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Limoges, France

Prieur D.,CEA Marcoule Nuclear Site | Prieur D.,Limoges National Superior School of Industrial Ceramics | Martin P.M.,French Atomic Energy Commission | Lebreton F.,CEA Marcoule Nuclear Site | And 6 more authors.
Journal of Solid State Chemistry | Year: 2012

Uranium-americium mixed oxides are promising fuels for achieving an efficient Am recycling. Previous studies on U 0.85Am 0.15O 2±x materials showed that the high α activity of 241Am induces pellet swelling which is a major issue for cladding materials design. In this context, X-ray Diffraction and X-ray Absorption Spectroscopy measurements were used to study self-irradiation effects on U 0.85Am 0.15O 2±x local structure and to correlate these results with those obtained at the macroscopic scale. For a cumulative α decay dose equal to 0.28 dpa, it was shown that non-defective fluorite solid solutions were achieved and therefore, that the fluorite structure is stable for the studied doses. In addition, both interatomic distance and lattice parameter expansions were observed, which only partially explains the macroscopic swelling. As expected, an increase of the structural disorder with self-irradiation was also observed. © 2012 Elsevier Inc. All rights reserved. Source

Rossi F.,Arts et Metiers ParisTech | Lambertin M.,Arts et Metiers ParisTech | Delfaut-Durut L.,CEA Valduc Center for Nuclear Studies | Maitre A.,SPCTS | Vilasi M.,University of Lorraine
International Journal of Materials Research | Year: 2010

Transformations undergone by lead - calcium alloys are numerous and have different kinetics from a few minutes to a few years. Anisothermal calorimetric measurements were performed to be able to identify these transformations quickly. It was then possible to identify five transformations. Complementary measurements have enabled us to define transformations with an in-situ electrical resistance measurement to follow the evolution of the calcium in solid solution and with an in-situ hardness measurement to characterise the mechanical properties. The aim of these results is to simulate the ageing and overageing of the alloy in isothermal conditions. Copyright © Carl Hanser Verlag GmbH & Co. KG. Source

De Romeo Banoukepa G.,University of Limoges | Antony R.,University of Limoges | Colas M.,SPCTS | Ratier B.,University of Limoges
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2010

Organic devices such as solar cells or light emitting diodes (OLEDs) have been intensively studied for the last decade, and have now the potential to reach the market for various applications. Nevertheless, various reports have shown that devices based on Indium Tin Oxide anode present a reduced efficiency due to indium diffusion into organic active layers. In this context, our work focus on the development and the characterization of alternative anodes based on Single Walled Carbon Nanotube (SWNT) Films. In particular, this work is devoted to the morphology and charge transport properties of carbon nanotube thin layers. SWNT films were prepared on glass substrates using the vacuum filtration method reported by Wu et al. As a second step, the films were dipped in a nitric acid and subsequently dried in order to reduce their sheet resistances. Raman spectroscopy is then used to chemically map the film surface, and allow us to assess the homogeneity of the achieved films. Finally, optical and electrical characterizations (measurements of the sheet resistance and optical transmission) provide evidence of a correlation between the quality of the surface and the nature of charge transport occurring in the prepared SWNT films. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA. Source

Landreau X.,SPCTS | Boens B.,LCSN | Lanfant B.,SPCTS | Merle T.,SPCTS | And 4 more authors.
Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2012 | Year: 2012

A coaxial injection microwave excited plasma torch operating at atmospheric pressure is applied to synthesizing SiO xH yC z nano-islands from hexamethyldisiloxane precursor on prepatterned Pt/Si(100) substrates. Herein we report on the spatial organization of these nano-islands in a square array of indents. Prior to the PECVD deposition, the Pt/Si(100) substrates are patterned by nano-indentation. SEM characterizations demonstrate that nano-indents act as trapping sites, allowing ripening of SiO xH yC z nano-dots at those locations during subsequent deposition and diffusion of chemical species on the surface. Results show that islands ordering is intrinsically linked to the nucleation and growth at indented sites and strongly depends on pattern parameters. Then, we report on the selective alkyno-functionalization of the nano-islands surface, followed by the addition of coumarin fluorophore through click-chemistry process for a sensing purpose. Source

Chehaidi S.,SPCTS | Foucaud S.,SPCTS | Maitre A.,SPCTS | Goursat P.,SPCTS
Powder Technology | Year: 2011

SiCNYO nanopowders have been elaborated by a spray pyrolysis method from an organometallic precursor which is synthesized by two different routes. Fourier-transform infrared spectroscopy and solid state nuclear magnetic resonance were used to identify the silylation and the amminolysis mechanism applied for the synthesis of each precursor. The SEM micrographs of the each "as-pyrolysed" product revealed spherical SiCNYO nanopowders with a bimodal size distribution. A drop-to-particle and a gas to particle exchanges seem to be the two mechanisms at the origin of grains size distribution. The nature and the reactivity of the carrier gas used in the aerosol indicate a significant influence on the powder morphology. It was found also that evaporation rate of the as-prepared precursor may lead to prevent the enlarging of particles. © 2010 Elsevier B.V. Source

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