Photoluminescence properties of samarium-doped TiO2 semiconductor nanocrystalline powders

In this work, the luminescence properties of samarium ions-doped titanium dioxide prepared by the sol-gel process were studied. A strong orange red emission (⁴G_5/2−⁶H_7/2 (orange) and ⁴G_5/2-⁶H_9/2 (red)) ascribed to the electron transitions in 4f⁵ configuration of Sm³⁺ ions was observed upon excitation into TiO₂ host. The energy transfer from TiO₂ to Sm³⁺ was verified and the relevant mechanism was discussed. In addition, the impacts of metal ion codopants upon the TiO₂:Sm³⁺ luminescence properties were studied. The results indicated that the central excitation band shifted to blue in the bismuth-codoped materials (0.5-4% in molar ratio), while it shifted to red in the zirconium-codoped materials. Such materials may find applications in white light-emission diode (LED) and tunable solid lasers.