Développement d'empilements métalo-diélectriques pour des applications optiques (conception, réalisation et caractérisation)

Les travaux de cette thèse concernent l'étude de l'influence des conditions de dépôt sur la microstructure et les propriétés optiques de monocouches dans le but de réaliser des filtres optiques particuliers commercialisables. La méthode de dépôt utilisée est l'évaporation par canon à électrons avec assistance ionique. L'un des deux projets a été de vérifier la faisabilité de filtres optiques infrarouges dans la gamme [2-15] m avec des matériaux non toxiques. Les monocouches des trois fluorures étudiées ont montré des comportements différents suivant les conditions de dépôt, notamment suivant la température du substrat qui influe fortement sur leur microstructure. L'association du BaF au germanium, avec des réglages optimisés, montre pour différents filtres réalisés des résultats proches de la théorie. Ces filtres sont donc commercialisables. Le second projet a été de développer une machine de dépôt dans le but de pouvoir réaliser des filtres complexes d'une centaine de couches d'épaisseur variable (de 15 à 300 nm) associant des monocouches de TiO à des monocouches de SiO . L'étude de l'influence des paramètres de dépôts (pression, assistance ionique, préchauffage du matériau) au travers différentes caractérisations (MEB, AFM, ellipsométrie) a permis une optimisation des réglages de l'enceinte de dépôt plus efficace et adaptée en fonction des spécifications des filtres optiques à réaliser. Puis, une étude ellipsométrique poussée de l'indice de réfraction des monocouches de TiO en fonction de leur épaisseur a conduit à une nette évolution des résultats pour la réalisation du filtre complexe.This thesis deals the study of deposition conditions 'effect on the microstructure and optical properties of monolayers in order to achieve marketable optical filters, with particular specifications. All filters and monolayers were deposited by ion-assisted electron-beam evaporation technique. One of the two projects was to test the feasibility of infrared optical filters in the range [2-15] m with non-toxic materials. The study of monolayers of three fluorides showed different behaviors depending on the deposition conditions especially as a function of the substrate temperature that affects their microstructure. For different filters realized, the association of BaF with germanium, settings of deposition optimized, shows results close to the theory and these filters are marketable. The second project was to develop a deposition chamber in order to realize complex filters built with one hundred layers of variable thickness (15 to 300 nm) associating monolayers of TiO with monolayers of SiO . The study of the influence of deposition parameters (pressure, ionic assistance, preheating of material) through different characterizations (SEM, AFM, ellipsometry) allowed the optimization of deposition's parameter settings more effective, and adapted according to the specifications of the optical filters to realize. Then, an ellipsometric advanced study of the refractive index of TiO monolayers depending on their thickness led to a significant change in results for the realization of complex filter.RENNES1-Bibl. électronique (352382106) / SudocSudocFranceF

Nanoarchitectonic photoelectrodes built‐up from octahedral metal atom cluster‐based building blocks for solar cell applications

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Multifunctional hybrid silica nanoparticles based on [Mo₆Br₁₄]²⁻ phosphorescent nanosized clusters, magnetic γ-Fe₂O₃ and plasmonic gold nanoparticles

International audienceWe report on the synthesis, characterization and photophysical study of new luminescent and magnetic hybrid silica nanoparticles. Our method is based on the co-encapsulation of single maghemite γ-Fe2O3 nanoparticles and luminescent molybdenum cluster units [Mo6Br(i)8Br(a)6](2-) through a water-in-oil (W/O) microemulsion technique. The as-prepared core-shell [Cs2Mo6Br14-γFe2O3]@SiO2 nanoparticles (45-53 nm) possess a single magnetic core (6, 10.5 or 15 nm) and the cluster units are dispersed in the entire volume of the silica sphere. The [Cs2Mo6Br14-γFe2O3]@SiO2 nanoparticles have a perfect spherical shape with a good monodispersity and they display red and near-infrared (NIR) emission in water under UV excitation, whose intensity depends on the magnetic core size. The hybrid nanoparticles have been characterized by transmission electron microscopy (TEM), high annular angular dark field scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray spectroscopy (EDX), UV-Vis-NIR spectroscopy and magnetometer SQUID analysis. Small gold nanoparticles were successfully nucleated at the surface of the hybrid silica nanoparticles in order to add plasmonic properties

Advances in the Engineering of Near Infrared Emitting Liquid Crystals and Copolymers, Extended Porous Frameworks, Theranostic Tools and Molecular Junctions Using Tailored Re6 Cluster Building Blocks

International audienceAt the occasion of the fiftieth birthday of the introduction of the term 'metal atom cluster' by F. A. Cotton in inorganic chemistry, it is the good time to make a review on the advances in the engineering of molecular assemblies and nanomaterials based on octahedral Re6 metal atom clusters. The latter exhibit unique intrinsic structural and physicochemical properties (orthogonal disposition of metallic sites that can be selectively functionalized, photoluminescence, redox, generation of singlet oxygen) that make them relevant building blocks for the structuration at the nanometric scale and functionalization of hybrid organic-inorganic materials and supramolecular frameworks. After synthesis by solid state chemistry techniques at high temperature, inorganic precursors built up on face-capped [(Re6Yi8)Ya6] cluster units (Y = chalcogen and/or halogen) can be functionalized via solution chemistry techniques or organic melts to form [(Re6Yi8)La6] (L = CN, OH, various organic ligands...). This work reports advances in the synthesis of [(Re6Yi8)Ya6] and [(Re6Yi8)La6] cluster units as well as on their use in the elaboration of supramolecular frameworks, nanoparticles, hybrid nanomaterials (co-polymers and liquid crystals) and active molecular junctions

Preparation of nitrogen doped zinc oxide nanoparticles and thin films by colloidal route and low temperature nitridation process

International audienceNitrogen doped zinc oxide (ZnO) nanoparticles have been synthesized using a colloidal route and low temperature nitridation process. Based on these results, 200 nm thick transparent ZnO thin films have been prepared by dip-coating on SiO2 substrate from a ZnO colloidal solution. Zinc peroxide (ZnO2) thin film was then obtained after the chemical conversion of a ZnO colloidal thin film by H2O2 solution. Finally, a nitrogen doped ZnO nanocrystalline thin film (ZnO:N) was obtained by ammonolysis at 250°C. All the films have been characterized by scanning electron microscopy, X-ray diffraction, X-Ray photoelectron spectroscopy and UV-Visible transmittance spectroscopy

Observation of stacking faults and photoluminescence of laurate ion intercalated Zn/Al layered double hydroxide

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Fabrication of Octahedral Tantalum Cluster Film by Electrophoretic Deposition

The octahedral Ta6Br14.8H2O cluster, one of the [M6Li12La6]n- octahedrons (M= Nb, Ta; Li= halogen, La= halogen or chalcogen), exhibits interesting oxido-reduction properties in solution1. The application of the [Ta6Bri12]2+ cores has been potentially studied in biotechnologies2, optical devices3, photovoltaic cells4 and catalysis5. Originating from the expectation to block the UV and NIR light on low-emissivity window, the Ta6Br14.8H2O cluster thin film on ITO glass has been fabricated by electrophoretic deposition (EPD) process, a fairly rapid and low cost two-step process well-known for ceramic shaping, conductive surface coating and easily scalable to industrial level. The interesting characteristic has been recognized that the green [Ta6Bri12]2+ cores (adsorbing Ultra-Visible range) easily transfers to brown [Ta6Bri12]3+/4+ cores (absorbing near-infrared range) when dissolved in different solvents. Therefore, selecting the medium and optimizing the concentration of water in solvent to obtain the green homogeneous suspension with high dissolution is the main purpose of study. Considering the green color and transmittance of solution, as well as FE-SEM surface morphology of the green film, 0.02 mL H2O per mL acetone was selected as the optimal ratio to obtain the green transparent suspension and possibility to fabricate the green film by EPD process. However, the [Ta6Bri12]2+ green film has been essentially incorporated with poly vinyl pyrrolidone (PVP) in order to improve the dispersion of Ta6Br14.8H2O clusters inside the suspension and effectively prevent the performance of new [Ta6Bri12]3+/4+ clusters (brown-color) by oxidizing reactions. Reference [1] A. Vogler et al., Inorg. Chem., 1983, 23 (10), 1360. [2] J. Knablein et al., J. Mol. Biol., 1997, 270, 1. [3] S. Cordier et al., J. Inorg. Organomet. Polym., 2015, 25, 189. [4] A. Renaud et al., Chemistry Select., 2016, 1, 2284. [5] A. Barras et al., Appl. Catal. B: Environ., 2012, 123,

Examples of Studies on Electrophoretic Deposition Process of Functional Thin Films

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Microstructural and magnetic characterization of Ni0.5Zn0.5Fe2O4 ferrite nanoparticles

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SYNTHESIS AND CHARACTERIZATION OF NANOCOMPOSITES COATING BASED ON INORGANIC OCTAHEDRAL CLUSTER UNITS FABRICATED BY ELECTROPHORETIC DEPOSITION PROCESS

Composite nanoarchitectures represent a new class of nanostructured entities that integrate various dissimilar nanoscale building blocks including clusters, particles, wires and films [1]. The heterogeneous composite nanostructured materials are composed by definition of multi-(nano)components, each tailored to address different requirements. As one of the nanocomponents, nanometer sized transition metal clusters (\u3c2 nm), which consist of less than a few dozens of metal atoms, could be defined as a link between atom and nanoparticle [2-7]. In this presentation, the first preparation of functional thin films based on octahedral molybdenum metal clusters deposited on ITO glass substrate by EPD will be discussed in detail [8]. More generally, we will focus on our recent results on thin films for optical and energy applications [9-10]. References [1] R. Liu et al., Chem. Commun., 2011, 47, 1384 [2] F. A. Cotton, Inorg. Chem., 1964, 3, 1217 [3] A. Perrin et al., C. R. Chimie, 2012, 15, 815 [4] Y. Luab et al., Chem. Soc. Rev., 2012, 41, 3594 [5] V. Fedorov, J. Clust. Sci., 2015, 26, 3 [6] S. Cordier et al., J. Inorg. Organomet. Polym., 2015, 25 189 [7] F. Grasset et al., Adv. Mater., 2008, 20, 1710 [8] T.K.N Nguyen et al., ECS J. Solid State Sci. Technol., 2016, (10) R178-R186 [9] T. G. Truong et al., Sci. Technol. Adv. Mat., 2016, 17(1), 443 [10] A. Renaud et al., ChemistrySelect, 2016, 1, 228