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 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+, respectively. The intensity of red emission increases with increasing Yb3+ ion concentration. The effect of Yb3+ ion concentration on the structures and upconversion luminescence mechanism were discussed.