Photoluminescence and cathodoluminescence of Eu:La2O3 nanoparticles synthesized by several methods

Abstract : Europium-doped La2O3 nanocrystalline powders with sizes ranging from 4 nm to 300 nm have been obtained by the modified Pechini, hydrothermal with conventional furnace, hydrothermal with microwave furnace, and precipitation with ultrasonic bath methods. X-ray diffraction techniques were used to study the evolution of the prepared gels towards the desired crystalline phase. We determined the size and the morphology of the nanoparticles by electronic microscopy. Finally, we studied and analyzed the luminescence properties of the trivalent europium in the hexagonal La2O3 nanocrystals by photoluminescence and cathodoluminescence

Effect of zeolitic imidazolate frameworks on the gas transport performance of ZIF8-poly(1,4-phenylene ether-ether-sulfone) hybrid membranes

This work reports the permeability of hydrogen, nitrogen, oxygen, carbon dioxide, methane, ethane and ethylene across ZIF-8/poly(1,4-phenylen ether-ether-sulfone) hybrid membranes containing 0, 0.10, 0.20 and 0.30 weight fractions of ZIF-8. The glass transition temperature is independent on the filler content suggesting that the filler does not affect the polymer chains mobility. The study was carried out at 1 bar in the range of 283–313 K and the diffusion coefficient of the gases was obtained in this range of temperature by means of the lag time method. The permeability and diffusion coefficients obey Arrhenius behavior and the activation energies associated with this processes were obtained from the slopes of the respective plots. The performance of the membranes as determined by the closeness of their selectivity to the Robeson’s upper bounds increases as the ZIF-8 content of the hybrid membranes increases. The membrane with 30% (w/w) content exhibits at 303 K pretty good selective properties for O2/N2 and H2/N2. The selectivity for C2H4/C2H6 is of the order of 3 with P(C2H4)∼= 3 Barrer. Extrapolation of the permeability data for H2/N2 at high temperatures gives a selectivity that coincides with that predicted by the Robeson limit for this pair of gasesThis work was supported by the CICYT through the grants MAT2008-06725-C03-01 and Project DGAPA IN-112109Peer reviewe