Ce3+,Tb3+,Eu3+共掺杂Sr2MgSi2O7体系的白色发光和能量传递机理

通过正交试验,采用高温固相法制备了Sr2-x-y-zMgSi2O7∶xCe3+,yTb3+,zEu3+系列样品.使用X射线衍射仪和荧光光谱仪表征了样品的物相和发光性质,并讨论了Ce3+-Tb3+-Eu3+共掺杂Sr2MgSi2O7体系中的能量传递过程.实验结果表明,在327 nm波长激发下,所合成荧光粉的发射峰主要位于387 nm(蓝紫)、542nm(绿)和611 nm(红)处;分别以387,542和611 nm为监控波长,所得激发光谱显示荧光粉在327 nm处有最好的激发.在327 nm光激发下,系列样品发光进入白光区.最优化的荧光粉为Sr1.91MgSi2O7∶0.01Ce3+,0.05Tb3+,0.03Eu3+,其色坐标为(0.337,0.313),是一种潜在的发光二极管(LED)用白色荧光粉.

White-light Emitting and Energy Transfer Mechanism in the Ce3+,Tb3+ and Eu3+ co-Doped Sr2MgSi2O7 Phosphor

Sr2MgSi2O7: Ce3+,Tb3+,Eu3+ phosphors were prepared by high temperature solid state reaction. Crystallization and optical properties were investigated via powder X-ray diffraction and fluorescence spectra, respectively. Under the excitation of ultraviolet(327 nm), the emission spectra of these phosphors exhibited multi-emission lines peaked at about 387(blue-purple color), 542(green color) and 611 nm(red color). Monitored at 387, 542 and 611 nm, respectively, the Sr2MgSi2O7: Ce3+,Tb3+,Eu3+ powder got optimally excited at λex=327 nm, the Sr2MgSi2O7: Tb3+ powder got optimally excited at λex=235 nm. It has been found that the chromaticity coordinates (0.337, 0.313) for the nominal composition Sr1.91MgSi2O7: 0.01Ce3+,0.05Tb3+,0.03Eu3+ is very close to the CIE(Commission International de I'Eclairage 1931 chromaticity) standard white coordinates (0.33, 0.33), showing that Sr1.91MgSi2O7: 0.01Ce3+,0.05Tb3+,0.03Eu3+ is a potential single-phased white phosphor for LED-based UV-chip. The energy transfer processes from Ce3+ to Tb3+ and from Ce3+ to Eu3+ were discussed. There may be two kinds of energy transfer process in the Sr2MgSi2O7: Ce3+,Tb3+,Eu3+ system, which is from Ce3+(5d) to Eu3+(5D4)+Tb3+(5D3,4) and Tb3+(5D2,3)→Ce3+(5d)→Eu3+(5L6).