Synthesis And Luminescent Properties Of Solid Solution Phosphor Based On Pyrosilicate And Ternary Sulfide

In recent years, white-light-emitting diodes (LEDs) have attracted much attention due to their superior features, such as high efficiency, compactness, long operational life-time, and environmental friendliness. At present, the commercial W-LED still fabricated by a blue InGaN LED chip and YAG:Ce3+yellow phosphor. Because of the lack of red-light contribution, the disadvantages of white LED by combining YAG:Ce3+and blue InGaN chip are poor color rendering index (Ra<85). Thus, a single-composition white-emitting phosphor is considered to be potentially useful to avoid those problems. So single-composition white-emitting phosphors become a hotspot for study.Pyrosilicate and Ternary Sulfide were selected as the host material of the phosphor, and Ce3+, Eu2+, Tb2+, Eu3+as activator ion. The luminescence properties of phosphor were researched though forming solid solution, aiming to obtain white-LED phosphor suitable for UV chip excitation.1. Synthesis and luminescence properties of Sr2Mg1-xZnxSi2O7:Ce3+, Tb3+,Eu3+phosphorSr2Mg1-xZnxSi2O7:Ce3+,Tb3+,Eu3+phosphorswere synthesized by conventional solid state method. The XRD analysis results indicated that Zn2+can replace Mg2+effectively and format solid solution. Under the excitation of387nm, the PL spectra consist of a broad emission in the blue region and a series of sharp line emissions at542and616nm. By adjusting the doping concentration of Ce3+, Tb3+, Eu3+, the emission intensity of phosphor in blue, green and red region can be adjusted, which could realize white light emission. Therefore, Sr2Mg1-xZnxSi207:Ce3+,Tb3+,Eu3+phosphors has potential application in white LED, which excited by ultraviolet. Especially when x=0.5, the ultraviolet excitation efficiency of this phosphors can be improved, when excited at327nm, the emission intensity of Ce3+and Tb3+were enhanced in different degrees.2. Synthesis and luminescence properties of M2Mgo.5Zno.5Si207:Ce3+, Tb3+, Eu3+(M=Ca, Sr, Ba)Adjusting the luminescence properties M2Mg0.5Zn0.5Si207:Ce3+,Tb3++, Eu3+phosphor through synthesis solid solution. Sr2-xCaxMg0.5Zn0.5Si2O7: Ce3+,Tb2+,Eu3+phosphor can be excited effectively under the387nm blue violet light and an emit387nm blue violet light,542nm green light and616nm red light at the same time. Tuning the doping concentration of Ce3+, Tb3+, Eu3+, the emission intensity of phosphor in blue, green and red region can be adjusted, which could realize white light emission also. When x increases from0to1, the blue violet emission of Ce3+shift to long wavelength direction, which may be related with the5d energy level splitting of Ce3+in the is different crystal fields. When x=1, the UV excitation efficiency of phosphor can be improved, when excited at327nm, the emission intensity of Ce3+and Tb3+are both enhanced. Inaddition, Sr2-xBaxMg0.5Zn0.5Si2O7: Ce3+, Tb3+, Eu3+solid solution phosphor can also be excited by329nm ultraviolet light, emitting blue violet light, green light and red light. It is worth mentioning that, the green emission band in the range of450-550nm ascribe to the emission of Tb3+and Eu2+, since the reduction of Eu3+in Ba2Mg0.5Zn0.5SiO07matrix. By adjusting the doping concentration of Ce3+, Tb3+and Eu3+, the color of phosphor can be adjusted. Therefore, Ba2Mg0.5Zn0.5Si2O7:Ce3+,Tb3+,Eu3+solid solution could be applied in white LED potentially.3. Synthesis and luminescence properties of Ba2Zn1-xMgxSi2O7:iCe3+, Eu3+phosphorBa1.97Zn1-xMgxSi2O7:0.03Eu3+phosphors can be effectively excited by ultraviolet light, the emission band peaks at500nm,590nm and610nm. The emission intensity can be adjusted by changing the ratio of Mg2+/Zn2+, due to the self-reduction reaction of Eu3+may be affectted by Mg2+. Under the excitation of380nm, Ba2Zn0.9Mg0.1Si2O7:0.03Eu3+and Ba2ZnSi2O7:0.03Eu3+phosphor provide white light emission. Under the excitation of330nm, Ba2Zn1-xMgxSi2O7:0.03Eu3+phosphor can emitting blue, green and red light, which attributed to Ce3+, Eu2+and Eu3+Tuning with the concentration of Ce3+, the emitting color can be tuned from green-blue region to red region. Under the excitation of330nm, the CIE color coordinate value of Ba2ZnSi2O7:0.03Eu3+,0.01Ce3+phosphor is close to the ideal of white light (0.33,0.33). Therefore, Ba2ZnSi207:0.03Eu3+,0.01Ce3+phosphor could be suitable for white LED. 4. Synthesis and luminescence properties BaY2-xAlxS4:0.5%Eu2+phosphorsBaY2-xAlYS4:0.5%Eu2+phosphors were synthesized by a high temperature solid-state method. Under the excitation of ultraviolet light, the PL spectra of BaY2S4:0.5%Eu2+phosphors consist of a broad emission in the red region from the electric-dipole-allowed4f-5d transitions of Eu2+. However BaAl2S4:0.5%Eu2+provide a green light emission at503nm. With the increase of Al3+concentration, the emission intensity at612nm decreased gradually, while the emission intensity at503nm decreased. Therefore, the spectroscopic properties of BaY2-xAlxS4:0.5%Eu2+can be tuned by the ratio of Y3+/Al3+. Under the excitation of383nm, the BaY2-xAlxS4:0.5%Eu2+(0.4≤x≤0.8) phosphor can provide emission at503nm and612nm, but under the excitation of475nm, the phosphor provide emission at612nm merely. BaY2-xAlxS4:0.5%Eu2+solid solution phosphor can be excited and emit light doubly.