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(116) Production(s) de LEVELUT C.

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Diffusion aux petits angles des Rayons X et des neutrons

Auteur(s): Levelut C.

Chapître d'ouvrage: Du Verre Au Cristal. Nucléation, Croissance Et Demixtion, De La Recherche Aux Applications, vol. p.235 chapitre 10 (2013)

diffusion aux petits angles des RX et des neutrons

Auteur(s): Levelut C.

Conférence invité: Du verre au cristal: nucléation et cristallisation des matériuax vitreux , ecole thématique GDR3338 (oleron, FR, 2013-05-13)

Mesure de tension de surface en température : application au cas verres de confinement des déchets nucléaires

Auteur(s): Faivre A., Bonnet L., Levelut C., Schuller Sophie

Conference: journées Bilan Matinex (lyon, FR, 2012-02-01)

Negative linear compressibility and complex high-P structure in Zn[Au(CN)2]2.

Auteur(s): Haines Julien, Catafesta Jadna, Cairns Andrew, Rouquette J, Levelut C., Goodwin Andrew, van Der Lee Arie, Dmitriev Vladimir

Conference: 27th European Crystallography meeting (bergen, NO, 2012-08-06)

Ref HAL: hal-00820755_v1
Exporter : BibTex | endNote
Résumé:

The structure of the framework material zinc dicyanoaurate is built up of tetrahedrally-coordinated Zn cations linked by linear [NC-Au-CN]- complex anions, which form a six-fold interpenetrated -quartz-type network. This material exhibits strong negative linear thermal expansion along the c direction due to framework flexibility [1]. In situ, single-crystal and powder x-ray diffraction under high pressure in diamond anvil cells indicate that the c lattice parameter increases by 8% from ambient pressure up to 1.8 GPa, which is the highest negative linear compressibility (NLC) known for any material. Structural data obtained from single crystal x-ray diffraction indicate that the NLC mechanism is linked to the closing of N-Zn-N angles and the bending of Au-C-N-Zn linkages. A large number of superlattice reflections are observed above 2 GPa, indicating that the unit cell is doubled in all three directions. This phase transition is accompanied by a strong decrease in NLC. Systematic absences indicate that the space group changes from P6222 to P6422 or vice versa depending on the absolute configuration of the initial crystal corresponding to an instability at one of the L points in the Brillouin zone. The resulting unit cell has the following lattice parameters at 3.6 GPa: a=14.485(2)Å, c=45.796(6)Å with 528 atoms per unit cell. The ZnAu2 sublattice of the new, high-pressure form was solved by direct methods and followed by the use of difference Fourier maps to locate the C and N atoms. A significant change occurs in the Au sublattice with the Au-Au interatomic vector becoming canted with respect to c. This provides an additional compression mechanism, which reduces the need for the structure to expand along c. These results provide a detailed structural mechanism for the exceptional and unusual mechanical properties of this material. [1] Goodwin, A. L., Kennedy, B. J.. & Kepert, C. J. (2009). J. Am. Chem. Soc. 131, 6334-6335. Keywords: structural phase transitions; high-pressure structure determination; mechanical properties of crystals

Amorphisation sous pression dan des aluminophosphates avec des porosités Uni- et Tridimensionnelles

Auteur(s): Alabarse Frederico, Haines Julien, Cambon Olivier, Levelut C., Haidoux Abel

Conference: 8ième Forum de Technologie des hautes pressions, mesures en conditions extrèmes (Enval, FR, 2012-10-22)

Diffusion des rayons X aux petits angles dans des verres, demixion, cristallisation

Auteur(s): Levelut C., Faivre A., Schuller Sophie, de Ligny Dominique, Cormier Laurent

Conference: 13ièmes journées de la Matière Condensée de la Société Française de Physique (Montpeliier, FR, 2012-08-27)

Amorphisation des aluminophosphates sous pression

Auteur(s): Alabarse Frederico, Haines Julien, Cambon Olivier, Levelut C., Haidoux Abel

Conference: 13ièmes journées de la Matière Condensée de la Société Française de Physique (Montpeliier, FR, 2012-08-27)

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(116) Production(s) de LEVELUT C.