Effect of sodium oxide and sodium fluoride in gadolinium phosphate glasses doped with Eu₂O₃ content

Sodium gadolinium phosphate oxide and sodium gadolinium oxyfluoride glasses doped with europium oxide were synthesized by melt-quenching method. The density, molar volume and refractive index of the glass samples were carried out. Density and molar volume of oxide glass is more than oxyfluoride glass. The average phosphate to phosphate distance for oxide glass seems to be more than oxyfluoride glass. Polaron radius, inter-ionic radius shows 1.181 nm, 2.88 nm and 1.174 nm, 2.86 nm for oxide glass and oxyfluoride glasses respectively. Oxide electronic Polarizability and optical basicity of the oxide glass are lower than oxy-fluoride glass. Theoretical optical basicity shows higher for oxide glass than oxyfluoride suggesting increase in covalency of the cation to oxygen bonds in oxide glass. Optical band gap was estimated and found to be 3.061eV and 3.204 eV for oxide and oxyfluoride glass. Theoretical two photon absorption coefficient β were evaluated and found to be 11.96 and 10.80 for oxide and oxyfluoride glasses respectively. Electron-phonon coupling strength were evaluated from the phonon side band spectra for the oxide and oxy-fluoride glasses. The asymmetry ratio (R) show higher for NaF doped glass than Na₂O confirming their role in elevated ionicity for oxyfluoride glass than oxide glass. Furthermore, the glasses were subjected to study for their luminescence properties of the oxide and oxyfluoride glass samples.