Structural and optical properties of the lead based glasses containing iron (III) oxide

Abstract Iron (III) oxide was used as a doping material of lead based glasses in order to improve their optical and conductive properties. The vitreous system with the following composition xFe 2 O 3 ∙(100 − x) [4PbO 2  · Pb], where x = 0–40 mol% Fe 2 O 3 was prepared by melt quenching method and were characterized by investigations of X-ray diffraction, FTIR, EPR, UV–Vis spectroscopy, gap energy and refractive index calculations. FTIR spectra analysis suggests that the excess of oxygen ions coming from the introduction of Fe 2 O 3 up to 40 mol% is possible due to the formation of [PbO 6 ] and [FeO 4 ] structural units. At high Fe 2 O 3 concentration, the unexpected intensity decrease of resonance line situated at g ~ 2, corresponding to clustering iron ions, could be the result of partial transformation of the Fe + 3 to Fe + 2 ions (Fe + 2 ions do not give EPR signal). The widening of UV–Vis bands situated in the region between 450 and 550 nm towards higher wavelengths when the Fe 2 O 3 concentration increases in network matrix can be attributed to the Fe + 2 ions presence, confirming the EPR results. The increase of the iron (III) oxide content in the host matrix implies a shift of the fundamental absorption edge towards higher wavelengths, the decrease of the band gap energy values and the increase of refractive index values lead the improvement of optical properties in the visible range as well as of conductive properties of studied materials. It is interesting to observe that the optical band gap energies for these glasses slightly decrease with the addition of Fe 2 O 3 concentration; it is due to the creation of non-bridging oxygens and the increase of disorder degree of the host matrix.