Structural dependent thermal and optical properties of rare earth doped glass with mixed glass formers

A series of glasses containing the glass formers, phosphate and tellurite, were prepared by varying the glass composition and rare earth doping concentration. The glass transition temperature TgTg decreased with the increase in the Na2ONa2O concentration and increased with phosphate addition. A structural analysis based on FTIR spectra is used to explain the observed changes in TgTg. The change in the bandwidth of Er fluorescence peaked around 1534 nm with glass composition and erbium concentration is reported. An analysis of the fluorescence spectra shows that a decrease in TeO3+δTeO3+δ and TeO3TeO3 units present in the phosphate modified glass as compared to the tellurite glass without it. A model is proposed for the local structure of Er doped sodium phosphotellurite glasses. The spectroscopic properties of Er2O3Er2O3 doped and Er2O3Er2O3–Yb2O3Yb2O3 codoped sodium phosphotellurite glasses are investigated.