Dielectric properties of Fe-doped TiO2 nanoparticles synthesised by sol–gel route

Fe-doped nanocrystalline samples of titanium oxide have been synthesised by sol–gel route and conventional sintering process at 450°C under atmospheric conditions. These samples are characterised by X-ray diffraction (XRD), X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) and dielectric property measurement. Samples with Fe content more than 4 mole% crystallises in rutile phase and those with less than 4 mole% crystallises in anatase phase. Nanocrystallite size has been controlled by Fe doping. Crystallite size was found to decrease with Fe concentration in the anatase phase samples whereas reverse happens in rutile phase samples of titanium oxide. There is a slight variation in numerical values of crystallite sizes measured by the two techniques: TEM and XRD peak broadening. The highest crystallite size was 86 nm in 10 mole% Fe-doped samples and the lowest 20 nm in 4 mole% Fe-doped sample. Large dispersions and anomalous values of the dielectric constant, er were observed at low f...