Research on Rare-earth Tungstates Red Phosphors for White-light Emitting Diodes

Three series of europium(Ⅲ) ion-doped tungstates red phosphors were prepared by the high temperature solid-state reaction method.Their photo-luminescent properties were investigated at room temperature.The results indicate that the phosphors show intensely red emission under 395 and 465 nm light excitation,matching with the light-emitting wavelength of a near-UV-emitting InGaN chip and a blue-emitting InGaN chip,respectively.Therefore the tungstates phosphors can be applied as an efficient red component for NUV InGaN-based and blue InGaN-based white LEDs.No concentration quenching of Eu3+ in Ca9Eu2W4O24 and Sr9Eu2W4O24 is observed,while the quenching concentration of Eu3+ in Ca3La2W2O12 is about 40%.Finally the related LEDs are fabricated with Ca9Eu2W4O24,Sr9Eu2W4O24 and Ca3La1.2Eu0.8W2O12,and the performances of these LEDs are discussed to analyze the advantage and deficiency of such tungstates phosphors in applications for WLEDs.