Raman spectroscopic characterization of Er3+ -doped tellurite-based glasses
Résumé
Er3+-doped tellurite-based glasses have been examined with the aim of determining the structural characteristics of systems with broad Er3+ emission bands. Raman spectroscopy was used for the characterization of the (100−x)TeO2–xZnO, and (100−x)TeO2–xPbO systems. Results show that in both cases, the addition of even small quantities of the metal oxide leads to a decrease in intensity of the ratio I(TeO4)/I(TeO3), with greater changes observed for the PbO systems. However, for higher concentrations (x>20% for ZnO and x>30% for PbO), concentrations at which these oxides behave as glass-formers, the I(TeO4)/I(TeO3) ratio becomes nearly constant, indicative of a blockage of the spatial orientation of the metal chains. The addition of a small amount of erbium ions (<1%) results in significant changes in the intensity of the low-frequency region and of the distribution of TeO3 and TeO3+1 groups in the case of PbO. Luminescence spectra of the Er3+-doped glasses show that the best luminescence properties are obtained when the TeO4 network is most intact, i.e. for low concentrations of the metallic oxide.