Effect of Yb3+ concentration on the structures and upconversion luminescence properties of Y2O3:Er3+ ultrafine phosphors

Y2O3:Er3- ultrafine phosphors with a varying Yb3+ ion concentration were prepared by a urea homogeneous precipitation method. The results of XRD show that all the samples are of a pure cubic structure and the average crystallite sizes can be calculated as 45, 34. and 28 nm for Y2O3:Er3+ Ultrafine phosphors with Yb3+ ion concentrations of 0, 10%, and 20%, respectively. The lattice constant and cell volume of the ultrafine phosphors decrease with enhancing Yb3+ ion concentration. The upconversion luminescence spectra of all the samples were studied under 980 nm laser excitation. The strong green and red upconversion emission were observed, and attributed to the H-2(11/2) -> I-4(15/2) -> S-4(3/2) I-4(15/2) and F-4(9/2) -> I-4(15/2) transitions of Er3+, respectively. The intensity of red emission increases with increasing Yb3+ ion concentration. The effect of Yb3+ concentration on the structures and upconversion luminescence mechanism were discussed.