The influence of the chemical state of silver on the enhancement of the Er3+ emission

This work deals with the study of the chemical state of Silver in Ag-exchange Er3+ doped silicate and phosphate glasses. The X-Ray Photoelectron spectroscopy shows that under annealing treatment silver in these two glasses behaves in a different fashion. In silica-based glasses thermal treatments lead to silver clusters which size is around 3-4nm. The different chemical environment in phosphate glasses induces a different organization of silver atoms in the glassy network. The XPS spectra indicate that now silver is present in both oxidized state and in very small nanoparticles of about 1nm size. These findings are corroborated by the absorption and emission spectra analysis and explained on the basis of the different chemical interaction between silver and the host medium. These preliminary results show that the chemical state of silver strongly influences the process of energy transfer from clusters to Er3+ dopant determining the degree of the Er3+luminescence enhancement.