Phase formation and luminescence properties in Eu3+-doped TiO2 nanoparticles prepared by thermal plasma pyrolysis of aqueous solutions

Eu3+-doped TiO2 nanopowders were synthesized by Ar/O2 induction thermal plasma pyrolysis of atomized aqueous solutions containing titanium(III) trichloride and europium(III) nitrate. TiO2 nanocrystals are mixtures of the anatase and rutile polymorphs, but the rutile content increases when more Eu3+ is added. The content of Eu3+ soluble in the TiO2 lattice was limited to 0.3% of Eu3+ above this, Eu2Ti2O7 pyrochlore was formed. Photoluminescence measurements revealed that the Eu3+-doped TiO2 nanopowders exhibited sharp emission at 617 nm, but emission through energy transfer from the TiO2 host to the activator Eu3+ ions was not observed.