UV excitation properties of Eu3+ at the S6 site in bulk and nanocrystalline cubic Y2O3

Increases of emission intensities for Eu3+ at the S6 site relative to that at the C2 site have been observed as UV excitation wavelength decreases from 300 to 200 nm in both bulk and nanocrystalline cubic Y2O3:Eu3+. Analysis of excitation spectra suggests that the energy transfer from the host prefers to the S6 site. In addition, spectral red-shift has been found in both charge transfer bands in nanocrystalline Y2O3:Eu3+ compared to the bulk material. The number ratio of S6 sites to C2 sites is also smaller in nanocrystalline Y2O3:Eu3+ than that in the bulk one.