Proton conductivity in Al-stevensite pillared clays

Fine stevensite mineral fraction (< 2 m) has been extracted from natural Moroccan ghassoulite clay. Thereafter, it has been pillared by Al13 polycations species. Physico-chemical characterization, performed using X-ray diffraction (XRD), thermal analysis (TG-TDA) and Scanning Electron Microscopy (SEM) equipped with X-ray Energy Dispersion (XED) analysis, has proved that stevensite pillaring has been successfully achieved. Electrical impedance measurements, carried out onto samples before and after pillaring operation, have shown an increase in proton conductivity for pillared with respect to pristine stevensite clay mineral.Fine stevensite mineral fraction (< 2 m) has been extracted from natural Moroccan ghassoulite clay. Thereafter, it has been pillared by Al13 polycations species. Physico-chemical characterization, performed using X-ray diffraction (XRD), thermal analysis (TG-TDA) and Scanning Electron Microscopy (SEM) equipped with X-ray Energy Dispersion (XED) analysis, has proved that stevensite pillaring has been successfully achieved. Electrical impedance measurements, carried out onto samples before and after pillaring operation, have shown an increase in proton conductivity for pillared with respect to pristine stevensite clay mineral

Transmission electron microscopy and high-resolution electron microscopy of growth defects in La 2- x Sr x CuO 4 thin films

International audienc

Microstructure and electrical properties of La2−xSrxCuO4-YBa2Cu3O7−δ multilayers deposited by laser ablation

International audienc

ETUDE DE LA STRUCTURE CRISTALLINE ET DE LA COMPOSITION DE FILMS D'ARSENIURE DE GALLIUM PULVERISES, AVEC OU SANS RECUIT LASER

Nous avons étudié par diffraction de rayons X et par analyse non dispersive de rayons X des couches minces polycristallines de Ga As. Ces couches minces sont déposées par pulvérisation cathodique R.F. sur des substrats dont la température est contrôlée. Nous avons utilisé des substrats amorphes : verre nu, verre recouvert de molybdéne, feuilles de molybdéne ainsi que des substrats monocristallins de germanium. Les meilleurs dépôts ont été obtenus sur Ge et sur feuille de Mo. L'état cristallin des films est suivi à partir du rapport des intensités des pics de diffraction I(111)/I(220). La composition des couches est étudiée à partir des raies Kα de Ga et de As. Cela nous a permis d'établir une corrélation entre l'écart à la stochiométrie et le décalage des pics de diffraction X. Un recuit effecfué avec un laser pulsé à rubis (40ns ; 0,35 J cm-2 et 0,15 J cm-2 ; spot de 6 mm de diamètre) permet d'améliorer la cristallisation en surface mais s'accompagne d'une légère effusion d'arsenic.We have investigated the crystal texture and the composition of Ga As films sputtered on vitreous glass, on Mo deposited on glass, on Mo sheet and on monocristalline Ge. There substrates can be heated. The better crystalline structure is obtained with Mo sheets and with monocristalline Ge. Variation of crystal size and texture is followed by the ratis intensity of (111)/(220) measured from the X-ray diffractometer traces. Composition of Ga As layers have been studied by non dispersive X-ray analysis in the SEM with the help of Kα lines of gallium and arsenic. We have established the correlation between the composition and the shift of the X-ray diffraction traces. The irradiation of the films with a pulsed rub laser (40ns ; 0,35 J cm-2 and 0,15 J cm-2 ; spot of 6 mm diameter) improves the crystallisation but gives rise to an arsenic effusion

Cross-sectional TEM investigations of the microstructure and film-substrate substrate interface in Y-Ba-Cu-O thin films

International audienc

TEM/AFM study of the growth of La2−xSrxCuO4 thin films laser deposited on (100) SrTiO3 substrates

International audienc

Crystallographic and dielectric properties of the LiZnAs(1-x)PxO4 solid solution

Crystallographic and dielectric studies of the system LiZnAsO4–LiZnPO4 have been investigated. Solubility limits of phosphorous into LiZnAsO4 was found. A new solid solution LiZnAs(1-x)PxO4 with 0 ≤ x ≤ 0.5 is then evidenced. IR spectra show the presence of XO4 groups in the network of these materials. Correlations between structure and dielectric properties are established.Crystallographic and dielectric studies of the system LiZnAsO4–LiZnPO4 have been investigated. Solubility limits of phosphorous into LiZnAsO4 was found. A new solid solution LiZnAs(1-x)PxO4 with 0 ≤ x ≤ 0.5 is then evidenced. IR spectra show the presence of XO4 groups in the network of these materials. Correlations between structure and dielectric properties are established

TEM characterization of high superconductive multilayered thin films

International audienc