Abstract: In order to obtain up-conversion luminescent materials with bright red emission, a series of Yb³⁺, Er³⁺, Mn²⁺-doped Gd₂O₃ microcrystals were prepared by simple chemical precipitation method, and their morphology, structure and luminescent properties were characterized. The results show that Gd₂O₃:10%Yb³⁺,1%Er³⁺ microcrystals exhibit a flower-like morphology, and the average diameter is 2.28 μm. After calcination at high temperature, the sample presents a cubic Gd₂O₃ structure with good crystallinity, and Mn²⁺ doping does not affect the morphology and crystal phase of the product. Under 980 nm near-infrared light excitation, Gd₂O₃:10%Yb³⁺,1%Er³⁺ microcrystals show orange-red luminescence, which corresponds to the ⁴F_9/2→⁴I_15/2 transition of Er³⁺. With the increase of Mn²⁺ doping concentration (molar fraction), the luminescence intensity of Gd₂O₃:10%Yb³⁺,1%Er³⁺, x%Mn²⁺ microcrystals first increases and then decreases, and the luminescence color gradually turns to red, which is consistent with the CIE color coordinate. At the same time, the up-conversion luminescence mechanism and the possible energy transfer process of Gd₂O₃:10%Yb³⁺,1%Er³⁺, x%Mn²⁺ microcrystals were analyzed according to the relationship between luminescence intensity and excitation power.

Key words: up-conversion luminescence, Gd₂O₃ doping, red emission, energy transformation, flower-like microcrystal, chemical precipitation method