Spectral difference between nanocrystalline and bulk Y2O3:Eu3+

In this Letter spectral difference between nanocrystalline yttria doped with europium (Y2O3:Eu3+) and the bulk ones was reported. Besides a 580.6-nm line similar to that in the bulk Y2O3:Eu3+, a new broad excitation line at 579.9 nm was observed in the nanocrystals (NCs). The lifetime of the 579.9-nm line became slightly shorter than that of the 580.6-nm line. The 579.9-nm line was attributed to the Eu3+ ions near the surface of the NCs. Due to numerous surface defects, the crystal field on the surface degenerated, leading the energy levels of the electrons in 4f state to shift.