The synthesis and characterization of Dy³⁺-doped gadolinium oxide phosphors for white light applications

Gd₂O₃: Dy³⁺ nanophosphors with doping concentration of 1-3 wt% were prepared by solution combustion method. During the synthesis, citric acid was used as fuel. The synthesized powder was annealed at different temperature. The samples were analysed by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (FE-SEM), Energy dispersive X-ray analysis (EDAX) and photoluminescence (PL) spectrum. The X-ray diffraction pattern confirmed the as synthesized sample showing the mixed phase of hexagonal CGd₂O₅ and cubic Gd₂O₃ and it transforms to pure cubic phase of Gd₂O₃ after annealing at 600°C. Particle size of the phosphors was calculated using Debye Scherrer formula and it was in the range 12nm-39nm. FTIR spectra were measured to evaluate the vibrational features of the sample. Chemical composition of the sample was identified based on EDAX spectra. Morphological observation showed the presence of irregular shaped particles. The photoluminescence measurements were used to explore the emission behaviour of Dy³⁺ ion activated Gd₂O₃ phosphors. Photoluminescence emission peak of Gd₂O₃: Dy³⁺ samples were observed at 483 run, 571 nm and 677 nm corresponding to the ⁴F_9/2-⁶H_15/2, ⁴F_9/2-⁶H_13/2 and ⁴F_9/2⁶-H_11/2 transition respectively. These results indicate that Gd₂O₃: Dy³⁺ phosphors may be excellent candidates for the applications of white-light-emitting diodes.