COMBUSTION SYNTHESIS AND LUMINESCENCE CHARACTERIZATION OF Ce~(3+) AND Dy~(3+) ACTIVATED K_2Ca(WO_4)_2 NOVEL PHOSPHORS

摘要

The Ce3+ and Dy3+ activated double tungstates, K2Ca(WO4)(2) were synthesized by the combustion method. The as-prepared compounds were characterized by X-ray diffraction (XRD) for confirming the completion of the synthesis reaction, phase purity, homogeneity, and crystallinity of the product. The morphological images obtained from scanning electron microscopy (SEM) characterization showed very well defined shapes of the particles of these phosphors. The Ce3+ and Dy3+ activated K2Ca(WO4)(2) phosphors were successfully excited at 345 nm and 354 nm, respectively, and at these excitation wavelengths, a very broad emission band covering the near ultraviolet (UV), blue, green, and yellow regions of visible spectrum was observed in both of the phosphors. The broad emission band, which can be ascribed to the self emission of the tungstate ion, coincides with the characteristic emission peaks of Ce3+ and Dy3+ ions. The photoluminescence (PL) properties of these phosphors indicate that they may be used for Hg-free solid state lighting (SSL) and white light emitting diodes (LEDs) applications.