6533b7d1fe1ef96bd125d749
RESEARCH PRODUCT
Structure of amorphous SiO 2 nanoparticles probed through the E′ γ centers
Franco Mario GelardiAdelina SporeaDan SporeaG. VaccaroSimonpietro AgnelloGianpiero BuscarinoC. Oproiusubject
Materials scienceElectronic Optical and Magnetic MaterialSettore FIS/01 - Fisica SperimentaleAnalytical chemistryNanoparticleSurfaces Coatings and FilmNanotechnologySurfaces Coatings and FilmsElectronic Optical and Magnetic Materialslaw.inventionAmorphous solidGeneral EnergyEnergy (all)lawParticle sizeIrradiationPhysical and Theoretical ChemistryElectron paramagnetic resonanceSpectroscopypoint defects silica nanoparticles electron paramagnetic resonanceRadiation resistanceFumed silicadescription
We report an experimental investigation by electron paramagnetic resonance (EPR) spectroscopy on the properties of the E′ γ centers induced by β-ray irradiation in nanoparticles of amorphous SiO 2 (fumed silica) with mean diameters from 7 up to 40 nm. We found that the E′ γ centers are induced in all the fumed silica types in the dose range 4-400 kGy. They are characterized by an EPR line shape similar to that observed in common bulk silica materials independently on the particle diameter. Moreover, the E′ γ center concentration decreases on decreasing of the particle size for each given dose. Our findings are interpreted in terms of a shell-like model of nanoparticles in which it is assumed that stable E′ γ centers can be mainly induced in the inner part of the particles, whereas those induced in the surface shell are supposed to be essentially unstable and rapidly disappear after irradiation. Furthermore, we have found that the same shell-like model naturally explains the actual radiation resistance observed for nanoparticles which has been previously tentatively attributed to the high O 2 content of the materials. © 2011 American Chemical Society.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2011-12-15 |