Sensitized Luminescence of Sm3+,Eu3+-Codoped TiO2 Nanoparticles

Sm3+,Eu3+-codoped TiO2 nanoparticles were prepared by a facile sol-gel-solvothermal method. Sm3+ and Eu3+ were successfully incorporated into a TiO2 lattice and resulted in intense emission lines with resolved crystal-field splitting, in spite of a large mismatch in ionic radius between trivalent lanthanides (Ln(3+)). and Ti4+. The intense sensitized emissions of Sm3+ and Eu3+ ions by TiO2 host were obtained at room temperature. In this case, Sm3+ also acts as a bridge to transfer energy from TiO2 host to Eu3+ ions, which was not observed in Eu3+-doped TiO2 nanoparticles. In comparison with direct excitation of lanthanide ions, the luminescence lifetimes of (4)G(5/2) of Sm3+ and D-5(0) of Eu3+ were observed to be significantly prolonged upon excitation above TiO2 band-gap. A sensitization mechanism to illustrate the energy transfer from TiO2 to Sm3+ and Eu3+ was proposed based on the optical behaviors of the codoped nanoparticles.