Synthesis, Morphology, and Optical Characterization of Nanocrystalline Er³⁺:Y₂O₃

We describe a methodology to synthesize trivalent-erbium (Er3+)-doped yttrium oxide (Y2O3) nanoparticles. An in-depth morphology analysis indicates that the average diameter of the individual nanoparticles is about 25 nm. To optically characterize the nanocrystalline material, the room-temperature absorption spectrum has been obtained between 400 and 900 nm. The spectrum consists of six absorption bands, including 2G(1)9/2, 4F3/2 + 4F5/2, 4F7/2, 2H(2)11/2 + 4S3/2, 4F9/2, and 4I9/2. The room-temperature fluorescence spectra of the Er3+ (4f11) 2H(2)11/2 + 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions were analyzed for the crystal-field splitting of the energy levels of these states of erbium. We have measured the lifetimes for the 2H(2)11/2 + 4S3/2 and 4F9/2 metastable states and have investigated the effects of Er3+ concentrations and particle size on the emission intensity and decay times. The experimental energies (Stark levels) agree well within the experimental error with the theoretical values reported earlier for bulk single crystalline Er3+:Y2O3. Detailed structural and optical analyses suggest that the nanoparticles of Er3+:Y2O3 have potential applications in diverse fields of photonics including laser systems and optical communication devices.