Luminescence of trivalent samarium ions in silver and tin co-doped aluminophosphate glass

This work presents the spectroscopic properties of trivalent samarium ions in a melt-quenched aluminophosphate glass containing silver and tin. Addition of 4 mol% of each Ag₂O and SnO into the glass system with 2 mol% Sm₂O₃ results in Sm³⁺ ions luminescence under non-resonant UV excitation owing to energy transfer from single silver ions and/or twofold-coordinated Sn centers. Assessment of luminescence spectra and decay dynamics suggest the energy transfer mechanism to be essentially of the resonant radiative type. Moreover, a connection between the luminescent and structural properties of the rare-earth doped glass system was demonstrated. Raman spectroscopy characterization revealed that no significant variation in the glass matrix is induced by Sm³⁺ doping at the concentration employed. A comparison was made with a structural study performed on the Eu³⁺ doped system (containing 2 mol% Eu₂O₃ along with 4 mol% of each Ag₂O and SnO) where the radiative energy transfer mechanism was previously established. The data appears consistent regarding the lack of variation in glass structure upon the Eu³⁺ and Sm³⁺ doping in connection with the dominance of the radiative transfer in the matrix. Thermal treatment of the material leads to precipitation of Ag nanoparticles of a broad size range inside the dielectric as observed by transmission electron microspcopy. Assessment of ⁴G_5/2 excited state decay in Sm³⁺ ions shows no influence from the silver particles.