Figure 3

(a) Emission spectra, (b) red to green intensity ratio and CIE (X, Y) chromaticity coordinates diagram of 1%Er³⁺, x%Tm³⁺ co-doped Y₂O₃ (x = 0, 0.2, 0.5, 1, 1.5). (c) Emission spectra and (d) Red to green intensity ratio and CIE (X, Y) chromaticity coordinates diagram of 1%Er³⁺, x%Ho³⁺ co-doped Y₂O₃ (x = 0, 0.2, 0.5, 1, 1.5).