Structural investigation of xFe_2O_3 · (100 - x)[P_2O_5·TeO_2] glass system by FT-IR study and EPR spectroscopy

摘要

Glasses from xFe_2O_3 •(100 - x)[P_2O_5 • TeO_2] 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% Fe_2O_3. The FT-IR spectrum of the P_2O_5 • TeO_2 glass matrix reveals a structure formed from PO_4, TeO_4 and TeO_3 units. The addition and the increasing of Fe_2O_3 content modify progressively the structure of the glass matrix. The local structure in the investigated glasses was revealed by means of EPR using Fe~(3+) (3d~5; ~6S_(5/2)) ions as paramagnetic probes. The EPR spectra present two resonance absorption lines characteristic to Fe~(3+) ions centred at g_(eff) ≈ 2.0, for 0.5 ≤ x ≤ 35 mol% and g_(eff)≈ 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.