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1. Oxygen crystallographic positions in thin films by non-destructive resonant elastic X-ray scattering

Author

Antonio Peña Corredor, Laurianne Wendling, Daniele Preziosi, Laurent Schlur, Cédric Leuvrey, Dominique Thiaudière, Erik Elklaim, Nils Blanc, Stephane Grenier, François Roulland, Nathalie Viart, and Christophe Lefevre

Subjects
General Biochemistry, Genetics and Molecular Biology
Abstract

Precisely locating oxygen atoms in nanosized systems is a real challenge. The traditional strategies used for bulk samples fail at probing samples with much less matter. Resonant elastic X-ray scattering (REXS) experiments in the X-ray absorption near-edge structure (XANES) domain have already proved their efficiency in probing transition metal cations in thin films, but it is not feasible to perform such experiments at the low-energy edges of lighter atoms – such as oxygen. In this study, the adequacy of using REXS in the extended X-ray absorption fine structure (EXAFS) domain, also known as extended diffraction absorption fine structure (EDAFS), to solve this issue is shown. The technique has been validated on a bulk FeV2O4 sample, through comparison with results obtained with conventional X-ray diffraction measurements. Subsequently, the positions of oxygen atoms in a thin film were unveiled by using the same strategy. The approach described in this study can henceforth be applied to solve the crystallographic structure of oxides, and will help in better understanding the properties and functionalities which are dictated by the positions of the oxygen atoms in functional nanosized materials.

Published
2022

3. Unveiling Unconventional Ferroelectric Switching in Multiferroic Ga0.6 Fe1.4O3 Thin Films Through Multiscale Electron Microscopy Investigations

Author

Anna Demchenko, Suvidyakumar Homkar, Corinne Bouillet, Christophe Lefèvre, François Roulland, Daniele Preziosi, Gilles Versini, Cédric Leuvrey, Philippe Boullay, Xavier Devaux, Nathalie Viart, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut Jean Lamour (IJL), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), ANR-18-CE24-0008,MISSION,Oxydes magnétoélectriques pour la SpinOrbitronique(2018), ANR-10-IDEX-0002,UNISTRA,Par-delà les frontières, l'Université de Strasbourg(2010), ANR-20-SFRI-0012,STRAT'US,Façonner les talents en formation et en recherche à l'Université de Strasbourg(2020), ANR-17-EURE-0024,QMAT,Quantum Science and Nanomaterials(2017), ANR-11-LABX-0058,NIE,Nanostructures en Interaction avec leur Environnement(2011), Viart, Nathalie, APPEL À PROJETS GÉNÉRIQUE 2018 - Oxydes magnétoélectriques pour la SpinOrbitronique - - MISSION2018 - ANR-18-CE24-0008 - AAPG2018 - VALID, Initiative d'excellence - Par-delà les frontières, l'Université de Strasbourg - - UNISTRA2010 - ANR-10-IDEX-0002 - IDEX - VALID, Façonner les talents en formation et en recherche à l'Université de Strasbourg - - STRAT'US2020 - ANR-20-SFRI-0012 - SFRI - VALID, and Quantum Science and Nanomaterials - - QMAT2017 - ANR-17-EURE-0024 - EURE - VALID

Subjects
Condensed Matter - Materials Science, precession-assisted electron diffraction tomography, Polymers and Plastics, Metals and Alloys, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], cationic mobility, Electronic, Optical and Magnetic Materials, high resolution scanning transmission electron microscopy, Functional oxides in thin films, Ceramics and Composites, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], spatially resolved EELS, non-conventional ferroelectricity
Abstract

International audience; Understanding the polarization switching mechanisms at play in ferroelectric materials is crucial for their exploitation in electronic devices. The conventional centrosymmetric reference structure-based mechanism which accounts for ferroelectricity in most of the usual displacive ferroelectric materials is too energy-demanding for some newly diagnosed ferroelectric materials such as the Ga2-xFexO3 (0.8 ≤ x ≤ 1.4) compounds. Some alternative theoretical propositions have been made and need experimental confirmation. A dual-scale electron microscopy study is performed on thin films of the Ga0.6Fe1.4O3 multiferroic compound. A wide scale precession-assisted electron diffraction tomography study first allows the determination of the structure the compound adopts in thin films, and even permits the refinement of the atomic positions within this structure. Cationic mobility is suggested for two of the atomic positions through the existence of extra electronic density. A local in situ high resolution scanning transmission electron microscopy study then allows confirming these mobilities by directly spotting the cationic displacements on successively acquired images. The whole study confirms an unconventional switching mechanism via local domain wall motion in this compound.

Published
2022

4. Promoting the magnetic exchanges in PLD deposited strained films of FeV2O4 thin films

Author

G. Roseau, G. Krieger, L. Wendling, Morgan Trassin, N. Viart, A. Pena Corredor, François Roulland, Geneviève Pourroy, and Christophe Lefevre

Subjects
Materials science, Spinel, chemistry.chemical_element, Vanadium, engineering.material, Condensed Matter Physics, Epitaxy, Oxygen, Pulsed laser deposition, Transition metal, chemistry, Chemical physics, engineering, Deposition (phase transition), General Materials Science, Thin film
Abstract

Materials Chemistry and Physics, 276, ISSN:0254-0584

Published
2022
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5. Ultrathin regime growth of atomically flat multiferroic gallium ferrite films with perpendicular magnetic anisotropy

Author

Suvidyakumar Homkar, François Roulland, Manfred Fiebig, Marc Lenertz, Sophie Barre, Daniele Preziosi, Xavier Devaux, Nathalie Viart, G. Versini, Corinne Bouillet, Morgan Trassin, Geneviève Pourroy, Johanna Nordlander, Christophe Lefevre, Cédric Leuvrey, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Institut Jean Lamour (IJL), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Department of Materials [ETH Zürich] (D-MATL), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), DEVAUX, XAVIER, Université de Strasbourg (UNISTRA)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), and Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Physics and Astronomy (miscellaneous), Spintronics, Condensed matter physics, Condensed Matter::Other, chemistry.chemical_element, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Condensed Matter::Materials Science, chemistry.chemical_compound, Magnetization, chemistry, Ferrimagnetism, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Spin Hall effect, Antiferromagnetism, Ferrite (magnet), General Materials Science, Gallium, 010306 general physics, 0210 nano-technology, Bismuth ferrite
Abstract

Physical Review Materials, 3 (12), ISSN:2475-9953

Published
2019

6. Magnetic and Polar Properties’ Optimization in the Magnetoelectric Ga2–xFexO3 Compounds

Author

Christian Meny, Gilles André, Florence Porcher, Christophe Lefevre, Nathalie Viart, François Roulland, and Alexandre Thomasson

Subjects
Materials science, Condensed matter physics, Magnetic moment, Aucun, Polarization (waves), Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, law.invention, SQUID, General Energy, Ferrimagnetism, law, Atom, Polar, Crystallite, Physical and Theoretical Chemistry, Néel temperature
Abstract

The influence of the iron content on the magnetic, polar, and magnetoelectric properties of Ga2-xFexO3 (x = 1.0; x = 1.4) polycrystalline samples was studied by a combined magnetic (SQUID) and structural (X-ray and temperature-dependent neutrons diffraction) study. As expected, the samples showed a ferrimagnetic structure, with moments aligned along the c axis. The Neel temperature increases with x, from 210 K for GaFeO3 to 360 K for Ga0.6Fe1.4O3. The magnetic moment is close to 3.8 mu B per iron atom for all compositions. The structural investigations show a decrease in the distortion parameters with increasing iron content, and computation of the polarization with a point-charge model gives a similar significant and temperature-independent value of approximate to 20 mu C/cm(2) for both compositions. This study clearly indicates that magnetic properties can be strongly enhanced by increasing the Fe content in the cell, while the non-negligible polarization value is preserved. Because the magnetoelectric coupling is also predicted to be preserved when increasing the iron content to x = 1.4, this composition is the most appropriate for applications.

Published
2013

7. Room temperature polarization in the ferrimagnetic Ga2-xFexO3 ceramics

Author

François Roulland, Nathalie Viart, Bohdan Kundys, Christophe Lefevre, Christian Meny, and Alexandre Thomasson

Subjects
Condensed Matter - Materials Science, Materials science, Condensed matter physics, Aucun, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Polarization (waves), Polarization density, Ferrimagnetism, visual_art, Iron content, Materials Chemistry, Ceramics and Composites, visual_art.visual_art_medium, Multiferroics, Ceramic, Néel temperature, Phase diagram
Abstract

The effect of the Fe-Ga ratio on the magnetic and electric properties of the multiferroic Ga2-xFexO3 compound has been studied in order to determine the composition range exhibiting magnetic and electric orders coexistence and their critical temperatures. A magnetoelectric phase diagram, showing the evolution of both the Neel magnetic ordering temperature and the electric ordering temperature, versus the iron content has been established for x values between 0.9 and 1.4. While the ferrimagnetic Neel temperature increases with the iron content, the electric ordering temperature shows an opposite trend. The electric polarization has been found to exist far above room temperature for the x value of 1.1 composition which shows the highest observed electric ordering temperature of approx. 580K. The compounds with x values of 1.3 and 1.4 are ferrimagnetic-electric relaxors with both properties coexisting at room temperature., Comment: Multiferroic GaFeO3

Published
2016
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8. ChemInform Abstract: Stabilization of Scandium Rich Spinel Ferrite CoFe2-xScxO4(x ≤ 1) in Thin Films

Author

Cédric Leuvrey, Geneviève Pourroy, Nathalie Viart, François Roulland, Sophie Barre, Emmanuel Autissier, Christophe Lefevre, G. Versini, and Alexandre Thomasson

Subjects
Spinel, chemistry.chemical_element, General Medicine, Substrate (electronics), engineering.material, Lattice mismatch, Spinel ferrite, Crystallography, Octahedron, chemistry, engineering, Scandium, Thin film, Cobalt
Abstract

Scandium rich cobalt ferrites Co y Fe 3− x − y Sc x O 4 with y ~1 never obtained in bulk could be stabilized in pulsed laser deposited thin films. Scandium contents of up to x =1 are reached. The cell parameter increases versus x as awaited when considering the size of scandium. It is equal to 0.8620 nm for x =1, significantly higher than that of CoFe 2 O 4 (0.8396 nm). The lattice mismatch between the MgO (100) substrate and the scandium-containing spinel leads to an increased roughness. Cobalt is displaced from the octahedral site by Sc and mainly occupies the tetrahedral sites for high x values.

Published
2016

9. Magnetic dilution of the iron sublattice in CoFe2−xScxO4 (0≤x≤1)

Author

Christophe Lefevre, François Roulland, Geneviève Pourroy, Jean-Marc Greneche, and Nathalie Viart

Subjects
Chemistry, Spinel, chemistry.chemical_element, Crystal structure, engineering.material, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Inorganic Chemistry, Crystallography, Nuclear magnetic resonance, Ferromagnetism, X-ray crystallography, Materials Chemistry, Ceramics and Composites, engineering, Curie temperature, Physical and Theoretical Chemistry, Hyperfine structure, Cobalt, Mossbauer spectrometry
Abstract

Substitution of Fe for Sc in CoFe2O4 spinel structure is presented. All CoFe2−xScxO4 compounds crystallize in the spinel type structure (space group Fd3m). By using X-ray diffraction studies, magnetic measurements and in-field 57Fe Mossbauer spectrometry, the limit of substitution has been determined to be equal to x=0.56. An increase in the cell parameter and the strains and a decrease in the apparent crystallites size are observed. For x>0.3, a partial oxidation of cobalt is evidenced and Co3+ is stabilized in the structure. A ferromagnetic behavior has been observed for all investigated compounds. As x increases, the Curie temperature and the hyperfine fields decrease. Following the Stephenson model, the diminution of TC is ascribed to a decrease of the main JAB interaction.

Published
2010

10. Effects of the sintering atmosphere on the BaZn1/3Ta2/3O3 based Cu multilayer ceramic capacitors

Author

François Roulland, Sylvain Marinel, Ahcène Chaouchi, Sophie d’Astorg, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Université Mouloud Mammeri [Tizi Ouzou] (UMMTO), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, and Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, chemistry.chemical_element, Sintering, Mineralogy, 02 engineering and technology, Dielectric, 7. Clean energy, 01 natural sciences, Atmosphere, Flux (metallurgy), 0103 physical sciences, Materials Chemistry, [CHIM]Chemical Sciences, Ceramic, Composite material, Ceramic capacitor, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Copper, chemistry, visual_art, Ceramics and Composites, visual_art.visual_art_medium, Sintering atmosphere, 0210 nano-technology
Abstract

Recent papers report that BaZn 1/3 Ta 2/3 O 3 (BZT) ceramic can be sintered at a temperature as low as 1050 °C owing to the use of flux agents like B 2 O 3 + LiF combined with a slight non-stoichiometry, whereas its usual sintering temperature is 1400 °C. This low sintering temperature (below the Cu's melting point = 1083 °C) opens the route to fabricate copper based multilayer ceramic capacitors, in condition that a reductive atmosphere is used during the sintering. This paper presents the effect of three various sintering atmospheres (air, H 2 (1%) in N 2 and H 2 (1%) in Ar) on the stability and the dielectric properties of BZT. It is researched a suitable sintering atmosphere to prevent Cu from oxidation and to preserve the dielectric properties of BZT. Using the appropriate atmosphere, copper based multilayer ceramic capacitors, with attractive dielectric properties, have been successfully processed.

Published
2007

11. Stabilization of scandium rich spinel ferrite CoFe(2-x)Sc(x)O4 (x <= 1) in thin films

Author

Cédric Leuvrey, Alexandre Thomasson, Christophe Lefevre, G. Versini, François Roulland, Sophie Barre, Nathalie Viart, Geneviève Pourroy, and Emmanuel Autissier

Subjects
Materials science, Spinel, Metallurgy, Aucun, chemistry.chemical_element, Substrate (electronics), engineering.material, Condensed Matter Physics, Epitaxy, Electronic, Optical and Magnetic Materials, Pulsed laser deposition, Inorganic Chemistry, Crystallography, chemistry, Octahedron, Materials Chemistry, Ceramics and Composites, engineering, Scandium, Physical and Theoretical Chemistry, Thin film, Cobalt
Abstract

Scandium rich cobalt ferrites Co y Fe 3− x − y Sc x O 4 with y ~1 never obtained in bulk could be stabilized in pulsed laser deposited thin films. Scandium contents of up to x =1 are reached. The cell parameter increases versus x as awaited when considering the size of scandium. It is equal to 0.8620 nm for x =1, significantly higher than that of CoFe 2 O 4 (0.8396 nm). The lattice mismatch between the MgO (100) substrate and the scandium-containing spinel leads to an increased roughness. Cobalt is displaced from the octahedral site by Sc and mainly occupies the tetrahedral sites for high x values.

Published
2015

12. Low temperature sintering of B2O3/LiNO3 added BaMg1/3Ta2/3O3 ceramics

Author

M. Pollet, G. Allainmat, Sylvain Marinel, François Roulland, Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, and Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Sintering, 02 engineering and technology, Dielectric, 01 natural sciences, law.invention, Atmosphere, chemistry.chemical_compound, law, 0103 physical sciences, [CHIM]Chemical Sciences, General Materials Science, Ceramic, Base metal, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, Barium oxide, Mechanical Engineering, Metallurgy, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Capacitor, chemistry, Mechanics of Materials, visual_art, Electrode, visual_art.visual_art_medium, 0210 nano-technology
Abstract

The lowering of the sintering temperature of BaMg1/3Ta2/3O3 (BMT) ceramic is investigated using sintering aids. First is considered the addition of B2O3 and it is shown that such addition allows to sinter BMT material at around 1100 °C, whereas the usual sintering temperature is higher than 1500 °C in air atmosphere. Sinterability of B2O3 added BMT material in reductive atmosphere (RA) is also discussed. To enhance the sintering temperature lowering, the combination of LiNO3 and B2O3 is secondly investigated. Using both sintering aids with appropriate amount, it is shown that BMT material can be sintered at 1050 °C in a reductive atmosphere as well as in air atmosphere while maintaining dielectric properties (e=24, |τe| 1000). These results are promising for the manufacturing of base metal electrodes (BME)–multilayers capacitor (MLCC).

Published
2003

13. Influence of both milling conditions and lithium salt addition on the sinterability of Ba(Zn1/3Ta2/3)O3

Author

François Roulland, Raphaël Terras, Sylvain Marinel, Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Permittivity, Materials science, chemistry.chemical_element, Sintering, 02 engineering and technology, Dielectric, 7. Clean energy, [CHIM]Chemical Sciences, General Materials Science, Ceramic capacitor, ComputingMilieux_MISCELLANEOUS, High-κ dielectric, Perovskite (structure), 020502 materials, Mechanical Engineering, Metallurgy, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Microstructure, 0205 materials engineering, chemistry, Chemical engineering, Mechanics of Materials, Lithium, 0210 nano-technology
Abstract

The complex perovskite oxide Ba(Zn 1/3 Ta 2/3 )O 3 (BZT) has been largely studied for its interesting dielectric properties. This material possesses a relatively high dielectric constant associated with very low losses at usual frequency applications. It can be used as hyperfrequency resonators or capacitors. Unfortunately, a high sintering temperature is required to achieve high-density materials (>1500 °C), which is too high for industrial applications. The development of base metal electrode multi layer ceramic capacitors (BME MLCC) requires a low sintering temperature to be co-sintered with non-noble metals such as Ni and Cu. The technological process has been investigated with respect to milling conditions and calcination parameters to optimise each fabrication step. In addition, lithium salt (Li 2 CO 3 , LiF, BaLiF 3 and LiNO 3 ) additions have been tested to lower the sintering temperature. The BZT sintering temperature can be lowered to 200 °C when 15 mol% of LiF is added without modifying permittivity and loss factors at 1 MHz. Each sample was characterised in terms of density, microstructure and dielectric properties.

Published
2003

14. Microwave properties and microstructures of LaTiO3 stabilized with NiO

Author

Jérôme Bernard, Jean-Marie Haussonne, François Roulland, J. El Fallah, and David Houivet

Subjects
Materials science, Non-blocking I/O, Analytical chemistry, Mineralogy, Sintering, Dielectric, Microstructure, visual_art, Materials Chemistry, Ceramics and Composites, visual_art.visual_art_medium, Ceramic, Electroceramics, Microwave, Perovskite (structure)
Abstract

(1-x)La 2/3 TiO 3 -xTiNiO 3 ceramics with x ranging from 0.01 to 0.2, were elaborated by conventional solid-state reaction starting from TiO 2 , La 2 O 3 , and NiO powders. These compositions have been identified as secondary phases detected in (Zr,Sn)TiO 4 ceramics sintered with La 2 O 3 and NiO. Microwave resonators were sintered at temperatures ranging from 1340 to 1380 C. These sintering temperatures have been determined taking into account thermodilatometric data. Microwave dielectric properties and microstructures were investigated. Perovskite phase La 2/3 TiO 3 was identified by XRD, SEM and EDS together with minor phases. Dielectric constants are in the 50-70 range and QF values, measured at 3 GHz, are close to 20 000 GHz. One significant composition is characterized by k = 69 and QF= 17,000 GHz at 3 GHz.

Published
2001

15. ChemInform Abstract: Magnetic Dilution of the Iron Sublattice in CoFe2-xScxO4 (0 ≤ x ≤ 1)

Author

Geneviève Pourroy, François Roulland, Christophe Lefevre, Nathalie Viart, and Jean-Marc Greneche

Subjects
Magnetic measurements, Magnetic dilution, Chemistry, Spinel, Mössbauer spectroscopy, Analytical chemistry, engineering, General Medicine, Powder xrd, engineering.material
Abstract

Substitution of Sc for Fe in CoFe2O4 spinel is investigated by powder XRD, magnetic measurements, and 57Fe Moessbauer spectroscopy.

Published
2011

16. In-situ formation of barium ferrite in iron-doped 'tetragonal tungsten bronze': Elaboration of room temperature multiferroic composites

Author

Elias Castel, François Roulland, Michaël Josse, Dominique Michau, Mario Maglione, Lydia Raison, Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB)

Subjects
Materials science, Multiferroics, chemistry.chemical_element, 02 engineering and technology, Tungsten, 010402 general chemistry, 01 natural sciences, chemistry.chemical_compound, Tetragonal crystal system, Ceramic, Composite material, Barium ferrite, Tetragonal tungsten bronze, Composites, [CHIM.MATE]Chemical Sciences/Material chemistry, Atmospheric temperature range, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Microstructure, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, chemistry, visual_art, visual_art.visual_art_medium, Ferrite (magnet), 0210 nano-technology
Abstract

International audience; Recent studies of ceramics of formula Ba2LnFeNb4O15 (Ln=rare earth) with the “tetragonal tungsten bronze” (TTB) structure have correlated their room temperature multiferroics properties to the occurrence of barium ferrite parasitic phases. This work presents the elaboration of Ba2LaFeNb4O15 and Ba2EuFeNb4O15 composite samples with an excess of hematite in the TTB nominal composition. The influence of crystal-chemistry on the phase content and properties of Ba2LnFeNb4O15 TTB composites is discussed. A particular focus on the mechanisms related to the in-situ formation of barium ferrite is given. We show that we can control the spurious ferrite phase in TTB multiferroic composites and thus modulate their magnetic response.

Published
2009

17. Influence of ceramic process and Eu content on the composite multiferroic properties of the Ba6−2xLn2xFe1+xNb9−xO30 TTB system

Author

Michaël Josse, François Roulland, Elias Castel, Mario Maglione, Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB)

Subjects
Solid-state chemistry, Materials science, Composite number, Sintering, Mineralogy, 02 engineering and technology, Dielectric, 01 natural sciences, Solid state chemistry, Phase (matter), 0103 physical sciences, Magnetic properties, General Materials Science, Multiferroics, Ceramic, Composite material, Composites, 010302 applied physics, Material sciences, Multiferroic properties, Tetragonal Tungsten Bronze, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Ferroelectricity, visual_art, Dielectric properties, visual_art.visual_art_medium, 0210 nano-technology
Abstract

International audience; The present work reports the optimisation of the composition and elaboration process of Ba6−2xLn2xFe1+xNb9−xO30 (0.6 x

Published
2009

18. Type I Base-Metal Electrode Multilayer Ceramic Capacitors

Author

David Houivet, M. Pollet, Jérôme Bernard, Jean-Marie Haussonne, Sylvain Marinel, François Roulland, Centre de physique moléculaire optique et hertzienne (CPMOH), Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1, Laboratoire Universitaire des Sciences Appliquées de Cherbourg (LUSAC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB), Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Université Sciences et Technologies - Bordeaux 1 (UB)-Centre National de la Recherche Scientifique (CNRS), Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, Electrolytic capacitor, Materials science, 02 engineering and technology, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, law.invention, Capacitor, Film capacitor, law, 0103 physical sciences, Electrode, [CHIM]Chemical Sciences, Composite material, 0210 nano-technology, Ceramic capacitor, Base metal, ComputingMilieux_MISCELLANEOUS, Electronic circuit
Abstract

International audience

Published
2006

19. Ba(Zn1/3Nb2/3)O3 sintering temperature lowering for silver co-sintering applications

Author

Sylvain Marinel, François Roulland, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)-Institut de Chimie du CNRS (INC)

Subjects
Materials science, Oxide, chemistry.chemical_element, Mineralogy, Sintering, 02 engineering and technology, Dielectric, 01 natural sciences, chemistry.chemical_compound, 0103 physical sciences, Materials Chemistry, [CHIM]Chemical Sciences, Ceramic, Composite material, Ceramic capacitor, ComputingMilieux_MISCELLANEOUS, Perovskite (structure), 010302 applied physics, Process Chemistry and Technology, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Microstructure, Copper, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, chemistry, visual_art, Ceramics and Composites, visual_art.visual_art_medium, 0210 nano-technology
Abstract

The complex perovskite oxide Ba(Zn1/3Nb2/3)O3 have been broadly studied due to its attractive dielectric properties which place this material as a good candidate for manufacturing type I capacitors or hyperfrequency resonators. The development of Base Metal Electrodes Multi Layer Ceramic Capacitors (BME-MLCC) require a low sintering temperature to be co-sintered with a low cost metal such as copper or silver. Unfortunately, BZN requires a high temperature (1350 °C according to the literature) to reach a satisfactory density (>90% of the theoretical one). The aim of this work is to lower the BZN sintering temperature to allow a co-sintering with copper or silver electrodes. For this goal, different sintering agents (lithium salts and glass phases) have been tested on the nominal compound. It is shown that an addition of 10 molar% B2O3 combined with 5 molar% LiF authorises a sintering temperature lowering near to 350 °C. If a slight non-stoichiometry in A site is combined to these sintering agents, it is possible to reach a sintering temperature lower than 950 °C without affecting the basic material properties. For each composition obtained, the ceramic is characterised in terms of final density, microstructure and dielectric properties. The silver co-sintering is also performed.

Published
2006

20. Effects of Glass Phase Additions and Stoichiometry on the Ba(Zn1/3X2/3)O3 (X = Ta or Nb) Sinterability and Dielectric Properties

Author

Sylvain Marinel, François Roulland, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, chemistry.chemical_element, Sintering, 02 engineering and technology, Dielectric, Electrochemistry, 01 natural sciences, Phase (matter), 0103 physical sciences, Materials Chemistry, [CHIM]Chemical Sciences, Ceramic, Electrical and Electronic Engineering, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, Metallurgy, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Microstructure, Copper, Electronic, Optical and Magnetic Materials, chemistry, Chemical engineering, Mechanics of Materials, visual_art, Ceramics and Composites, visual_art.visual_art_medium, 0210 nano-technology, Stoichiometry
Abstract

Ba(Zn1/3X2/3)O3 materials where X = Ta or Nb (respectively named BZT and BZN) exhibit attractive properties suitable for applications in type I Multi Layer Ceramics Capacitors (MLCC). Nevertheless, to produce such components using Base Metal Electrodes such as copper, a significant reduction of their sintering temperature is required. The aim of this work is first to study the effects of glass phases additions and secondly the stoichiometry influence on the sintering temperature of BZT and BZN. It is shown for example, that our materials can be sintered in air at a temperature lowered by 450∘C when sintering agents (B2O3 with LiF) are combined with a slight non-stoichiometry. The sintered samples are characterised in terms of final density, microstructure and phase content and it was underlined that such modifications (additions and stoichiometry) does not affect the dielectric properties.

Published
2005

21. Synthesis and characterisation of the double perovskite Ba2(Zn0.5Ti0.5X)O6 (X=Nb, Ta) ceramics

Author

François Roulland, Sylvain Marinel, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, and Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Permittivity, Materials science, Tantalum, Niobium, chemistry.chemical_element, Mineralogy, 02 engineering and technology, Dielectric, 010403 inorganic & nuclear chemistry, 01 natural sciences, Phase (matter), [CHIM]Chemical Sciences, General Materials Science, ComputingMilieux_MISCELLANEOUS, Perovskite (structure), Mechanical Engineering, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Microstructure, 0104 chemical sciences, Crystallography, chemistry, Mechanics of Materials, 0210 nano-technology, Stoichiometry
Abstract

Ba 2 (Zn 0.5 Ti 0.5 X )O 6 compounds from the general ABO 3 perovskite family were synthesized by the classical solid-state route for X = Nb and Ta with various A/B ratios (1.005, 1 and 0.995). After the calcination step at 1100 °C, both compounds ( X = Nb and Ta) contain mainly the cubic disordered ‘Ba 2 (Zn 0.5 Ti 0.5 X )O 6 ’ phase but traces of BaTiO 3 and secondary phases are often detectable. Nevertheless, after the sintering stage at higher temperature (from 1300 to 1500 °C) and for all A/B ratios investigated, Ti enters into the cubic perovskite structure, resulting in the formation of a unique ‘Ba 2 (Zn 0.5 Ti 0.5 X )O 6 ’ phase. Attractive dielectric properties have been measured on the tantalum-based compound for A/B = 0.995 ( Q ∼2000 at 7.4 GHz and ɛ = 39.6) as well as on the niobium-based phase for A/B = 1.005 ( Q ∼2200 at 6.1 GHz and ɛ = 54.8). All these characteristics were confirmed at 1 MHz and a linear dependence of the permittivity versus temperature from −60 to 180 °C has also been evidenced for both formulations. Sinterability, dielectric properties and microstructure of such compounds are discussed with respect to the stoichiometry.

Published
2005

22. High decrease in CaZrO3 sintering temperature using complex fluoride fluxes

Author

M. Pollet, François Roulland, Sylvain Marinel, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Permittivity, Materials science, Analytical chemistry, Sintering, Mineralogy, 02 engineering and technology, Dielectric, 01 natural sciences, chemistry.chemical_compound, 0103 physical sciences, Materials Chemistry, [CHIM]Chemical Sciences, Ceramic, ComputingMilieux_MISCELLANEOUS, Eutectic system, Phase diagram, 010302 applied physics, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, chemistry, visual_art, Ceramics and Composites, visual_art.visual_art_medium, Dielectric loss, 0210 nano-technology, Fluoride
Abstract

The effects of complex fluoride flux on the sintering and the electric/dielectric properties of CaZrO 3 ceramics are investigated. Four fluoride mixtures are tested: LiF-CaF 2 -SrF 2 , LiF-CaF 2 -BaF 2 , LiF-SrF 2 -BaF 2 and LiF-BaF 2 -B 2 O 3 . They are used because each of their associated phase diagrams shows the existence of an eutectic composition having a low melting temperature. This liquid phase is used to promote the densification at low temperature. The effect of various additions (nature and quantity) are also investigated to optimise the resulting thermal and physical properties. In terms of sintering behaviour, the results are unambiguous, leading to a drastic decrease of the densification temperature with all the non-boric additions (≤1000°C). The dc/ac measurements carried out on the materials sintered at low temperature (900 and 1000°C) and either in air or in reductive atmosphere follow the same trend when using non-boric additions, with high permittivities (>25), low dielectric losses (

Published
2005

23. Low temperature sintering of the binary complex perovskite oxides xBa(Zn1/3Ta2/3)O3+(1−x)Ba(Mg1/3Ta2/3)O3

Author

Sylvain Marinel, G. Allainmat, François Roulland, M. Pollet, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Analytical chemistry, Oxide, Mineralogy, Sintering, chemistry.chemical_element, 02 engineering and technology, Dielectric, 7. Clean energy, 01 natural sciences, chemistry.chemical_compound, 0103 physical sciences, Materials Chemistry, [CHIM]Chemical Sciences, Ceramic capacitor, ComputingMilieux_MISCELLANEOUS, Perovskite (structure), 010302 applied physics, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Copper, Nickel, chemistry, Ceramics and Composites, Dielectric loss, 0210 nano-technology
Abstract

The interest for the complex perovskites oxides is known since several years. Ba(Zn 1/3 Ta 2/3 )O 3 (BZT) and Ba(Mg 1/3 Ta 2/3 )O 3 (BMT) have been broadly studied due to their attractive dielectric properties suitable for applications such as multilayer ceramic capacitors or hyperfrequency resonators. They hence exhibit at 1 MHz very low dielectric losses combined with a high relative dielectric constant which is stable with the temperature. Unfortunately, these materials needs a too high temperature to reach a satisfying density. The BMT sintering temperature is indeed higher than 1500 °C, which is too high to envisage a co-sintering with copper ( T f = 1083 °C) or nickel ( T f = 1450 °C). To lower the sintering temperature, a glass phase addition is performed on the complex formulations x Ba(Zn 1/3 Ta 2/3 )O 3 + (1 − x )Ba(Mg 1/3 Ta 2/3 )O 3 (with x = 0, 1/3, 1/2, 2/3 and 1). These mixtures are envisaged to explore their dielectric properties. The sintering temperature lowering reached is higher than 400 °C when 10 molar% of borate oxide is added to the mixtures and their dielectric properties are very attractive ( ɛ = 25 and τ ɛ = −59 ppm/°C for x = 1/3) for the fabrication of base metal electrodes multi layer ceramic capacitors (BME-MLCC).

Published
2005

24. Lowering of BaB′1/3B″2/3O3 complex perovskite sintering temperature by lithium salt additions

Author

Sylvain Marinel, Raphaël Terras, François Roulland, Gilles Allainmat, M. Pollet, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)-Institut de Chimie du CNRS (INC)

Subjects
Materials science, Inorganic chemistry, Sintering, chemistry.chemical_element, 02 engineering and technology, Dielectric, 01 natural sciences, 7. Clean energy, chemistry.chemical_compound, 0103 physical sciences, Materials Chemistry, [CHIM]Chemical Sciences, Ceramic, Ceramic capacitor, ComputingMilieux_MISCELLANEOUS, Perovskite (structure), 010302 applied physics, Lithium nitrate, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, chemistry, Chemical engineering, visual_art, Ceramics and Composites, visual_art.visual_art_medium, Dissipation factor, Lithium, 0210 nano-technology
Abstract

Complex perovskite materials with the formula BaB' 1/3 B 2/3 O 3 have been broadly studied for their attractive dielectric properties. These materials exhibit a high relative dielectric constant and a very low dissipation factor. For example, the BaMg 1/3 Ta 2/3 O 3 material has a relative dielectric constant close to 26 with a dissipation factor lower than 10 -4 at 1 MHz. These properties are very promising for applications such as hyper-frequency resonators or/and capacitors. Unfortunately, a high temperature is necessary to achieve a satisfying densification of this materials family (> 1400 °C) whereas the lowering of this temperature is more and more crucial from the industrial point of view. In particular, the development of Base Metal Electrodes Multi-Layer Ceramic Capacitors (BME-MLCC) requires the sintering of dielectric materials at low temperatures (< 1100 °C). The aim of the study is thus to lower the sintering temperature of these materials. For this goal, lithium salts (Li 2 CO 3 , LiF, BaLiF 3 and LiNO 3 ) have been tested as sintering agents to densify BaZn 1/3 Ta 2/3 O 3 , BaMg 1/3 Ta 2/3 O 3 and BaZn 1/3 Nb 2/3 O 3 materials. It is shown, for example, that the BaMg 1/3 Ta 2/3 O 3 sintering temperature is lowered by 300 °C when 15 mol % of lithium nitrate is added without affecting the dielectric properties at I MHz. For the best sintering agents investigated and each studied materials, the ceramic is characterised in terms of final density, microstructure and dielectric properties and densification mechanisms are discussed.

Published
2004

25. Effects of iron concentration and cationic site disorder on the optical properties of magnetoelectric gallium ferrite thin films

Author

Sukgeun Choi, Nathalie Viart, Cédric Leuvrey, Mebarek Alouani, Sophie Barre, William Jo, Christophe Lefevre, G. Versini, Alexandre Thomasson, Fatima Ibrahim, Christian Meny, Emmanuel Autissier, Olivier Crégut, and François Roulland

Subjects
Work (thermodynamics), Chemistry, Oscillator strength, General Chemical Engineering, Cationic polymerization, Analytical chemistry, chemistry.chemical_element, Density functional theory, General Chemistry, Thin film, Gallium, Spectral line, Characterization (materials science)
Abstract

Room-temperature dielectric function e = e1 + ie2 spectra of magnetoelectric Ga2−xFexO3 (x = 0.9, 1.0, and 1.4) thin films are determined by spectroscopic ellipsometry (SE) as a function of Fe concentration x. The SE data are analysed by a multilayer model with a series of Tauc-Lorentz oscillators. While the threshold energies slightly decrease as x increases, the oscillator strength shows a strong composition-dependence for the major optical structure at ∼3.5 eV. The experimental data are compared to the e spectra obtained by density functional theory (DFT) calculations. Even though the overall shape of e spectra is consistent, the experimental data and calculated spectra show a clear discrepancy in the oscillator's strength ratio of the two optical structures at ∼3.5 and ∼6.0 eV. The DFT calculations suggest that a significant disordering in the cationic (Ga and Fe) sites in Ga2−xFexO3 is present in thin films, which influences their optical properties. This work demonstrates a successful application of optical characterization for determining the cationic sites occupation in thin films, which in turn improves our understanding of Physics and Chemistry in Ga2−xFexO3 thin films and paves a pathway to the development of new multifunctional devices.

Published
2013

26. Effects of Glass Phase Additions and Stoichiometry on the Ba(Zn1/3X2/3)O3 (X = Ta or Nb) Sinterability and Dielectric Properties.

Author

François Roulland and Sylvain Marinel

Abstract

Abstract Ba(Zn1/3X2/3)O3 materials where X = Ta or Nb (respectively named BZT and BZN) exhibit attractive properties suitable for applications in type I Multi Layer Ceramics Capacitors (MLCC). Nevertheless, to produce such components using Base Metal Electrodes such as copper, a significant reduction of their sintering temperature is required. The aim of this work is first to study the effects of glass phases additions and secondly the stoichiometry influence on the sintering temperature of BZT and BZN. It is shown for example, that our materials can be sintered in air at a temperature lowered by 450°C when sintering agents (B2O3 with LiF) are combined with a slight non-stoichiometry. The sintered samples are characterised in terms of final density, microstructure and phase content and it was underlined that such modifications (additions and stoichiometry) does not affect the dielectric properties. [ABSTRACT FROM AUTHOR]

Published
2005

27. Nouvelles approches pour le design de composites multiferroïques nanostructurés de type (1-3)

Author

Basov, Sergey, Catherine Elissalde, Luc Piraux, Valérie Vigneras [Président], Eric Bousquet [Rapporteur], Nathalie Viart [Rapporteur], Sandrine Payan, Mario Maglione, François Roulland, Kristiaan Temst, Bernard Nysten, Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Bordeaux, Université catholique de Louvain (1970-....), and STAR, ABES

Subjects
[CHIM.MATE] Chemical Sciences/Material chemistry, Multiferroics, Ferromagnetic, [CHIM.MATE]Chemical Sciences/Material chemistry, Ferromagnétiques, Ferroélectriques, Multiferroiques, Ferroelectric, Nanocomposites
Abstract

Multiferroic materials including magnetoelectric materials that combine magnetic and ferroelectric orders have attracted great attention due to a possible strain-mediated coupling leading to potential applications in memories, sensors, detectors, spintronic and microwave devices. The number of single-phase multiferroic materials operating at room temperature being limited, we are exploring artificially designed multiferroic nanostructures consisting of ferroelectric and ferrimagnetic oxides. Current work is focused on strain-mediated magnetoelectric effect, which allows to generate a spontaneous polarization or magnetization by an applied magnetic field (direct ME effect) and electric field (converse ME effect) respectively. ME effects can be observed at room temperature through interface and strain interaction in two-phase multiferroic nanocomposites. The combination of piezoelectric materials PbZr0.52Ti0.48O3 (PZT), Ba0.7Sr0.3TiO3 (BSTO), BaTiO3 (BTO) and magnetostrictive CoFe2O4 (CFO) materials have been intensively studied in multiferroic nanocomposites. The community has been able to demonstrate large magnetoelectric coupling at room temperature in epitaxial thin films, so called 2-2 connectivity system, but a key limitation in epitaxially grown thin films is a substrate imposed clamping effect limiting thin film’s strain. Designing innovative architectures is a challenge in the field of multiferroic nanocomposites. Our work is focused on vertically aligned multiferroic nanostructures, so called (1-3) connectivity nanocomposites, where one-dimensional ferrimagnetic CoFe2O4 nanostructures (1) are embedded into three-dimensional PZT, BTO and BSTO layers (3). New routes were considered to design three kinds of materials: i) vertically aligned CFO nanowire arrays surrounded by PZT nanotubes embedded into alumina membranes; ii) vertically aligned CFO nanopillar arrays embedded in thin BTO, BSTO and PZT layers supported on Si substrates; ii) 3-D interconnected CFO nanowire networks embedded in a thick PZT matrix. The objectives of the present work are to control the oxidation of metallic CoFe2 nanowires and nanopillars to control the morphology and density of CFO nanostructures, to control the resistivity and dielectric losses of the nanocomposites at the interface region, and to increase the magnetoelectric coupling of the multiferroic nanocomposites by increasing the interfacial surface area between the two ferroic phases.The first geometry we are developing is a deposition by sol-gel dip impregnation of PZT nanotube arrays into self-supported porous alumina membranes, followed by an electrodeposition and thermal oxidation of CoFe2 nanowire arrays within PZT nanotubes. The second architecture we are focusing on is a deposition by RF magnetron sputtering of BSTO and BTO layers and by sol-gel dip coating of PZT layers onto vertically aligned CoFe2 and CoFe2O4 nanopillar arrays supported on Si substrates. The CoFe2 oxidation is conducted in-situ during the BSTO and BTO sputter deposition. Free-standing CoFe2 nanopillar arrays are obtained by electrodeposition into anodized alumina nanoporous structures and chemical dissolution of alumina templates. The last geometry is prepared using a combination of electrodeposition into self-supported porous polymer membranes and sol-gel processes. The PZT-CFO nanostructures are prepared using impregnation of thick PZT layers into self-supported CoFe2 3D nanowire networks on Si substrates by sol-gel method and their simultaneous oxidation during PZT layers crystallization. Specific attention was focused on interfaces through microstructural and morphological evaluations of nanocomposites using XRD, HRSEM, TEM and EDS characterizations. The performances of the nanocomposites were evaluated using magnetic, dielectric, ferroelectric and ME measurements, an alternating gradient magnetometer, impedance analyser, PFM and the ME susceptometer operated inside PPMS were utilized, respectively., Les matériaux multiferroïques sont des matériaux multifonctionnels qui possèdent simultanément des propriétés magnétiques et ferroélectriques. Les perspectives d’applications sont ainsi très nombreuses dans les domaines de l’électronique (mémoires, dispositifs spintroniques et hyperfréquences). Le nombre restreint de matériaux multiferroïques monophasés a conduit au développement de nanostructures multiferroïques artificielles constituées d'oxydes ferroélectriques et ferrimagnétiques. Ce travail de thèse est axé sur l'effet magnétoélectrique (ME), obtenu pour de telles hétérostructures via la contrainte, qui permet de manipuler la polarisation spontanée ou l’aimantation par l’application d’un champ magnétique (effet ME direct) et d’un champ électrique (effet ME converse) respectivement. Les effets ME peuvent être observés à température ambiante grâce aux effets d’interfaces et de contraintes dans les nanocomposites multiferroïques. La combinaison de matériaux piézoélectriques PbZr0.52Ti0.48O3 (PZT), Ba0.7Sr0.3TiO3 (BSTO), BaTiO3 (BTO) et de matériaux magnétostrictifs CoFe2O4 (CFO) a été largement exploitée pour l’élaboration de nanocomposites multiferroïques. Les travaux issus de la littérature montrent l’existence d’un fort couplage magnétoélectrique à température ambiante dans des films minces épitaxiés (systèmes de connectivité 2-2), mais un verrou est l’effet de « bride » (clamping effect) induit par le substrat. La conception d'architectures innovantes est un défi dans le domaine des nanocomposites multiferroïques. Ce travail est axé sur les composites de type (1-3) au sein desquelles des nanostructures ferrimagnétiques CoFe2O4 unidimensionnelles (1) sont incorporées dans des couches tridimensionnelles PZT, BTO et BSTO (3). De nouvelles approches ont été envisagées pour concevoir trois types de matériaux: i) des réseaux de nanofils CFO unidirectionnels entourés de nanotubes PZT imprégnés dans des membranes d'alumine; ii) des nanopilliers CFO incorporés dans des couches minces de BTO, BSTO et PZT; ii) des réseaux de nanofils CFO interconnectés 3-D intégrés dans une matrice PZT. Nos principaux objectifs visent i) la maîtrise de l’étape d’oxydation des nanofils et des nanopilliers métalliques CoFe2 afin de contrôler la morphologie et la densité des nanostructures CFO, ii) le contrôle des caractéristiques diélectriques des nanocomposites, iii) l’augmentation du couplage magnétoélectrique en optimisant la densité d’interfaces entre les deux phases ferroïques.La première architecture développée est un dépôt par imprégnation sol-gel de nanotubes PZT dans des membranes d'alumine poreuses autosupportées, suivie d'une électrodéposition des nanofils CoFe2 dans les nanotubes PZT et de leur oxydation par traitement thermique. La deuxième architecture repose sur un dépôt par pulvérisation cathodique magnétron en radiofréquence de couches BSTO et BTO et sur un dépôt par sol-gel de couches PZT, sur des réseaux de nanopilliers CoFe2 et CoFe2O4 alignés verticalement sur des substrats Si. L'oxydation de CoFe2 est réalisée in situ lors du dépôt par pulvérisation cathodique de BSTO et BTO. Les réseaux de nanopilliers CoFe2 sont obtenus par électrodéposition dans des structures nanoporeuses en alumine anodisée qui sont ensuite dissoutes. La dernière architecture proposée est obtenue en combinant l'électrodéposition des nanofils CoFe2 dans des membranes polymères poreuses, et le procédé sol-gel. Les nanostructures PZT-CFO sont préparées par imprégnation sol-gel de couches épaisses PZT dans des réseaux de nanofils CoFe2 et leur oxydation simultanée au cours de la cristallisation des couches PZT.Une attention particulière a été accordée aux effets d’interfaces par le biais des études microstructurales et morphologiques des nanocomposites (XRD, HRSEM, TEM et EDX). Les caractérisations magnétiques, diélectriques, ferroélectriques et magnétoélectriques ont permis d’évaluer les performances des différents nanocomposites élaborés.

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