Synthesis and fluorescence properties of Y2O3:Eu by molten salt synthesis method

Red phosphors Y2O3:Eu were synthesized via molten salt synthesis method with the eutectic mixtures of KNO3-NaNO3 or KCl-NaCl as the fluxes. The as-prepared samples were investigated by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer. The results showed that as-synthesized phosphors had good cubic crystallinity and the effect of annealing temperature on crystallinity was significant. Furthermore, different special morphologies of products were obtained in terms of different fluxes. In the fluorescence spectra, not only did the products present common excitation band at 254 nm, which belongs to Eu3+-O2− charge-transfer state transition, two strong bands at 394 and 466 nm attributed to 7F0, 1−5L6, 7F0, 1−5D2 transitions of Eu3+ ions, respectively, also appeared, both of which were in good agreement with the requirements of phosphors for white light-emitting diodes. Under different excitation wavelengths, the relative intensity of emission at 611 nm pumped by 466 nm was much stronger than that of emission excited by 254 nm and the effect of fluxes contents on the fluorescence property was also discussed.