The structural and spectroscopic properties of Na<sub>2</sub>O-Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2-x</sub>P<sub>2</sub>O<sub>5</sub> glasses (x=0 to 7 mol%) are investigated. Both Raman and IR spectra reveal that discrete phosphate species ([PO<sub>4</sub><sup>-3</sup>, [PO<sub>3</sub>O<sub>1/2</sub>]<sup>-2</sup>) with low polymerization degree can be formed in the silicate glass. These phosphate structures scavenge non-bridging oxygen ions and cations from the silicate network, resulting in an increase of the glass transition temperature. According to the Judd-Ofelt intensity parameters (Ω<sub>2</sub>, Ω<sub>4</sub>, Ω<sub>6</sub>) of Er<sup>3+</sup>, the asymmetry of local environment around Er<sup>3+</sup> becomes higher, and the bond covalency between Er<sup>3+</sup> and O<sup>2-</sup> decreases after P<sub>2</sub>O<sub>5</sub> is introduced. In the emission spectra, photoluminescence intensity increases with increasing P<sub>2</sub>O<sub>5</sub> concentration and the spectra are inhomogeneously broadened, revealing that the ligand electric field around Er<sup>3+</sup> is dramatically changed, and the glass matrix becomes disordered.
© 2012 Chinese Optics LettersPDF Article