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Synthèse, caractérisation et spectroscopie de nanoparticules de Co et (coeur) Co / (coquille) CoO auto-organisées

Abstract : One of the present challenges in the field of nanomaterial chemistry is to develop strategies aimed at controlling not only the growth of metal nanoparticles (NPs), but also their long-distance organization. Another important goal is controlling the oxidation of NPs and especially the formation of complex oxides having a core (metal) @ shell (metal oxide) architecture. In this context, by revisiting micellar synthesis, a strategy based on the modification of solvent-controlled ligand-ligand interactions was established, following the modeling of the Hansen solubility, of controlling the size of cobalt NPs (3.8 nm to 9.1 nm). Dodecanoic acid NPs passives and protects from oxidation and coalescence (TEM & SAXS control). Hexagonal lattice monolayers and face-centered 3D fcc superlattices were obtained. Using two oxidation strategies combined with annealing, dry and in solution, core / shell NPs: Co (ferro) @CoO (antiferromagnetic)/ were prepared with a polycrystalline metal core cfc or monocrystalline hcp. The preliminary study of the magnetic properties (SQUID) shows that the Co / CoO interface favors a moderate ferromagnetic / antiferromagnetic exchange interaction. Raman spectroscopy, a non-invasive method, under different laser excitations allows the simultaneous analysis of the metal particle (phase control and measurement of diameters from Lamb's modes), coating agent and its interaction with the NP and the possible oxide shells (CoO/CoOH, CO3O4) as well as the dynamics of the dodecanaote chains. Infrared analysis indicates hydroxylation of the unoxidized NPs. The vibrational techniques appear well adapted to the multi-scale control of NPs assemblies and supracrystals.
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Submitted on : Friday, March 23, 2018 - 1:01:41 AM
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  • HAL Id : tel-01741351, version 1

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Salvatore Costanzo. Synthèse, caractérisation et spectroscopie de nanoparticules de Co et (coeur) Co / (coquille) CoO auto-organisées. Chimie-Physique [physics.chem-ph]. Université Pierre et Marie Curie - Paris VI, 2017. Français. ⟨NNT : 2017PA066190⟩. ⟨tel-01741351⟩

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