Preparation and Characterization of CaF2:Yb3 +, Er3+ Up-Conversion Phosphor

In this work, up-conversion phosphor CaF2:Yb3 +, Er3+ was synthesized by the co-precipitation method. X-ray Diffraction (XRD) and Photoluminescence Spectra (PL) were used to characterize the samples. The effects of annealing temperature and Yb3+ and Er3+ concentrations on the luminescence properties were discussed. Strong green and red light were obtained under 980 nm laser excitation, the optimal annealing temperature was 600 °C, while the optimal doping concentration was 8 mol% Yb3+ and 0.6 mol% Er3+. The green (540 nm and 552 nm) and red (652 nm and 669 nm) up-conversion luminescence peaks can be ascribed to the transitions of 4S3/2-4I15/2 and 4F9/2-4I15/2, respectively. The up-conversion luminescence intensities of the green and red emitting peaks can be changed by adjusting the concentration ratio of Yb3+ and Er3+. Hence, it can potentially be used as the red light conversion agent. The dependence of up-conversion intensities (CaF2:Yb3+, Er3+) on excitation power indicated that two-photon absorption processes were responsible for green and red luminescence.