Synthesis and spectroscopic properties of LiY(WO_4)(MoO_4): Eu~(3+) red phosphors for white LEDs

摘要

A series of LiY(WO_4)(MoO_4):Eu~(3+) red phosphors have been synthesized by solid state reactions at high temperatures. The effect of Eu~(3+) doping concentration, calcination temperature, reaction time and ratio of W/Mo on the optical properties of the red phosphors are studied and optimized. The phase impurity and spectroscopic properties are characterized by X-Ray Diffraction (XRD) and Photo-Luminescence (PL) spectra respectively. It is found that all the samples can be excited efficiently both by near ultraviolet light (395 nm) and blue light (464.5 nm), which match well with the emission of GaN based LED chips. The luminescent intensity maximizes for the sample of Eu~(3+) 5 mol% in doping concentration (replacing Y) and W:Mo=1:1 in mole with calcinated of 750°C. To improve the dispersion and change the morphology of the phosphor powders, the sample is post-processed through ultrasonic dispersing method and the luminescent intensity of the post-treated sample increases by nearly 20%.