Preparation and Performance of SrWO4:RE3+ (RE = Eu, Sm, Pr) Fluorescent Powders for White Leds

The SrWO4:RE3+ (RE = Eu, Sm, Pr) fluorescent powders are synthesized using a high-temperature solid-state method. The phase structures and morphologies of the fluorescent powders are examined using X-ray diffraction and field-emission scanning electron microscopy, respectively. The results reveal that pure phase SrWO4 can be prepared via calcination at 900oC for 4 h and that doping with rare-earth ions has no effect on the crystal phase of the fluorescent powders; SrWO4 powders doped with three rare-earth ions all form spherical-like structures. The luminescence properties of the samples are evaluated using a fluorescence spectrometer, and the excitation and emission spectra of the SrWO4:RE3+ (RE = Eu, Sm, Pr) fluorescent powders are analyzed. The results indicate that SrWO4:Eu3+ fluorescent powder can be effectively excited by ultraviolet light at 395 nm and emit red light at 615 nm when a doping concentration of Eu3+ is 7%; Sm3+- and Pr3+-doped SrWO4 can emit red light at 650 and 687 nm when excited at 406 and 460 nm, respectively, with a doping concentration of 5% each. A W-LED device with SrWO4:Eu3+ pink fluorescent powder and a 395-nm UV chip is successfully assembled. The chromaticity coordinates of the device are (0.3055, 0.3532), exhibiting prominent white light. SrWO4:RE3+ (RE = Eu, Sm, Pr) fluorescent powders are expected to be red suorescent powders for UV-excited white LEDs.