Structural studies of iron-doped TiO2 nano-composites by Mossbauer spectroscopy, X-ray diffraction and transmission microscopy

The iron-doped TiO2, nano-composites prepared by sol-gel method and calcined at 923 K have been investigated by means of Mossbauer spectroscopy, X-ray diffraction and transmission electron microscopy. The results indicate that TiO2 exists mainly in the form of anatase phase with a grain size of about 10-20nm. Only about 1.5wt% Fe incorporates into the lattice of anatase and forms a substitutional Fe0.02Ti0.98O2, solid solution for all samples. We present that a superparamagnetic alpha-Fe-2-O-3 phase is produced in iron-doped TiO2 nano-composites. There is a maximum of 4.0 wt% Fe in the superparamagnetic alpha-Fe2O3 in the doping content of 10 wt% Fe, and the amount of ferromagnetic alpha-Fe2O3 increases largely with the iron-doped concentration. We propose that the Fe sites in the iron-doped TiO2, are composed of substitutional FexTi1-xO2, superparamagnetic alpha-Fe2O3 and ferromagnetic alpha-Fe-2-O-3. (c) 2005 Elsevier B.V. All rights reserved.