Lu2O3:Er3+ powders were synthesized by chemical coprecipitation. Ultraviolet, violet and blue upconversion properties of Lu2O3:Er3+ powders as a function of Er3+ concentration were investigated upon 514.5 nm laser excitation. The cross relaxation of P-2(3/2) + I-4(15/2) -> H-2(9/2) + I-4(13/2) was supposed to be responsible for the adjustable spectral distribution of upconversion emissions. Based on spectral, concentration and pump power dependence analyses, the upconversion mechanisms were proposed. Moreover, Stokes luminescent properties of Lu2O3:Er3+ powders were also observed upon 514.5 nm laser excitation. These spectra showed the same concentration-dependent characteristics, and the dependence of emission spectra on Er3+ concentration could be well explained with the cross relaxation of F-4(7/2) + I-4(11/2) -> F-4(9/2) + F-4(9/2). (C) 2013 Elsevier Ltd. All rights reserved.