Synthesis and single near-infrared upconversion luminescence of a novel Yb3+/Er3+ co-doped CaY₂O₄ phosphor

In this work, a single near-infrared (NIR) upconversion phosphor of Yb[Formula: see text]/Er[Formula: see text] co-doped CaY 2 O 4 was prepared using an equivalent substitution strategy. The CaY 2 O 4 structure features a (R 2 O 4 ) 2 -framework of double octahedra, with rare earth ions located within the framework. When irradiated with a 980[Formula: see text]nm near-infrared (NIR) laser, the phosphor emits 829[Formula: see text]nm NIR light. The main excitation mechanism of the NIR emission was explained by the characterization of power dependence, absorption spectrum, and down shift-conversion spectra. The energy transfer (ET) process is the promotion of Er[Formula: see text] ions from the 4 I[Formula: see text] energy level to the 4 F[Formula: see text] energy level, and finally relax to 4 I[Formula: see text] energy level. The phosphor has potential application value in the biomedical field and bio-imaging due to its emission of NIR upconversion luminescence.