Structural investigation of xFe2O3 · (100 − x)[P2O5 · TeO2] glass system by FT-IR study and EPR spectroscopy

Glasses from xFe2O3 · (100 − x)[P2O5 · TeO2] system, with 0 ≤ x ≤ 50 mol%, were investigated by X-ray diffraction, FT-IR and EPR spectroscopies. The XRD patterns show a vitreous state of studied samples for x ≤ 35 mol% Fe2O3. The FT-IR spectrum of the P2O5 · TeO2 glass matrix reveals a structure formed from PO4, TeO4 and TeO3 units. The addition and the increasing of Fe2O3 content modify progressively the structure of the glass matrix. The local structure in the investigated glasses was revealed by means of EPR using Fe3+ (3d5; 6S5/2) ions as paramagnetic probes. The EPR spectra present two resonance absorption lines characteristic to Fe3+ ions centred at geff ≈ 2.0, for 0.5 ≤ x ≤ 35 mol% and geff ≈ 4.3, for 0.5 ≤ x ≤ 5 mol%. The variation of the EPR parameters, the intensity and line-width of these absorption lines, with iron ions composition has been followed.