Etude par microscopie electronique a haute resolution des etapes initiales de transformations a l'etat solide

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

L'usage des indicateurs recherche : témoignages d'établissements. Etude bibliométrique du pôle universitaire d'Aix-Marseille pour le Comité d'Orientation Scientifique

National audienceCette communication présente d'une étude bibliométrique réalisée en 2006 pour la tenue d'un comité d'orientation scientifique organisé à l'initiative des trois universités d'Aix Marseille. Cette étude bibliométrique était l'un des nombreux d'outils proposés au comité d'orientation scientifique (une quarantaine d'experts externes) pour l'assister dans son travail de recommandation. Les résultats de l'étude offrait une vision globale et > de l'activité et de l'évolution du pôle scientifique de la région d'Aix-Marseille. La méthodologie employée pour cette étude était fortement inspirée de la méthode d'analyse des portefeuilles d'activités stratégiques mise en œuvre lors d'une analyse concurrentielle. La transposition de cette méthode a nécessité de définir les unités scientifiques stratégiques, de choisir les pôles universitaires >, de choisir le critère de mesure de l'activité scientifique, d'étudier l'évaluation de la dynamique des deux précédents facteurs au fil du temps et au final la construction d'une représentation graphique du positionnement du portefeuille scientifique du pôle Aix-Marseille et de sa dynamique. Cette étude bibliométrique a permis de confirmer la politique scientifique affichée par le pôle d'Aix Marseille et de donner une vision globale de son positionnement international. Elle a également eu un rôle pédagogique. Elle a permis d'habituer les acteurs de la recherche à l'utilisation des indicateurs bibliométriques dans un cadre d'auto-évaluation

Ti segregation at CoSi grain boundaries

International audienceThe localization of Ti at grain boundaries after the phase formation of CoSi 2 on Si(111) from a Co-Ti bilayer is examined. For the chemical analysis at the atomic scale, atom probe tomography (APT) is applied. The structure of grain boundaries is analyzed by high resolution transmission electron microscopy (HR TEM). A polycrystalline CoSi 2 film has been formed after annealing. Inside the grains of CoSi 2 , Ti is determined to be present in low concentration of 0.2 at %. An excess of Ti is measured at the grain boundaries. The Ti excess varies for different grain boundaries. HR TEM shows different distances between defects for varying misorientation. The distances between defects are compared with theoretical misfits at the grain boundaries. A relationship between the Ti excess at grain boundaries determined by APT and the defect densities of grain boundaries analyzed by HRTEM is proposed

Methods for Gibbs triple junction excess determination: Ti segregation in CoSi2 thin film

International audienceDiffusion barriers play an important role in numerous phase formation processes. A well known example in microelectronics is the reactive diffusion growth of silicide thin films which are applied as contact materials. In this work, the effect of a Ti interlayer on the kinetics of the formation of CoSi by reactive diffusion is investigated. Therefore, Co(100 nm)/Ti(5 nm) deposited on Si(111) is annealed at various temperatures. Transmission electron microscopy and atom probe tomography allo

High resolution transmission electron microscopy correlated to in-field Mössbauer spectrometry to investigate exchange coupling behavior and surface frustrated moments

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Origin of the superstructure elucidated by atomic resolution HAADF-STEM and HREM in the Ce10W22O81 lanthanide tungstate phase

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Heart rhythm characterization through induced physiological variables

International audienceAtrial fibrillation remains a major cause of morbi-mortality, making mass screening desirable and leading industry to actively develop devices devoted to automatic AF detection. Because there is a tendency toward mobile devices, there is a need for an accurate, rapid method for studying short inter-beat interval time series for real-time automatic medical monitoring. We report a new methodology to efficiently select highly discriminative variables between physiological states, here a normal sinus rhythm or atrial fibrillation. We generate induced variables using the first ten time derivatives of an RR interval time series and formally express a new multivariate metric quantifying their discriminative power to drive state variable selection. When combined with a simple classifier, this new methodology results in 99.9% classification accuracy for 1-min RR interval time series (n = 7,400), with heart rate accelerations and jerks being the most discriminant variables. We show that the RR interval time series can be drastically reduced from 60 s to 3 s, with a classification accuracy o

Selective Growth of Graphene-Confined Inkjet-Printed Sn Nanoparticles on Plastic Using Intense Pulsed Light Annealing

International audiencePrinting graphene-based nanomaterials on flexible substrates has become a burgeoning platform for next-generation technologies. Combining graphene and nanoparticles to create hybrid nanomaterials has been proven to boost device performance, thanks to their complementary physical and chemical properties. However, high growth temperatures and long processing times are often required to produce high-quality graphene-based nanocomposites. For the first time, we report a novel scalable approach for additive manufacturing of Sn patterns on polymer foil and their selective conversion into nanocomposite films under atmospheric conditions. A combination of inkjet printing and intense flashlight irradiation techniques is studied. Light pulses that are selectively absorbed by the printed Sn patterns cause a temperature of over 1000 °C to be reached locally in a split second without damaging the underlying polymer foil. The top surface of the polymer foil at the interface with printed Sn becomes locally graphitized and acts as a carbon source, transforming printed Sn into Sn@graphene (Sn@G) core–shell patterns. Our results revealed a decrease in electrical sheet resistance, with an optimal value (Rs = 72 ± 2 Ω/sq) reached when light pulses with an energy density of 12.8 J/cm2 were applied. These graphene-protected Sn nanoparticle patterns exhibit excellent resistance against air oxidation for months. Finally, we demonstrate the implementation of Sn@G patterns as electrodes for Li-ion microbatteries (LIBs) and triboelectric nanogenerators (TENGs), showing remarkable performance. This work offers new insight into the development of a versatile, eco-friendly, and cost-effective technique for producing well-defined patterns of graphene-based nanomaterials directly on a flexible substrate using different light-absorbing nanoparticles and carbon sources