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(116) Production(s) de LEVELUT C.
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Zr-atom at the origin of the exceptional piezoelectric properties in PbZr0.52Ti0.48O3 
Auteur(s): Rouquette Jérôme, Al-Zein A., Fraysse Guillaume, Haines Julien, Papet Philippe, Hehlen B., Levelut C., Aquilanti Giuliana, Dammak Hichem
Conference: EMRS 2010- Fall Meeting (Warsaw, PL, 2010-09-13)
Ref HAL: hal-00546900_v1
Exporter : BibTex | endNote
Résumé: PZT is the most commonly used piezoelectric material. In spite of intensive experimental and theoretical studies, no model at the atomic scale has been proposed to explain the large piezoelectric effect in PZT, (d33= 520 pC/N), compared to the low piezoelectric response in the simple end-member lead titanate PbTiO3 with no-Zr (d33= 35 pC/N). X-ray absorption spectroscopy (XAS) appears as the technique of choice not only to clarify the role of Zr, but also to quantify the Zr displacement through the Ferroelectric-Paraelectric (F-P) transition. We clearly show evidence of the polar character of the Zr-atoms in PZT with a Zr-shift which will produce a small polarization. Such an atomic configuration for one type of atoms leads to relatively easy switching, i.e. relatively low electric field to align the Zr-polar atoms, which will create a favorable energetic situation for the cooperative switching of the strongly polar Ti-O dipole and would therefore account for the large piezoelectric effect in PZT1. In mixed B-cation systems of the perovskite ABO3 systems, such local configurations for one type of B cations leads to relatively easy switching giving rise to exceptional ferro/piezoelectric properties. Our recent “in-situ” XAS measurements of the giant piezoelectric effect in PbZn1/3Nb2/3O3 single crystal as a function of electric field confirms that large Zn atoms (small polarization) are easily poled and cooperatively align the strong Nb-O dipoles. 1 PRB 81, 174110 (2010)
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P-T-E studies of lead-based perovskite ferroelectric materials
Auteur(s): Rouquette J., Al-Zein A., Fraysse G., Dammak Hichem, Hehlen B., Levelut C., Papet P., Haines J.
Conférence invité: Electronic Materials and Applications (Florida, US, 2010-01-20)
Ref HAL: hal-00546894_v1
Exporter : BibTex | endNote
Résumé: Due to their exceptional ferroelectric properties, lead-based perovskite materials (PbB'B''O3) have been the subject of numerous studies. The different solid solutions exhibit their highest electromechanical responses for compositions lying at the so-called morphotropic phase boundary (MPB) between the rhombohedral (R3m) and tetragonal (P4mm) phases. Ferroelectric properties are dependent on 3 variables: applied electric field, temperature and mechanical stress σij. The effect of hydrostatic pressure on the physical properties of ferroelectrics is actually under intense investigations. In technological applications, large stress fields can be observed in miniaturized components or in ferroelectric dots. Additionally in the literature, experiments and theoretical calculations have indicated the existence of an intrinsic short range dynamical disorder over nearly the entire lead-based perovskite materials systems. Therefore the structural and dynamical behavior of lead-based perovskite materials as a function of P,T,E has to be entirely considered in the fundamental understanding of the ferroelectric-to-ferroelectric and ferroelectric-to-paraelectric phase transitions of such important technological materials. Based on neutron diffraction, X-ray diffraction, dielectric measurements, resonance Raman spectroscopy and X-Ray absorption Spectroscopy, we will present an overview of our new results.
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Etude de l'amorphisation sous pression de la zéolite AlPO4-54 par spectroscopie Raman
Auteur(s): Alabarse Frederico, Souleiman M., Haines Julien, Cambon Olivier, Levelut C., Bourgogne David
Conference: 7ième forum de technologie des hautes pressions: la pression pourquoi ? les nouveaux enjeux. (Biarritz, FR, 2010-10-11)
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:Désactivation de l'amorphisation de la silicalite SiO$\_2$ sous pression par
insertion de l'argon ou de CO$\_2$
Auteur(s): Haines Julien, Cambon Olivier, Levelut C., Santoro Mario, Gorelli Federico, Garbarino Gaston
Conference: 7ième forum de technologie des hautes pressions: la pression pourquoi ? les nouveaux enjeux. (Biarritz, FR, 2010-10-11)
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Spectroscopie infrarouge dans des zéolithes
Auteur(s): Levelut C., Haines Julien, Alabarse Frederico, Bantignies J.-L., Maurin D., Cambon Olivier, Creff Gaelle, Roy Pascale
Conference: 7ième forum de technologie des hautes pressions: la pression pourquoi ? les nouveaux enjeux. (Biarritz, FR, 2010-10-11)
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:Nouvelle forme de silica amorphe - comportement sous pression
Auteur(s): Levelut C., Santoro Mario, Haines Julien, Gorelli Federico
Conference: 12ièmes Journées de la Matière Condennsée de la Société Française de Physiqu (, FR, 2010-08-23)
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Comparison between ionic implantation and thermal treatments effects in normal and anomalous glasses
Auteur(s): Faivre A., Peuget S., Levelut C.
Conference: NCM11, 11th international conference on the structure of non-crystalline materials (PARIS, FR, 2010-06-27)
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