The structural study of Fe2O3-TeO2-B2O3-SrF2 glasses by EPR and IR spectroscopies

The local structure of Fe2O3-TeO2-B2O3-SrF2 glasses was studied by recordin g the EPR and IR absorption spectra. Structural changes and increasing glas s stability were evidenced with the addition of Fe2O3 in the sample. The di stribution of isolated paramagnetic ions in sites of strongly distorted oct ahedral symmetry was detected at low concentration (up to 3 mol% Fe2O3) by means of EPR measurements. For x > 3 mol% Fe2O3, the clustered iron ions be come progressively preponderent in the system. Mixed valence states of iron ions involved in dipole-dipole and superexchange type interactions were al so evidenced. The IR spectra analysis revealed the BO3, BO4 and B2O6 units in the structure of tellurite investigated glasses. Among these structural units, those containing the threefold boron atoms are predominant.