Upconversion luminescent materials of Y–Gd oxysulfide binary system codoped with Yb and Er

(Y_1−xGd_x)₂O₂S:0.08Yb/0.02Er powders doped with different concentrations of Gd³⁺ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0) were prepared by flux method. The effects of Gd³⁺ doping amount on the phase composition, the crystal structure, the luminescent intensity, the emission color, phonon energy and forbidden bandwidth of Y₂O₂S:Yb/Er were investigated by XRD, UPL, CIE, RAMAN and R%, respectively. (Y_1−xGd_x)₂O₂S:Yb/Er powders doped with different concentrations of Gd³⁺ were all pure oxysulfide phase. Upconversion luminescent intensity of (Y_0.9Gd_0.1)₂O₂S:Yb/Er was the maximum. Green and red emission intensity of Y₂O₂S:Yb/Er was increased by three times with doping 10 mol% Gd³⁺ ions. The emission color was basically yellow. Gd³⁺ ions optimized the crystal structure of Y₂O₂S, changed the crystal field of Er³⁺ and Yb³⁺ ions, and improved the upconversion luminescent properties.