Optical absorption, ESR, FT-IR spectral studies of iron ions in lead oxyfluoro silicate glasses

► The spectral studies suggested that existence of Fe3+ ion in lead oxyfluoro silicate glasses. ► At high concentration of Fe2O3, Fe3+ ions reduced to Fe2+. ► The conversion of some [FeO4] to [FeO6] structural units takes place. Melt quenching technique is used for the preparation of lead oxyfluoro silicate glasses containing iron ions. Optical absorption, ESR, FT-IR spectral investigations are carried out to study local structure in glass network. The optical absorption spectra contains three optical absorption bands in visible – NIR regions. The ESR spectra exhibit resonance signals at g=9.4, 4.2 and 2.0. The resonances at g=9.4 and 4.2 are attributed to Fe3+ ions in rhombic and axial symmetry sites, respectively. The g=2.0 resonance signal is due to dipolar interaction. The optical absorption together with ESR measurements suggested that iron ions are dominant presence in the trivalent state. The FT-IR spectral analysis indicates a gradual transformation of iron ions from tetrahedral sites to octahedral sites as the concentration of Fe2O3 is increased in the glass matrix. The physical parameters like density, refractive index, interionic distance along with spectroscopic parameters are measured for these glasses.