Publications

Affichage de 891 à 900 sur 1005

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Evidence of ferroelectricity in metastable Sm2Ti2O7 thin film

Zhenmian Shao, Sébastien Saitzek, Anthony Ferri, Mohamed Rguiti, Loïc Dupont, Pascal Roussel, Rachel Desfeux

The synthesis by the sol-gel route of metastable Sm 2Ti 2O 7 thin film is reported. While for standard conditions of pressure and temperature, the Sm 2Ti 2O 7 compound crystallizes in a cubic/pyrochlore structure, in the form of a thin film (grown on (110)-oriented SrTiO 3 substrate), a monoclinic/…

Journal of Materials Chemistry, 2012, 22 (19), pp.9806. ⟨10.1039/c2jm16261j⟩. ⟨hal-02269084⟩

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Processing and dielectric properties of ZnTiO3 ceramics prepared from nanopowder synthesised by sol-gel technique

Ahcene Chaouchi, Malika Saidi, Sophie d'Astorg, Sylvain Marinel

ZnTiO3 nanopowders were obtained by sol-gel method. The nanopowders were characterised by means of TGA/DTA analysis, X-ray diffraction, TMA analysis and SEM characterisation. The results show that the crystalline structure of the sol-gel powders was obtained at 600°C, with crystallite sizes of 10…

Processing and Application of Ceramics, 2012, 6 (2), pp.83-89. ⟨10.2298/PAC1202083C⟩. ⟨hal-02450348⟩

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Frittage, propriétés mécaniques et fonctionnalisation de biocéramiques mono et biphasées, Sintering, mechanical properties and functionalization of single and two-phase bioceramics

Emmanuelle Rguiti-Constantin

Ce mémoire de thèse traite de la synthèse, de la densification, de la caractérisation mécanique et de la fonctionnalisation de biocéramiques de phosphates de calcium mono et biphasées. Les poudres phosphocalciques ont été synthétisées par la technique de précipitation en phase aqueuse par mélange…, This thesis deals with synthesis, densification, mechanical characterization and functionalization of mono- and biphasic calcium phosphate bioceramics. Calcium phosphate powders were synthesized by aqueous precipitation technique by mixing salts of calcium and phosphate. The Ca/P ratio of reactants…

Génie mécanique [physics.class-ph]. Université de Valenciennes et du Hainaut-Cambrésis, 2011. Français. ⟨NNT : 2011VALE0032⟩. ⟨tel-03416182⟩

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Local Parametric Bézier Interpolants for Triangular Meshes, Interpolants paramétriques locaux sous forme Bézier pour des maillages triangulaires

Maria Alessandra Boschiroli

Problems of Reverse Engineering type are recurrent in computer graphics. They consist in the reconstruction of objects from point clouds. The existing solutions generally use triangular meshes since they are sufficiently general to represent surfaces of arbitrary genus. The goal of this thesis was…, Un problème récurrent en informatique graphique est la reconstruction d'objets à partir de nuages de points. Les solutions existantes consistent à interpoler les données par des triangles plans. Les maillages triangulaires sont utilisés surtout parce qu'ils permettent de reproduire des…

Mathematics [math]. Université de Valenciennes et du Hainaut-Cambrésis; Università degli Studi di Milano-Bicocca, 2011. English. ⟨NNT : 2011VALE0019⟩. ⟨tel-03350487⟩

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Micro-Macro Correlation in Ferroelectric Materials: Depolarization Mechanism Owing Mechanical Stress

Abdelowahed Hajjaji, Mohamed Rguiti, Yahia Boughaleb, Zina Sassi, Sophie d'Astorg, Rith Ly, Christian Courtois, Gérard Moreau, Anne Leriche

Piezoelectric ceramics are commonly used in numerous piezoelectric actuators and sensors. Most ferroelectric materials behave as piezoelectric for low driving levels. The increase of electric field, temperature or stress levels leads to a depoling and results in some degradation of dielectric and…

Sensor letters, 2011, 9 (6), pp.2190-2193. ⟨10.1166/sl.2011.1792⟩. ⟨hal-04283044⟩

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Variétés de Richardson : multiplicités et désingularisation, Richardson varieties: multiplicities and desingularization

Michaël Balan

Une variété de Richardson est l'intersection d'une variété de Schubert directe avec une variété de Schubert opposée dans une variété de drapeaux. Dans cette thèse, on s'intéresse aux singularités des variétés de Richardson. Un résultat de Kreiman et Lakshmibai donne la multiplicité d…, A Richardson variety is the intersection of a direct Schubert variety with an opposite Schubert variety inside a fiag variety. ln this thesis, we are interested in the singularities of Richardson varieties. A result of Kreiman and Lakshmibai gives the multiplicity at a T-fixed point on a Richardson…

Mathématiques [math]. Université de Valenciennes et du Hainaut-Cambrésis, 2011. Français. ⟨NNT : 2011VALE0027⟩. ⟨tel-03416030⟩

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Influence of hydrothermal synthesis conditions on BNT-based piezoceramics

Jean-François Trelcat, Sophie d'Astorg, Philippe Champagne, Christian Courtois, Mohamed Rguiti, Anne Leriche

The Bi0.5Na0.5TiO3 perovskite (BNT) is a very promising lead-free candidate for piezoelectric applications. Nevertheless a low reproducibility is commonly reported for the solid state synthesized BNT. In this work, the hydrothermal synthesis was investigated to improve the BNT ceramics…

Journal of the European Ceramic Society, 2011, 31 (11), pp.1997-2004. ⟨10.1016/j.jeurceramsoc.2011.04.025⟩. ⟨hal-04283000⟩

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Microstructure and Nanoscale Piezoelectric/Ferroelectric Properties in La 2 Ti 2 O 7 Thin Films Grown on (110)‐Oriented Doped Nb:SrTiO 3 Substrates

Zhenmian Shao, Sébastien Saitzek, Pascal Roussel, Anthony Ferri, Émilie Bruyer, Adlane Sayede, Mohamed Rguiti, Olivier Mentré, Rachel Desfeux

(00l)‐Oriented La 2 Ti 2 O 7 (LTO) thin films with monoclinic perovskite‐layer structure [a = 7.806(2) Å, b = 5.552(3) Å, c = 13.015(5) Å, β = 98.62(2)°] have been grown by a sol–gel route on conducting (110)‐oriented doped Nb:SrTiO 3 (STO) substrates. The narrow rocking curves (0.24° width for 004…

Advanced Engineering Materials, 2011, 13 (10), pp.961-969. ⟨10.1002/adem.201100105⟩. ⟨hal-04282981⟩

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Limit behaviors of some boundary value problems with high and/or low valued parameters, Comportement limite de certains problèmes aux limites avec de grands et/ou petits paramètres

Salima Hassani

To our knowledge a systematic analysis of general systems of partial differential equations, where one parameter tends to infinity in a sub-domain that squeezes to a smooth hyper-surface of codimension 1 was not performed. In order to treat such problems, for a family of bilinear forms depending on…, A ce jour, aucune analyse systématique et générale des équations aux dérivées partielles où un paramètre tend vers l’infini dans un sous-domaine contenant une hyper-surface régulière de codimension 1 n’a été effectuée. Afin de traiter ce type de problèmes pour une famille de formes bilinéaires…

Mathematics [math]. Université de Valenciennes et du Hainaut-Cambrésis; Université Djillali Liabès (Sidi Bel-Abbès, Algérie), 2011. English. ⟨NNT : 2011VALE0015⟩. ⟨tel-03350322⟩

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Characterization of sol–gel synthesised lead-free (1−x)Na0.5Bi0.5TiO3–xBaTiO3-based ceramics

A. Chaouchi, S. Kennour, Sophie d'Astorg, Mohamed Rguiti, Christian Courtois, S. Marinel, M. Aliouat

The crystal structure, microstructure, dielectric and ferroelectric properties of (1 − x)Na0.5Bi0.5TiO3–xBaTiO3 ceramics with x = 0, 0.03, 0.05, 0.07 and 0.1 are investigated. A structural variation according to the system composition was investigated by X-ray diffraction (XRD) analyses. The…

Journal of Alloys and Compounds, 2011, 509 (37), pp.9138-9143. ⟨10.1016/j.jallcom.2011.06.085⟩. ⟨hal-02450370⟩