白色荧光粉CaF2∶Yb3+/Eu3+/La3+的制备及其上转换发光特性

采用改进的两步高温固相熔融法制备了Yb^3+、Eu^3+、La^3+共掺杂CaF 2的上转换荧光粉。基于荧光猝灭原理,通过改变La^3+掺杂浓度来调节CaF 2∶Yb^3+/Eu^3+材料的发光性能,并在980 nm近红外光激发下,获得了该材料的白色上转换发光(UCL)。在该发光体系中,Yb^3+不仅起到了敏化Eu^3+的作用,同时,Yb^3+二聚体(Yb^3+-dimer)自身合作发出波长范围480~540 nm的绿色荧光。而白光三基色中的绿光正是来自Yb^3+二聚体的合作发光。Eu^3+则作为激活剂,同时发出红色和蓝色荧光。荧光寿命测试结果表明Yb^3+-dimer与Eu^3+之间存在有效的能量传递。值得注意的是,在980 nm激光激发下,1%La^3+掺杂的样品表现出最佳的红、绿、蓝三基色光比列,实现了材料的上转换白光发射,其色度坐标为(0.311,0.340)。

Synthesis and Upconversion Luminescence Properties of White Phosphor CaF2∶Yb3+/Eu3+/La3+

Yb^3+,Eu^3+,La^3+co-doped CaF 2 upconversion phosphors were synthesized by a modified two-step high temperature solid phase method.On the basis of fluorescence quenching theory,the luminescence properties of CaF 2∶Yb^3+/Eu^3+materials were adjusted by changing the doping concentrations of La^3+,and the white upconversion luminescence(UCL)of these materials was obtained under a 980 nm laser.In this UCL system,Yb^3+not only sensitizes Eu^3+but also cooperates with neighboring Yb^3+to emit green luminescence in the wavelength range of 480-540 nm.This green luminescence just happens to be an important component of white light.In addition,Eu^3+ions act as activators and emit both red and blue luminescence,providing two other elements in the tri-color light.Fluorescence dynamical analysis indicates that an efficient energy transfer exists between the Yb^3+-dimers and Eu^3+ions.It is remarkable that the white UCL can be achieved from the 1%La^3+-doped sample,and the color coordinate is(0.311,0.340).