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Ben Smida Y.,Universite Ibn Tofail | Guesmi A.,Universite Ibn Tofail | Guesmi A.,Institute Preparatoire Aux Etudes dIngenieurs dEl Manar | Driss A.,Universite Ibn Tofail
Acta Crystallographica Section E: Structure Reports Online | Year: 2013

The title compound, lithium dicobalt(II) triarsenate, LiCo 2As3O10, was synthesized by a solid-state reaction. The As atoms and four out of seven O atoms lie on special positions, all with site symmetry m. The Li atoms are disordered over two independent special (site symmetry -1) and general positions with occupancies of 0.54 (7) and 0.23 (4), respectively. The structure model is supported by bond-valence-sum (BVS) and charge-distribution (CHARDI) methods. The structure can be described as a three-dimensional framework constructed from bi-octahedral Co 2O10 dimers edge-connected to As3O10 groups. It delimits two sets of tunnels, running parallel to the a and b axes, the latter being the larger. The Li+ ions are located within the intersections of the tunnels. The possible motion of the alkali cations has been investigated by means of the BVS model. This simulation shows that the Li + motion appears to be easier mainly along the b-axis direction and that this material may possess interesting conduction properties. © Ben Smida et al. 2013. Source


Nait-Abdelaziz M.,University of Lille Nord de France | Nait-Abdelaziz M.,Lille Laboratory of Mechanics | Zairi F.,University of Lille Nord de France | Zairi F.,Lille Laboratory of Mechanics | And 4 more authors.
Mechanics of Materials | Year: 2012

Using the fracture mechanics framework, a fracture criterion based upon the intrinsic defect concept was developed to predict the failure of rubber parts under biaxial monotonic loading. This fracture criterion requires as input data the fracture toughness of the material in terms of critical value of the J integral, the constitutive law of the material and the breaking stretch of a smooth specimen under uniaxial tension. To develop this criterion a generalized expression of the J integral under biaxial loading is proposed on the basis of finite element calculations on a RVE containing a small circular defect. The estimated failure elongations were found in very nice agreement with experimental data on two kinds of rubber materials. Moreover, we have also shown that this criterion could be extended to the failure analysis of thermoplastic polymers. © 2012 Elsevier Ltd. All rights reserved. Source


Ali Tabarki M.,Tunis el Manar University | Ben Smida Y.,Tunis el Manar University | Guesmi A.,Tunis el Manar University | Guesmi A.,Institute Preparatoire Aux Etudes dIngenieurs dEl Manar | Besbes R.,Tunis el Manar University
Acta Crystallographica Section E: Crystallographic Communications | Year: 2015

The title compound, C20H72ClN2O3, was obtained via an original synthesis method. The central heterocyclic ring adopts a shallow envelope conformation, with the N atom bearing the cyclopentane ring as the flap [deviation from the other atoms = 0.442 (2) Å]. The cyclopentane ring adopts a twisted conformation about one of the CN-C bonds: the exocyclic C-N bond adopts an equatorial orientation. The dihedral angles between the central ring (all atoms) and the pendant five- and six-membered rings are 10.3 (2) and 87.76 (14)°, respectively. In the crystal, C-H⋯O interactions link the molecules into [011] chains. A weak C-H⋯Cl interaction links the chains into (100) sheets. A mechanism for the cyclization reaction is proposed. Source


Guesmi A.,Universite Ibn Tofail | Guesmi A.,Institute Preparatoire Aux Etudes dIngenieurs dEl Manar | Driss A.,Universite Ibn Tofail
Acta Crystallographica Section E: Structure Reports Online | Year: 2012

In the title compound, trisodium dicobalt arsenate diarsenate, Na 3Co2AsO4As2O7, the two Co atoms, one of the two As and three of the seven O atoms lie on special positions, with site symmetries 2 and m for the Co, m for the As, and 2 and twice m for the O atoms. The two Na atoms are disordered over two general and special positions [occupancies 0.72 (3):0.28 (3) and 0.940 (6):0.060 (6), respectively]. The main structural feature is the association of the CoO 6 octahedra in the ab plane, forming Co4O20 units, which are corner- and edge-connected via AsO4 and As 2O7 arsenate groups, giving rise to a complex polyhedral connectivity with small tunnels, such as those running along the b- and c-axis directions, in which the Na+ ions reside. The structural model is validated by both bond-valence-sum and charge-distribution methods, and the distortion of the coordination polyhedra is analyzed by means of the effective coordination number. © 2012 International Union of Crystallography. Source


Marzouki R.,Laboratoire Of Materiaux Et Cristallochimie | Guesmi A.,Laboratoire Of Materiaux Et Cristallochimie | Guesmi A.,Institute Preparatoire Aux Etudes dIngenieurs dEl Manar | Zid M.F.,Laboratoire Of Materiaux Et Cristallochimie | Driss A.,Laboratoire Of Materiaux Et Cristallochimie
Annales de Chimie: Science des Materiaux | Year: 2013

The structural study of the compound Na4CO5,63Alo,91(AsO4)6 [1], the first explored in the system, shows that the material forms a three dimensional framework with hexagonal tunnels running along the [100] and communicate along [010] direction with tetragonal windows where Na+cations are located. Complementary infrared (IR) and complex impedance (CI) spectroscopies studies were carried out. Analysis by scanner electronic microscope (S.E.M) was done for the state. The ionic conductivity measurements were performed on pellets of polycrystalline powders. The monovalent cations conduction pathways in the crystal bulks are simulated by means of the bond valence model (BVS). © Lavoisier, Paris Physico-chimie d'un monoarséniate mixte. Source

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