Eu^(2+),Dy^(3+)(Gd^(3+))共掺杂CaSi_2N_2O_2荧光粉发光性质

Luminescence Properties of CaSi_2N_2O_2:Eu^(2+) Phosphors Codoped with Dy^(3+) or Gd^(3+)

在还原气氛下采用高温固相法合成了白光发光二极管(LED)用荧光粉Ca_(0.98-y)Si_2N_2O_2:0.02Eu^(2+),yM^(3+),其中M为Gd(1%～12%)或者Dy(0.25%～6%)。利用X射线衍射仪分析其物相结构,发现稀土离子的掺入并没有改变其主晶相,仍为单斜结构。利用荧光分光光度计测试并分析激发光谱与发射光谱,样品在380 nm处有很宽的激发谱带,在位于550 nm处存在很宽的发射谱带,此发射谱归因于Eu^(2+)离子5d-4f的电子跃迁。Dy^(3+)与Gd^(3+)离子对Eu^(2+)发光具有明显的敏化作用:Dy^(3+)的摩尔分数为1%时,发光强度增加39%,达到最大值;Gd^(3+)则在摩尔分数为6%时,发光强度最强,增强了43%。并根据掺杂离子的能级特点对其发光微观机制进行了初步探讨。

CaSi_2 N_2O_2 codoped with 2%Eu（fixed） and varying M concentrations（Gd：1%～12%,Dy：0.25%～6%） for white LED are prepared by solid-state synthesis method.Crystalline phase is investigated by powder X-ray diffractormeter（XRD）,and it is found That,the Eu,M-codoped Ca_（1-H） Si_2N_2O_2 phosphors have the monoclinic structure.Excitation spectra and emission spectra are investigated by spectrometer.The results indicate that there is a broader emission band centered at 550 nm when excited by 380 nm,which was ascribed to the electronic transition of the Eu^（2＋）.Dy^（3＋） and Gd^（3＋） ions successfully play the role of sensitizer for energy transfer in the system.The addition of M remarkably enhances the luminescent intensity by the factor of 139%and 143%for Dy and Gd respectively.The luminescence mechanism of phosphors codoped with Dy^（3＋） or Gd^（3＋） ions is also investigated.