Preparation and luminescent properties of novel red phosphors for white-light emitting diodes (W-LEDs) application

A series of Eu³⁺–Gd³⁺ co-doped solid solution of Ca_0.54Sr_{0.46–1.5x–1.5z}Eu_zGd_x (MoO₄)_y (WO₄)_1−y (x=0.01–0.20, y=0–1.0, z=0.01–0.30) have been prepared by solid-state reactions. It is found that appropriate amount of Mo⁶⁺ or W⁶⁺, Eu³⁺ and Gd³⁺concentrations can enhance the luminescent intensity and improve crystal structure. These phosphors can be effectively excited by ultraviolet light at 394 nm and blue light at 465 nm (f–f transition) and emits red light (616 nm) with line spectrum. The wavelengths at 394 and 465 nm are nicely fitted in with the widely applied output wavelengths of ultraviolet or blue LED chips.