ELECTRONIC CONFINEMENT OF SILVER NANOCLUSTERS IN Er3+-ACTIVATED SILICATE AND PHOSPHATE GLASSES

In this work the silver chemical state in Ag-exchanged Er3+ doped silicate and phosphate glasses is analyzed. X-Ray Photoelectron spectroscopy (XPS) shows that thermal annealing leads to a different behavior of silver atoms in these two systems. In silicate glasses silver aggregates in nanoparticles. In phosphate glasses silver is in an oxidized state and in very small metallic nanoparticles. These results are corroborated by the fact that the surface plasmon absorption band is observed in the absorption spectra of silicate glasses, whereas is absent in the case of the phosphate glasses. These evidences explain also the occurrence or the lack of Er3+ luminescence enhancement in the silicate and phosphate silver-exchanged glasses, respectively.