Oxygen vacancies contained TiO2 spheres: facile fabrication and enhanced ferromagnetism

Uniform TiO2 spheres with a size of around 400 nm have been successfully synthesized by a facile approach from Ti powders. The obtained TiO2 spheres exhibit a good anatase structure ever before the annealing treatment. Through the measurement of UV-Vis spectra and XPS spectra, it was proved that the as-obtianed TiO2 spheres contained a lot of oxygen vacancies (Vo). After annealed, the concentration of Vo are decreased seriously. Magnetic measurements showed that the ferromagnetism (FM) of the TiO2 spheres also decreased with the annealing treatment, which informs the larger the concentration of Vo is, the stronger the FM becomes. These results indicate that the FM in undoped TiO2 can be contributed to oxygen vacancies. Moreover, the facile and low cost synthesis method makes the products to be promising materials for spintronic devices.