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Morniroli J.P.,Ecole Nationale Superieure de Chimie de Lille | Ji G.,CNRS Materials and Transformations Unit of UMET | Jacob D.,CNRS Materials and Transformations Unit of UMET
Ultramicroscopy | Year: 2012

This systematic method allows the unambiguous identification of the extinction and diffraction symbols of a crystal by comparison of a few experimental Precession Electron Diffraction (PED) patterns with theoretical patterns drawn for all the extinction and diffraction symbols. The method requires the detection of the Laue class, of the kinematically forbidden reflections and of the shift and periodicity differences between the reflections located in the First-Order Laue Zone (FOLZ) with respect to the ones located in the Zero-Order Laue Zone (ZOLZ). The actual space group can be selected, among the possible space groups connected with each extinction symbol or diffraction symbol, from the identification of the point group. This point group is available from observation of the 2D symmetry of the ZOLZ on Convergent-Beam Electron Diffraction (CBED) patterns. © 2012 Elsevier B.V. Source

Jacob D.,CNRS Materials and Transformations Unit of UMET | Ji G.,CNRS Materials and Transformations Unit of UMET | Morniroli J.P.,Ecole Nationale Superieure de Chimie de Lille
Ultramicroscopy | Year: 2012

Precession Electron Diffraction and Convergent-Beam Electron Diffraction are used in a complementary way to determine the space group of three known structures following the general method described in the first part of this paper. The selected structures concern a monoclinic example (coesite SiO 2 with space group C2/c) and two cubic examples (γ-Al 4Cu 9 with space group P4̄3m and pyrite FeS 2 with space group Pa3̄). For each case, a minimum number of zone axis patterns are used to determine the space group without ambiguity, which illustrates the simplicity and reliability of the method. © 2012 Elsevier B.V. Source

Zinck P.,University of Lille Nord de France | Zinck P.,Ecole Nationale Superieure de Chimie de Lille | Zinck P.,French National Center for Scientific Research
Polymer International | Year: 2012

Coordinative chain transfer polymerization (CCTP) is a reversible group transfer polymerization involving a transition metal catalyst and a main group metal alkyl. CCTP affords well-controlled polymerizations of olefins and conjugated dienes with catalyst economy and good potential for polymer end-functionalization. New concepts have recently emerged in this field, affording unprecedented control over both microstructure and architecture of the resulting polymers and copolymers. These concepts are presented and discussed in this perspective. © 2011 Society of Chemical Industry. Source

Becquart C.S.,Ecole Nationale Superieure de Chimie de Lille | Becquart C.S.,Electricite de France | Domain C.,Electricite de France
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2011

This article gives an overview of the strategy followed nowadays to model the evolution of metallic alloy microstructures under irradiation. For this purpose, multiscale approaches are very often used, which rely on modeling techniques appropriate to each time and space scale. The main methods used are ab-initio calculations, classical molecular dynamics (MD), kinetic Monte Carlo (KMC), mean field rate theory (MFRT), and dislocation dynamics (DD). These methods are briefly presented along with some of their typical uses and main drawbacks. Some examples are provided of the typical information obtained with each of the techniques. © 2010 The Minerals, Metals & Materials Society and ASM International. Source

Ji G.,CNRS Materials and Transformations Unit of UMET | Morniroli J.-P.,Ecole Nationale Superieure de Chimie de Lille
Journal of Applied Crystallography | Year: 2013

The space group of a new metastable orthorhombic Al2Cu phase, located in the Al-rich interfacial region of an Al-Cu friction stir weld, was unambiguously identified as Ic2m by a recently developed systematic method combining precession electron diffraction and convergent-beam electron diffraction. This metastable phase has the same tetragonal lattice as its stable θ-Al2Cu counterpart (tetragonal, I4/mcm, No. 140). The tetragonal-to-orthorhombic symmetry lowering is due to slight modifications of the atomic positions in the unit cell. This metastable phase can be transformed into the stable θ-Al2Cu phase by in situ irradiation within the transmission electron microscope. Copyright © International Union of Crystallography 2013. Source

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