Study On The Preparation And Luminescence Properties Of Eu³⁺-doped Tungstate And Molybdate Red Phosphor For White LED

White LED with high light efficiency, long life, impact resistant, resistant to vibration, no pollution, etc, and is becoming a new generation of green lighting light source. Currently, the color rendering index, color temperature and other properties of commercial white LED are not excellent due to the lack of red-light component. So, it is urgent to develop a red phosphor which can be effectively excited by blue or near ultraviolet light for white LED. Among lots of rare earth-doped red phosphor, tungstate and molybdate doped by rare earth are considered as superior red phosphors because of easy synthesis, stable performance, pure color effectively excited by blue or near ultraviolet light(400 nm) and the strongest emission at 615nm. In order to find suitable commercial red phosphor for white LED, the luminescence properties of ABO4:Eu3+:M+(A=Ca, Sr, Ba; B=Mo, W; M=Li, Na, K) red phosphors were researched.The research used tungstate and molybdate as host materials, Eu3+as doping ion to synthesize a series of A1-xMoO4:Eu3+x(A=Ca, Sr, Ba) red phosphors which have scheelite structure of tetragonal crystal system via high temperature solid state reaction. The crystal structure and luminescent properties of phosphors were characterized by XRD (X-ray diffraction) and PL (fluorescence spectrophotometer). The results show that physical and chemical performance of this series of luminous powder is stable. They can be effectively stimulate by the near ultraviolet light (394nm), and produce the 5D0â†'7F2 characteristic red transition emission; Excitation intensity enhances continuously with Eu3+ion concentration increases until x= 0.05, when x>0.05, the excitation intensity decreases with increasing concentration; In the A1-xMoO4:Eu3+x (A=Ca, Sr, Ba) phosphors, with the increase of ionic radius of the alkaline earth metal ion A2+, the emission intensity will decrease, and the luminous intensity of the CaMoO4:Eu3+is the largest.A series of Ca0.95MoO4:Eu3+0.05:M+x(M=Li, Na, K) luminous powder were prepared to modify Cao.95Mo04:Eu3+o.o5 by introducing charge compensation. Fluorescence spectra show that charge compensation does not affect the structure of the phosphor, but emission intensity enhances continuously with M+ion concentration increases until x=0.04 which is M+/Eu3+=0.8, when x>0.04, the emission intensity decreases with increasing concentration; With the increase of ionic radius of the charge compensation M+, the emission intensity will decrease, and the luminous intensity of Ca0.95MoO4:Eu3+0.05:Li+o.o4 is the largest.Based on the process and doping concentration, a series of Ca1-xWO4:Eu3+x which also have scheelite structure of tetragonal crystal system were obtained. With the help of PL, the samples can be effectively excited by the near ultraviolet light (394 nm) and it can be observed the 5D0â†'7F1(593nm),5D0â†'7F2 (615nm),5D0â†'7F3 (655nm),5D0â†'7F4 (702nm) characteristic transition emission of Eu3+. Compared to Ca1-xMoO4:Eu3+x, the luminous intensity reaches maximum when x=0.07.Using charge compensation to enhance the luminous intensity of Ca1-xWO4:Eu3+x.The emission and excitation spectra of Cao.95W04:Eu3+0.05:M+x(M=Li, Na, K) display that the position of peak does not move; When x= 0.04 which is M+/Eu3+=0.8,the emission intensity is largest; With the increase of ionic radius of the charge compensation M+, the emission intensity will decrease, therefore, the luminous intensity of Ca0.95WO4:Eu3+o.o5:Li+o.o4 is the largest.