Search results for "GEL GLASS"

showing 2 items of 2 documents

EXAFS studies on the local structure of Er3+ ions in silica xerogels co-doped with aluminium

2001

The local environment around Er3+ ions in wet and densified (at 900°C) silica xerogels (pure and co-doped with aluminium) has been studied at the Er L3-edge by X-ray absorption spectroscopy using the fluorescence detection technique. The radial distribution functions (RDF), reconstructed from X-ray absorption fine structure (EXAFS), show several changes in the local co-ordination of erbium ions upon densification: shortening of the Er-O and Er-Si/Al distances, decrease of the co-ordination numbers and broadening of the Er-O RDF. The effect of Al co-doping is clearly discerned by EXAFS in both the first and second co-ordination shells for densified gels and mainly in the second shell for wet…

X-RAY-ABSORPTION; GEL GLASS; FLUORESCENCE; silica xerogels; erbiumGEL GLASSMaterials scienceAbsorption spectroscopyExtended X-ray absorption fine structureDopingAnalytical chemistrychemistry.chemical_elementMineralogyCondensed Matter PhysicsSilica xerogelsFluorescenceElectronic Optical and Magnetic MaterialsIonErbiumerbiumchemistryAluminiumX-RAY-ABSORPTIONMaterials ChemistryCeramics and CompositesFLUORESCENCEAbsorption (chemistry)Aluminum
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Hydrogen-Related Paramagnetic Centers in Ge-Doped Sol-Gel Silica Induced by γ-Ray Irradiation

2006

We have studied the generation mechanisms of H(II) paramagnetic centers in Ge-doped silica by investigating up to 104 mol ppm sol-gel Ge-doped silica materials. We have considered materials with the same concentrations of Ge but that are produced by two different densification routes that give rise to different concentrations of Ge-related oxygen deficient centers (GeODC(II)). These centers are characterized by an optical absorption band at ∼5.2 eV (B2 β band) and two related emissions at ∼3.2 eV and ∼4.3 eV. The GeODC(II) content was estimated by absorption and emission measurements. The H(II) centers were induced by room temperature γ-ray irradiation and their concentration was determined…

Materials scienceSilica gelDopingAnalytical chemistryGeneral ChemistryCondensed Matter PhysicsElectronic Optical and Magnetic Materialslaw.inventionBiomaterialschemistry.chemical_compoundParamagnetismchemistrylawAbsorption bandMaterials ChemistryCeramics and CompositesIrradiationAbsorption (chemistry)Electron paramagnetic resonancesol-gel glasses aerogel germanium doping germanium defects photosensitivityNuclear chemistrySol-gelJournal of Sol-Gel Science and Technology
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