Investigation of activated oxygen molecules on the surface of Y2O3 nanocrystals by Raman scattering

Activation of surface oxygen molecules on cubic Y2O3 nanocrystals (NCs) is investigated. As the annealing temperature under O2 is increased, the strong Raman band at 965 cm−1 previously never assigned weakens gradually, while the intensity of the 378 cm−1 Raman band arising from Y3+-O2− vibration increases. X-ray diffraction reveals no structural change during annealing and energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and theoretical calculation suggest that the interstitial oxygen O22− connected to the F centers gives rise to the 965 cm−1 Raman band. The results provide direct evidence of the existence of activated oxygen ions on Y2O3 NCs.