Characterisation of Fe2TiO5nanocrystallites synthesised via homogeneous precipitation

Pseudobrookite (Fe2TiO5) is the prototype of a series of semiconductor materials, which have similar crystal structures, and has various applications. To study its structure, formation mechanism and optical properties, we synthesised well-crystallised Fe2TiO5 nanocrystallites at 800°C using a precursor consisting of equimolar Ti4+ and Fe3+ ions. The precursor was prepared via a homogeneous precipitation method, in which urea was used as the precipitator when it gradually hydrolysed. Both X-ray diffraction analysis and high-resolution transmission electron microscope images indicate that the synthetic Fe2TiO5 is an orthorhombic structure. It is suggested that all Ti4+ ions occupy certain 8f sites in the Fe2TiO5 crystal structure. We think that the synthetic Fe2TiO5 originated from anatase and Fe2O3, and Fe3+ ions in the precursor promoted the transforming of anatase into rutile. The synthetic Fe2TiO5 has an absorption threshold (∼580 nm) in visible light region and has a band gap of ∼2·05 eV.