Showing papers by "Philippe Belleville published in 2010"

Hybrid Membranes for Proton Exchange Fuel Cell

Abstract: Fuel cell technology has merged in recent years as a keystone for future energy supply. The proton exchange membrane fuel cell (PEMFC) is one of the most promising projects of this energy technology program; the PEMFC is made of a conducting polymer that usually operates at temperatures in the range 20-80°C. In order to reach high energy consumption application like transportation, the using temperatures need to be increased above 100°C. Sol-gel organic/inorganic hybrids have been evaluated as materials for membranes to full file the high temperature using requirement. These new materials for membrane need to retain water content and therefore proton conductivity property with using temperature and time. The membranes also need to be chemical-resistant to strong acidic conditions and to keep their mechanical properties regarding stacking requirements. In order to! answer all these specifications, the proposed hybrid membranes are based on nanoporous inorganic phase embedded in an organic polymer in which chemical grafting and conductivity network microstructure are optimized to preserve both water-uptake and proton conductivity at higher temperatures. Such very promising results on these new hybrids are presented and discussed regarding electrochemical properties/microstructure

Preparation de sols d'oxydes metalliques stables, utiles notamment pour la fabrication de films minces a proprietes optiques et resistants a l'abrasion

Abstract: L'invention se rapporte a un procede de preparation de sols d'oxydes metalliques, a composante aqueuse, qui sont stables dans le temps et qui permettent notamment de fabriquer des films minces presentant a la fois des proprietes optiques et de resistance a l'abrasion remarquables. Ce procede comprend : (i) le remplacement par de l'eau de tout ou partie de l'alcool ou des alcools presents dans un sol alcoolique d'un oxyde metallique, de pH neutre ou basique, et eventuellement (ii) l'ajustement du pH du sol aqueux ou partiellement aqueux ainsi obtenu a une valeur d'au moins 8. L'invention se rapporte egalement a un procede de fabrication de films a partir de ces sols et, en particulier de films minces a proprietes optiques et resistants a l'abrasion. Applications : fabrication de composants optiques pour lasers de puissance, fabrication de fibres optiques, de tubes cathodiques, etc.

Synthesis of Scandium Oxide Nanoparticles from Solution

Abstract: Scandium oxides nanopowders have been synthesized using a sol-gel route. ScOOH nanoparticles have been first prepared in solution using ScCl3, xH2O as precursor. Influence of pH and reflux time on particles size and shape has been studied. Sc2O3 nanoparticles were then obtained after ScOOH sol drying. Sols were characterized by laser granulometry, thermogravimetry and differential analysis (TGA- DSC). Depending on pH, 40 to 1000 nm size ScOOH particles can be obtained. At a given pH, the reflux time duration also influences the ScOOH particles size. The ScOOH sol can be used to prepare highly pure Sc2O3 nanopowders. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microcopy (TEM), were used to characterize Sc203 nanopowders obtained from the various ScOOH solutions. The DSC and laser granulometry data indicate a strong relation between the nanoparticles size and the temperature of transformation of g-ScOOH to Sc2O3. Depending on the sol preparation various particles Sc2O3 size can then be obtained allowing the selection of the more suitable powder for transparent ceramic preparation.