Oxygen vacancies contained TiO₂ spheres: facile fabrication and enhanced ferromagnetism

摘要

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.