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3 results on '"Electron-Diffraction"'

1. Ab initio investigation of the relative stability of silicogermanates and their (Alumino)Silicates counterparts

Author

Johan A. Martens, Bogdan Harbuzaru, Elsy El Hayek, Céline Chizallet, IFP Energies nouvelles (IFPEN), Center for Surface Chemistry and Catalysis, and Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven)

Subjects
12-RING CHANNELS, Technology, Materials science, Materials Science, Ab initio, QUATERNARY AMMONIUM, CATALYTIC-PROPERTIES, Materials Science, Multidisciplinary, 02 engineering and technology, ELECTRON-DIFFRACTION, Silicogermanate, 010402 general chemistry, DFT, 01 natural sciences, Catalysis, LARGE-PORE ZEOLITE, chemistry.chemical_compound, Aluminosilicate, Molecule, CRYSTAL-STRUCTURE, General Materials Science, Nanoscience & Nanotechnology, Zeolite, Substitution reaction, Science & Technology, BETA-ZEOLITE, Chemistry, Physical, PREFERENTIAL LOCATION, [CHIM.CATA]Chemical Sciences/Catalysis, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Stabilization, Silicate, 0104 chemical sciences, Chemistry, Applied, Chemistry, Crystallography, chemistry, Mechanics of Materials, Post-treatment, Reagent, Physical Sciences, Post-treatmen, Science & Technology - Other Topics, PURE POLYMORPH-C, 0210 nano-technology, GERMANOSILICATE MOLECULAR-SIEVES
Abstract

International audience; The diversity of synthetic zeolites with silicogermanate composition has grown significantly. Many of these zeolites have large pores, thanks to the double 4-ring (d4r) structural subunits occupied by Ge atoms. The wide pores make them potentially interesting for catalytic transformation of bulky molecules, but the thermal and hydrothermal stability and the acidity are insufficient for practical applications. In the present work, the stability of known silicogermanate zeolite structures and their silicate and aluminosilicate analogues is evaluated using periodic density functional theory calculations. The thermodynamics of isomorphic substitution of Ge atoms for Si and Al via chemical processes are investigated. The study reveals that thermodynamically, (alumino)silicate counterparts of all known silicogermanates are intrinsically stable, and that the energetics of isomorphic substitution reactions of Ge atoms are almost independent of the distribution of d4r units in the different framework topologies. Chlorides are found better isomorphic substitution reagent candidates, at least theoretically. This work opens perspectives for the catalytic use of stable derivatives of silicogermanate zeolites.

Published
2020
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2. Polarity of prismatic facets delimiting WC grains in WC–Co alloys

Author

Marc Loubradou, Sabine Lay, Patricia Donnadieu, Science et Ingénierie des Matériaux et Procédés (SIMaP), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
MECHANISM, HRTEM, Materials science, Morphology (linguistics), Polarity (physics), Interfaces, Alloy, General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, engineering.material, ELECTRON-DIFFRACTION, 01 natural sciences, Prismatic facets, Crystal, Structural Biology, 0103 physical sciences, WC-Co alloys, General Materials Science, Composite material, High-resolution transmission electron microscopy, 010302 applied physics, CRYSTAL, [CHIM.MATE]Chemical Sciences/Material chemistry, Cell Biology, QUANTITATIVE-ANALYSIS, 021001 nanoscience & nanotechnology, EVOLUTION, Grain growth, Crystallography, chemistry, Electron diffraction, CEMENTED CARBIDES, engineering, GROWTH, MORPHOLOGY, SHAPE, 0210 nano-technology, Carbon, POLARITY
Abstract

This study reports a determination of the polarity of WC facets in WC–Co alloys sintered at the liquid state. In these alloys, WC grains are delimited by basal facets and two sets of { 1 0 1 ¯ 0 } prismatic facets, one set of facets being much more developed than the other. A variation of the shape is observed as a function of the composition of the alloy. High resolution transmission electron microscopy is used to investigate the polarity of the prismatic facets owing to the typical triangular patterns appearing on the images. The effect of the composition is investigated using two alloys with different carbon potentials and one containing VC and Cr3C2 as grain growth inhibitors. The interpretation of the images shows that in all cases, the same set of prismatic planes is favoured.

Published
2010
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3. Natural speciation of Mn, Ni, and Zn at the micrometer scale in a clayey paddy soil using X-ray fluorescence, absorption, and diffraction

Author

Delphine Tisserand, Michel L. Schlegel, Nicolas Geoffroy, Sophie Rihs, Zueng-Sang Chen, Matthew A. Marcus, Daniel Chateigner, Alain Manceau, Caterina Tommaseo, Nobumichi Tamura, Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS), Centre de géochimie de la surface (CGS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Service de Physique et de Chimie des Surfaces et Interfaces (SPCSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Advanced Light Source [LBNL Berkeley] (ALS), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Department of Agricultural Chemistry, National Taiwan University [Taiwan] (NTU), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Institut des Sciences de la Terre [2011-2015] (ISTerre [2011-2015]), Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble [1985-2015] (OSUG [1985-2015]), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Environmental Geochemistry Group, Université Joseph Fourier - Grenoble 1 (UJF), Centre National de la Recherche Scientifique (CNRS)-Université Louis Pasteur - Strasbourg I-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement (LAMBE - UMR 8587), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-Université d'Évry-Val-d'Essonne (UEVE)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine, Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Analyse et environnement (LAE), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS), Département de Physico-Chimie (DPC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
CONTAMINATED DREDGED SEDIMENT, Materials science, XRD, MANGANESE NODULES, media_common.quotation_subject, EXAGS spectroscopy, Analytical chemistry, chemistry.chemical_element, X-ray fluorescence, EXAFS SPECTROSCOPY, Manganese, Zinc, 010501 environmental sciences, Vermiculite, ELECTRON-DIFFRACTION, 010502 geochemistry & geophysics, 01 natural sciences, Mn, soil, P-EXAFS, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Geochemistry and Petrology, Silicate minerals, Zn, SXRF, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, media_common, Ni, METAL SORBED BIRNESSITE, x-ray fluorescence, paddy soil, FERROMANGANESE NODULES, Ultisol, heavy metal, QUANTITATIVE SPECIATION, Speciation, x-ray diffraction, speciation, chemistry, CRYSTAL-CHEMISTRY, Soil water, PRINCIPAL COMPONENT ANALYSIS, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], POLARIZED EXAFS
Abstract

International audience; The natural speciation of Mn (0.19 g/kg), Ni (46 mg/kg), and Zn (42 mg/kg) in the argillic horizon (120 cm depth, pH = 5.6) of an Ultisol from a paddy soil in northern Taiwan was investigated by advanced X-ray synchrotron techniques. Microchemical associations were imaged by synchrotron-based X-ray microfluorescence, host minerals were identified by standard and micrometer-resolved X-ray diffraction, and the local coordination environment of Mn, Ni, and Zn was probed using extended X-ray absorption fine structure (EXAFS) spectroscopy on a powdered sample and a soil thin section, and polarized EXAFS spectroscopy on a highly textured self-supporting clay film from the < 2 mu m fraction of the soil. Manganese was concentrated in Fe-Mn soft mottles (44.4 g/kg) as turbostratic hexagonal birnessite and lithiophorite having Mn3+/Mn4+ atomic ratios of similar to 20% and 50%, respectively. Quantitative analysis of high-order scattering paths of the EXAFS spectrum for natural and synthetic (Al0.67Li0.32)(Mn0.684+Mn0.323+)O-2(OH)(2) lithiophorite revealed that Mn3+ and Mn4+ are ordered in the [(Mn0.684+Mn0.323+)O-2](0.32-) layer. A structural model is proposed, in which Mn4+ and Mn3+ are ordered similarly to Al and Li in the [(A(0.67)(3+)Li(0.32)(+))(OH2)O-2](0.32+) layer, with Mn3+ cations being surrounded by six Mn4+, and Mn4+ cations by three Mn3+ and three Mn. Similar cation ordering in the manganese and aluminum layers likely provides a more homogeneous local balance of the excess and deficit of charges in each layer and increases the stability of lithiophorite. Ni (r = 0.70 angstrom) substitutes for Mn (r(Mn4+) = 0.54 angstrom, r(Mn3+) = 0.65 angstrom) in the manganese layer in the natural lithiophorite. In contrast, Zn (r = 0.74 angstrom) fills vacant sites in the gibbsitic layer of natural lithiophorite, in a similar manner as lithium (r = 0.74 angstrom) in synthetic lithiophorite. The partitioning of Ni and Zn between the two layers is a result of the general preference of Ni, whose size is intermediate between those of Mn3+ and Li+, for slightly smaller sites. In contrast with nickel, which is detected only where there is lithiophorite, the Zn-lithiophorite association found in Fe-Mn mottles is not representative of the bulk soil. The combined use of X-ray diffraction, and powder and polarized EXAFS spectroscopy revealed that Zn is predominantly bound to hydroxy-Al interlayers sandwiched between 2:1 vermiculite layers in the fine soil matrix. The incorporation of Zn in the gibbsitic layer of both lithiophorite and vermiculite helps increase the stability of these minerals by providing positive charge to balance the negative charge from the 2:1 phyllosilicate layer and the [(Mn0.684+Mn0.323+)O-2](0.32-) layer of lithiophorite. This binding environment for zinc is probably the main mechanism by which zinc is sequestered in acidic to near-neutral aluminum-rich clayey soils.

Published
2005
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