Dissertations / Theses on the topic 'Nanoparticules métaux de transition'
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Wang, Qi. "Synthèse, applications catalytiques et études théoriques de nanoparticules et nanoclusters de métaux de transition." Thesis, Rennes 1, 2020. http://www.theses.fr/2020REN1S029.
Full textThe design and synthesis of late transition-metal nanoparticles (TMNPs) have raised great interest due to their applications in catalysis, nanomedicine, sensing and photonics. Two series of “click” dendrimers have been synthesized and used to stabilize TMNPs. The ferrocenyl (Fc) terminated “click” dendrimers were used to effectuate the electronic switching of AuNPs stabilization. The triethylene glycol (TEG) terminated “click” dendrimers were used to synthesize various mono- and bi-TMNPs, which were further employed as homogeneous catalysts for H2 generation upon hydrolysis of ammonia borane. On the other hand, theoretical research using DFT calculations have been devoted to study the relationship between structure and properties of nanoclusters. With the help of the superatoms concept, icosahedral [Au32]q and [Au33]q were investigated and the stability and precise structure of some of them predicted. The ligated cluster Au32Cl8(PH3)12 was also simulated and compared with the synthesized clusters. Two different families of bi-metallic nanoalloy clusters, the [MH2Cu14(dtp)6(CCPh)6]n+ (M = Cu, Ag, Au: n = 1; M = Ni, Pd, Pt: n = 0) and [AuCu11(dtp)6(CCPh)3Cl] species. We have rationalized the stability and structure of these compounds, most of them being so far hypothetical
Duphil, Dominique. "Synthèse et caractérisation de nanoparticules de fullerènes de dichalcogénures de métaux de transition MX2 (où M=Mo, W ; X=S, Se)." Paris 12, 2003. https://athena.u-pec.fr/primo-explore/search?query=any,exact,990002113970204611&vid=upec.
Full textThree synthetic methods for the formation of MX2 (M=Mo, W ; X=S, Se) nanoparticles have been developed. The first is based on the reaction of M(CO)6 and X in p-xylene under refluxing conditions. A powder of amorphous nanoparticles is obtained, and crystallises after annealing at 550°C. The sulphides have a spaghetti-like morphology, with van der Waals planes curved and in every direction; selenides crystallise as nanoplatelets with straight. Aligned sheets. The second method uses a system consisting of two non-miscible solvents : DMSO and nonanethiol. After annealing, MoS2 fullerene-like nanoparticles are obtained. The third method is spray pyrolysis. MS4(NH4)2 bas been dissolved in water or ethanol, and then sprayed at 750 or 900°C in a furnace. Particles obtained from water solutions are spherical and crystallised. Fullerene-like MoS2 is obtained from ethanol, whereas the WS2 forms a new type of rectangular fullerene-like particles (‘bucky boxes”)
Krishnan, Deepthy. "Nanoparticules mono- et bimétallique stabilisées par des liquides ioniques fonctionnalisés : synthèse et application en catalyse." Electronic Thesis or Diss., Toulouse 3, 2023. http://www.theses.fr/2023TOU30270.
Full textMetal nanoparticles (MNPs) are recognized attractive materials for application in the field of catalysis due to their remarkable high surface-to-volume ratio that induces a high number of potential active sites. It is well known that stabilizers play an important role in synthesis and catalytic performance of MNPs. They protect the NPs structure, thereby preventing agglomeration or aggregation that may occur due their high surface energy. Additionally, stabilizers can influence the electronic properties of the NPs, optimizing their reactivity and selectivity in catalytic reactions. Thus, appropriate selection and utilization of stabilizers are crucial factors for modifying and enhancing the performance of NPs across a diverse range of catalytic reactions including hydrogenation of various substrates. Among all possible stabilizers for MNPs, ionic liquids (ILs) can be employed for the synthesis of MNPs. ILs possesses intriguing physical and chemical properties and presents the advantage to act both as stabilizer and solvent in the reaction, resulting in reduced utilization of chemicals and limit waste, which limits the environmental footprint. Careful tailoring of imidazolium based ILs with functional groups has proven a relevant way to improve catalytic performance of MNPs. In this context, a series of RuNPs and NiNPs were synthesized by the organometallic approach in functionalized imidazolium ionic liquids (FILs) with methoxy- and cyano-groups (abbreviated as MEM, MME and CN). Well-dispersed and narrow-sized RuNPs ranging from 1.3 to 2.2 nm were obtained as well as NiNPs ranging between 2.8 and 6.9 nm depending on the IL functionalization. Thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) allowed to study the interaction between the NPs and the ILs. RuNPs stabilized by the methoxy-containing FILs (MEM and MME) displayed a good balance between catalytic activity and stability when applied in the hydrogenation of styrene at mild reaction conditions. Moreover, the Ru/FILs showed complete selectivity towards ethylbenzene at milder reaction conditions (5 bar, 30 °C) than reported in literature for other RuNP catalysts. All the Ni/ILs systems were found to be efficient catalysts for the hydrogenation of 2-cyclohexe-1-none under the applied reaction conditions (substrate/Ni ratio of 100/1, 130 °C, 10 bar H2), providing full substrate conversion and complete selectivity towards hydrogenation of the olefinic bond in short reaction time (1 h). Bimetallic RuReNPs were also synthesized with an average size of 1.6 and 3.3 nm in unfunctionalized (H) and MEM ILs, respectively, but neither of the systems catalyzed the hydrogenation of amides, which is reputed as a challenging reaction due to the high stability of amides. In summary, the PhD work led to the synthesis of novel Ru, Ni and RuRe bimetallic NPs in MEM and MME ILs, and insights into structure-performance relations in hydrogenation catalysis. The work provides perspectives for future development within both the fields of nanochemistry and selective catalysis
Guralskyi, Illia. "Nano-objets à transition de spin : élaboration, organisation sur des surfaces et étude de leurs propriétés physiques par des méthodes optiques." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1900/.
Full textThe dissertation is devoted to the preparation of some nanoobjects based upon spin crossover complex [Fe(hptrz)3](OTs)2 (where hptrz is 4-heptyl-1,2,4-triazole), their morphology and properties study. By reaction in reverse microemulsions the spin crossover nanoparticles of 35-70 nm in size and with a different aggregation rate were obtained. The lust was achieved varying the quantities of reagents and water in micellar system. Different approaches toward nano- and microobjects of the complex in homogeneous media were developed. It was found that a direct reaction between salt and ligand, depending on the solvent and the stabilizer, can result in nanoparticles of different size and morphology. The method of complex precipitation allowed to obtain the small nanoparticles with a size related effect. The thin films with spin crossover were elaborated by deposition of the complex from its solution in chloroform. This complex was also structured onto surface by means of soft lithography. Spin transition in these nanoobjects onto surface was studied by UV spectroscopy. Optical diffraction and delocalized plasmon resonance were firstly used for the detection of spin state change in 35 nm film, and also for the detection of methanol. The fluorescent approach permitted to follow the spin crossover phenomenon in a single nanoobject
Boucher, Aude-Claire. "Recherche de catalyseurs peu sensibles à la présence de monoxyde de carbone pour piles à combustible PEMFC alimentées en gaz de reformage." Poitiers, 2002. http://www.theses.fr/2002POIT2291.
Full textThe aim of this work was to prepare and to characterize platinum-based bimetallic catalyst before testing their electrocatalytic activities, as fuel cell anode, in presence of some ppm of carbon monoxide. In order to avoid platinum poisoning, another metal such as tin is added. This process results in a material more tolerant to CO. A supported Pt-Sn catalyst was prepared by a chemical route, using a platinum carbonyl complex. This material was characterized by physical and chemical methods which indicate that it is constituted of nanostructured Pt3Sn particles. These particles have a narrow distribution size with a mean diameter of approximately 2 nm. Its activity towards CO, particularly in fuel cell conditions, was compared with an analogue commercial catalyst. This electrochemical study shows that the catalyst prepared from the carbonyl precursor is less sensitive to CO than the commercial one
Manchon, Delphine. "Réponse optique de nano-objets uniques anisotropes : de l’or aux métaux de transition." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10172/document.
Full textThe optical response of noble metal nanoparticles (NPs) are known to be dominated by the Localized SurfacePlasmon Resonance (LSPR), which is highly sensitive to the size of the NPs, their shape and their environment.This optical response can be studied on single nanoparticles thanks to a highly sensitive setup based on theSpatial Modulation Spectroscopy (SMS) which gives access to their absolute extinction cross-section on a widespectral range (300–900 nm). Moreover, the morphology of the same objects studied in optics is characterized bya direct observation in Transmission or Scanning Electron Microscopy (TEM or SEM).In this work, a new setup allowing the measurement of both the extinction and the scattering of a single nanoobjecthas been developed. This technique allows a quantitative measurement of the scattering cross-sectionprovided the angular distribution of the scattered light by the NP is known.The second part is related to experimental and theoretical optical studies and morphological observationsthrough TEM and SEM of exotic nano-objects. First, a systematic study performed on a large number of goldbipyramids, chemically elaborated, has shown that the LSPR located in the red is highly sensitive to theirmorphology and to the environment. Thus, these objects can likely be used as biological sensors. In addition,emergence of a resonance induced by plasmon coupling has been evidenced on lithographed nano-antennasbased on transition metal (Pd, Pt, Cr) for which no LSPR is usually expected. This opens up prospects for novelapplications by extending the field of plasmonics to metals of various chemical properties (photocatalysis,magneto-optics)
Fu, Fangyu. "Synthèses et applications catalytiques de nanoparticules d’élements de transition." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0195/document.
Full textCatalysis is a key element in chemical synthesis, and current research is focusing on making catalytic processes cleaner in the context of green chemistry. In this spirit, this thesis involves the research of nanoparticle (NP) catalysts used in aqueous medium, without toxic ligand and in very small quantities toward a variety of useful processes. The synthesis of the catalytic NPs used cations of the transition elements of the right of the periodic table and of reducing agents capable of rapidly reducing these cations to atoms of zero oxidation state aggregating into small catalytically active metal NPs. The chosen reducing agents were organic (naphthyl sodium) or organometallic (19-electron) sandwich complexes of iron such as [Fe(I)Cp*(ŋ6-C6Me6)] or cobalt such as [Co(II)Cp*2], (Cp* = ŋ5-C5Me5)) used as electron reservoirs. The supports limiting the aggregation of the metal NPs were the solvent (polyethylene glycol, first part of the thesis), the cations of the organometallic electron reservoirs (2nd part of the thesis) or a zeolitic imidazolate framework (MOF of ZIF-8 type, 3rd part of the thesis). Instead of a metal cation, it has also been possible to use a cluster such as [Au25(SR) 18] (R = CH2CH2Ph) as a precursor, in which case the reduction was limited to a simple electron transfer producing an anionic cluster stabilized by the congested sandwich counter cation of the electron reservoir. The small NPs thus stabilized proved to be excellent "green" catalysts for several C-C or C-N reactions and hydrogen production by hydrolysis of metal hydrides in an aqueous medium under very mild conditions. This latter reaction was efficiently catalyzed by Ni2Pt@ZIF-8 bimetallic NPs with a spectacular synergy between the two metals
Kamouni, Belghiti Dounia. "Réseaux d'électrodes en diamant fonctionnalisées par des nanoparticules à base de métaux de transition pour applications analytiques." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066055/document.
Full textBoron-doped polycrystalline diamond electrodes (BDD) exhibit a number of advantages, including a wide potential window above 3V in aqueous media, a low background current, and excellent resilience to corrosion and fouling. These properties make it a very interesting material for the development of chemical sensors. In order to enhance the reactivity of the BDD electrodes towards a wider range of chemical compounds, we have studied the possibility to deposit on the electrode surface nanoparticles based on transition metals such as platinum or iridium. These nanoparticles exhibit an interesting electro-catalytic activity and open the way to the detection of products derived from enzymatic reactions, pesticides or many other electrochemically non-active species. The aim of this thesis work has been to propose a new method for the deposition of metallic nanoparticles on the diamond surface and to characterize them from a structural and electrochemical point of view. The objective is to develop a multi-sensor detection system composed of several BDD electrodes each functionalized using a different metal catalyst in the form of nanoparticles. The detection system thus enables to obtain a characteristic chemical fingerprint of the product to detect. By assembling several of such sensors, and coupling them with algorithmic learning / recognition methods, the system provides an improved selectivity, in a similar way to an “electronic tongue”. This was applied to several case studies, including the detection of hydrogen peroxide, scatol, indole, paraoxon and imidaclopride
Dennler, Samuel. "Structure et magnétisme de systèmes mixte 3d/4d et 3/d/5d : une étude ab initio des alliages macroscopiques aux nanoparticules." Toulouse 3, 2004. http://www.theses.fr/2004TOU30173.
Full textVarious mixed Co/Rh and Co/Pt systems from the macroscopic surface and bulk alloys down to the small nanoclusters have been studied within the density functional theory. Co atoms generally induces significantly enhanced magnetic moments at their 4d/5d neighbors, while they retain their magnetic moment even in an highly mixed environment, leading to substantial average moments in good agreement with earlier experiments. The respective influences of alloying and reduced coordination effects are discussed. Emphasis is given to the determination of the strong interplay between structure, chemical order and magnetic properties. The oscillating RKKY-like character of the Co-induced moments, combined to their significant enhancement at the surface, leads to a particularly complex magnetic pattern. The Co doping effect appears to be the most efficient for large, low-magnetic 4d/5d particles, even if in this case small antiparallel induced moments may slightly moderate the magnetic enhancement
Binotto, Ghislain. "Poudres d’oxydes de métaux de transition à texture, morphologie et taille contrôlées : de l’électrochimie à la catalyse." Amiens, 2008. http://www.theses.fr/2008AMIE0127.
Full textThe Li-ion battery technology is so far the best candidate to match the growing demand for portable and automotive power sources. The recent focus on nanomteric electrode materials for Li-ion cells leads us to consider Co3O4 precipitated in aqueous solution (Co3O4-P). This material is made of crystallized nanometric particles (40 Å), forming porous micrometric agglomerates exhibiting a very narrow porosity distribution. A structural investigation shows a partial cationic delocalization in 16c and 48f sites, in an extent inversely proportional to the size of the coherent domains. The powder texture is maintained, and therefore the optimum electrochemical performances, are obtained through the oxide/carbon mixing in suspension in a solvent. A capacity of more than 600 mAh/g is reached along twenty cycles. The first cycle irreversible capacity is equivalent to that of micrometric materials, suggesting that the formatting step is not responsible for this irreversibility, partially attributed to the formation of -CoO. The drop in capacity along cycling is mostly due to the dissolution of the active material in the electrolyte, and to the effects of the irreversible decomposition of the solvent. Different kinetic decomposition tests (NH3, toluene, H2O2, CO) demonstrated the catalytic efficiency of Co3O4-P. Preliminary catalytic and electrochemical results for Co3O4-P and post-annealed materials as catalysts in Li/O2 batteries, mainly regarding the lowering of the cell polarization, let us consider this set of materials as an ideal tool for bridging the electrochemistry and catalysis domains
Pradère, Caroline. "Nouvelle génération d'airbag à base d'un complexe de métaux de transition et d'un oxyde métallique à l'état nanométrique." Toulouse 3, 2005. http://www.theses.fr/2005TOU30244.
Full textWe were interested in the design of a new composition for airbag systems using an inorganic transition metal complex and a metal oxide at a nanometer size. The coordination complexes must meet specific criteria established by industrial standards, such as a thermal stability until 150°C and non toxic elements. Four new heterometallic complexes have been prepared that fit all the criteria established by the automotive industry. The synthesis of two coordination complexes have been scaled up and then introduced in some compositions of ammonium nitrate. We measured the combustion rate for all these compositions. Cuprous oxide with a nanometer size has been obtained by reduction of a metal salt under dihydrogen pressure. We have also proposed a simple and efficient method to obtain copper nanoparticles with controlled sizes and shapes
Manchon, Delphine. "Réponse optique de nano-objets uniques anisotropes : de l'or aux métaux de transition." Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00993802.
Full textWang, Changlong. "Nanomatériaux à base de métaux de transition pour la catalyse." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30106/document.
Full textTransition metal nanocatalysis is a promising area, where increased efficiency, greenness and reusability are actively sought. In this spirit, the thesis has been devoted to the synthesis, characterization and catalytic applications of new transition metal nanomaterials. Amphiphilic ligand stabilized transition metal nanoparticles catalysts have provided excellent catalytic performances in terms of activity, stability and recyclability in the 4-nitrophenol reduction, Suzuki-Miyaura coupling, transfer hydrogenation and alkyne-azide cycloaddition reactions with low amounts of metal loadings. Moreover, an efficient amphiphilic "click" CuI catalyst was also designed for part-per-million levels of alkyne-azide cycloaddition reaction in water. The design, synthesis and catalytic application of heterogeneous nanocatalysts based on graphene and metal organic framework supports have also been carried out, and their excellent catalytic properties in 4-nitrophenol reduction, Sonogashira coupling, alkyne-azide cycloaddition and hydrolysis of ammonia-borane for hydrogen generation in water under ambient conditions have been disclosed
Mazilu, Irina. "Nanoparticules métalliques déposées sur des matériaux poreux multifonctionnels pour des applications catalytiques." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2268.
Full textThe objective of the Ph.D. thesis is the development of new catalytic systems based on non-noble metal nanoparticles (Cu and/or Co MNPs) hosted in functional mesostructured hosts. To this aim, various supports are prepared by doping SBA-15 with Al, Ga and Fe heteroatoms using the two-step pH-adjustment method or by coating the SBA-15 surface with Al, Ga and Fe oxides using the melt infiltration approach. Likewise, hybrid organic-silica SBA-15 supports are obtained by partial extraction of the Pluronic P123 surfactant. The characterization and catalytic results show that the functionalization of SBA-15 supports with heteroatoms or with polyether groups originating from the native surfactant represents new strategic lines to achieve an enhanced control on the local environments of hosted MNPs and to engineer both the metal-support interaction and nanoparticle size, ultimately to fine tuning the performances of Cu and/or Co-based nanocatalysts in terms of activity and chemoselectivity for the liquid-phase hydrogenation of unsaturated aldehydes, such as cinnamaldehyde. Furthermore, SBA-15 materials containing Fe species in isolated and/or highly dispersed states are evaluated for the Fenton-type peroxidation of Reactive Red 120 azo dye, exhibiting excellent catalytic properties for the dye degradation
Polteau, Baptiste. "Étude de semi-conducteurs de type p nanostructurés à base de métaux de transition pour une application en DSSC-p." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S046/document.
Full textTo improve the performances of p-Dye Sensitized Solar Cell (p-DSSC), this thesis work focuses on the synthesis and the characterization of p-type semiconductors (p-SCs) nanomaterials. These p-SCs with some specifications (low energy valence band, high specific surface area, high conductivity and transparency) were thoroughly studied. In this context, a strategy was developed to improve the NiO nanoparticles properties (commonly used as a reference) with higher nickel non-stoichiometry and nitrogen doping to promote the stabilization of the Ni3+/Ni2+ mixed valence (origin of the p-typness). This study was initiated with a nanostructured mixed valent Ni3O2(OH)4 precursor. Its thermal decomposition in air and ammonia at low temperature (250 °C) allows the formation of nanostructured Ni1-xO with a large amount of Ni vacancies (VNi = 25 %), a high specific surface area (240 m2.g-1) and a nitrogen doping (NiO:N). Moreover, two non-oxides materials with delafossite structure type, namely - nickel carbodiimide (NiNCN) and manganese carbodiimide (MnNCN) - were prepared and characterized as new p-type semiconductors. Thus, the first p-DSSC with NiNCN material was built with success
Zinovyeva, Veronika. "Matériaux composés (polymères électroactif - nanoparticules de métal) et liquides ioniques." Thesis, Dijon, 2010. http://www.theses.fr/2010DIJOS056.
Full textThe actual PhD thesis is devoted to syntheses of composite materials combining conducting polymers with transition metals, their characterization with the use of a large set of modern physical, chemical and electrochemical methods and initial studies of their catalytic applications. These processes were realized both in conventional (aqueous and organic) media and in room-temperature ionic liquids. As an approach for the chemical synthesis, a simple one-pot non-template method, consisting in the chemical reduction of various inorganic salts by pyrrole monomer in a set of solvents, was applied. Polymerization of pyrrole with the use of Fe(III), Cu(II) and Pd(II) salts as oxidants was carried out in a wide range of reaction conditions. The kinetics of the polymerization process was studied by UV-visible spectroscopy and DLS. The obtained materials were characterized by means of cyclic voltammetry, elemental CHNS analysis, ICP-AES, AFM, SEM, EDX, TEM, XRD, XPS, XAS, IR techniques. Catalytic and electrocatalytic properties of the synthesized Pd/polypyrrole nanocomposites were analyzed for the direct catalytic arylation of heteroaromatics and electrooxidation of ascorbic acid. Alternative ways to conducting polymer preparation in the form of films and powders inside ionic liquids, in comparison to those in conventional media, were described. The influence of the synthesis conditions and of the solvent nature on electrochemical properties and morphology of conducting polymers was discussed. The electrooxidation of ferrocene in ionic liquids was investigated in details, and a model for the diffusional transport in these viscous media was proposed
Koffi, Roger Konan. "Synthèse et caractérisation d'électrocatalyseurs de réduction du dioxygène tolérants au méthanol." Poitiers, 2004. http://www.theses.fr/2004POIT2308.
Full textIn the context of developpement of new Pt based materious namly for cathode of Direct Methanol Fuel Cell (DMFC), PtM/C catalysts ( M: transitional metal : Cr, Fe, Co, Ni,) have been synthesed in an organic solvent from metallic salts by following chemical reduction way so called colloidal method. Tow strategies have been used during this synthesis: the addition of colloidal solutions and the coreduction. Then bimetallic catalysts with various atomic ratio Pt(1-x)Crx/XC72 supported on carbon Vulcan were prepared. The size of nanoparticles obtained is around 4-5 nm. The electrocatlytic activities of bimetallic systems toward oxygen reduction reaction in methanol-free or methanol-containing acid electrolyte are higher than to those obtained on monometallic catalysts. Pt0. 8Cr0. 2/XC72, Pt0. 7Cr0. 3/XC72 catalysts showed the best catalytic activities and good tolerance of methanol. The enhancement of activities due to the presence of chromium can be explained by electronic effects. Power densities obtained on samples PtCr/XC72 are around 60-70 mW/cm-2
Larquet, Clément. "Nanoparticles of lanthanide and transition metal oxysulfides : from colloidal synthesis to structure, surface, optical and magnetic properties." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS432.pdf.
Full textThe first part of this thesis is dedicated to lanthanide oxysulfides Ln2O2S. In the bibliographic introduction, the history and properties of the bulk compounds are presented. The reaction conditions of the syntheses of Ln2O2S nanoparticles are then detailed. Gd2O2S nanoparticles are obtained via a synthesis in organic medium using Gd(acac)3, S8 and Na(oleate). Unsupported Ce2O2S nanoparticles are obtained for the first time by keeping the nanoparticles under inert atmosphere from the synthesis to the storage. The solid solution between Gd and Ce enables the formation of (Gd,Ce)2O2S nanoparticles. Their surface and their optical and magnetic properties are studied. For the first time, a formation mechanism with nucleation and growth steps is proposed. The alkaline source which is crucial for the crystallization is still debated; the mechanistic study unveiled a new role of formation of oleate aliphatic bilayers. A second part deals with the transition metal oxysulfides. After a quick introduction on the bulk phases, the scarce nanoscaled compounds are presented. The synthesis of Ln2O2S nanoparticles used in the first part is transposed to p- and d- block transition metals. Because of the differences in the coordination modes of the metals, the transposition is challenging but promising results were obtained with several metals. A last chapter is dedicated to the synthesis of nickel sulfides and oxysulfides at ambient temperature using a reactive complex of nickel and S8
GAUDRY, Mélanie. "Propriétés optiques d'agrégats mixtes de métaux de transition en matrice d'alumine : Effets de taille et de composition." Phd thesis, Université Claude Bernard - Lyon I, 2002. http://tel.archives-ouvertes.fr/tel-00001513.
Full textDennler, S. "Structure et magnétisme de systèmes mixtes 3d/4d et 3d/5d : une étude ab initio des alliages macroscopiques aux nanoparticules." Phd thesis, Université Paul Sabatier - Toulouse III, 2004. http://tel.archives-ouvertes.fr/tel-00266714.
Full textCiotonea, Carmen. "Synthèse et caractérisation de catalyseurs monométalliques et bimétalliques à base de métaux de transition pour les réactions d'hydrogénation chimiosélective." Thesis, Poitiers, 2015. http://www.theses.fr/2015POIT2264/document.
Full textThe development of efficient transition metal based catalysts for the chemoselective hydrogenation reaction of cinnamaldehyde is studied. The active phases, studied in this work, are among the transition metals (Ni, Co and Cu), supported on porous ordered materials. This study can be divided in two different sections, according to the support nature. The first part concerns the dispersion of transition metals on SBA-15 type silica support. In the first chapter is presented the transition metal dispersion (Ni, Co and Cu) using IWI-MD (Incipient Wetness Impregnation –Mild Drying) method. Studies performed, to optimize active phase dispersion, are: (i) influence of support texture, (ii) influence of drying temperature, (iii) influence of drying time, (iv) influence of metal loading. In the second chapter, Ni, Co and Cu catalytic materials are prepared using deposition precipitation method. In the third chapter is described the transition metal dispersion using melt infiltration method (MI), optimized to ensure a complete infiltration of metallic precursors in the support porosity before oxide phase formation. The second section of the Ph.D. is related to the dispersion of transition metal over ordered mesoporous alumina (AMO) supports. Catalytic materials, based on Ni and Cu over AMO (obtained by EISA process - Evaporation Induced by Self-Assembly), are produced. Parameters studied are: effect of support texture, effect of preparation route (IWI-MD, MI and TS)
Wojcieszak, Robert. "Catalyseurs de nickel Supportés Préparés par la Méthode de l'Hydrazine Aqueuse. Propriétés Hydrogénantes et Stockage d'Hydrogène : Effet du Support. Effet de l'Ajout d'Argent." Nancy 1, 2006. http://docnum.univ-lorraine.fr/public/SCD_T_2006_0023_WOJCIESZAK.pdf.
Full textWe have studied Ni or NiAg nanoparticles obtained by the reduction of nickel salts (acetate or nitrate) by hydrazine and deposited by simple or EDTA-double impregnation on various supports (g-Al2O3, amorphous or crystallized SiO2, Nb2O5, CeO2 and carbon). Prepared catalysts were characterized by different methods (XRD, XPS, low temperature adsorption and desorption of N2, FTIR and FTIR-Pyridine, TEM, STEM, EDS, H2-TPR, H2-adsorption, H2-TPD, isopropanol decomposition) and tested in the gas phase hydrogenation of benzene or as carbon materials in the hydrogen storage at room temperature and high pressure. The catalysts prepared exhibited better dispersion and activity than classical catalysts. TOF's of NiAg/SiO2 or Ni/carbon catalysts were similar to Pt catalysts in benzene hydrogenation. Differences in support acidity or preparation method and presence of Ag as metal additive play a crucial role in the chemical reduction of Ni by hydrazine and in the final properties of the materials. Ni/carbon catalysts could store significant amounts of hydrogen at room temperature and high pressure (0. 53%/30 bars), probably through the hydrogen spillover effect
Salvaggio, Ermelinda. "Nanoparticles of Nitride-based Materials for Plasmonics and Lossy-mode Resonance." Electronic Thesis or Diss., Troyes, 2022. http://www.theses.fr/2022TROY0011.
Full textIn this manuscript, we study different transition metal nitrides (TiN, ZrN and HfN) whose properties and optical characteristics are related to their composition, dielectric environment, size and shape. We describe the sputtering technique used to deposit nitride films on silicon (111) and fused silica substrates. The x-ray diffraction measurements show the crystal structures of the films and give a measure of their grain size as the nitrogen flux varies. The x-ray reflectometry gives a measurement of density, thickness and roughness of the films. The atomic force microscopy, allows a characterization of the surface roughness. The ellipsometry provides refractive indices and extinction coefficients that will be used to extract the Faraday and Joules numbers. The spectrophotometric measurements provide transmission spectra used to derive the optical band gap energies. From nitride thin films, we fabricated arrays of nanoparticles with controlled shape, size and period using the EBL technique.Their extinction spectra clearly show that the resonance peaks strictly depend on the size, shape, stoichiometry and period of the nanoparticles array.The measured extinction spectra are compared to those simulated using FDTD method and they show that there is a good agreement between experimental measurements and simulations. We thus demonstrated the interest of using these materials as alternatives to the noble metals conventionally used in plasmonics
Azizi, Yassine. "Influence des propriétés de surface d'oxydes mixtes sur l'ancrage de particules d'or : application dans des réactions catalytiques d'oxydation et d'hydrogénation de l'acétylène." Strasbourg, 2009. http://www.theses.fr/2009STRA6059.
Full textThe active of gold nanoparticles, is affected by many parameters extensively described in the literature: pH and concentration of the solution, IEP of the support, type of heat treatment, etc. This work describes the steps of development of catalysts based on gold supported on single oxides CeO2, TiO2 and ZrO2 and binary mixed oxides as solid solution: CeO2-ZrO2, TiO2- ZrO2 and CeO2-TiO2 with various ratios Ce/Zr, Ti/Zr and Ce/Ti and the subsequent applications of these catalysts in oxidation reactions and selective hydrogenation of acetylene. The comparison of the physicochemical properties of various catalysts showed the strong influence of the surface state of the support on the particle size and on the reactivity in CO and the complexity of metal-support interactions from the preparation of catalysts. We have highlighted the influence of support on the mechanisms in the reactions involving acetylene
Capitolis, Jérôme. "Synthèse de nanoparticules d'oxydes de titane ou de vanadium à basse valence." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS499.pdf.
Full textThis PhD work deals with the development of new synthesis pathways for low valence titanium or vanadium oxide nanoparticles. These oxides are attracting an increasing interest for applications such as thermoelectricity, data or energy storage, especially at the nanoscale where performances can be enhanced. However the synthesis of these solids at nanoscale is a challenge. In this work, the synthesis of nanoparticles of several low or mixed valence titanium oxides is studied. The approach that are explored are based on the reduction of titanium dioxide nanoparticles by metallic hydrides in molten salts. It enables control over phase, size and morphology of the nanoparticles. The synthesis of V2O3 nanoparticles from molecular precursors in molten salts has also been developed, in order to control the structure, size and morphology of the nanoparticles. This pathway enables the synthesis of a non-identified vanadium containing oxide and lays the foundation for the synthesis of vanadium Magnéli phases at the nanoscale. Finally the surface reactivity of nanoparticles of Ti4O7 and Ti6O11 Magnéli phases were explored by Near ambient pressure-X ray photoelectron spectroscopy
Bouet, Louis. "Valley dynamics and excitonic properties in monolayer transition metal dichalcogenides." Thesis, Toulouse, INSA, 2015. http://www.theses.fr/2015ISAT0033/document.
Full textThe possibility of isolating transition metal dichalcogenide monolayers by simple experimental means has been demonstrated in 2005, by the same technique used for graphene. This has sparked extremely diverse and active research by material scientists, physicists and chemists on these perfectly two-dimensional (2D) materials. Their physical properties inmonolayer formare appealing both fromthe point of view of fundamental science and for potential applications. Transition metal dichalcogenidemonolayers such asMoS2 have a direct optical bandgap in the visible and show strong absorption of the order of 10% per monolayer. For transistors based on single atomic layers, the presence of a gap allows to obtain high on/off ratios.In addition to potential applications in electronics and opto-electronics these 2D materials allow manipulating a new degree of freedom of electrons, in addition to the spin and the charge : Inversion symmetry breaking in addition to the strong spin-orbit coupling result in very original optical selection rules. The direct bandgap is situated at two non-equivalent valleys in k-space, K+ and K−. Using a specific laser polarization, carriers can be initialized either in the K+ or K− valley, allowing manipulating the valley index of the electronic states. This opens up an emerging research field termed "valleytronics". The present manuscript contains a set of experiments allowing understanding and characterizing the optoelectronic properties of these new materials. The first chapter is dedicated to the presentation of the scientific context. The original optical and electronic properties of monolayer transition metal dichalcogenides are demonstrated using a simple theoreticalmodel. The second chapter presents details of the samples and the experimental setup. Chapters 3 to 6 present details of the experiments carried out and the results obtained. We verify experimentally the optical selection rules. We identify the different emission peaks in the monolayer materials MoS2, WSe2 and MoSe2. In time resolved photoluminescence measurements we study the dynamics of photo-generated carriersand their polarization. An important part of this study is dedicated to experimental investigations of the properties of excitons, Coulomb bound electron-hole pairs. In the final experimental chapter, magneto-Photoluminescence allows us to probe the electronic band structure and to lift the valley degeneracy
Cazayus-Claverie, Emmanuelle. "Matériaux pour les batteries Li-AIR : nouvelles approches vers des nano-hétérostructures spinelles/graphène pour électrode à air." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066508/document.
Full textThis research work is focused on the design and characterisation of cobalt based oxides nanospinels anchored onto the surface of reduced graphene oxides (RGO) nanosheet, which will serve as bifunctional catalysts for the new generation lithium-air batteries. Whereas nanospinels are relatively simple to synthesize by conventional colloidal routes as nanoparticles dispersed into an aqueous solution, the synthesis we developed relies on a hydrothermal microwave treatment in the 100°C-200°C range. The main challenges of this nano-heterostructures synthesis was to create the interface between the nanoparticles and the RGO directly during the nanoparticles nucleation. RGO are very efficient microwave absorbers and could then convert microwave irradiation into heat in order to trigger precipitation of the spinel at the surface of the RGO sheet.Starting from Co3O4 as proof-of-concept material, the synthesis protocol has been successfully adapted to address binary oxides by substituting cobalt with first row transition metals such as nickel, manganese or iron. The precipitation of binary and ternary oxides was achievable thanks to a good understanding of the Pourbaix diagrams of all cations to adjust the acido-basic and redox conditions.Finally, the electrocatalytic activity of these supported spinel oxides was measured for both the oxygen reduction and oxygen evolution reactions (ORR and OER). The gap between the ORR and the OER potentials was significantly lowered by the presence of Co3O4 nanoparticles on the RGO, thus assuring the reversibility of this catalytic system, which is to be integrated in future scale-up test
Arnedo-Sanchez, Leticia. "Lanthanide and transition metal complexes as building blocks for supramolecular functional materials." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF047.
Full textThis thesis deals with coordination compounds based on transition metals and lanthanides as key components of functional materials. Besides a brief summary of photophysics, supramolecular gels and metal nanoparticles, an overview of the instruments and techniques employed in this work is included. This thesis is further divided into four chapters focused on optically active metalcomplexes (chapters 3 and 4), stimuli responsive metallogels (chapter 5) and functionalized nanomaterials for sensing applications (chapter 6). In chapter 3, the synthesis and characterization of anionic lanthanide complexes is reported. Analytical techniques, emission spectroscopy and X-ray crystallography were employed to characterize these complexes. ln chapter 4, the study of light emitting metal complexes is extended to transition metal complexes, in particular to iridium (lll) complexes. A family of neutral bis-cyclometallated iridium (lll) complexes that exhibit an intense red emission under photo- or electro-excitation is studied. ln chapter 5 the design and investigation of a new family of low molecular weight gelators based on perfluorinated terpyridines is reported. The morphology and mechanical and thermodynamical properties of these metallogels is studied. Chapter 6 studies the excellent cooperation between coordination compounds and nanomaterials to yield optical sensors. A new colorimetric sensor for pyrophosphate consisting of gold nanoparticles acting as reporting units functionalized with a thiol-modified aminoterpyridine-Zn complex is described
He, Wenyan. "Coupling of an electrochemical process and a biological treatment for specific pollutant removal-Electrode surface functionalization." Rennes, Ecole nationale supérieure de chimie, 2016. http://www.theses.fr/2016ENCR0035.
Full textThe electrocatalytic reduction coupled to a biological process is a promising alternative for the degradation of chlorinated compounds. The selective cleavage of the carbon-chlorine bond in aqueous media was implemented for detoxification and to improve the biodegradability of chlorinated compounds. The mineralization of the electrolyzed solution can then be achieved by a biological treatment. The dechlorination was studied with the aid of transition metal complexes and Ag nanoparticles because of their high catalytic activity, leading to a total degradation of the organohalogenated studied compounds with good selectivity. The modification of graphite felt with Ni(tmc)Br2 or [Co(bpy(CH2OH)2)2]2+ complex highlighted the catalyst stability and current efficiency for dechlorination of 1,3-dichloropropane and alachlor , respectively, compared to the homogeneous process. Deschloroalachlor, was the main by-product of the electroreduction of alachlor, indicating the high selectivity of the Co complex system. The biodegradability of the solution was improved to 0. 31±0. 04 using Ag nanoparticles modified Ni foam in 0. 05 M NaOH solution with production of other dechlorinated by-products apart from deschloroalachlor, highlighting the interest of this new material. The new Ag nanoparticles modified graphite felt with Ni layer aimed at improving the catalytic performance of cathode by increasing the surface area of the support
Dorolti, Eugen. "Nanomatériaux magnétiques à haute performance à base de métal de transition et de terre rare : carbures Sm-Fe-Ga." Paris 12, 2005. https://athena.u-pec.fr/primo-explore/search?query=any,exact,990002286580204611&vid=upec.
Full textThe intermetallic samarium-iron compounds, partially substituted by gallium, into which a light element as carbon is inserted, present a strong magnetocrystalline anisotropy, required for applications in the area of permanent magnets or for magnetic recording. The nanocrystalline state optimizing the extrinsic magnetic characteristics is obtained by high energy milling with a subsequent annealing, and leads according to the annealing temperature, to the known equilibrium phases and to their less understood out-of-equilibrium precursors. We have established the composition, the structural and magnetic properties of the precursor of the equilibrium phase Sm2(Fe,Ga)17 i. E. Sm(Fe,Ga)9 and its carbides by X-ray diffraction, Mössbauer spectroscopy, magnetization measurements, and electron microscopy. Throughout the study, the results on the out-of-equilibrium precursors are systematically confronted with the results of their equilibrium homologous, specially prepared for this comparison
Khazzan, Salwa. "Systèmes nanocristallins Sm1-s(Fe,Mo)5+2s : étude des propriétés structurales et magnétiques." Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00600687.
Full textOuld-Hamouda, Amine. "Étude des transitions de phase photo-induites dans des matériaux métalliques et organométalliques." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0112/document.
Full textThis thesis is dedicated to the study of laser-induced phase transitions in metallic and metaly organic materials. The studies presented here are guided by the recording and storage of digital information. Firstly, we focused on THz and Raman spectroscopy of two different iron Fe (II) spin crossover complexes. The spectra we recorded using these two methods are compared to numerical simulations obtained with the DFT. We have also studied the spin state transition induced byCO2 lasers in polymeric spin crossover materials. A simple experimental setup allowing data recording in this type of materials is presented. Secondly, we studied the reversible metal (λ metastable to semiconductor (β stable) phasetransition in nanoparticles of a Titanium oxide (Ti3O5), excited with nanosecond laser pulses.More specifically, we studied the kinetic aspects of this transition. It appears that the λ→β transition occurs in hundreds of nanoseconds while the β→λ transition is achieved in a few tens of nanoseconds. The photothermal mechanisms leading to this transition accounts very well to these experimental observations. Finally, we present the study of Rb0.94Mn[Fe (CN)6]0.98.0.3H2O, a Prussian blue analogue which is bistable at room temperature. Using secondy and thirdyharmonic generation, we measured the effective secondy and thirdyorder nonlinearities of this compound in low and high temperature phases. We show that we can photo-switch the linear and nonlinear optical properties of this material. THz spectroscopy and generation in this material are also presented
Luo, Jingjie. "Formation de nanoparticules d'or supportées sur silice Stöber : mécanismes et applications." Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-01038161.
Full textMottaghizadeh, Alireza. "Non-conventional insulators : metal-insulator transition and topological protection." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066652/document.
Full textThis manuscript presents an experimental study of unconventional insulating phases, which are the Anderson insulator, induced by disorder, the Mott insulator, induced by Coulomb interactions, and topological insulators.In a first part of the manuscript, I will describe the development of a method to study the charge response of nanoparticles through Electrostatic Force Microscopy (EFM). This method has been applied to magnetite Fe3O4 nanoparticles, a material that presents a metal-insulator transition, i.e. the Verwey transition, upon cooling the system below a temperature Tv=120K. In a second part, this manuscript presents a detailed study of the evolution of the Density Of States (DOS) across the metal-insulator transition between an Anderson-Mott insulator and a metallic phase in the material SrTiO3 and this, as function of dopant concentration, i.e. oxygen vacancies. We found that in this memristive type device Au-SrTiO3-Au, the dopant concentration could be fine-tuned through electric-field migration of oxygen vacancies. In this tunnel junction device, the evolution of the DOS can be followed continuously across the metal-insulator transition. Finally, in a third part, the manuscript presents the development of a method for the microfabrication of Aharonov-Bohm rings with the topological insulator material, Bi2Se3, grown by molecular beam epitaxy. Preliminary results on the quantum transport properties of these devices will be presented
Younsi, Khedidja. "Etude expérimentale et théorique des propriétés structurales et magnétiques des nanomatériaux Pr(Co,Fe)3." Phd thesis, Université Paris-Est, 2011. http://tel.archives-ouvertes.fr/tel-00674871.
Full textWang, Jingjuan. "Design of efficient catalysts for hydrogenation of carbon oxides to alcohols and olefins." Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10052/document.
Full textCatalytic hydrogenation of carbon monoxide and carbon dioxide leads to valorisation of syngas which can be produced from fossil and renewable resources. This thesis addresses design of new catalysts for synthesis of alcohols and olefins from syngas containing carbon monoxide and carbon dioxide. Catalyst characterization has demonstrated formation of bimetallic particles in copper-cobalt mixed supported catalysts and enrichment of metallic particles with copper on the outer surface in the reduced catalysts. Comparison with catalytic data suggests that these bimetallic particles probably contain the active sites for the synthesis of alcohols from syngas. The supports (SiO2, Al2O3 and carbon nanotubes), and some promoters, especially iron, also have a very strong influence on the catalyst performance. Promotion with iron also increases productivity of Rh catalysts in the synthesis of ethanol from syngas. The formation of interfaces between the iron and rhodium seems to improve the selectivity of this reaction to ethanol, while carbon monoxide conversion principally depends on rhodium dispersion. The Fe/ZrO2 catalysts promoted with potassium showed a very important selectivity for the synthesis of olefins from carbon dioxide. This increase in selectivity was attributed to the synergy between iron and oxidized species Fe0/χ-Fe5C2 which are involved in this reaction
Atoini, Youssef. "New luminescent hybrid materials : synthesis and properties." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF004/document.
Full textThe aim of this thesis is the synthesis, characterization and investigation of luminescent metalcomplexes, and in particular of Pt(II) compounds, their aggregation properties in solution but inconfined space as well. The incorporation of transition metal complexes in porous structure, and inparticular in a metal-organic framework (MOF), by post-synthesis grafting, have been investigated.Luminescence properties of amphiphilic Pt(II) complexes were enhanced inside mesoporous silicananoparticles by the creation of a confined space. Similar effect is observed by deposition offunctionalized Pt(II) complexes on gold nanoparticles surface. Luminescence of metal organicframework was tuned by post-synthetic grafting of Ir(III) and Pt(II) complexes
M'Nasri, Najib. "Elaboration de nanomatériaux composites métal@nanoparticules de silice mésoporeuses (MSN) : étude des performances catalytiques en phase aqueuse et des propriétés d'adsorption sélective du diiode en phase gaz." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20199.
Full textThe objective of this thesis was to develop efficient synthesis routes to prepare mesoporous silica-based nano-sized particles, designated as MSN, with controllable morphology and derivatised with selected transition metals. One-pot preparation and surface functionalisation procedures based on the insertion of the metal-phase precursor into the porogen aggregates were thoroughly optimised leading to silica particles containing such single metals as copper, palladium, platinum, silver or gold, as well as a two-metal phase of copper and palladium or that of palladium and platinum. It was demonstrated that the highly dispersed metal phase was localised on the pore surface and therefore it was readily accessible to the target chemicals on which to base the catalytic performance of the resulting materials. Among others, the remarkable catalytic performance of the Cu@MSN material in Huisgen and Sonogashira reactions and its propensity to undergo efficient recycling were proven through laboratory-scale testing. Experimental study of the selective adsorption of iodine vapour onto MSN supports functionalised with silver nanoparticles indicated an excellent retention capacity of such materials
Billaud, Pierre. "Propriétés optiques de nanoparticules uniques de métaux nobles." Phd thesis, Université Claude Bernard - Lyon I, 2006. http://tel.archives-ouvertes.fr/tel-00213213.
Full textAnres, Pascal. "Etude thermodynamique des alliages : métaux de transition - métaux sp." Aix-Marseille 1, 1997. http://www.theses.fr/1997AIX11045.
Full textWandersman, Elie. "Transition vitreuse de nanoparticules magnétiques en interaction." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00193960.
Full textCásek, Petr. "Propriétés électroniques d'oxydes de métaux de transition." Paris 11, 2004. http://www.theses.fr/2004PA112015.
Full textIn this work we report results of our theoretical studies of the electronic properties of two different types of transition metal oxides. In the first part, we concentrate on the structural and electronic properties of SrTiO3 overlayers on MgO(001) using density functional theory (DFT) within the local density approximation (LDA). In particular, we show that only the TiO2/MgO contact is thermodynamically stable, and that many characteristics of the true SrTiO3(001)/MgO(001) interface are recovered already when a SrTiO3 bilayer is adsorbed (e. G. , vanishing valence band offset, structural distortions, charge transfer, etc. ). Considering an oxygen vacancy at the interface, we show that its formation energy is basically determined by the one of the corresponding clean surface. In the second part, we focus on the optical response of the high-Tc cuprate superconductors. We use a simple many-body hamiltonian and the finite temperature perturbation theory to calculate the real part of the conductivity. In particular, we explore the origin of the onset located for optimum doped Yba2CU3O(7-[delta]) around ~ 350 cm^(-1). We also discuss the position and the shape of the peak in the effective spectral function W(w)
Benoit, Roland. "Nanoparticules de bismuth : synthèse, caractérisation et nouvelles propriétés." Orléans, 2005. http://www.theses.fr/2005ORLE2082.
Full textHelgadottir, Inga. "Synthèse Contrôlée de Nanoparticules de Métaux Oxophiles en Milieu Liquide lonique pour Applications en Microélectronique." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10286.
Full textSmall size (below 10 nm) metallic nanoparticles and metallic nanoalloys have attracted much interest in a range of applications, which require precise control of size, composition, and morphology, in chemically significant quantities. Hence, the variety of compositions and structures (size, morphology, atomic arrangement) bring a vast range of possibilities. This PhD was aimed at expanding the knowledge already obtained in this laboratory on monometallic nanoparticles. Indeed, it has been demonstrated that the decomposition of organometallic precursors in selected ionic liquids can lead to the formation of stable suspensions of metallic nanoparticles below 5 nm. In this context, a first achievement in this work has been to push this route towards more oxophilic, less approachable metals, such as tantalum. Besides, this route has been shown to generate bimetallic nanoparticles upon decomposition of mixtures of precursors, with size, structure and composition controlled, such as Ru@Cu. This PhD work has dentified the mechanism of formation of these nanoalloys, developing a versatile route that could be used to design nanoalloys to fulfill specific applications, e.g., RuNi, RuTa, CuNi, etc
Desbiens, Jessie, and Jessie Desbiens. "Synthèse et caractérisation de nanoparticules de polymère dopées d'un complexe luminescent et de nanoparticules d'argent." Doctoral thesis, Université Laval, 2012. http://hdl.handle.net/20.500.11794/23691.
Full textLa synthèse et la caractérisation de nanoparticules de polymère dopées d’un complexe luminescent et de nanoparticules d’argent ont été réalisées. La polymérisation en mini-émulsion a permis d’obtenir des nanoparticules de polystyrène dopées d’un complexe luminescent. La concentration de complexe d’europium maximale pouvant être atteinte, sans qu’il y ait déstabilisation de l’émulsion, est de 2% (m/m). Il est également possible de préparer des nanoparticules de polymère contenant le complexe luminescent, ainsi que des nanoparticules métalliques. Pour ce faire, le complexe et les nanoparticules métalliques doivent être dispersés dans le monomère de départ. Il est donc nécessaire de modifier la surface des nanoparticules métalliques afin qu’il y ait une bonne affinité entre les nanoparticules métalliques et le polymère. Il est intéressant de confiner les nanoparticules métalliques dans la même particule de polymère que le luminophore afin d’observer leur impact sur la luminescence. Le rehaussement ou l’exaltation de la luminescence au voisinage de nanoparticules métalliques est un phénomène bien connu. Lorsqu’une nanoparticule métallique est excitée par une onde électromagnétique qui correspond à la fréquence de résonnance du nuage électronique de la particule, une augmentation du champ électrique est engendrée à proximité de la particule et a pour effet de rehausser la luminescence des luminophores à proximité. Les propriétés optiques des nanoparticules hybrides obtenues (polystyrène/complexe luminescent/argent) montrent, qu’effectivement, en présence d’argent, une augmentation de l’intensité lumineuse peut être observée.
Cauchy, Thomas. "Système magnétiques complexes avec des métaux de transition." Phd thesis, Université d'Angers, 2007. http://tel.archives-ouvertes.fr/tel-00346321.
Full textCauchy, Thomas. "Systèmes magnétiques complexes avec des métaux de transition." Angers, 2007. http://www.theses.fr/2007ANGE0047.
Full textA methodology based on the density functional theory has been used to study firstly, the unusual magnetic properties of organometallics raidcals of the [CpNi(dithiolene)] family with for exemple a strong antiferromagnetic coupling through a weak interaction, and secondly the exchange interaction in iron and manganese polynuclear systems with oxo bridging ligands. Therefore, the exchange coupling constants have been calculated for the complexes fe4 with a butterfly geometry, Fe5, Fe6, Mn4 butterfly type, Mn10, Mn19 and Mn25. We wera able to establish magnetostructurals correlations and correlations between the exchange coupling constants and the cations electronic configuration in the iron and manganese butterfly complexes. The results obtained for the others complexes with a higher nuclearity show similar trends as observed in theses correlations, notably the ferromagnetic interactions in the Mn10 and Mn19 complexes
Standaert, Alain R. "Synthèse de ligands nouveaux pour les métaux de transition." Doctoral thesis, Universite Libre de Bruxelles, 1989. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/213216.
Full textMangeney, Claire. "Polymères conducteurs pour l'adressage moléculaire des métaux de transition." Paris 7, 2000. http://www.theses.fr/2000PA077146.
Full textFörster, Georg Daniel. "Modélisation atomique de nanoparticules métalliques sur substrats carbonés et graphène épitaxié sur métaux." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10150/document.
Full textApplications of metal nanoparticles require monodisperse and stable assemblies on a substrate such as graphene or graphite. Epitaxial graphene on metal (GOM) has attracted research interest because it contributes to the self-organisation of adsorbates. The difference in the lattice constants of graphene and metal leads to a moiré that contains certain regions that are favorable for adsorption. This work is mainly concerned with the Ru-C and Pt-C systems where we were interested in the bare substrate of GOM, adsorbates deposited thereon and metal clusters on graphite. Bond order potentials allow to carry out molecular dynamics studies for systems of realistic size and at finite temperature. In the case of the Pt-C, a parametrization is available in the literature. However, for Ru-C systems a custom parametrization effort based on data from electronic structure calculations was necessary. This atomistic model neglects long ranged dispersion forces that are important for adsorption phenomena on extended substrates. Based on the Grimme models, we developed an implicit description that takes the layered structure and the semi-infinite extension of the substrate into account. Also, screening effects that are important for metal materials are taken into account. Based on this force field, we show results concerning the properties of adsorbates on carbon substrates while evaluating the dispersion model. With the help of molecular dynamics simulations, the stability of adsorbates and graphene has been studied in the context of vibrational and diffusion dynamics. In agreement with experiments, the mobility of the adsorbates on graphite is high in comparison with adsorbates on GOM