Structural studies on iron-tellurite glasses prepared by sol-gel method

In this study, we report structural properties of the iron-tellurite glasses obtained using the sol-gel synthesis. The samples were characterized by X-ray diffraction, FTIR, UV-vis and EPR spectroscopy. Our results indicate dominant presence of iron ions in the trivalent state and the existence some Fe2+ ions. The analysis of the IR spectra indicates a gradual transformation of iron ions from tetrahedral into octahedral sites when the concentration of Fe(NO3)(3) is increased beyond 0.64 mol%. EPR studies show that the increase of Fe(NO3)(3) content in the host matrix induces the growth of the number of effective g values. This can be explained considering that the orbitals of O2- ion with a large spin-orbit interaction constant will interact with the 3d orbital of Fe3+ ion bonded to this O2- ion, thus leading to appearance of an orbital angular momentum which contributes to the magnetic moment of Fe3+ ion. A strong dipolar interaction, which is more predominant in a glass with higher content of Fe(NO3)(3), causing a localized magnetic field along the site of the Fe3+ ions and the increase the effective g values. (C) 2010 Elsevier B.V. All rights reserved.