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 3 + /Er 3 + 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 nm near-infrared (NIR) laser, the phosphor emits 829 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 3 + ions from the 4 I 1 3 ∕ 2 energy level to the 4 F 9 ∕ 2 energy level, and finally relax to 4 I 9 ∕ 2 energy level. The phosphor has potential application value in the biomedical field and bio-imaging due to its emission of NIR upconversion luminescence.