Eu³⁺, Bi³⁺ codoped Lu₂O₃ nanopowders: Synthesis and luminescent properties

Eu³⁺, Bi³⁺ codoped Lu2O3 powders (Eu = 2.5 at.%, Bi = 0-3.0 at.%) were prepared using the sol-gel method. Fourier transform infrared spectroscopy, x-ray diffraction, and excitation and emission spectra were carried out to characterize the synthesis, structure, and luminescent properties. The excitation spectra show a strong peak at 350-390 nm, corresponding to the Bi^{3+ 1}S0 → ³P1 transition, and the emission spectra present the emission from ⁵D0 → ⁷F J (J = 0, 1, 2, 3, 4) level of Eu³⁺. The intensity of the reddish emission at 612 nm was monitored as a function of the Bi³⁺ content and showed a light yield increment of ≈400% compared to a monodoped sample at 1.0% at. Bi³⁺, produced by an energy transfer process from Bi³⁺ to Eu³⁺. This was a consequence of the overlapping of the Bi^{3+ 3}P1 → ¹S0 emission with the f-f Eu³⁺ transitions.