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Article dans une revue

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⟩

Article dans une revue

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⟩

Article dans une revue

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⟩

Article dans une revue

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⟩

Article dans une revue

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⟩

Article dans une revue

Efficient 3D numerical prediction of the pressure wave generated by high-speed trains entering tunnels

David Uystepruyst, Mame William-Louis, Emmanuel Creusé, Serge Nicaise, François Monnoyer de Galland

The topic of this paper is to present a new methodology for the three-dimensional numerical simulation of the entrance of high-speed trains in a tunnel. The movement of the train is made thanks to a technique of sliding meshes and a conservative treatment of the faces between two domains. All parts…

Computers and Fluids, 2011, 47 (1), pp.165-177. ⟨10.1016/j.compfluid.2011.03.005⟩. ⟨hal-00768640⟩

Article dans une revue

Influence of porosity on the mechanical properties of microporous β-TCP bioceramics by usual and instrumented Vickers microindentation

Arnaud Tricoteaux, E. Rguiti, Didier Chicot, L. Boilet, Michel Descamps, Anne Leriche, J. Lesage

Beta-tricalcium phosphate [Ca3(PO4)2, β-TCP] is a bioresorbable material showing an excellent biocompatibility. However, sintering of β-TCP is difficult and the material presents poor mechanical strength and a low resistance to crack-growth propagation. In this study, influence of the porosity on…

Journal of the European Ceramic Society, 2011, 31 (8), pp.1361-1369. ⟨10.1016/j.jeurceramsoc.2011.02.005⟩. ⟨hal-03577737⟩

Article dans une revue

Modeling and characterization of piezoelectric cantilever bending sensor for energy harvesting

R. Ly, Mohamed Rguiti, Sophie d'Astorg, A. Hajjaji, Christian Courtois, Anne Leriche

The main aim of this work is to enhance the conversion of mechanical energy into electrical energy by using direct piezoelectric effect. Under the assumption of the Euler–Bernoulli Beam Theory, a piezoelectric cantilever bending of 31-effect was developed. The equations of motion for the global…

Sensors and Actuators A: Physical , 2011, 168 (1), pp.95-100. ⟨10.1016/j.sna.2011.04.020⟩. ⟨hal-04282958⟩

Article dans une revue

Exponential stability of the wave equation with boundary time-varying delay

Serge Nicaise, Cristina Pignotti, Julie Valein

We consider the wave equation with a time-varying delay term in the boundary condition in a bounded and smooth domain [\Omega\subset\RR^n.] Under suitable assumptions, we prove exponential stability of the solution. These results are obtained by introducing suitable energies and suitable Lyapunov…

Discrete and Continuous Dynamical Systems - Series S, 2011, 4 (3), pp.693-722. ⟨10.3934/dcdss.2011.4.693⟩. ⟨hal-00599629⟩

Article dans une revue

Quadratic functors on pointed categories

Manfred Hartl, Christine Vespa

We study polynomial functors of degree $2$, called quadratic, with values in the category of abelian groups $Ab$, and whose source category is an arbitrary category $\C$ with null object such that all objects are colimits of copies of a generating object $E$ which is small and regular projective;…

Advances in Mathematics, 2011, 226 (5), pp.3927-4010. ⟨10.1016/j.aim.2010.11.008⟩. ⟨hal-00334292v3⟩