthanide, Solvent extraction, Inorganic chemistry, 0211 other engineering and technologies, 02 engineering and technology, Diluent, Industrial and Manufacturing Engineering, chemistry.chemical_compound, 020401 chemical engineering, Nitric acid, Materials Chemistry, 0204 chemical engineering, Imide, TBP, 021102 mining & metallurgy, Lanthanide(III) Ions, Ligand, Extraction (chemistry), Metals and Alloys, Synergism, TODGA, Ionic liquids, Solvent, chemistry, Ionic liquid, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph]
Abstract

The recovery and separation of trivalent lanthanides into individual elements is difficult owing to their similar chemical behaviours. In this study, the solvent extraction of trivalent lanthanide ions from nitric acid solutions in an organic phase comprising a mixture of two electrically neutral extractants, viz. tri(n-butyl)phosphate (TBP) and N,N,N′,N′-tetra(n-octyl)diglycolamide (TODGA), is investigated. The hydrophobic room-temperature ionic liquid (IL), 1-methyl-3-butyl-imidazolium bis(trifluoromethanesulfonyl)imide, is employed as a more environmentally benign diluent compared to the conventional molecular solvents. The results reveal that the addition of TBP as a co-extractant with TODGA not only significantly enhances the metal ion extraction but also affords high intra-lanthanide ion selectivity. This is attributed to the formation of complex lanthanide species with both TBP and TODGA. In addition, when IL is used as a diluent, the cationic exchange between metal–organic ligand species and IL cations, as well as neutral complex extraction result in a more efficient extraction. Moreover, the hydrophobic anionic IL entities can also be involved in the extraction mechanism, affording lipophilic metal–organic ligand complexes. The synergistic solvent combination of TODGA, TBP, and IL can afford an excellent separation of the lanthanide(III) ions.

Published
2020

44. Glycine Residue Twists HOMO…HOMO Interactions in a Molecular Conductor

Author

Leokadiya V. Zorina, Abdelkrim El-Ghayoury, Sergey V. Simonov, Patrick Batail, Pascale Auban-Senzier, Cécile Mézière, Enric Canadell, Pere Alemany, MOLTECH-Anjou, Université d'Angers (UA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institute of Solid State Physics of the Russian Academy of Sciences, Russian Academy of Sciences - Chernogolovka, Institute of Solid State Physics, Russia, Russian Academy of Sciences [Moscow] (RAS), Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Institut de Ciència de Materials de Barcelona (ICMAB), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Agence Nationale de la Recherche (France), Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Economía y Competitividad (España), and Generalitat de Catalunya

Subjects
Anions, Oligòmers, Chemistry, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Teoria del funcional de densitat, General Chemistry, Condensed Matter Physics, 3. Good health, Conductor, Crystallography, Residue (chemistry), Radical ion, Oligomers, [CHIM]Chemical Sciences, General Materials Science, ComputingMilieux_MISCELLANEOUS, Density functionals
Abstract

We report on radical cation salts of EDT-TTF cores bearing a glycine residue with hydrogenosulfate, [HSO4–], or the amphoteric para-carboxybenzenesulfonate, [HO2C-C6H4-SO3–]. In (EDT-TTF-CO-NHCH2-CO2H)2+[HSO4–], orthogonal pairs of oxygen atoms of the tetrahedral sulfonate anions engage in hydrogen bonds building the two-dimensional (2D) chess-board pattern of orthogonal dimers typical of a κ-phase 2D metal. We find by tight-binding and density functional theory analysis of the band structure that, as a result of the structure-directing role of the Gly residue, HOMO···HOMO interactions in (EDT-TTF-CO-NHCH2-CO2H)2+[HSO4–] are twisted away from the usual in-plane isotropy of κ-phases toward a very uncommon quasi-one-dimensional electronic structure with electronic localization. Transport measurements confirm the highly conducting, yet weakly localized regime. The ability of para-carboxybenzenesulfonate to act as a bimolecular, dianionic unit of double spatial extension is fulfilled in (EDT-TTF-CO-NHCH2-CO2H)22+[HO2C-C6H4-SO3–]2, where the charge is balanced by diamagnetic dimers leaving no carrier left available in the lattice., L.Z. and S.S. gratefully acknowledge support from the CNRS and the Region Pays de la Loire for an associated researcher ́ and postdoctoral position, respectively. Financial support from the ANR PNANO Project TTF-Based Nanomat ANR-07- NANO-030-01 is gratefully acknowledged. Work in Spain was supported by MICIU (PGC2018-096955-B-C44 and PGC2018-093863-B-C22), MINECO through the Severo Ochoa (SEV-2015-0496) and Maria de Maeztu (MDM2017-0767) Programs and the Generalitat de Catalunya (2017SGR1506 and 2017SGR1289).

Published
2020

46. Barium ions in liquid helium

Author

V. B. Shikin, I. Chikina, Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire ( LIONS ), Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Energie (ex SIS2M) ( NIMBE UMR 3685 ), Institut Rayonnement Matière de Saclay ( IRAMIS ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ) -Institut Rayonnement Matière de Saclay ( IRAMIS ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Russian Academy of Sciences - Chernogolovka, Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire (LIONS), Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Energie (ex SIS2M) (NIMBE UMR 3685), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Physics and Astronomy (miscellaneous), General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, Dielectric, 01 natural sciences, Molecular physics, law.invention, Ion, Condensed Matter::Materials Science, law, 0103 physical sciences, Cluster (physics), Physics::Atomic Physics, 010306 general physics, Laser ablation, Liquid helium, Barium, 021001 nanoscience & nanotechnology, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Ion implantation, chemistry, [ CHIM.THEO ] Chemical Sciences/Theoretical and/or physical chemistry, 0210 nano-technology, Superfluid helium-4
Abstract

International audience; We discuss the properties of barium clusters (neutral or charged) implanted into liquid helium and propose a model where individual barium atoms cannot form negative ions, whereas a barium cluster composed of many barium atoms can. This property is important from the standpoint of applications involving laser ablation of barium metal surfaces in liquid helium. We note the qualitative differences in the mechanisms of formation of quasi-one-dimensional chains of metal or dielectric dust during its implantation into superfluid helium. A likely scenario for a dispersed metal is the dendritic breakdown in a parallel plate capacitor filled with metal dust and a finite potential difference between the plates. It is not possible to use the dendritic mechanism of cluster evolution for the dielectric problem and the details of this mechanism do not agree well with existing observations. We outline a scenario alternative to the vortex formation of long chains with dielectric links.

Published
2018

47. Electrocatalytic properties of manganese and cobalt polyporphine films toward oxygen reduction reaction

Author

Mikhail A. Vorotyntsev, Pawel J. Kulesza, Magdalena Skunik-Nuckowska, Olivier Heintz, O. I. Istakova, Dmitry V. Konev, Beata Dembinska, Charles H. Devillers, Mendeleev University of Chemical Technology of Russia, Institute for Problems of Chemical Physics, Russian Academy of Sciences - Chernogolovka, Faculty of Chemistry, Warsaw University of Technology, Warsaw University of Technology [Warsaw], Institut de Chimie Moléculaire de l'Université de Bourgogne [Dijon] (ICMUB), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-Institut de Chimie du CNRS (INC), Laboratoire Interdisciplinaire Carnot de Bourgogne [Dijon] (LICB), Université de Bourgogne (UB)-Université de Technologie de Belfort-Montbeliard (UTBM)-Centre National de la Recherche Scientifique (CNRS), Institute of Problems of Chemical Physics of RAS, Russian Academy of Sciences [Moscow] (RAS), and Russian Foundation for Basic Research 16-03-00916 A European Commission through the Graphene Flagship - Core 1 project GA-696656

Subjects
conjugated porphyrin polymer, General Chemical Engineering, Inorganic chemistry, FOS: Physical sciences, chemistry.chemical_element, 02 engineering and technology, Electrolyte, Manganese, positive potentials, phthalocyanines, 010402 general chemistry, 01 natural sciences, catalysts, Analytical Chemistry, Catalysis, porphine, [CHIM.ANAL]Chemical Sciences/Analytical chemistry, frameworks, Electrochemistry, [CHIM]Chemical Sciences, dioxygen reduction, Condensed Matter - Materials Science, metalloporphyrins, Aqueous solution, Ion exchange, Magnesium, Electroactive polymers, Materials Science (cond-mat.mtrl-sci), Oxygen electroreduction, electropolymerization, fuel-cell cathode, 021001 nanoscience & nanotechnology, Metalloporphines, 0104 chemical sciences, Polymer film coated electrode, chemistry, 0210 nano-technology, Platinum, Cobalt, Mg(II) porphine
Abstract

International audience; Novel member of polymetalloporphines, namely manganese polymetalloporphine of type I (pMnP-I) obtained by ion exchange from magnesium polyporphine of type I (pMgP-I) is reported for the first time and compared to its cobalt analogue (pCoP-I). Both polymer films have been obtained via two-step procedure: demetaladon of the pMgP-I electrode film via its exposure to trifluoroacetic acid solution, resulting in formation of the metal-free polyporphine of type I (pH(2)P-I) followed by electrochemically induced incorporation of Co or Mn ions from the acetonitrile solution of cobalt and manganese perchlorates. A further oxidative transformation of pCoP-I, polymer films has led to the corresponding polyporphines of type II, pCoP-II and pMnP-II, possessing such unique features as condensed polymer structure with a very high density of active sites and high electronic conductivity within a very broad potential range including the one corresponding to the neutral (uncharged) state of the polymer matrix. Both polymers of type II also exhibit interesting electrocatalytic activity toward oxygen electroreduction in aqueous neutral (pH 6.7) and alkaline (pH 13) media which was evaluated under cyclic voltammetric and steady-state conditions. The results demonstrate that the efficiency (regardless of the electrolyte) of both polymetalloporphines is comparable to bare platinum electrode. The effect of annealing of polymer-modified electrodes on their catalytic properties has also been considered.

Published
2018

48. Surprising dependence of the current density of bromate electroreduction on the microelectrode radius as manifestation of the autocatalytic redox-cycle (EC″) reaction mechanism

Author

A. E. Antipov, Mikhail A. Vorotyntsev, Mikhail M. Petrov, Maria A. Shamraeva, Dmitry V. Konev, Mendeleev University of Chemical Technology of Russia, Lomonosov Moscow State University (MSU), Institute for Problems of Chemical Physics, Russian Academy of Sciences - Chernogolovka, Institut de Chimie Moléculaire de l'Université de Bourgogne [Dijon] (ICMUB), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-Institut de Chimie du CNRS (INC), and Russian Science Foundation 15-13-20038

Subjects
Bromine/bromide redox mediation, steady-state conditions, Inorganic chemistry, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Ion, lcsh:Chemistry, Autocatalysis, chemistry.chemical_compound, Bromide, square-wave voltammetry, Electrochemistry, [CHIM]Chemical Sciences, Autocatalytic cycle, 2nd-order reactions, limiting currents, cation adsorption, Bromine, acidic-solution, anion, Radius, electrode, 021001 nanoscience & nanotechnology, Bromate, 0104 chemical sciences, Microelectrode, lcsh:Industrial electrochemistry, lcsh:QD1-999, chemistry, kinetics, Chemical physics, Disk microelectrode, transport, Comproportionation reaction, 0210 nano-technology, Current density, lcsh:TP250-261
Abstract

Bromate reduction from strongly acidic solutions under steady-state conditions in the presence of a very small amount of bromine has been studied voltammetrically at disk microelectrodes of various radii. In conformity with theoretical predictions the intensity of the average current density depends on the electrode size in a non-monotonous manner, passing through a maximum for a certain radius. This behavior is a direct consequence of the autocatalytic character of this process where the non-electroactive bromate anion is reduced owing to the catalytic cycle based on the bromine/bromide redox-mediator couple. The experimentally observed dependence of the maximal current density, jmax, on the inverse disc radius, 1/r0, for electrodes of larger sizes approaches a straight line corresponding to the “strong current limit”, which exceeds the diffusion-limited current density for bromate ion. Keywords: Autocatalytic cycle, Bromine/bromide redox mediation, Comproportionation reaction, Disk microelectrode

Published
2018

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