一种新型发红光材料SrGdGa3O7：Eu^3＋及其性质研究

A New Phosphor SrGdGa_3O_7:Eu^(3+) and its Luminescent Properties

采用高温固相法合成了发红光的荧光粉SrGdGa3O7:Eu3+。漫反射光谱和激发光谱中Eu3+的电荷迁移带、Eu3+离子f→f跃迁以及Gd3+离子8S7/2→6I7/2的跃迁相互吻合;监测Eu3+离子的特征发射,激发谱中有Gd3+离子的激发线表明存在Gd3+→Eu3+的能量传递。发射光谱中以5D0→7F2跃迁为主,表明Eu3+离子所占据的晶体学格位没有对称中心的Cs格位。根据低温下的发射光谱计算了7F1和7F2能级完全解除简并后的每个分裂能级的位置。Eu3+的发射发生明显的温度猝灭现象,同时发射谱线的分辨率也逐渐降低。Eu3+离子的5D0→7F2跃迁在不同温度下的荧光衰减曲线相似;随着温度的升高,荧光发射强度衰减越快,但是仍然处于毫秒数量级;5D0→7F2跃迁是宇称和自旋禁阻的跃迁,所以荧光衰减时间比较长。

Phosphor SrGdGa3O7：Eu^3＋ has been synthesized by solid-state reaction at high temperature. The bands of f→f transfer of Eu^3＋ and ^＊S7/2→^6I7/2 transfer of Gd^3＋ appear in the exicitation spectrum, which is consistent with diffuse reflectance spectrum. When monitored by 613 nm, there are ^8S7/2 -6I7/2 and ^8S7/2 -^6P7/2 transitions of Gd^3＋, indicating that the energy transfer from Gd^3＋ to Eu^3＋ happens. Emission spectrum is dominated by the main lines at 613 nm due to the ^5D0 -^7F2 transition, indicating Eu^3＋ occupies Gd site （Cs） without inversion symmetry. The splitted energy levels of ^7F1 and ^7F2 have been calculated by emission spectrum at 12 K. Emissionintensity of Eu^3＋ decreases gradually with temperature increasing, and the resolution of emission peak also decreases. Decay curves of Eu^3＋ （^5Do→^7 F2 ） at different temperature are similar and emission intensity decrease with temperature increasing. The lifetime of Eu^3＋ is in the order of millisecond, which is reasonable for the forbidden transfer （^5Do→^7F2 ）.