Raman spectroscopic characterization of Er3+-doped tellurite-based glasses

Er3+-doped tellurite-based glasses have been examined With the aim of deter mining the structural characteristics of systems with broad Er3+ emission b ands. 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 decrea se in intensity of the ratio I-(TeO4)/I-(TeO3), with greater changes observ ed 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 o f a blockage of the spatial orientation of the metal chains. The addition o f 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 gl asses show that the best luminescence properties are obtained when the TeO4 network is most intact, i.e. for low concentrations of the metallic oxide. (C) 2001 Elsevier Science B,V. All rights reserved.