Green upconversion luminescence in Er3+: BaTiO3 films

Green upconversion emissions at 548 and 528 nm have been obtained from sol- gel derived nanocrystalline Er3+:BaTiO3 films under 980 nm excitation. The green emissions are attributed to the ground-state (I-4(15/2)) -directed tr ansitions from H-2(11/2) (528 nm) and S-4(3/2) (545 nm) of Er3+ ions. Analy sis of the temporal evolution of the emission at 548 nm shows that both exc ited state absorption of individual ion and energy transfer between the two neighboring ions contribute to the upconversion emissions in Er3+ (3 mol % ):BaTiO3 film. The lifetime of the dominant emission at 518 nm is about 90 mu s. (C) 2000 American Institute of Physics. [S0003-6951(00)02131-8].