The effect of Ce concentration on the structural and optical properties of YGG:Ce phosphor

Y3(1-x) Ga5O12 phosphors doped with different Ce3+ concentration (with x = 0.005, 0.01, 0.02, 0.03, 0.04, 0.05) were prepared by sol-gel method. X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), scanning electron microscope (SEM), Infrared (IR) spectroscopy, photopluminescence (PL) and thermo-luminescence (TL) were used to characterize the phase structure and optical properties of the samples. XRD and XPS results reveal that the Ce3+ ions have entered into the YGG matrix and the lattice expansion is produced by the incorporation of Ce3+ ions. SEM analysis indicates the yttrium gallium garnet (YGG) phase has good quality, high purity and regular morphology after sintering at 1100 °C. IR spectrum analysis has confirmed the peaks with wave-numbers greater than 1000 cm−1are significantly reduced after sintering at 1100 °C. The results of TL glow curves show that three peaks with suitable trap depths exist in the phosphors and the maximum TL intensity of the phosphors is observed at x = 0.01. Optical absorption spectra obtained for the Ce3+doped YGG phosphors have illustrated the absorption bands at 298 and 424 nm are related to the Ce ions. The excitation and emission peaks of YGG:Ce phosphors are obtained at 443 and 522 nm respectively, corresponding to the 4f↔5d transition of Ce ions. The luminescence (both PL and TL) performance of phosphors strongly depend on the Ce3+ ions and YGG:Ce phosphor has the best luminescence performance when x = 0.01.