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étude d'agrégats d'oxydes de terres rares

Abstract : This work relates to the synthesis and the study of rare earth oxide nanoparticles. The clusters are synthesized by LECBD (Low Energy Cluster Beam Deposition) then deposited on different substrates for analysis. The X ray photoelectron spectroscopy shows that the produced aggregates have the stoichiometry of bulk material. The deposits are observed by electronic microscopy. Under the usual conditions the aggregates deposited have a size slightly dispersed around an average value of 3nm. The clusters are then crystallized and present a particular form, the rhombic dodecahedron. The conservation of the crystalline structure as well as the particular stability of the rhombic dodecahedron are discussed in relation to the properties of the ionic bond. The properties of luminescence of Eu3+ doped Gd2O3 made it possible to highlight a structure transition for the aggregates of very small size. This transition can be explained by the Gibbs pressure induced by the surface stress. The simulation of the luminescence of the clusters shows the major influence of surface in the inhomogenous widening of the luminescence spectra of the nanoparticles. Quantum confinement in Eu3+ doped Gd2O3 is shown. The behavior observed presents similarities with that of less ionic materials. An interpretation is proposed.
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Submitted on : Friday, September 7, 2007 - 5:31:18 PM
Last modification on : Thursday, October 15, 2020 - 9:00:03 AM
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  • HAL Id : tel-00170447, version 1

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David Nicolas. étude d'agrégats d'oxydes de terres rares. Physique [physics]. Université Claude Bernard - Lyon I, 2007. Français. ⟨tel-00170447⟩

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