Search results for "Isotope exchange"

showing 3 items of 3 documents

Oxygen isotopic exchange: A useful tool for characterizing oxygen conducting oxides

2005

International audience; The 18O/16O isotope exchange depth profile technique (IEDP) followed by SIMS characterizations was applied to dense membranes of pure ionic conductors and mixed ionic/electronic conducting materials. It is a very useful tool since we obtain in both cases data concerning the oxygen diffusion in the bulk and the oxygen exchange at the surface of the materials. Comparisons were done, including results concerning the role of the surface with regards to the oxygen reduction reaction. Detailed experimental and analytical processes are given.

Oxygen transport propertiesOxygen reductionDiffusionInorganic chemistryAnalytical chemistrychemistry.chemical_elementIonic bonding02 engineering and technologyConductivity010402 general chemistryHeterogeneous catalysis01 natural sciencesOxygenCatalysisIsotope exchangeCatalysisSOFCProcess Chemistry and TechnologyMixed conducting oxides[CHIM.MATE]Chemical Sciences/Material chemistry021001 nanoscience & nanotechnology0104 chemical sciencesMembranechemistry[ CHIM.MATE ] Chemical Sciences/Material chemistry0210 nano-technologyPACS: 66.30−h (diffusion in solids); 72.60+g (mixed conductivity and conductivity transitions)
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Modification of vacuum-ultraviolet absorption of SiOH groups in SiO2 glass with temperature, F2 laser irradiation, and H–D isotope exchange

2006

Abstract Variations of vacuum-ultraviolet (VUV) absorption of silanol (SiOH) groups in synthetic wet SiO 2 glass with temperature, exposure to F 2 laser light, and with H–D isotope exchange were examined at photon energies below 8 eV. The intensity of the VUV absorption band decreases with cooling or with exposure to F 2 laser light. The spectral changes in both cases are qualitatively similar and are attributed to an alternation of the bonding configuration of SiOH groups from isolated into hydrogen-bonded states. However, the resultant states are distinctly different: the hydrogen-bonded state formed on cooling is restored reversibly to the isolated state on heating, while that induced by…

PhotonChemistryAnalytical chemistryCondensed Matter PhysicsLaserElectronic Optical and Magnetic MaterialsIsotope exchangelaw.inventionSilanolchemistry.chemical_compoundAbsorption bandlawMetastabilityMaterials ChemistryCeramics and CompositesIrradiationGround stateJournal of Non-Crystalline Solids
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Selective oxidative dehydrogenation of ethane over SnO2-promoted NiO catalysts

2012

[EN] Ni-Sn-O mixed oxides catalysts have been investigated for the oxidative dehydrogenation of ethane. The catalysts were prepared through the evaporation of aqueous solutions of nickel nitrate and tin oxalate and finally calcined in air at 500 degrees C for 2 h. These materials have been characterized by several techniques (N-2-adsorption, X-ray diffraction, High-Resolution Electron Microscopy, temperature programmed reduction, X-Ray Photoelectron Spectroscopy, Fourier Transformed Infrared Spectroscopy of adsorbed CO and O-18/O-16 isotope exchange). The addition of just a tiny amount of tin highly increases the selectivity to ethylene (from ca. 40% to 80-90%). Thus, high selectivity to et…

SnO2-promotedInorganic chemistrychemistry.chemical_elementInfrared spectroscopyTin oxideCatalysisOxalateCatalysisEthane ODHNiO catalystsEthane oxidationchemistry.chemical_compoundNickelEthyleneTin oxidechemistryDehydrogenationPhysical and Theoretical ChemistryTemperature-programmed reductionTinOxidative dehydrogenation of ethaneNickel oxideCatalyst characterization (XPS HREM oxygen isotope exchange FTIR CO adsorbed)
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