Influence of Yb doping on optical and upconversion photoluminescence properties of Yb-, Er-co-doped Y₂O₃ transparent ceramics prepared by SPS

x% Yb-, 0.5% Er-co-doped Y₂O₃ transparent ceramics (x = 0, 0.1, 0.5, 1.0, 5.0 and 10) were prepared by the spark plasma sintering, and then we evaluated the effect of Yb doping on optical and upconversion (UC) photoluminescence (PL) properties. Under an excitation at 380 nm, the sharp emission peaks appeared around 550 and 660 nm, and the quantum yield was approximately 2%. The PL decay curves monitoring around 550 nm were fitted by a single exponential decay function. The decay time constants were 0.03–0.11 ms, and the values were typical for the 4f → 4f transitions of Er³⁺. Regarding the UC PL properties, the sharp UC emission peaks around 550 and 660 nm were observed, and the UC emission intensity of 5.0% Yb-, 0.5% Er-co-doped Y₂O₃ transparent ceramic sample was the highest among the prepared samples. With increasing x, the chromaticity of UC emission color was tuned from green to red region. Regarding the UC PL decay curves, the rise time became slower as increasing x. This behavior is one of the evidence of energy transfer from Yb³⁺ to Er³⁺.