Optical studies of sub-3 nm Eu2O3 and Gd2O3:Eu3+ nanocrystals

Colloidally stable sub-3 nm Eu2O3 and Gd2O3:Eu3+ nanocrystals have been synthesized via a hot solution phase technique. Optical properties of the nanocrystals are studied as a function of size. Both nanocrystal compositions exhibit a new optical signature, an emission peak at 620 nm. Intensity modulation of this peak has been observed for all nanocrystal sizes, suggesting surface-dependent or crystal-field dependent effect. Photoluminescence intensity of smaller Eu2O3 nanocrystals was comparable to that of the Gd2O3:Eu3+ nanocrystals.