Ultraviolet (UV)/blue upconverted luminescent properties of the cubic Y2O3:Er3+ nanocrystals as a function of the erbium concentration were investigated upon 488 nm Ar+ laser excitation. The remarkable decrease of upconverted emission intensity and the quenching of the P-2(3/2) -> I-4(11/2)/I-4(13/2) transitions were observed in the Y2O3 nanocrystals with high erbium concentration. The emission spectra and the exciting power dependence of upconverted luminescent intensities reveal that the possible upconversion mechanisms are excited-state absorption (ESA) and energy transfer (ET). Moreover, a UV/violet upconverted emission spectrum of nanocrystalline Y2O3:Er3+ upon 980 run light excitation was also observed and a three-photon process made a contribution to this upconverted emission. (c) 2005 Elsevier B.V. All rights reserved.