SnO2:Eu nanoparticles dispersed in silica: A low-temperature synthesis and photoluminescence study

SnO2:Eu and SnO2:Eu nanoparticles dispersed in silica matrix were prepared at a relatively low temperature of 185 deg. C in ethylene glycol medium. For as-prepared SnO2:Eu nanoparticles there exists a weak energy transfer from the SnO2 host to the Eu3+ ions. However, the energy transfer can be significantly improved by dispersing the Eu3+-doped SnO2 nanoparticles in silica matrix. Effective shielding of surface Eu3+ ions in SnO2:Eu nanoparticles from the stabilizing ligand by silica matrix is the reason for the improved extent of energy transfer. Increase in asymmetric ratio of luminescence (ratio of the intensity of the electric dipole allowed transition, 5D0→7F2, to magnetic dipole allowed transition, 5D0→7F1) for SnO2:Eu nanoparticles dispersed in silica compared to that of SnO2:Eu nanoparticles, has been attributed to the distorted environment around surface Eu3+ ions brought about by the presence of both tin and silicon structural units. 119Sn and 29Si MAS NMR studies on this sample confirmed that there is no interaction between the tin and silicon structural units even after heating the samples at 900 deg. C