Effect of iron on the dielectric properties of silicate glasses prepared by sol-gel.

The sol-gel method is a very flexible route for producing sieving matrix such as SiO₂ with pore radii in nanoscale region to embed oxide particles like Fe₂O₃. In this work, iron oxide nanoparticles embedded in a SiO₂ glassy matrix prepared by the sol-gel method have been investigated as a function of Fe/Si ratio. Different composition of dried gels with 1, 2, 10 and 20 mol% of Fe₂O₃ in the SiO₂ matrix were heat-treated (HT) in air, at temperatures from 400 ºC up to 1400 °C. The structure and morphology of the obtained glasses and glass-ceramics were studied by X-ray powder diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). Impedance spectroscopy measurements and magnetic characterization were performed as function of temperature and the results are related with the microstructure. The X-ray diffraction patterns showed that increasing the amount of Fe₂O₃ oxide promotes the formation of crystalline phases, in particular silicate phases. The increase of the heat-treatment temperature has a similar behavior. The electrical and dielectric properties were related with these structural modifications and with the sample morphology. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]