Luminescent properties of transparent nanostructured Eu3+ doped SnO2-SiO2 glass-ceramics prepared by the sol-gel method

Nanostructured silica based ceramic samples of composition (100 - x)SiO2-xSnO(2), doped with 0.4 mol% of Eu3+ and with x from I to 10, have been developed after a thermal treatment of precursor sol-gel glasses. A structural analysis has been performed by x-ray diffraction and high resolution transmission electron microscopy. The mean radius of the obtained SnO2 nanocrystals, ranging from 2 to 5 nm, is comparable to the exciton Bohr radius, corresponding to wide bandgap semiconductor quantum dots in an insulator SiO2 glass. A spectroscopy study in terms of emission and excitation spectra has been carried out as a function of SnO2 concentration. Moreover, time-resolved fluorescence measurements have also been performed in order to discern the emission of ions in glassy and nanocrystalline environments. The nanocrystal sizes have been obtained and compared by using the Brus and Scherrer equations.