Author: "Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)" - Searchworks@Jio Institute Digital Library Search Results

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331 results on '"Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)"'

1. Wavelet-based multiresolution analysis coupled with deep learning to efficiently monitor cracks in concrete

Author: Sébastien Jacques, Ahcene Arbaoui, Abdeldjalil Ouahabi, Madina Hamiane, Université Mohamed Akli Ouelhadj de Bouira (UMAOB), Imagerie et cerveau (iBrain - Inserm U1253 - UNIV Tours ), Université de Tours-Institut National de la Santé et de la Recherche Médicale (INSERM), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Royal University for Women (RUW), Université de Tours (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Jacques, Sebastien, Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Identification scheme, 010504 meteorology & atmospheric sciences, Computer science, Multiresolution analysis, 0211 other engineering and technologies, TA630-695, 02 engineering and technology, 01 natural sciences, Convolutional neural network, Wavelet, crack monitoring, TJ1-1570, Mechanical engineering and machinery, [SPI.MECA.GEME] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanical engineering [physics.class-ph], wavelet-based multiresolution analysis, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, [SPI.ACOU]Engineering Sciences [physics]/Acoustics [physics.class-ph], [SPI.ACOU] Engineering Sciences [physics]/Acoustics [physics.class-ph], Artificial neural network, Structural engineering (General), business.industry, Mechanical Engineering, Deep learning, Ultrasonic testing, deep learning, Pattern recognition, non-destructive ultrasonic testing, [SPI.MECA.GEME]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanical engineering [physics.class-ph], [SPI.GCIV]Engineering Sciences [physics]/Civil Engineering, Mechanics of Materials, Pattern recognition (psychology), [SPI.GCIV] Engineering Sciences [physics]/Civil Engineering, concrete, Artificial intelligence, business
Abstract: International audience; This paper proposes an efficient methodology to monitor the formation of cracks in concrete after non-destructive ultrasonic testing of a structure. The objective is to be able to automatically detect the initiation of cracks early enough, i.e. well before they are visible on the concrete surface, in order to implement adequate maintenance actions on civil engineering structures. The key element of this original approach is the wavelet-based multiresolution analysis of the ultrasonic signal received from a sample or a specimen of the studied material subjected to several types of solicitation. This analysis is finally coupled to an automatic identification scheme of the types of cracks based on artificial neural networks (ANNs), and in particular deep learning by convolutional neural networks (CNNs); a technology today at the cutting edge of machine learning, in particular for all applications of pattern recognition. Wavelet-based multiresolution analysis does not add any value in detecting fractures in concrete visible by optical inspection. However, the results of its implementation coupled with different CNN architectures show cracks in concrete can be identified at an early stage with a very high accuracy, i.e. around 98%, and a loss function of less than 0.1, regardless of the implemented learning architecture.
Published: 2021

2. Homogenization of periodic 1-3 piezocomposite using wave propagation: Toward an experimental method

Author: Franck Levassort, Anne-Christine Hladky-Hennion, Renald Brenner, Remi Rouffaud, Antoine Balé, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Institut Jean Le Rond d'Alembert (DALEMBERT), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Acoustique - IEMN, Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), This work was supported by the French Research Agency (Grant No. ANR HEcATE 14-CE07-0028)., ANR-14-CE07-0028,HEcATE,Matériaux piézoélectriques alternatifs haute performance : vers des solutions respectueuses de l'environnement(2014), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), Acoustique - IEMN (ACOUSTIQUE - IEMN), and Université catholique de Lille (UCL)-Université catholique de Lille (UCL)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA)
Subjects: Materials science, Acoustics and Ultrasonics, Wave propagation, Piezoelectric materials, 01 natural sciences, Homogenization (chemistry), [SPI.MAT]Engineering Sciences [physics]/Materials, symbols.namesake, Acoustic transducers, Lamb waves, Arts and Humanities (miscellaneous), Approximation error, 0103 physical sciences, Finite-element analysis, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Slowness, 010301 acoustics, [SPI.ACOU]Engineering Sciences [physics]/Acoustics [physics.class-ph], 010302 applied physics, Numerical analysis, Mathematical analysis, Vibrometer, Fourier analysis, Finite element method, Dielectric properties, symbols, Medical imaging, Elastic modulus
Abstract: International audience; 1-3 piezocomposites are first choice materials for integration in ultrasonic transducers due to their high electromechanical performance, particularly, in their thickness mode. The determination of a complete set of effective electroelastic parameters through a homogenization scheme is of primary importance for their consideration as homogeneous. This allows for the simplification of the transducer design using numerical methods. The method proposed is based on acoustic wave propagation through an infinite piezocomposite, which is considered to be homogeneous material. Christoffel tensor components for the 2 mm symmetry were expressed to deduce slowness curves in several planes. Simultaneously, slowness curves of a numerical phantom were obtained using a finite element method (FEM). Dispersive curves were initially calculated in the corresponding heterogeneous structure. The subsequent identification of the effective parameters was based on a fitting process between the two sets of slowness curves. Then, homogenized coefficients were compared with reference results from a numerical method based on a fast Fourier transform for heterogeneous periodic piezoelectric materials in the quasi-static regime. A relative error of less than 2% for a very large majority of effective coefficients was obtained. As the aim of this paper is to implement an experimental procedure based on the proposed homogenization scheme to determine the effective parameters of the material in operating conditions, it is shown that simplifications to the procedure can be performed and a careful selection of only seven slowness directions is sufficient to obtain the complete database for a piezocomposite containing square-shaped fibers. Finally, further considerations to adapt the present work to a 1-3 piezocomposite with a fixed thickness are also presented.
Published: 2021

3. Design and Development of a Tunable Ferroelectric Microwave Surface Mounted Device

Author: Caroline Borderon, Hartmut Gundel, Kevin Nadaud, Ala Sharaiha, Raphaël Renoud, Abdullah Haskou, Stéphane Ginestar, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), French National Research Agency (ANR) in the frame of the Project SENSAS, Nantes Université (NU)-Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Permittivity, Materials science, Acoustics and Ultrasonics, Ferroelectric devices, 01 natural sciences, law.invention, agility, [SPI]Engineering Sciences [physics], law, 0103 physical sciences, Electrical and Electronic Engineering, 010301 acoustics, Instrumentation, business.industry, tunable antenna, article, Biasing, Ferroelectric applications, Ferroelectricity, Capacitor, microwave radiation, Optoelectronics, Dielectric loss, Radio frequency, business, Decoupling (electronics), Microwave
Abstract: International audience; Based on a BaSrTiO ferroelectric thin film, a discrete tunable surface mounted device (SMD) capacitor has been developed for microwave frequency applications. The proposed SMD topology has the particular advantage of inherent decoupling between the RF signal and the dc biasing voltage, necessary to tune the ferroelectric permittivity. The design and technological development of the SMD component is presented, and the synthesis of the ferroelectric thin film is summarized. Material characterization shows convenient tunability, while low dielectric losses at 10 MHz. The integration of the SMD tunable capacitor into a Planar Inverted-F Antenna has been done in order to evaluate the agility and tunability performance of the antenna.
Published: 2020

4. Acoustic Properties of Porous Lead Zirconate Titanate Backing for Ultrasonic Transducers

Author: Danjela Kuscer, Tina Bakaric, Julien Bustillo, Marc Lethiecq, Silvo Drnovšek, Franck Levassort, Jozef Stefan Institute [Ljubljana] (IJS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Acoustics and Ultrasonics, Attenuation, [CHIM.MATE]Chemical Sciences/Material chemistry, Lead zirconate titanate, 01 natural sciences, Signal, Piezoelectricity, [SPI]Engineering Sciences [physics], chemistry.chemical_compound, Transducer, chemistry, visual_art, 0103 physical sciences, visual_art.visual_art_medium, Ultrasonic sensor, Ceramic, Electrical and Electronic Engineering, Composite material, 010301 acoustics, Instrumentation, ComputingMilieux_MISCELLANEOUS, Acoustic attenuation
Abstract: For transducer design, it is essential to know the acoustic properties of the materials in their operating conditions. At frequencies over 15 MHz, standard methods are not well adapted because layers are very thin and backings have very high attenuation. In this article, we report on an original method for measuring the acoustic properties in the 15–25 MHz frequency range, corresponding to typical skin-imaging applications, using a backing/piezoelectric multilayer structure. Onto a porous Pb(Zr0.53Ti0.47O3 (PZT) substrate, a piezoelectric PZT-based layer with a thickness of $\sim 20~\mu \text{m}$ was deposited and directly used to excite an acoustic signal into water. Herein, the measured signal corresponds to the wave that is first reflected on a target in water, then propagates back to the multilayer structure, and is transmitted through the thick film and further to the rear face of the porous backing, where it is again reflected and returns to the piezoelectric thick film, thus avoiding overlap with the electrical excitation signal. Two types of PZT backings with similar porosity of ~20% and spherical pores with size of 1.5 and 10 $\mu \text{m}$ were processed. The ultrasound group velocities were measured at ~3500 m/s for both samples. The acoustic attenuation of the backings with pore size of 1.5 and 10 $\mu \text{m}$ were 12 and 33 dB/mm, respectively, measured at 19 MHz. This advanced measuring technique demonstrated potential for the simple measurements of acoustic properties of backing at high frequencies in operating conditions. Importantly, this method also enables rapid determination of the minimum required thickness of the backing to act as a semi-infinite medium, for high-frequency transducer applications.
Published: 2020

5. Microstructure evolution and electromechanical properties of (K,Na) NbO 3 ‐based thick films

Author: Hana Uršič, Hugo Mercier, Franck Levassort, Danjela Kuscer, Jozef stefan Institute- Electronic ceramic department K5 (IJS-K5), Jozef Stefan Institute [Ljubljana] (IJS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010302 applied physics, Materials science, Sintering, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, 021001 nanoscience & nanotechnology, Microstructure, 01 natural sciences, [SPI]Engineering Sciences [physics], Electrophoretic deposition, 0103 physical sciences, Materials Chemistry, Ceramics and Composites, Composite material, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2020

6. Complex Epitaxy of Tetragonal Tungsten Bronze K–Ta–Nb–O Nanorods

Author: Loïc Joanny, Francis Gouttefangeas, Valérie Demange, Quentin Simon, Maryline Guilloux-Viry, Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Synthèse Caractérisation Analyse de la Matière (ScanMAT), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Region Bretagne, Rennes Metropole Region Bretagne, Departement d'Ille et Vilaine, European Union (CPER-FEDER 2007-2014) - European Union (EU) [39126, 37339], European Union (CPER 2015-2020 MULTIMAT ScanMAT), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut de Chimie du CNRS (INC), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010302 applied physics, Materials science, chemistry.chemical_element, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, General Chemistry, Substrate (electronics), Tungsten, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Epitaxy, 01 natural sciences, Ferroelectricity, Pulsed laser deposition, Tetragonal crystal system, Crystallography, thin films, chemistry, 0103 physical sciences, KTN, General Materials Science, Nanorod, Thin film, 0210 nano-technology, TTB
Abstract: International audience; Tetragonal tungsten bronze (TTB) phases possess numerous important properties (ferroelectricity, multiferroicity, piezoelectricity, optical nonlinearity, electro-optics) that can be achieved by modifying their composition, in addition to their ability to grow as very anisotropic crystals. In this study, K-5.06(Ta0.57Nb0.43)(10.99)O-30 tetragonal tungsten bronze phase thin films were grown by a pulsed laser deposition technique on (001)SrTiO3 and R-plane sapphire substrates. The films grew according to two modes with respect to the substrate surface, that is, as vertical nanorods with the [001] direction perpendicular to the substrate surface and as horizontal nanorods with the [001] orientation parallel to the substrate surface and < 310 > out-of-plane direction. Both vertical and horizontal nanorods present epitaxial relationships with the substrates. Careful study of epitaxial relationships showed a complex growth on both substrates that can be described in the framework of domain matching epitaxy resulting in several antiphase domain formations for both kinds of nanorods. These particular configurations are due to a high degree of coincidence between cations (anions) of the film with those of the substrate. This study shows the ability of ferroelectric TTB phases to grow as one-dimensional objects with the possibility to tailor their polarization direction either normal to or parallel to the substrate surface.
Published: 2020

7. Liquid crystal ordering of nucleic acids

Author: Yves Lansac, Prabal K. Maiti, Suman Saurabh, Supriyo Naskar, Yun Hee Jang, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Stacking, 02 engineering and technology, Molecular Dynamics Simulation, 010402 general chemistry, 01 natural sciences, Molecular dynamics, Liquid crystal, Nucleic Acids, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Potential of mean force, Anisotropy, ComputingMilieux_MISCELLANEOUS, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Aspect ratio (image), Liquid Crystals, 0104 chemical sciences, Chemical physics, Volume fraction, Nucleic Acid Conformation, Thermodynamics, Umbrella sampling, 0210 nano-technology
Abstract: Several analytical calculations and computer simulations propose that cylindrical monodispersive rods having an aspect ratio (ratio of length to diameter) greater than 4 can exhibit liquid crystal (LC) ordering. But, recent experiments demonstrated the signature of LC ordering in systems of 4- to 20-base pair (bp) long nucleic acids (NAs) that do not satisfy the shape anisotropy criterion. Mechanisms of end-to-end adhesion and stacking have been proposed to explain this phenomenon. In this study, using all-atom molecular dynamics (MD) simulation, we explicitly verify the end-to-end stacking of double-stranded RNA (dsRNA) and demonstrate the LC ordering at the microscopic level. Using umbrella sampling (US) calculation, we quantify the potential of mean force (PMF) between two dsRNAs for various reaction coordinates (RCs) and compare our results with previously reported PMFs for double-stranded DNA (dsDNA). The PMF profiles demonstrate the anisotropic nature of inter-NA interaction. We find that, like dsDNA, dsRNA also prefers to stack on top of each other while repelling sideways, leading to the formation of supra-molecular-columns that undergo LC ordering at high NA volume fraction (φ). We also demonstrate and quantify the nematic ordering of the RNAs using several hundred nanosecond-long MD simulations that remain almost invariant for different initial configurations and under different external physiological conditions.
Published: 2020

8. An Original Two-Dimensional Analytical Model for Investigating Coupled Vibrations of Finite Piezoelectric Resonators

Author: Ding, Wenxiang, Bavencoffe, Maxime, Lethiecq, Marc, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SPI]Engineering Sciences [physics], [MATH]Mathematics [math], ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2021

9. Niobates ferroelectric thin films: i/ growth and characterization of perovskite and TTB phases in the K-Na-Nb-O system; ii/ potential of application in high frequency miniature tunable devices

Author: Aspe, Barthélemy, Demange, Valérie, Castel, Xavier, Gautier, Brice, Simon, Quentin, Albertini, David, Zaghrioui, Mustapha, Nadaud, Kevin, Députier, Stéphanie, Bouquet, Valérie, Sauleau, Ronan, Guilloux-Viry, Maryline, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut des Nanotechnologies de Lyon (INL), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Nantes Université (NU)-Université de Rennes 1 (UR1), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-École Centrale de Lyon (ECL), Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Castel, Xavier
Subjects: [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.ELEC] Engineering Sciences [physics]/Electromagnetism, [SPI.MAT] Engineering Sciences [physics]/Materials, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract: International audience
Published: 2021

10. Tunability Investigation in the BaTiO3-CaTiO3-BaZrO3 Phase Diagram Using a Refined Combinatorial Thin Film Approach

Author: B. Negulescu, Patrick Poveda, Mario Maglione, Quentin Simon, Sandrine Payan, P. Gardes, Nazir Jaber, Christophe Daumont, Jérôme Wolfman, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), 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), STMicroelectronics, This research was funded by Investissement d’Avenir project Tours2015 and by Région Centre Val de Loire ARD Project MAPS., Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Tours-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, 02 engineering and technology, Dielectric, 01 natural sciences, Pulsed laser deposition, law.invention, law, 0103 physical sciences, lead-free relaxor, Materials Chemistry, Figure of merit, Breakdown voltage, Thin film, dielectric, 010302 applied physics, BCTZ, business.industry, Surfaces and Interfaces, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Engineering (General). Civil engineering (General), Ferroelectricity, Surfaces, Coatings and Films, Capacitor, thin films, tunable capacitors, Optoelectronics, Dielectric loss, TA1-2040, PLD, 0210 nano-technology, business
Abstract: Tunable ferroelectric capacitors, which exhibit a decrease in the dielectric permittivity under an electric field, are widely used in electronics for RF tunable applications. Current devices use barium strontium titanate (BST) as the tunable dielectric, but new applications call for tunable materials with specific performance improvements. It is then of crucial importance to dispose of a large panel of electrically characterized materials to identify the most suited compound for a given set of device specifications. Here, we report on the dielectric tuning properties of Ba1−xCaxTi1−yZryO3 (BCTZ) thin films libraries (0 ≤ x ≤ 30% and 0 ≤ y ≤ 28.5%) synthesized by combinatorial pulsed laser deposition (CPLD). An original CPLD approach allowing reliable and statistical ternary phase diagrams exploration is reported. The effects of Ca and Zr content on tunability, breakdown voltage and dielectric losses are explicated and shown to be beneficial up to a certain amount. Compounds close to (Ba0.84Ca0.16)(Ti0.8Zr0.2)O3 exhibit the highest figures of merit, while a zone with compositions around (Ba0.91Ca0.09)(Ti0.81Zr0.19)O3 show the best compromise between tuning ratio and figure of merit. These results highlight the potential of BCTZ thin films for electrically tunable applications.
Published: 2021
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11. Investigation of electrical activity at the AlN/Si interface using scanning capacitance microscopy and scanning spreading resistance microscopy

Author: Bah, Micka, Valente, Damien, Lesecq, Marie, Defrance, N., Barros, Maxime Garcia, De Jaeger, Jean-Claude, Frayssinet, Eric, Comyn, Remi, Ngo, Thi Huong, Alquier, Daniel, CORDIER, Yvon, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Puissance - IEMN (PUISSANCE - IEMN), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Centre de recherche sur l'hétéroepitaxie et ses applications (CRHEA), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), This work was supported by the technology facility network RENATECH and the French National Research Agency (ANR) through the projects ASTRID GoSiMP (ANR-16-ASTR-0006-01) and the 'Investissements d’Avenir' program GaNeX (ANR-11-LABX-0014)., Renatech Network, ANR-16-ASTR-0006,GoSiMP,Optimisations combinées par l'épitaxie pour composants hyperfréquences de puissance GaN sur Silicium(2016), ANR-11-LABX-0014,GANEX,Réseau national sur GaN(2011), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), Université catholique de Lille (UCL)-Université catholique de Lille (UCL)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Université Nice Sophia Antipolis (1965 - 2019) (UNS), Lesecq, Marie, Optimisations combinées par l'épitaxie pour composants hyperfréquences de puissance GaN sur Silicium - - GoSiMP2016 - ANR-16-ASTR-0006 - ASTRID - VALID, Laboratoires d'excellence - Réseau national sur GaN - - GANEX2011 - ANR-11-LABX-0014 - LABX - VALID, and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SPI]Engineering Sciences [physics], [SPI] Engineering Sciences [physics]
Abstract: ORAL; International audience; This work aims to understand the origin of propagation losses in GaN-on-Si devices at microwave frequencies thanks to original AFM's electrical modes such as scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM). AlN films on Si substrate were grown using Metalorganic Vapor Phase Epitaxy (MOVPE) technique. SCM and SSRM measurements evidence a p-type conductive channel as well as a pn-junction beneath the AlN/Si interface. The diffusion depths of Al and Ga atoms obtained by Secondary Ion Mass Spectroscopy (SIMS) are in good agreement with those deduced from SCM and SSRM. Sample grown at lower temperature (1000°C) exhibits a conductive channel and a junction over a shallow depth explaining its lower propagation losses in comparison with those synthesized at higher temperature (1150°C). Thus, monitoring the dopant diffusion beneath the AlN/Si interface is crucial to achieve efficient GaN-on-Si microwave power devices.
Published: 2021

12. Core@shell nanocomposites Fe7C3 / FexOy /C obtained by high pressure-high temperature treatment of ferrocene Fe(C5H5)2

Author: A. O. Baskakov, Igor S. Lyubutin, V. A. Davydov, K. O. Funtov, Yu. A. Nikiforova, L.F. Kulikova, Alexander L. Vasiliev, S. S. Starchikov, V. N. Agafonov, V.A. Zayakhanov, Marianna V. Lyubutina, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Iron oxide, chemistry.chemical_element, Nanoparticle, 02 engineering and technology, engineering.material, 010402 general chemistry, 01 natural sciences, law.invention, Carbide, chemistry.chemical_compound, law, General Materials Science, Wüstite, Crystallization, ComputingMilieux_MISCELLANEOUS, Magnetite, General Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [PHYS.MECA.ACOU]Physics [physics]/Mechanics [physics]/Acoustics [physics.class-ph], Chemical engineering, chemistry, engineering, Orthorhombic crystal system, 0210 nano-technology, Carbon
Abstract: The core@shell nanostructures were obtained in the process of transformation of ferrocene Fe(C5H5)2 at high pressure (HP) of 8 GPa and high temperature (HT) of 900 °C with an isothermal exposure time t varying from 10 to 10000 s. At t > 300 s, the iron carbide o-Fe7C3 nanoparticles with an orthorhombic crystal structure (sp.gr. Pnma) can be created, which are dispersed in highly defective carbon matrix. After opening the high-pressure cell, a series of redox reactions occurs, leading to a formation of iron oxides on the surface of the iron carbide core. When the size of Fe7C3 nanoparticle is less than critical one the nanoparticle is fully oxidized, while in the larger particle an amorphous iron oxide shell is formed. A sequential increase in t initiates crystallization processes both in the iron carbide subsystem and in the carbon subsystem, resulting in the formation of core@shell Fe7C3/FexOy/C structures. Iron oxides with a cubic spinel-type structure (Fe3O4/γ-Fe2O3) appear in the shell. However, under oxygen reduction, part of magnetite can be transformed into wustite FeO. The magnetic properties of magnetite and wustite are radically different, and by varying the thickness of these layers, structures with the desired functional properties can be obtained.
Published: 2021

13. Synchronous E-learning in Higher Education during the COVID-19 Pandemic

Author: Abdeldjalil Ouahabi, Thierry Lequeu, Sébastien Jacques, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Imagerie et cerveau (iBrain - Inserm U1253 - UNIV Tours ), Université de Tours (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Tours (UT), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Université de Tours-Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Tours, Centre National de la Recherche Scientifique (CNRS)-Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), and Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Tours (UT)
Subjects: Higher education, Computer science, Process (engineering), business.industry, [SHS.EDU]Humanities and Social Sciences/Education, 4. Education, Synchronous e-learning, Distance education, Teleconference, COVID-19, 02 engineering and technology, Remote knowledge acquisition and assessment, [SPI.TRON]Engineering Sciences [physics]/Electronics, 03 medical and health sciences, 0302 clinical medicine, Incentive, Management system, 0202 electrical engineering, electronic engineering, information engineering, Mathematics education, 020201 artificial intelligence & image processing, 030212 general & internal medicine, Digital learning, Digital divide, business
Abstract: International audience; Since the beginning of the COVID-19 pandemic, students around the world have seen their schooling completely disrupted. Their teachers had to reorganize in a hurry to be able to give their classes synchronously but at a distance. Thanks to strong political incentives, both at the national and university levels, many tools have been massively deployed: digital learning management systems (e.g. Moodle), collaborative digital platforms (e.g. Google Meets, Microsoft Teams and Zoom), social networks (e.g. Facebook and Twitter) and even the telephone. While the COVID-19 pandemic has highlighted the essential role of digital technologies in higher education, major issues arise regarding the quality of distance education, the learning process itself and the assessment of knowledge and skills. In this study, 81 engineering students in France were followed during several periods of containment in order to provide some answers to these questions. The results of the various knowledge tests carried out at a distance show that the students obtained local scores similar to those expected from face-to-face teaching. According to the results of the satisfaction surveys, for 91.4% of students who had sufficient hardware and software resources, the synchronous approach to e-learning presented few barriers. For the 8.6% of students affected by the digital divide, telephone communications and social networks played a major role in the learning process.
Published: 2021

14. Selective Confinement of Cd II in Silica Particles Functionalized with β‐Keto‐Enol‐Bisfuran Receptor: Isotherms, Kinetic and Thermodynamic Studies

Author: Mustapha Zaghrioui, Abderrahman Elidrissi, Smaail Radi, Yann Garcia, Said Tighadouini, Laboratoire de Chimie Appliquée et Environnement | Laboratory of Applied and Environmental Chemistry [Université Mohammed Premier Oujda] (LCAE), Université Mohammed Premier [Oujda], GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Institute of Condensed Matter and Nanosciences (MOST-Chemistry), Université Catholique de Louvain = Catholic University of Louvain (UCL), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Cadmium, chemistry.chemical_element, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, Keto–enol tautomerism, 010402 general chemistry, 021001 nanoscience & nanotechnology, Kinetic energy, 01 natural sciences, 0104 chemical sciences, Inorganic Chemistry, chemistry, Computational chemistry, [SDE]Environmental Sciences, 0210 nano-technology, Receptor, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2019

15. Lead-free piezoelectric crystals grown by the micro-pulling down technique in the BaTiO3–CaTiO3–BaZrO3 system

Author: Karol Bartosiewicz, Vincent Motto-Ros, H. Cabane, Mario Maglione, Mai Pham Thi, Ana Borta-Boyon, O. Benamara, Franck Levassort, Akira Yoshikawa, Kei Kamada, Kheirreddine Lebbou, Guillaume Alombert-Goget, Jérôme Debray, Philippe Veber, Luminescence (LUMINESCENCE), Institut Lumière Matière [Villeurbanne] (ILM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Tohoku University [Sendai], Cristaux Massifs (CrisMass), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Spectrométrie des biomolécules et agrégats (SPECTROBIO), Thales Research and Technology [Palaiseau], THALES, CristalInnov, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), 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), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, 9 mm caliber, Analytical chemistry, Micro-pulling-down, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, General Chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Piezoelectricity, 0104 chemical sciences, Crystal, Partition coefficient, Lead-free, Piezoelectrics, Micro-pulling down, General Materials Science, 0210 nano-technology, Spectroscopy, Elemental segregation, Perovskite (structure), Solid solution
Abstract: International audience; BaTiO3-based crystal fibres with mm-sized grains were grown by the micro-pulling down technique from the BaTiO3–CaTiO3–BaZrO3 solid solution with pulling velocities of about 6, 9 and 15 mm h−1. The natural growth direction was identified as (001)pc. For the pulling velocities of about 15 mm h−1 and 9 mm h−1, effective partition coefficients have been calculated from Castaing micro-probe measurements, and gave, respectively, 1.3 and 2 for Zr, and 0.95 and 0.9 for Ca. Laser-induced breakdown spectroscopy measurements reveal a strong inhomogeneity and variations of Zr contents while Ca contents show an opposite variation trend with a more steady distribution. Coexistence of two crystallized perovskite solid solutions is suggested. Most efficient polycrystals with mm-sized grains and 0.5 mol% Zr and 11 mol% Ca as average contents exhibit Curie temperatures higher than 113 °C, electromechanical coupling factors kt up to 41% and piezoelectric charge coefficients d33 up to 242 pC N−1 at room temperature. These values are similar to piezoelectric coefficients reported in the literature for oriented flux-grown single crystals with close compositions. Both chemical and physical results obtained in the BCTZ system make the μ-PD technique a promising way to improve the piezoelectric response of lead-free solid solution-based single crystals.
Published: 2019

16. Electronic and nuclear magnetic anisotropy of cobalt-doped ZnO single-crystalline microwires

Author: Sylvain Bertaina, Fabian Delorme, Adrien Savoyant, Fabien Giovannelli, O. Pilone, Institut des Matériaux, de Microélectronique et des Nanosciences de Provence (IM2NP), Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Context (language use), 02 engineering and technology, 01 natural sciences, law.invention, Crystal, law, Local symmetry, 0103 physical sciences, 7550Pp, General Materials Science, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Electrical and Electronic Engineering, Anisotropy, Electron paramagnetic resonance, Hyperfine structure, 7630Fc, 7530Gw, 010302 applied physics, Condensed matter physics, Doping, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 3. Good health, Magnetic anisotropy, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], numbers: 6172uj, 0210 nano-technology
Abstract: International audience; Using electron paramagnetic resonance (EPR), we investigate the electronic and nuclear magnetic properties of ZnO:Co single crystals, grown by the optical furnace method. The high crystal quality of the studied samples allows for the determination of the full hyperfine and g tensors. We explain how the local magnetic anisotropy of the Co 2+ impurities is used as a very fine probe for the local symmetry and crystal quality of the host. The temperature-and power-study of EPR intensities recorded in three static-and microwave-field configurations give a qualitative insight into the dynamics of spin-lattice and spin-spin relaxations. In addition, in the context of nanostructures, we explain how a detailed analysis of the intensities anisotropy can reveal the proportion of ordered and disordered phases.
Published: 2019

17. Reducing the thermal conductivity of La2Mo2O9 with a trivalent praseodymium substitution for its potential use as a thermal barrier coating

Author: V. Tezyk, Fabien Giovannelli, Etienne Sabarthes, Fabian Delorme, Philippe Lacorre, Cécile Autret, Gwenaël Corbel, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Institut des Molécules et Matériaux du Mans (IMMM), Le Mans Université (UM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, 010405 organic chemistry, Praseodymium, Analytical chemistry, chemistry.chemical_element, Sintering, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, 0104 chemical sciences, [PHYS.COND.CM-S]Physics [physics]/Condensed Matter [cond-mat]/Superconductivity [cond-mat.supr-con], Inorganic Chemistry, Thermal barrier coating, Thermal conductivity, chemistry, Phase (matter), [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [CHIM.CRIS]Chemical Sciences/Cristallography, Lanthanum, Thermal stability, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], ComputingMilieux_MISCELLANEOUS, Powder diffraction
Abstract: (La1-xPrx)2Mo2O9 powders were synthesized by solid state reaction for x = 0.00, 0.10, 0.25, 0.50, 0.75 and 1.00. Dense pellets were obtained by conventional sintering in air. Their thermal stability and thermal conductivity were measured from 100 to 700 °C and their cell parameters refined from X-ray powder diffraction pattern by the Rietveld method. A 50 mol% isovalent substitution of lanthanum in La2Mo2O9 by praseodymium stabilizes the high temperature β phase while reducing the thermal conductivity of the parent compound by 11-18%. For a praseodymium content x higher than 0.75, the thermal conductivity increases and a phase transition similar to that of La2Mo2O9 is observed except that the room temperature phase appears to be this time triclinic in symmetry.
Published: 2019

18. Numerical investigation of the maximum thermoelectric efficiency

Author: Limelette, Patrice, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS]Physics [physics], lcsh:Physics, lcsh:QC1-999
Abstract: International audience; The maximum thermoelectric efficiency that is given by the so-called dimensionless figure of merit ZT is investigated here numerically for various energy dependence. By involving the electrical conductivity σ, the thermopower α, and the thermal conductivity κ such that ZT = α 2 × σ × T/κ, the figure of merit is computed in the frame of a semiclassical approach that implies Fermi integrals. This formalism allows us to take into account the full energy dependence in the transport integrals through a previously introduced exponent s that combines the energy dependence of the quasiparticles' velocity, the density of states, and the relaxation time. While it has been shown that an unconventional exponent s = 4 was relevant in the context of the conducting polymers, the question of the maximum of ZT is addressed by varying s from 1 up to 4 through a materials quality factor analysis. In particular, it is found that the exponent s = 4 allows for an extended range of high figure of merit toward the slightly degenerate regime. Useful analytical asymptotic relations are given, and a generalization of the Chasmar and Stratton formula of ZT is also provided.
Published: 2021

19. Diffuse shear wave spectroscopy for soft tissue viscoelastic characterization

Author: Samuel Callé, L. Kritly, J.-P. Remenieras, S. Beuve, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: Shear waves, Materials science, Acoustics and Ultrasonics, Acoustics, 01 natural sciences, Vibration, Imaging phantom, Viscoelasticity, Elastic Modulus, 0103 physical sciences, medicine, Particle velocity, 010306 general physics, 010301 acoustics, Elastic modulus, ComputingMilieux_MISCELLANEOUS, [SPI.ACOU]Engineering Sciences [physics]/Acoustics [physics.class-ph], medicine.diagnostic_test, Fourier Analysis, Phantoms, Imaging, Viscosity, Spectrum Analysis, Stiffness, Reproducibility of Results, Signal Processing, Computer-Assisted, Equipment Design, Image Enhancement, Elasticity Imaging Techniques, Elastography, medicine.symptom, Phase velocity, Rheology, Algorithms
Abstract: In order to limit and slow the development of diseases, they have to be diagnosed early as possible to treat patients in a better and more rapid manner. In this paper, we focus on a noninvasive and quick method based on diffuse fields in elastography to detect diseases that affect the stiffness of organs. To validate our method, a phantom experiment numerically pre-validated is designed. It consists of seven vibrators that generate white noises in a bandwidth of [80–300] Hz and then a complex acoustic field in a phantom. Waves are tracked by a linear ultrasound probe L11-4v linked to a Verasonics Vantage System and are converted into a particle velocity 2D map as a function of time. The phase velocity of the shear waves is calculated using a temporal and 2D spatial Fourier transform and an adapted signal-processing method. Shear wave velocity dispersion measurement in the frequency bandwidth of the vibrators enables one to characterize the dynamic hardness of the material through the viscoelastic parameters μ and η in an acquisition time shorter than a second (Tacq = 300 ms). With the aim of estimating the consistency of the method, the experiment is performed N = 10 times. The measured elastic modulus and viscous parameter that quantify the dynamic properties of the medium correspond to the expected values: μ = 1.23 ± 0.05 kPa and η = 0.51 ± 0.09 Pa∙s.
Published: 2021

20. Effect of ink formulation on the inkjet printing process of Al–ZnO nanoparticles

Author: Olga Shavdina, Christine Vautrin-Ul, Arnaud Stolz, Nadjib Semmar, Chantal Boulmer-Leborgne, Jimmy Nicolle, Valérie Bertagna, Fabien Giovannelli, Céline Grillot, Groupe de recherches sur l'énergétique des milieux ionisés (GREMI), Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Interfaces, Confinement, Matériaux et Nanostructures ( ICMN), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Région Centre Val-de-Loire, APR IR 2016 - IMERSYOM, and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Aluminum-Zinc Oxide, Nanoparticle, 02 engineering and technology, Substrate (printing), 010402 general chemistry, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Viscosity, Colloid and Surface Chemistry, Jetting parameters, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Thin film, Ink formulation, Aqueous solution, Precipitation (chemistry), Drop (liquid), Surfaces and Interfaces, General Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Surfaces, Coatings and Films, Inkjet printing, Chemical engineering, 0210 nano-technology, Layer (electronics)
Abstract: This study focuses on the inkjet printing of aluminum-doped zinc oxide (AZO) spherical and platelet nanoparticle-based nanoflakes with typical sizes ranging from 700 to 800 nm. The AZO nanoparticles were synthesized by aqueous precipitation. The preparation of the solvent-based inks was performed with the control of the viscosity, ink stability, and nanoparticle dispersion. The results showed that the viscosity for nanoparticle dispersions slightly changes (from 6.9 to 8.7 cPs) when the nanoparticles mass concentration increases from 1.8 to 10%. In order to achieve thin films of AZO nanoparticles, we optimized the printing process by real-time monitoring of drop velocity with a stroboscopic camera. This technology involves direct patterning of a functional material by tiny MEMS-jets on a flexible and rigid substrate at specific locations. The lowest concentration of AZO nanoparticles corresponding to 1.8% enables printing several times during the nanoparticle dispersions and the clogging of printhead nozzles is less pronounced. In our conditions, the optimum voltage value is 25 V to achieve a drop velocity from 7 to 9 m/s. In the case of nanospheres with 10% of AZO nanoparticles, for a large dropspace (90 $$\mu$$ m), the individual printed droplets appear as a sequence of linear dots. When the drop spacing decreases to 75 $$\mu$$ m, isolated drops start to overlap and merge. Further decrease in the drop spacing eliminates scalloping and leads finally to a regular and continuous layer at 55 $$\mu$$ m.
Published: 2021

21. Inkjet-printing-derived lead-zirconate-titanate-based thick films for printed electronics

Author: Silvo Drnovšek, Danjela Kuscer, Franck Levassort, Jozef Stefan Institute [Ljubljana] (IJS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Thick films, Piezoelectricity, 02 engineering and technology, 010402 general chemistry, Lead zirconate titanate, 01 natural sciences, [SPI]Engineering Sciences [physics], chemistry.chemical_compound, lcsh:TA401-492, General Materials Science, Electronics, Ceramic, Composite material, Printed electronic, ComputingMilieux_MISCELLANEOUS, Mechanical Engineering, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Grain size, 0104 chemical sciences, Transducer, Inkjet printing, chemistry, Mechanics of Materials, Printed electronics, visual_art, visual_art.visual_art_medium, Electromechanical properties, lcsh:Materials of engineering and construction. Mechanics of materials, 0210 nano-technology, Actuator
Abstract: We have investigated the processing of lead-zirconate-titanate-based thick films by inkjet printing Pb(Zr0.53Ti0.47)0.98Nb0.02O3 with a 6 mol% excess of PbO nanosized powder dispersed in water. Different waveforms were employed to determine the optimum size and shape of the drops. A uniform, defect-free pattern with dimensions of 4 mm × 4 mm can be printed using 20 V and a drop spacing of 20 μm. The inkjet-printed films were heated to 400 °C to remove the organics and subsequently sintered at 750 and 850 °C. The correlations between the density, grain size and electromechanical properties of the thick films and bulk ceramics are qualitatively discussed. A thickness coupling factor of 46% was obtained for a 15-μm-thick film sintered at low temperature of 850 °C, which is comparable to the value of the bulk ceramic with an identical nominal chemical composition. Our results are important for the economic and environmental-benign printing of piezoelectric materials applicable in variety of electronic devices, such as sensors, actuators, transformers, piezoelectric energy harvesters and transducers.
Published: 2021

22. Toward a highly efficient large surface Perovskite Silicon 4-Terminal tandem module

Author: Sophie Bernard, Marion Provost, Nathanaelle Schneider, Damien Coutancier, Romain Bodeux, Thomas Guillemot, Valerie Daniau, Sebastien Jutteau, Stéphane Collin, Emilie Raoult, Jean Rousset, Armelle Yaiche, Institut Photovoltaïque d’Ile-de-France (UMR) (IPVF), École polytechnique (X)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-TOTAL FINA ELF-EDF (EDF)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Photovoltaïque d’Ile-de-France (ITE) (IPVF)-Air Liquide [Siège Social], Plate-Forme de Recherche en Imagerie Cellulaire de Haute-Normandie (PRIMACEN), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institute for Research and Innovation in Biomedicine (IRIB), Normandie Université (NU)-Normandie Université (NU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Glycobiologie et Matrice Extracellulaire Végétale (Glyco-MEV), Normandie Université (NU)-Normandie Université (NU), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), EDF R&D (EDF R&D), EDF (EDF), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Centre de Nanosciences et de Nanotechnologies [Marcoussis] (C2N), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-High-tech Research Infrastructures for Life Sciences (HeRacLeS), Normandie Université (NU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Fabrication, Silicon, business.industry, Photovoltaic system, chemistry.chemical_element, Perovskite solar cell, [CHIM.MATE]Chemical Sciences/Material chemistry, Active surface, 7. Clean energy, Die (integrated circuit), chemistry, Stack (abstract data type), Optoelectronics, business, ComputingMilieux_MISCELLANEOUS, Perovskite (structure)
Abstract: This work presents a path to the fabrication of highly efficient, large size 4-Terminal (4T) perovskite silicon tandem. As a first step, our deposition process of perovskite based on spin coating was transferred to slot die coating, enabling large surface areas. Simultaneously, a semitransparent perovskite solar cell was designed to ensure a high optical transmission in the near-infrared (NIR) and we achieved a transmission of 90% at 900 nm, in good agreement with the optical simulation. As a second step, a stack reproducing the perovskite solar cell has been packaged with an n-PERT silicon cell in a box printed in 3D to form a pseudo-tandem with 16 cm2 active area. This device allows to guarantee its durability and to precisely assess the performances of the filtered silicon bottom cell thanks to correct optical alignment. It also minimizes optical losses between both silicon bottom and perovskite top cells. Combining a 16.9% perovskite top cell (active surface of 0.09 cm2) deposited by slot die and a 6.4% filtered silicon bottom cell results in an efficiency of 23.3% for a 4T tandem solar cell. Moreover, a filtered silicon solar with 8.2% efficiency is obtained using a perovskite solar cell stack optimized for NIR. The fabrication of 4T tandem over 16 cm2 active area are currently in progress and will be discussed.
Published: 2021

23. A Highly Efficient Algorithm for Phased-Array mmWave Massive MIMO Beamforming

Author: Althuwayb, Ayman, Hashim, Fazirulhisyam, Liew, Jiun, Khan, Imran, Lee, Jeong, Affum, Emmanuel, Ouahabi, Abdeldjalil, Jacques, Sebastien, Jouf University (SAUDI ARABIA), Faculty of Engineering, Universiti Putra Malaysia, Serdang, Selangor, Universiti Putra Malaysia, University of Engineering and Technology [Peshawar] (UET), Chung-Ang University [Seoul], Kwame Nkrumah University of Science and Technology [GHANA] (KNUST), Imagerie et cerveau (iBrain - Inserm U1253 - UNIV Tours ), Université de Tours-Institut National de la Santé et de la Recherche Médicale (INSERM), LIMPAF Laboratory [Bouira, Algeria] (Department of Computer Science), Université de Bouira, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Jacques, Sebastien, Université de Tours (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: mmWave, algorithm, phased array, [INFO]Computer Science [cs], [INFO] Computer Science [cs], antenna beamforming, [SPI.TRON] Engineering Sciences [physics]/Electronics, 5G, [SPI.TRON]Engineering Sciences [physics]/Electronics
Abstract: International audience; With the rapid development of the mobile internet and the internet of things (IoT), the fifth generation (5G) mobile communication system is seeing explosive growth in data traffic. In addition, low-frequency spectrum resources are becoming increasingly scarce and there is now an urgent need to switch to higher frequency bands. Millimeter wave (mmWave) technology has several outstanding features-it is one of the most well-known 5G technologies and has the capacity to fulfil many of the requirements of future wireless networks. Importantly, it has an abundant resource spectrum, which can significantly increase the communication rate of a mobile communication system. As such, it is now considered a key technology for future mobile communications. MmWave communication technology also has a more open network architecture; it can deliver varied services and be applied in many scenarios. By contrast, traditional, all-digital precoding systems have the drawbacks of high computational complexity and higher power consumption. This paper examines the implementation of a new hybrid precoding system that significantly reduces both calculational complexity and energy consumption. The primary idea is to generate several sub-channels with equal gain by dividing the channel by the geometric mean decomposition (GMD). In this process, the objective function of the spectral efficiency is derived, then the basic tracking principle and least square (LS) techniques are deployed to design the proposed hybrid precoding. Simulation results show that the proposed algorithm significantly improves system performance and reduces computational complexity by more than 45% compared to traditional algorithms.
Published: 2021

24. Distance Learning in Higher Education in France during the COVID-19 Pandemic Chapter 4

Author: Sébastien Jacques, Abdeldjalil Ouahabi, Jacques, Sebastien, Nina Tomaževič, Dejan Ravšelj and Aleksander Aristovnik, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Imagerie et cerveau (iBrain - Inserm U1253 - UNIV Tours ), Université de Tours (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS)-Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Tours (UT), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Université de Tours-Institut National de la Santé et de la Recherche Médicale (INSERM), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Digital transformation, [SHS.EDU]Humanities and Social Sciences/Education, [SHS.EDU] Humanities and Social Sciences/Education, [SPI.NRJ]Engineering Sciences [physics]/Electric power, ComputingMilieux_COMPUTERSANDEDUCATION, COVID-19, Distance learning, Higher education, [SPI.TRON] Engineering Sciences [physics]/Electronics, [SPI.NRJ] Engineering Sciences [physics]/Electric power, [SPI.TRON]Engineering Sciences [physics]/Electronics
Abstract: International audience; Since the beginning of the COVID-19 pandemic, students around the world have seen their schooling completely disrupted. Their teachers have had to reorganize in a hurry and even develop digital skills to be able to teach their classes synchronously but at a distance. Thanks to strong political incentives, both at national and university level, many tools have been massively deployed: digital learning management systems (e.g. Moodle), collaborative digital platforms (e.g. Google Meets, Microsoft Teams and Zoom) and even social networks (e.g. Facebook and Twitter). While this unprecedented health crisis has demonstrated the essential role of digital technologies in higher education, major questions arise regarding the quality of distance education, the learning process itself and the evaluation of knowledge and skills acquired at a distance. In this policy paper, about a hundred students from engineering schools and master's degrees in France were followed during several periods of confinement in order to provide some answers to these questions. The performance of the students in this very particular context is analyzed. The feelings of students, but also those of teachers, are also discussed, both on the use of digital technologies and on the digital transformation of higher education
Published: 2021

25. Nb and Cu co-doped (La,Sr)(Co,Fe)O 3 : a stable electrode for solid oxide cells

Author: Neacsa, D., Abbassi, K., Guesmi, H., Coddet, P., Vulliet, J., El Amrani, M., Dealmeida-Didry, S., Roger, S., Ta Phuoc, V., Sopracase, R., Gervais, F., Autret-Lambert, C., GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: [CHIM.MATE]Chemical Sciences/Material chemistry, [CHIM.INOR]Chemical Sciences/Inorganic chemistry
Abstract: International audience; Solid oxide cells (SOCs) are electrochemical devices that convert the chemical energy of a fuel into electricity. With regard to electrodes, the development of materials with mixed conduction properties is a key issue for improving the performance of SOCs at high temperatures. New Cu and Nb co-doping La1−xSrxFeyCo1−yO3−δ (LSCF) materials were studied as electrode materials on yttria-stabilized zirconia (YSZ) supports. The results show that Cu0.05 + Nb0.05 co-doped LSCF maintains a stable cubic structure even after several heat treatments and has better conductivity than a classically used LSCF.
Published: 2021

26. Fabrication of Oriented n‐Type Thermoelectric Polymers by Polarity Switching in a DPP‐Based Donor–Acceptor Copolymer Doped with FeCl 3

Author: Huiyan Zeng, Viktoriia Untilova, Bruno Schmaltz, P. Limelette, Nicolas Berton, Olivier Boyron, Mohammed Mohammed, Martin Brinkmann, Institut de Chimie de Strasbourg, Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Physico-chimie des Matériaux et des Electrolytes pour l'Energie (PCM2E), Université de Tours (UT), Laboratoire de Chimie, Catalyse, Polymères et Procédés, R 5265 (C2P2), Centre National de la Recherche Scientifique (CNRS)-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Université de Tours, Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: Conductive polymer, chemistry.chemical_classification, Materials science, Fabrication, Polarity (physics), Doping, 02 engineering and technology, Polymer, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, [CHIM.POLY]Chemical Sciences/Polymers, chemistry, Chemical engineering, Thermoelectric effect, Copolymer, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, Donor acceptor
Abstract: International audience; n‐Type‐doped polymers are key elements to fabricate all‐polymer thermoelectric generators but they are challenging to produce. Herein, a new strategy is proposed, which is based on polarity switching upon doping of a donor–acceptor (D–A) copolymer based on diketopyrrolopyrrol (DPP) and quintethiophene (5T) with FeCl3. Polarity switching from p‐type to n‐type is observed upon increasing the doping concentration of FeCl3. An analysis based on nonmonotonic density of states is proposed, which accounts for the main experimental trends and demonstrates that the polarity switch is governed by the electronic band filling that is determined by the dopant concentration. The influence of the curvature of the density of states is in addition discussed and a complete description of the doping induced transport regimes is proposed. This polarity switching depends on the molecular weight Mn of the polymer and shifts to higher FeCl3 concentrations with increasing Mn. This behavior is attributed to the change of the width of the density of states with Mn. The combination of polarity switching and alignment is a means to produce n‐type‐like oriented and conducting polymers with enhanced power factors up to 10 µW K−2 m−1 along the chain direction.
Published: 2021

27. Remote Knowledge Acquisition and Assessment During the COVID-19 Pandemic

Author: Abdeldjalil Ouahabi, Sébastien Jacques, Thierry Lequeu, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Ecole Polytechnique de l'Université de Tours (Polytech Tours ), Université de Tours, Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT), Centre National de la Recherche Scientifique (CNRS)-Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)
Subjects: Higher education, Computer science, Process (engineering), [SHS.EDU]Humanities and Social Sciences/Education, Distance education, Data security, Theory and practice of education, computer.software_genre, Education, Knowledge acquisition and assessment, synchronous e-learning, 03 medical and health sciences, 0302 clinical medicine, Videoconferencing, Mathematics education, ComputingMilieux_COMPUTERSANDEDUCATION, Relevance (information retrieval), Distance learning, 030212 general & internal medicine, Digital divide, LB5-3640, Synchronous elearning, LC8-6691, business.industry, 4. Education, 05 social sciences, General Engineering, 050301 education, COVID-19, Special aspects of education, Knowledge acquisition, [SPI.TRON]Engineering Sciences [physics]/Electronics, business, 0503 education, computer
Abstract: International audience; On 16 March 2020, as a result of the unprecedented global health crisis linked to the emergence of a new form of coronavirus (COVID-19), the 74 universities of France closed their doors, forcing nearly 1.6 million students, as well as their teachers, to find solutions and initiatives that could ensure continuity in teaching. In the reliance on videoconferencing tools, chat, the sharing of documents/tutorials/videos/podcasts, and the use of social networks, many ideas have emerged, but no consensus has developed nor has a common way of doing things been adopted by a majority of teachers. Some software tools, such as Zoom, have also been questioned over data security issues or excessive intrusion into the student learning process. Nevertheless, in these uncertain times, much had to be done so that students can acquire the requisite knowledge, develop skills, and build on what they have learned. How can we ensure that the learning process is as smooth as possible for everyone involved? How can we evaluate knowledge and skills learned at a distance, and their relevance? Four groups of electronic and electrical engineering students in France were monitored during the containment period in order to provide answers to these questions. Lectures, tutorials, practical work, and projects were carried out using the Microsoft Teams and Zoom video conferencing and chat tools to complement activities made available through the digital work environment. In order to ensure equity among all students, especially in view of the digital divide, open access tools/software/applications have been promoted. In the various surveys completed, the engineering students asserted their complete satisfaction with the learning process, the use of distance tools, and the level of mastery of these tools by their teachers. The results of the various knowledge tests show that, for the same course, distance learning does not reduce the performance of the engineering students. Indeed, they obtained local grades similar to those expected in face-to-face teaching. The results presented in this article are not intended to highlight the virtues of distance education, but rather to open up a debate and reflect more widely on the sustainability of this transformation of education in universities.
Published: 2020

28. Perovskite and tetragonal tungsten bronze phase thin films in the K-Na-Nb-O system: structural and dielectric characterizations

Author: Aspe, Barthélemy, Demange, Valérie, Castel, Xavier, Gautier, Brice, Simon, Quentin, Albertini, David, Zaghrioui, Mustapha, Nadaud, Kevin, Députier, Stéphanie, Bouquet, Valérie, Sauleau, Ronan, Guilloux-Viry, Maryline, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Synthèse Caractérisation Analyse de la Matière (ScanMAT), Université de Rennes (UR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut des Nanotechnologies de Lyon (INL), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-École Centrale de Lyon (ECL), Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Castel, Xavier
Subjects: [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.ELEC] Engineering Sciences [physics]/Electromagnetism, [SPI.MAT] Engineering Sciences [physics]/Materials, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract: International audience
Published: 2020

29. Defects and microstructure of highly conducting Al-doped ZnO ceramics obtained via spark plasma sintering

Author: Maud Barré, Abdelhadi Kassiba, Guorong Li, Malgorzata Makowska-Janusik, Liaoying Zheng, Qianying Sun, Tian Tian, Haoxian Chen, Isabelle Monot-Laffez, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Shanghai Institute of Ceramics, Chinese Academy of Science (CAS), Institute of semiconductors [Chinese Academy of Sciences - Beijing] (IOS), Institut des Molécules et Matériaux du Mans (IMMM), Le Mans Université (UM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Jan Dlugosz University in Czestochowa, and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Photoluminescence, Materials science, High conductivity, AlZn-Zni complex, Spark plasma sintering, Sintering, SPS, 02 engineering and technology, 01 natural sciences, ZnO ceramic, symbols.namesake, Electrical resistivity and conductivity, Al-doped, 0103 physical sciences, Materials Chemistry, [CHIM]Chemical Sciences, Ceramic, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, Doping, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Microstructure, [PHYS.MECA.ACOU]Physics [physics]/Mechanics [physics]/Acoustics [physics.class-ph], Chemical engineering, visual_art, Ceramics and Composites, symbols, visual_art.visual_art_medium, 0210 nano-technology, Raman spectroscopy
Abstract: International audience; Al-doped ZnO ceramics were sintered by conventional sintering method and spark plasma sintering (SPS) respectively. Electrical properties and microstructure have been investigated by various measurements. The samples sintered via SPS exhibit a huge electrical conductivity, up to 3.0 × 105 S/m at room temperature, which was much higher than that of the sample sintered via the conventional sintering. Structural and morphorlogical characterizations pointed out that the further incorporation of Al ions and the absence of a secondary phase, contribute to the increase of the carrier concentration. Raman spectroscopy revealed the occurrence of structural distortions and a disorder induced by Al doping. Photoluminescence spectra were interpreted by different electronic active defects such as the defect complexes (AlZn-Zni) which play a key for the high electrical conductivity. Thus, SPS and Al doping modified the microstructure and the concentration of the electronic active defects to ensure high electrical conductivities in doped ZnO-based ceramics.
Published: 2020

30. Towards valorizing natural coals in sodium-ion batteries: impact of coal rank on energy storage

Author: Abou-Rjeily, John, Laziz, Noureddine Ait, Autret-Lambert, Cecile, Outzourhit, Abdelkader, Sougrati, Moulay-Tahar, Ghamouss, Fouad, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Chemistry, Energy science and technology, lcsh:R, lcsh:Medicine, [CHIM]Chemical Sciences, lcsh:Q, lcsh:Science, Article, Materials science, ComputingMilieux_MISCELLANEOUS
Abstract: Coal samples of different ranks were investigated through various compositional, morphological/structural, and textural experiments prior to their electrochemical implementation in Na-ion half-cells. The purity of coals proved insignificant while distinctions in the flake size, pore width, pore distribution, ID/IG ratio, crystallite parameters (La and Lc) along with adjacent parameters, such as the R-empirical parameter, i.e., limited parallel graphene stacking proved more relevant for Na+ storage into the negative host electrodes. Coal powders were identified via a two-step TGA analysis technique displaying the overall carbon content of the coals and the impurities. Coal-based anode materials were prepared from raw and pyrolyzed coals (at 800 °C under argon gas-flow) and cycled in Na-ion half-cells to further investigate the impact of the coal rank on the energetic properties. High volatile bituminous coal with lower graphene stacking and augmented nanoscopic pores delivered higher reversible capacity in comparison with semi-anthracite coal, whether in their raw (67 vs. 54 mAh/g) or pyrolyzed (214 vs. 64 mAh/g) states, respectively vs. Na/Na+. The dominance of HVBC over SAC due to enhanced properties as R-empirical parameter, ID/IG ratio, and internal porosity. This study provides an exhaustive methodology to assess other carbonaceous anode materials further to evaluate their energy storage capabilities.
Published: 2020

31. Etude des propriétés diélectriques en couches minces d’une nouvelle phase dans le système K-Na-Nb-O pour des applications en hyperfréquences

Author: ASPE, Barthélemy, Demange, Valérie, Castel, Xavier, Simon, Quentin, Zaghrioui, Mustapha, Nadaud, Kevin, Députier, Stéphanie, Gouttefangeas, Francis, Sauleau, Ronan, Guilloux-Viry, Maryline, Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Synthèse Caractérisation Analyse de la Matière (ScanMAT), Université de Rennes (UR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Castel, Xavier, Nantes Université (NU)-Université de Rennes 1 (UR1), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.ELEC] Engineering Sciences [physics]/Electromagnetism, [SPI.MAT] Engineering Sciences [physics]/Materials, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract: National audience
Published: 2020

32. Texturation of lead-free BaTiO3 based piezoelectric ceramics

Author: Marchet, Pascal, Prato, Angel, Levassort, Franck, Bantignies, Claire, Borta-Boyon, Ana, Hladky, Anne-Christine, IRCER - Axe 3 : organisation structurale multiéchelle des matériaux (IRCER-AXE3), Institut de Recherche sur les CERamiques (IRCER), Institut des Procédés Appliqués aux Matériaux (IPAM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut des Procédés Appliqués aux Matériaux (IPAM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Vermon S.A., Thales Research and Technology [Palaiseau], THALES, Centre National de la Recherche Scientifique (CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Acoustique - IEMN, Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), THALES [France], Acoustique - IEMN (ACOUSTIQUE - IEMN), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SPI]Engineering Sciences [physics]
Abstract: oral invité; International audience; Piezoelectric ceramics have been integrated for a long time in a widerange of devices, particularly in ultrasonic applications (sonar systems,medical imaging...) and most of them use Pb(Zr,Ti)O3 (PZT) materials.However, due to health care and environmental problems, lead contentmust be reduced in such applications. Among the few lead-freematerials families which can be considered for the replacement of PZT,BaTiO3 appear as interesting because of its piezoelectric properties atroom temperature and capacity to be modulated by doping, even ifCurie temperature is not very high (120°C).However, ceramics are generally limited by their isotropic nature. Forthis reason, texturing process was developed in order toimprove/optimize their electromechanical properties. The aim of thepresent study is thus to obtain textured BaTiO3 based materials byusing the templated grain growth process (TGG) and to measure theirpiezoelectric properties.Doped and undoped BaTiO3 powders were prepared by classical solidstate route while BaTiO3 templates were elaborated by a molten saltsprocess. Green ceramics were then obtained by tapecasting of a slurrycontaining templates and matrix particles dispersed in theappropriated solvent. After drying, green sheet was cut, stacked,pressed and then sintered at the appropriated temperature, in order toobtain thick or thin samples. This process allowed obtaining highlyorientedmaterials (texturation degree 70% to 90%). Piezoelectricproperties were investigated, for doped and undoped samples, and fordifferent sintering parameters. Some samples appears as veryinteresting for piezoelectric applications with d33* higher than 300 pC/N, against 180 pC/N for BaTiO3 ceramics obtained by classical way.
Published: 2020

33. Evaluation of capacitive micromachined ultrasonic transducers for passive monitoring of microbubble-assisted ultrasound therapies

Author: Jean-Luc Gennisson, Ambre Dauba, Anthony Novell, Dominique Certon, Jordane Goulas, Laurène Jourdain, Laurent Colin, Benoit Larrat, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Unité BioMaps (BIOMAPS), Service Hospitalier Frédéric Joliot (SHFJ), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), LaBoratoire d'Imagerie biOmédicale MultimodAle Paris-Saclay (BIOMAPS), Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), ANR-19-CE19-0011,DROPMUT,Thérpie du ceveau augmentée par nano-gouttelettes et contrôlée par CMUT(2019), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Acoustics and Ultrasonics, Acoustics, Ultrasonic Therapy, Transducers, Ultrasound exposure, 01 natural sciences, 030218 nuclear medicine & medical imaging, Physics::Fluid Dynamics, 03 medical and health sciences, [SPI]Engineering Sciences [physics], 0302 clinical medicine, Capacitive micromachined ultrasonic transducers, Harmonic response, Arts and Humanities (miscellaneous), 0103 physical sciences, Physics::Atomic and Molecular Clusters, Animals, Ultrasonics, 010301 acoustics, Ultrasonography, Microbubbles, business.industry, Ultrasound, Skull, Passive monitoring, Biasing, Rats, Physics::Space Physics, Macaca, Microtechnology, business
Abstract: Passive cavitation detection can be performed to monitor microbubble activity during brain therapy. Microbubbles under ultrasound exposure generate a response characterized by multiple nonlinear emissions. Here, the wide bandwidth of capacitive micromachined ultrasonic transducers (CMUTs) was exploited to monitor the microbubble signature through a rat skull and a macaque skull. The intrinsic nonlinearity of the CMUTs was characterized in receive mode. Indeed, undesirable nonlinear components generated by the CMUTs must be minimized as they can mask the microbubble harmonic response. The microbubble signature at harmonic and ultra-harmonic components (0.5–6 MHz) was successfully extracted through a rat skull using moderate bias voltage.
Published: 2020

34. A core-shell synthesis of CaCu3Ti4O12 (CCTO) ceramics showing colossal permittivity and low electric losses for application in capacitors

Author: Sonia De Almeida-Didry, Cécile Autret-Lambert, François Gervais, Meledje Martin Nomel, Anthony Lucas, Samir Merad, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: Permittivity, Materials science, Sintering, 02 engineering and technology, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, 0104 chemical sciences, law.invention, Barrier layer, Capacitor, law, visual_art, visual_art.visual_art_medium, General Materials Science, Grain boundary, Dielectric loss, Ceramic, Composite material, 0210 nano-technology, Ceramic capacitor, ComputingMilieux_MISCELLANEOUS
Abstract: A core-shell synthesis is applied to CaCu3Ti4O12, a material that shows colossal permittivity. The objective was to test several bulk permittivity of the shell material in order to reach a large capacity of the grain boundaries after sintering. The permittivity is improved with certain shells while the bulk resistivity reaches levels approaching that of commercial grain boundary barrier layer (GBBL) ceramic capacitors. The highest permittivity is confirmed to be related to the highest capacity of grain boundaries. The bulk resistivity is related to that of grain boundaries. If one attaches the more important weight to a high bulk resistivity without need of permittivity larger than 15,000, as in commercial GBBL ceramic capacitors, several samples appear convenient. On the other hand, much higher permittivity can be reached like in CCTO with a shell of TiO2 but at the expense of dielectric losses, possibly due to oxygen departure from stoichiometry. Thermal post-treatment under various controlled atmosphere have been applied to reduce dielectric losses.
Published: 2020

35. Ageing of glass passivated TRIAC devices under thermal and electrical stress

Author: Gaël Gautier, Y. Buvat, Emilien Bouyssou, B. Morillon, STMicroelectronics [Tours] (ST-TOURS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Passivation, TRIAC, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Stress (mechanics), [SPI]Engineering Sciences [physics], Reliability (semiconductor), Thermal, Electrical and Electronic Engineering, Composite material, 0210 nano-technology, Safety, Risk, Reliability and Quality, Silicate glass, Layer (electronics), ComputingMilieux_MISCELLANEOUS
Abstract: A new silicate glass passivation was studied on Metal-Dielectrics-Semiconductor structures to characterize the reliability performances of TRIAC devices. The presence of mobile ions was identified in the glass affecting the reliability performances. The addition of a semi-insulating passivation layer turns out to drastically improve the reliability performances of TRIAC devices.
Published: 2020

36. Dispositif et procédé d’identification d’une contamination gazeuse

Author: Hernandez, Luis Iglesias, Certon, Dominique, Michaud, Jean-François, Shanmugam, Priyadarshini, Colin, Laurent, Dufour, Isabelle, Laboratoire de l'intégration, du matériau au système (IMS), Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics
Published: 2020

37. Dispositif et procédé de détection d’hydrogène

Author: Hernandez, Luis Iglesias, Certon, Dominique, Michaud, Jean-François, Shanmugam, Priyadarshini, Colin, Laurent, Dufour, Isabelle, Laboratoire de l'intégration, du matériau au système (IMS), Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics
Published: 2020

38. Properties comparison of three HF (50 MHz) single-element transducer radiation patterns with different focusing principles

Author: Jean-Marc Grégoire, Sean Toffessi Siewe, Franck Levassort, Samuel Callé, Aline Banquart, Frédéric Ossant, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Imagerie et cerveau (iBrain - Inserm U1253 - UNIV Tours ), Université de Tours (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Université de Tours-Institut National de la Santé et de la Recherche Médicale (INSERM)
Subjects: [PHYS]Physics [physics], Materials science, business.industry, Bandwidth (signal processing), Single element, 010103 numerical & computational mathematics, Zone plate, Radiation, 01 natural sciences, Piezoelectricity, [PHYS.MECA.ACOU]Physics [physics]/Mechanics [physics]/Acoustics [physics.class-ph], law.invention, 010101 applied mathematics, [SPI]Engineering Sciences [physics], Optics, Transducer, law, Focal length, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 0101 mathematics, business, Image resolution, ComputingMilieux_MISCELLANEOUS
Abstract: This numerical study compares the acoustic performance of three focalization principles (using a concave piezoelectric element, a lens, or a Fresnel Zone Plate) for a high-frequency (50 MHz) PVDF-based single-element transducer. A pseudo-spectral time-domain method was used to simulate the ultrasound wave propagation in water and to deduce acoustic properties in the focal zone. The focal distance was investigated between 10-20 mm with a step of 1 mm. The external diameter was identical for all configurations and fixed at 6 mm. The results showed a similar behavior between the concave shape and acoustic lens in terms of spatial resolution. However, the comparison showed a significant loss in sensitivity (−22 dB) for the FZP technique mainly due to the large bandwidth at −6 dB (27 MHz) of the electric excitation signal. But, with low bandwidth excitation signal, the simulation showed better performance in the focal zone with FZP transducer and a sensitivity difference with the two others configurations in the range 4.5-8.5 dB.
Published: 2020

39. Activité électrique de l'interface AlN/Si: identification de l'origine principale des pertes de propagation en hyperfréquences dans les composants GaN sur Silicium

Author: Bah, Micka, Valente, Damien, Lesecq, Marie, Defrance, Nicolas, Garcia barros, Maxime, De Jaeger, Jean-Claude, Frayssinet, Eric, Comyn, Rémi, Ngo, Thi Huong, Alquier, Daniel, Cordier, Yvon, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Puissance - IEMN (PUISSANCE - IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Centre de recherche sur l'hétéroepitaxie et ses applications (CRHEA), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), This work was supported by the technology facility network RENATECH and the French National Research Agency (ANR) through the projects ASTRID GoSiMP (ANR-16-ASTR-0006-01) and the 'Investissement d’Avenir' program GaNeX (ANR-11-LABX-0014)., Renatech Network, ANR-16-ASTR-0006,GoSiMP,Optimisations combinées par l'épitaxie pour composants hyperfréquences de puissance GaN sur Silicium(2016), ANR-11-LABX-0014,GANEX,Réseau national sur GaN(2011), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SPI]Engineering Sciences [physics], [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics
Abstract: International audience; AlN nucleation layers are the basement of GaN-on-Si structures grown for light-emitting diodes, high frequency telecommunication and power switching systems. In this context, our work aims to understand the origin of propagation losses in GaN-on-Si High Electron Mobility Transistors at microwaves frequencies, which are critical for efficient devices and circuits. AlN/Si structures are grown by Metalorganic Vapor Phase Epitaxy. Acceptor dopant in-diffusion (Al and Ga) into the Si substrate is studied by Secondary Ion Mass Spectroscopy and is mainly located in the first 200 nm beneath the interface. In this region, an acceptor concentration of a few 1018cm-3 is estimated from Capacitance-Voltage (C-V) measurements while the volume hole concentration of several 1017 cm-3 is deduced from sheet resistance. Furthermore, the combination of scanning capacitance microscopy and scanning spreading resistance microscopy enables the 2D profiling of both the p-type conductive channel and the space charge region beneath the AlN/Si interface. We demonstrate that samples grown at lower temperature exhibit a p-doped conductive channel over a shallower depth which explains lower propagation losses in comparison with those synthesized at higher temperature. Our work highlights that this p-type channel can increase the propagation losses in the high-frequency devices but also that a memory effect associated with the previous sample growths with GaN can noticeably affect the physical properties in absence of proper reactor preparation. Hence, monitoring the acceptor dopant in-diffusion beneath the AlN/Si interface is crucial for achieving efficient GaN-on-Si microwave power devices.
Published: 2020

40. Highly textured lead-free piezoelectric polycrystals grown by the micro-pulling down freezing technique in the BaTiO3 –CaTiO3 system

Author: Kei Kamada, Franck Levassort, Vincent Motto-Ros, Sébastien Pairis, Philippe Veber, Ana Borta-Boyon, Akira Yoshikawa, Jérôme Debray, Matias Velázquez, Karol Bartosiewicz, Ruben Vera, Luminescence (LUMINESCENCE), Institut Lumière Matière [Villeurbanne] (ILM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Tohoku University [Sendai], Cristaux massifs (NEEL - CrisMass), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Croissance Cristalline et MicroAnalyse (NEEL - C2MA), Spectrométrie des biomolécules et agrégats (SPECTROBIO), Thales Research and Technology [Palaiseau], THALES [France], GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Science et Ingénierie des Matériaux et Procédés (SIMaP), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Centre de diffractométrie Henri Longchambon, Institut de Chimie de Lyon, École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, Cristaux Massifs (CrisMass), Optique et microscopies (POM), THALES, Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010302 applied physics, [PHYS]Physics [physics], Materials science, Micro-pulling-down, 02 engineering and technology, General Chemistry, Dielectric, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Piezoelectricity, [SPI]Engineering Sciences [physics], Impurity, 0103 physical sciences, [CHIM]Chemical Sciences, General Materials Science, Grain boundary, Crystallite, Composite material, 0210 nano-technology, Electron backscatter diffraction, Solid solution
Abstract: International audience; Highly textured cm-sized (Ba1−xCax)TiO3 (x = 0.05) polycrystals at off-eutectic composition were grown by the micro-pulling down freezing technique from a BaTiO3–CaTiO3 system at a high pulling velocity of about 48 mm h−1. Textured polycrystals exhibiting submillimetre-sized dendrites along the (110)pc growth direction and geometrical grains along the (100)pc direction were revealed by a complementary analysis performed by Laue diffraction and EBSD techniques. An average Ca content of about x = 0.0435 was measured throughout the whole volume of the boule and led to an effective partition coefficient of Ca of about 0.87. LIBS measurements highlighted the local segregation of Ca and major impurity contents within dendrites, grains and at the grain boundaries. Dielectric and piezoelectric measurements performed on oriented polycrystalline textured samples led to Curie temperatures up to 116 °C and d33 up to 214 pC N−1, in very good agreement with literature values. Both chemical and physical results obtained in the BCT system make the μ-PD technique a promising and alternative way to improve the piezoelectric response of lead-free solid solution-based crystals through their texturing along preferential crystallographic directions.
Published: 2020

41. Formation of interstitial silicon defects in Si- and Si,P-doped nanodiamonds and thermal susceptibilities of SiV − photoluminescence band

Author: Valery A. Davydov, Sumin Choi, Taras Plakhotnik, Viatcheslav N. Agafonov, L.F. Kulikova, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Brightness, Photoluminescence, Materials science, Silicon, Analytical chemistry, chemistry.chemical_element, Bioengineering, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Homogeneity (physics), General Materials Science, Electrical and Electronic Engineering, Nanodiamond, ComputingMilieux_MISCELLANEOUS, Mechanical Engineering, Doping, General Chemistry, Spectral bands, Atmospheric temperature range, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [PHYS.MECA.ACOU]Physics [physics]/Mechanics [physics]/Acoustics [physics.class-ph], chemistry, Mechanics of Materials, 0210 nano-technology
Abstract: We have produced two types of synthetic nanodiamonds Si- and Si,P-doped and have characterized the thermal susceptibilities of the spectral band of silicon-vacancy (SiV-) centers at approximately 740 nm in each case. The covered temperature range from 295 to 350 K is of interest for thermometry in biological systems. Comparison of the relative brightness of the Si- and Si,P-doped crystals shows that phosphorous significantly increases average concentration and homogeneity of distribution of SiV- centers in nanodiamonds. Moreover, linear dependence on temperature of the zero-phonon line width in Si-doped crystals is 0.061(2) nm K-1 but is 0.047(3) nm K-1, about 35% smaller in Si,P-doped nanodiamonds. This proves control of SiV- properties with additional chemical doping and close proximity of Si and P atoms.
Published: 2020

42. Strain wave pathway to semiconductor-to-metal transition revealed by time-resolved X-ray powder diffraction

Author: Simon Ebner, Majed Chergui, Hervé Cailleau, Paul Beaud, Henrik T. Lemke, Eric Collet, Gerhard Ingold, Alexei Bosak, Andrej Babic, Dmitry Ozerov, S. Vetter, Laurent Cario, Roman Bertoni, Laurent Guérin, Pavle Juranić, Michael Wulff, Giulia F. Mancini, Vincent Esposito, T. Zmofing, Alexander Roland Oggenfuss, Aldo Mozzanica, Shin-ichi Ohkoshi, Yunpei Deng, Maciej Lorenc, Ivan Usov, Serhane Zerdane, Matteo Levantino, Akos Schreiber, Marco Cammarata, Roman Mankowsky, Elzbieta Trzop, Rolf Follath, P. Böhler, Céline Mariette, S. Redford, C. Svetina, Olivier Hernandez, Leonardo Sala, A. Volte, X. Dong, L. Patthey, Hiroko Tokoro, V. Ta Phuoc, B. Lépine, A. Keller, Etienne Janod, Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), The University of Tokyo (UTokyo), Université de Tsukuba = University of Tsukuba, SwissFEL, Paul Scherrer Institut, SLAC National Accelerator Laboratory (SLAC), Stanford University, Ecole Polytechnique Fédérale de Lausanne (EPFL), European Synchrotron Radiation Facility (ESRF), IM‐LED LIA, Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), ANR-16-CE30-0018,ELASTICA,Cooperativité Elastique Photo-Induite dans des Matériaux Bistables avec Changement de Volume(2016), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: Diffraction, Phase transition, Materials science, Electronic properties and materials, Bistability, Science, FOS: Physical sciences, General Physics and Astronomy, Physics::Optics, Applied Physics (physics.app-ph), 02 engineering and technology, 01 natural sciences, General Biochemistry, Genetics and Molecular Biology, Article, Condensed Matter::Materials Science, 0103 physical sciences, Physics::Atomic and Molecular Clusters, [CHIM]Chemical Sciences, 010306 general physics, [PHYS]Physics [physics], Condensed Matter - Materials Science, Multidisciplinary, Condensed matter physics, Materials Science (cond-mat.mtrl-sci), Physics - Applied Physics, General Chemistry, Acoustic wave, 021001 nanoscience & nanotechnology, 3. Good health, Phase transitions and critical phenomena, Picosecond, Femtosecond, 0210 nano-technology, Ultrashort pulse, Powder diffraction
Abstract: Thanks to the remarkable developments of ultrafast science, one of today's challenges is to modify material state by controlling with a light pulse the coherent motions that connect two different phases. Here we show how strain waves, launched by electronic and structural precursor phenomena, determine a macroscopic transformation pathway for the semiconducting-to-metal transition with large volume change in bistable Ti$_3$O$_5$ nanocrystals. Femtosecond powder X-ray diffraction allowed us to quantify the structural deformations associated with the photoinduced phase transition on relevant time scales. We monitored the early intra-cell distortions around absorbing metal dimers, but also long range crystalline deformations dynamically governed by acoustic waves launched at the laser-exposed Ti$_3$O$_5$ surface. We rationalize these observations with a simplified elastic model, demonstrating that a macroscopic transformation occurs concomitantly with the propagating acoustic wavefront on the picosecond timescale, several decades earlier than the subsequent thermal processes governed by heat diffusion., 30 pages (including supplementary text), 5 main figures, 9 supplementary figures; corrected author list
Published: 2020

43. A Boundary Element Model for CMUT-Arrays Loaded by a Viscoelastic Medium

Author: Nicolas Senegond, Dominique Certon, Maxime Hery, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Vermon SA, Tours, and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Acoustics and Ultrasonics, Acoustics, Capacitive sensing, 01 natural sciences, Viscoelasticity, Viscosity, [SPI]Engineering Sciences [physics], Transducer, Capacitive micromachined ultrasonic transducers, 0103 physical sciences, Ultrasonic sensor, Electrical and Electronic Engineering, 010301 acoustics, Instrumentation, Electrical impedance, Boundary element method, ComputingMilieux_MISCELLANEOUS
Abstract: This work is an extension of a model previously developed by our group to simulate the electroacoustic response of capacitive micromachined ultrasonic transducer (CMUT)-based linear arrays acoustically loaded by a fluid medium. The goal is to introduce the viscoelasticity effects of the propagation medium into the modeling. These effects are mainly due to the passivation layer used to protect the transducer, i.e., a silicon polymer, a few hundred micrometers thick. The passivation layer is also required to ensure good acoustic coupling between the transducer front face and human skin. The theoretical approach relies on the determination of a new boundary matrix to simulate the acoustic coupling between the CMUT array and the viscoelastic medium. The complete numerical implementation of a 3-D Green's function for a viscoelastic half-space is hence described. In order to reduce computing time, an optimization was carried out through vectorization and parallelization methods. A comparison is then performed with the analytical solutions, from the literature, obtained for elastic half-space. An experimental validation of shear viscosity effects is performed through electrical impedance measurements of the CMUT linear arrays loaded by oils of varying viscosity. A very good agreement is obtained, showing that the model correctly takes the shear viscosity effects on the mechanical response of the CMUT into account, i.e., a shift in the resonance frequency and a diminution in the mechanical quality factor are observed.
Published: 2020

44. High-rate cyclability and stability of LiMn2O4 cathode materials for lithium-ion batteries from low-cost natural β−MnO2

Author: Fouad Ghamouss, Cécile Autret-Lambert, John Abou-Rjeily, Noureddine Ait Laziz, Ilham Bezza, Moulay Tahar Sougrati, Physico-chimie des Matériaux et des Electrolytes pour l'Energie (PCM2E), Université de Tours, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Réseau sur le stockage électrochimique de l'énergie (RS2E), Université de Picardie Jules Verne (UPJV)-Institut de Chimie du CNRS (INC)-Aix Marseille Université (AMU)-Université de Pau et des Pays de l'Adour (UPPA)-Université de Nantes (UN)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Collège de France (CdF (institution))-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Université Grenoble Alpes (UGA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), Université de Tours (UT), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Aix Marseille Université (AMU)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Collège de France (CdF (institution))-Université de Picardie Jules Verne (UPJV)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Université Grenoble Alpes (UGA), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM), and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Energy Engineering and Power Technology, chemistry.chemical_element, 02 engineering and technology, Electrolyte, Manganese, engineering.material, 010402 general chemistry, 01 natural sciences, 7. Clean energy, law.invention, law, [CHIM]Chemical Sciences, General Materials Science, Calcination, ComputingMilieux_MISCELLANEOUS, Pyrolusite, Renewable Energy, Sustainability and the Environment, Spinel, 021001 nanoscience & nanotechnology, Cathode, 0104 chemical sciences, chemistry, Chemical engineering, engineering, Lithium, 0210 nano-technology, Capacity loss
Abstract: The implementation of spinel LiMn2O4 in lithium-ion batteries has been long established commercially and well-reported academically. Nowadays, most commercial spinel LiMn2O4 electrodes are synthesized by electrolytic manganese dioxide (EMD) precursors. However, using earth-abundant and inexpensive pyrolusite (β-MnO2) as reported in this work, offers several advantages. The synthesis of spinel LiMn2O4 using β-MnO2 precursors by solid-state reaction followed by thermal calcination under air generated micro rod-like lithium impregnated powders. Examining the electrochemical performance of these active materials upon Li-ion intercalation registered an initial specific discharge capacity of 95 mA h g-1. The synthesized cathode material was able to cycle at high rates (up to 9C) while retaining half of its initial discharge capacity, with just an overall drop reaching 7% of its capacity. Distinctive stability after 500 cycles at combined charge/discharge rates was recorded with a minute irreversible capacity loss and an overall capacity drop of 3%. This work authenticates the use of natural pyrolusite ingredients as a precursor for spinel LiMn2O4 synthesis besides providing economic and ecological assertions with the synthesis technique implemented.
Published: 2020

45. Strategies to Enhance ZnO Nanogenerator Performance via Thermal-Annealing and Cryo-Cooling

Author: Poulin-Vittrant, Guylaine, Nadaud, Kevin, Chandraiahgari, Chandrakanth Reddy, Alquier, Daniel, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), EnSO project has been accepted for funding within the Electronic Components and Systems For European Leadership Joint Undertaking in collaboration with the European Union’s H2020 Framework Programme (H2020/2014-2020) and National Authorities [Grant agreement No. 692482]., French National Research Agency [Grant agreement ANR-14-CE08-0010-01], Region Centre [Grant agreements 2014-00091629 and 2016-00108356], GREMAN UMR 7347, CNRS, Université de Tours, INSA-CVL, EnSO, ANR-14-CE08-0010,FLexIBLE,Microgénérateur souple à base de nanofils ZnO et couche mince Lithium(2014), European Project: 692482,H2020,H2020-ECSEL-2015-2-IA-two-stage,EnSO(2016), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: thermal annealing, Condensed Matter - Materials Science, liquid nitrogen, hydrothermal method, [SPI.NRJ]Engineering Sciences [physics]/Electric power, post-growth treatment, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, zinc oxide, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, piezoelectric nanogenerators
Abstract: Piezoelectric capacitive NanoGenerators (NG) based on vertically grown crystalline zinc oxide nanowires (ZnO-NWs) have been fabricated using a low-cost and scalable hydrothermal method on gold-coated silicon substrates, which served as both a seed layer and a conductive bottom electrode. Morphological and structural characterizations demonstrate that the obtained ZnO NWs are dense, uniformly distributed, vertically well aligned and exhibit good crystal quality. The piezoelectric NG consists of ZnO-NWs grown on a gold-coated silicon substrate, parylene-C matrix, titanium/aluminium top electrode and poly(dimethylsiloxane) (PDMS) encapsulating layer. In order to enhance the NG performances, which is the main goal of this study, two distinctly different post-growth treatments, namely thermal annealing in ambient air and cryo-cooling by immersion in liquid nitrogen, are applied and their effect studied. Achieving the high performance of NG via the combination of high-quality NWs growth and subsequent post-growth treatment is presented. Superior global performance of NG has been observed with a post-treatment of cryo-cooling for an optimum duration compared to the thermal annealing signifies the simplicity and novelty of the work. The proposed strategies highlight the role of post-growth treatments towards the fabrication of high-performance functional NG to be incorporated into future smart objects.
Published: 2020

46. Tetragonal tungsten bronze phase thin films in the K–Na–Nb–O system: Pulsed laser deposition, structural and dielectric characterizations

Author: Kevin Nadaud, Xavier Castel, Ronan Sauleau, Anne Waroquet, Quentin Simon, Stéphanie Députier, Mustapha Zaghrioui, Brice Gautier, David Albertini, Maryline Guilloux-Viry, Barthélemy Aspe, Valérie Demange, Francis Gouttefangeas, Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Synthèse Caractérisation Analyse de la Matière (ScanMAT), Université de Rennes (UR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), INL - Dispositifs Electroniques (INL - DE), Institut des Nanotechnologies de Lyon (INL), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École Centrale de Lyon (ECL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), INL - Plateforme Technologique Nanolyon (INL - Nanolyon), Région Bretagne, CPER SCANMAT 2015-2020, Seventh Framework Programme, European Regional Development Fund, Ministère de l'Education Nationale, de l'Enseignement Superieur et de la Recherche, Rennes Métropole, Département d’Ille et Vilaine, Département des Côtes d’Armor, Saint-Brieuc Armor Agglomération, SOPHIE/STIC & Ondes, Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Rennes-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES), Institut d'Electronique et de Télécommunications de Rennes (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École Centrale de Lyon (ECL), Université de Lyon, Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École Centrale de Lyon (ECL), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Nantes Université (NU)-Université de Rennes 1 (UR1), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-École Centrale de Lyon (ECL), Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)
Subjects: Materials science, Visualization Q Simon: Conceptualization, Writing, Writing - Original Draft, Analytical chemistry, chemistry.chemical_element, Supervision, Resources X Castel: Conceptualization, 02 engineering and technology, Dielectric, Tungsten, Writing F Gouttefangeas: Formal Analysis, 010402 general chemistry, 01 natural sciences, funding acquisition B Gautier: Conceptualization, Pulsed laser deposition, [SPI.MAT]Engineering Sciences [physics]/Materials, Tetragonal crystal system, Project Administration, Formal Analysis, Visualization K Nadaud: Conceptualization, Materials Chemistry, funding acquisition M Guilloux-Viry: Conceptualization, Thin film, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, ComputingMilieux_MISCELLANEOUS, Writing -Original draft, Visualization, Investigation, Resources R Sauleau: Conceptualization, Mechanical Engineering, Metals and Alloys, Credit Authors Statement B Aspe: Conceptualization, 021001 nanoscience & nanotechnology, Ferroelectricity, Resources M Zaghrioui: Conceptualization, Resources, 0104 chemical sciences, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, chemistry, Visualization S Députier: Conceptualization, Mechanics of Materials, funding acquisition, Sapphire, Dissipation factor, funding acquisition A Waroquet: Investigation, Visualization V Demange: Conceptualization, Visualization D Albertini: Formal Analysis, 0210 nano-technology
Abstract: International audience; Pulsed laser deposition parameters have been determined to synthesize pure Tetragonal Tungsten Bronze (TTB) phase thin films in the (K,Na)–Nb–O system (KNN). In relation to the high volatility of alkaline elements, it was found that the target composition and the target-substrate distance are of first importance. The TTB phase was identified by X-ray and electron diffraction and the surface microstructure consisting mainly of nanorods supports the formation of hallmark of the TTB phase. Poly-oriented nanorods have been obtained on both C-plane sapphire and (111)Pt/TiO2/SiO2/(001)Si substrates whereas horizontal nanorods oriented along the (hk0) planes have been grown on (100) and (110) SrTiO3. All the nanorods are parallel together when grown on (110) SrTiO3 and they present two in-plane orientations rotated of 90° from each other on (100) SrTiO3. Dielectric characteristics (dielectric permittivity εr, and loss tangent tanδ) have been measured at low (1 kHz - 1 MHz) and high (1 GHz–40 GHz) frequencies, on films deposited on Pt coated silicon and sapphire, respectively. A value of εr = 200 at 1 kHz with tanδ = 0.015 were measured in a parallel plate capacitor configuration, whereas εr = 130 and tanδ = 0.20 at 10 GHz were retrieved from transmission lines printed on the KNN TTB thin film grown on C-plane sapphire. Raman investigations of the TTB films were performed in the temperature range 77–873 K, confirming the TTB phase formation and the absence of structural transition. Piezoelectric Force Microscopy measurements evidenced a piezoelectric signal although no switching could be performed. However the dielectric measurements, complicated by high leakage currents when a DC voltage was applied, did not evidence any proof of ferroelectricity for the undoped KNN TTB films whereas results reported on other niobates (A,A′)6Nb10O30 (with A: K, Na and A’: Sr, Ba, Ca) have shown Curie temperatures, lying between 156 °C and 560 °C, separating the paraelectric phase (space group: P4/mbm N°127) and the ferroelectric one (space group: P4bm N°100).
Published: 2020

47. Zero-Level Packaged RF-MEMS Switched Capacitors on Glass Substrates

Author: Clement Hallepee, Nesrine Belkadi, Kevin Nadaud, Damien Passerieux, Pierre Blondy, Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), XLIM (XLIM), Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), MINACOM, Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), MINACOM (XLIM-MINACOM), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: Microelectromechanical systems, Materials science, Passivation, business.industry, Mechanical Engineering, 020206 networking & telecommunications, 02 engineering and technology, Nitride, 021001 nanoscience & nanotechnology, law.invention, [SPI.TRON]Engineering Sciences [physics]/Electronics, chemistry.chemical_compound, Capacitor, Silicon nitride, chemistry, Plasma-enhanced chemical vapor deposition, law, 0202 electrical engineering, electronic engineering, information engineering, Optoelectronics, Electrical and Electronic Engineering, Thin film, 0210 nano-technology, business, Layer (electronics), ComputingMilieux_MISCELLANEOUS
Abstract: This article presents the design, realization and measurement of thin-film packaged RF-MEMS switched capacitors for millimeter-wave applications. Packaging is included in the MEMS fabrication process, with silicon nitride thin film shell above MEMS structure. Thin-film packaging is done using a combination of electron beam evaporated metal and silicon nitride PECVD deposition. The package hermeticity has been evaluated after the first metal sealing layer deposition, indicating that the protective nitride shells are hermetic enough before the final PECVD passivation. The devices have been fabricated on glass substrates, allowing for further combination with low loss, millimeter-wave passive circuits. The MEMS capacitors are actuated by deflecting thin gold metal membrane towards the package dielectric layer, increasing the capacitance by a factor 3, from 25 fF to 75 fF. The device size, including its hermetic packaging, is $70\times 50\,\,\mu \text{m}^{\mathbf {2}}$ . Reliability has been evaluated, through 12-hour hold-down test measurements. [2019-0060]
Published: 2020

48. Characterization of 1-3 Piezocomposite Using Lamb Waves Propagation

Author: Rouffaud, Rémi, Hladky, Anne-Christine, Certon, Dominique, Balé, Antoine, Levassort, Franck, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Acoustique - IEMN, Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Acoustique - IEMN (ACOUSTIQUE - IEMN), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.MECA.VIBR]Physics [physics]/Mechanics [physics]/Vibrations [physics.class-ph], Lamb waves, Piezocomposite, Characterization, Ultrasound, [PHYS.MECA.ACOU]Physics [physics]/Mechanics [physics]/Acoustics [physics.class-ph]
Abstract: International audience; Due to their enhanced electromechanical properties with respect to conventional piezoelectric ceramics, 1-3 piezocomposite (1-3PC) materials are predominant in high performance ultrasonic array. Their complete effective electroelastic modulus (EEM) has a significant importance for numerical simulations to study undesired effects that almost depend on the transverse characteristics of the 1-3PC, such as mechanical cross-talks caused by Lamb waves. To determine the effective elastic, piezoelectric and dielectric tensors, theoretical homogenization models are available in literature. However, complete and accurate databases of each phase are required. In this work, a new method, based on direct measurements of propagative Lamb waves, is proposed to determine a complete 1-3PC EEM under operating conditions. First, in order to determine the 1-3PC EEM, experimental dispersion curves of the low-order Lamb waves are necessary. Then, experimental data are fitted using a recursive method that combines the theoretical curves obtained with Finite Element method and a fitting process based on a genetic algorithm. The cost function of this method intends to minimize the distance in the (w,k)-space between the three first symmetric and antisymmetric theoretical Lamb modes and those which were measured. A 1-3PC made of Pz27/Epoxy resin (70% volume fraction) with a pitch of 610�m was used to perform the measurements. Mass electrode covers the whole bottom surface while a thin rectangular electrode (15x1.11 mm2) was deposited on the top surface and aligned with the pillars of the 1-3PC to favor an particular propagation direction. Several electrode patterns were tested to change the propagation direction. Finally, a scanning laser vibrometer was used to measure normal displacements at the sample surface. Complete EEM was so obtained. These first results enable to demonstrate the efficiency and the robustness of this method for determining EEM experimentally. Other propagation directions were used to increase the solution?s accuracy.
Published: 2020
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49. Cmut Time of Flight Gas Sensor By Phase Shift Measurement

Author: Luis Iglesias, Priyadarshini Shanmugam, Jean-François Michaud, Isabelle Dufour, Dominique Certon, Daniel Alquier, Laboratoire de l'intégration, du matériau au système (IMS), Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université Sciences et Technologies - Bordeaux 1, and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0303 health sciences, 03 medical and health sciences, Time of flight, 0302 clinical medicine, Materials science, Capacitive micromachined ultrasonic transducers, Acoustics, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 030217 neurology & neurosurgery, ComputingMilieux_MISCELLANEOUS, 030304 developmental biology
Abstract: Introduction The most common approach to measure a gas concentration consists in coating the exposed part of a sensor with a functionalized film in order to absorb the targeted gas [1]. However, it is well known that a sensitive coating compromises the long term stability of the sensor mostly due to aging of such film [2]. This has resulted in an increasing interest in uncoated sensors, which rely on the change of the physical properties (mass density for instance) of their surrounding gas despite their lack of selectivity. One example of uncoated sensors are time of flight sensors. Capacitive micromachined ultrasonic transducers (CMUTs) [3], have been previously used for time of flight gas sensing due to their easy integration capabilities. However, these methods rely on peak detection algorithms which can be very complex and hard to integrate. In this study, we present a new simple approach using the phase shift of a continuous ultrasonic wave to measure the time of flight between two CMUT arrays. The principle of this method along with the experimental setup and results will be presented in the following sections. Sensor Figure 1 shows a picture of the sensor used in this study. It consists of an array of thousands of CMUTs as the one illustrated in Figure 2 fabricated according to [4]. By applying a bias Vdc and an alternative voltage Vdc between its electrodes, the top electrode vibrates generating an ultrasonic mechanical vibration in the gas (emitter mode). Similarly, when the membrane vibrates due to a mechanical vibration of the gas, the CMUT’s capacitance changes generating an electrical signal (receiver mode). Principle The experimental setup schematics are shown in Figure 3. One CMUT array working as emitter (1) generates a continuous ultrasonic wave at a given angular frequency (ω) through a network analyzer in gain/phase configuration (2). The wave propagates through the gas at a velocity (C) that depends on the gas composition. For this study the gas consists of N2 (similar to air) and either CO2 or H2. In the case of an ideal gas, its expression is given by Equation 1 where R = 8.314 J.K-1.mol-1, T = 20°C, x is the molar fraction of a gas (either N2 or the mixture), M is the corresponding molar mass and γ is the adiabatic index given by Equation 2 where cp and cv are, respectively, the isobar and isochoric heat capacitance per unit mass. After a delay τ, the wave reaches a second CMUT array (3) working in receiver mode. The generated signal is conditioned by a charge amplifier (4) and then injected back to the network analyzer. At a given time t, the phase difference φ between the emission and the reception is proportional to τ as shown in Equation 3. Therefore, the slope of the curve φ(ω ) changes when the gas composition changes. To verify this experimentally, the curves φ( w) are shown for pure N2 (black), 4% of H2 in N2 (blue) and 4% of CO2 in N2 (green) in Figure 4. Results 1-Sensitivity Tests under H2 and CO2 in N2 at different concentrations (4%, 3%, 2% and 1%) were performed and are shown respectively in Figure 5 and Figure 6. From these measurements, the calibration curves were obtained with good linearity (Figure 7). The sensitivities (slope of the curves) to each gas were measured and their values are, respectively, S{H2,exp}=-92ns/% and S{CO2,exp}=55ns/%. Their corresponding theoretical values around a given concentration (xmix=4%) can be approximated by Equation 4. The obtained values are respectively, S{H2,th}=-135ns/% and S{CO2,th}=97ns/% which are consistent with the experiments. 2-Limit of Detection Finally, knowing the sensitivity to a gas Sgas , a theoretical limit of detection (LOD) can be estimated with Equation 5 where σ=1ns, is the noise standard deviation of the sensor. The obtained values for H2 and CO2 are, respectively, LODH2 =0.03%, LODCO 2 =0.05%. In order to verify this experimentally, tests at low concentrations for H2 and CO2 were performed and are shown, respectively, in Figure 8 and Figure 9. The obtained results are consistent with the calculations. Conclusion In this study we presented a new way of determining the concentration of binary gas mixtures without a sensitive chemical coating through a time of flight measurement. We verified this method using N2 as a reference and both CO2 and H2 as analytes. Finally, we showed experimentally that the LOD in N2 is less than 0.03% for H2 and less than 0.05% for CO2 which, despite being worse than what has been reported with a coated sensor, remain comparable to the state of the art of uncoated sensors and to some commercial coated sensors. References [1] Göpel, W. New Materials and Transducers for Chemical Sensors. Sens. Actuators B Chem. 1994, 18 (1–3), 1–21. https://doi.org/10.1016/0925-4005(94)87049-7. [2] Romain, A. C.; Nicolas, J. Long Term Stability of Metal Oxide-Based Gas Sensors for e-Nose Environmental Applications: An Overview. Sens. Actuators B Chem. 2010, 146 (2), 502–506. https://doi.org/10.1016/j.snb.2009.12.027. [3] Shanmugam, P.; Iglesias, L.; Michaud, J.-F.; Dufour, I.; Alquier, D.; Colin, L.; Certon, D. CMUT Based Air Coupled Transducers for Gas-Mixture Analysis. In 2018 IEEE International Ultrasonics Symposium (IUS); IEEE: Kobe, 2018; pp 1–4. https://doi.org/10.1109/ULTSYM.2018.8579789. [4] Heller, J.; Boulme, A.; Alquier, D.; Ngo, S.; Certon, D. Performance Evaluation of CMUT-Based Ultrasonic Transformers for Galvanic Isolation. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 2018, 65 (4), 617–629. https://doi.org/10.1109/TUFFC.2018.2796303. Figure 1
Published: 2020

50. Electrical control of the elastic wave propagation in a piezoelectric plate: reduction of the crosstalk in a multi- element ultrasonic transducer

Author: Fei, Linyu, Haumesser, Lionel, Tran-Huu-Hue, Louis-Pascal, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.MECA.VIBR]Physics [physics]/Mechanics [physics]/Vibrations [physics.class-ph], multi-element ultrasonic transducers, piezoelectric material, phononic crystals, [PHYS.MECA.ACOU]Physics [physics]/Mechanics [physics]/Acoustics [physics.class-ph]
Abstract: International audience; The cross couplings in a multi-element ultrasonic transducer create perturbations in its radiation, affecting image quality. The crosstalk phenomenon increases the number of vibrating elements by comparison to the number of electrically excited elements and produces spurious guided modes. Solutions have been proposed to reduce the crosstalk, for example, the passive mechanical decoupling between the elements, i.e. varying the depth of the periodic cut of the piezoelectric ceramics and also an active electrical decoupling [1], in applying to the other elements, except to the active one, a suitable electric voltage. This work proposes another possibility by using a passive electrical decoupling. A homogeneous piezoelectric plate, covered on one side by a 1D periodic arrangement of thin metallic electrodes and on the other side by a full metallic electrode, is considered. Through electrical boundary conditions applied to the electrodes, band gap location and width of guided elastic waves can be tuned to a range including the resonance frequency of the first piezoelectric thickness mode. Finite element analysis and experimental measurements show the appearance of band gaps in the dispersion curves, which limits the inter-element couplings and thus the parasitic signals in the radiation. Bibliography: [1] BYBI, A., et al. Electrical method for crosstalk cancellation in transducer arrays. NDT & E International, 2014, vol. 62, p. 115-121.
Published: 2020
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