B离子对SiO_2基质凝胶中Eu^(3+)特征光谱的加强作用

Enhanced Emission From Eu^(3+) in B Ions Doped Sol-gel SiO_2 Phosphors

使用正硅酸乙酯、硼酸和硝酸铝为前驱体,硝酸铕为掺杂剂,以溶胶-凝胶法制备了Eu单掺和Eu、B共掺的SiO2干凝胶,并成功地在钠钙玻璃上制备了光洁度很好的掺杂SiO2多层薄膜.利用荧光光谱、红外光谱(IR)、X射线衍射(XRD)等技术研究了B离子、退火温度对样品发光性能的影响.荧光光谱显示发光体能产生很强的红色发光,经500℃以上退火处理,产生6条谱带,分别归属于Eu3+的5D0→7FJ(J=0,1,2,3,4)的电子跃迁,5D0→7F1的跃迁分裂为两个峰.实验结果表明,B离子的加入,由于在材料中形成了Si-O-B键,使Eu3+的配位环境的对称性降低,加强了Eu3+的红光发射.退火处理改变了材料的网络结构,降低了水和羟基的含量有助于提高发光强度,但退火温度太高(850℃),发生了荧光猝灭效应,源于稀土离子发生位置迁移形成的团簇.XRD测试结果显示材料是非晶态的.

Eu single doped and Eu,B co-doped SiO2 xerogels and films were prepared by sol-gel process, using tetraethoxy silane, boric acid and aluminium nitrate as precursors, europium nitrate as the dopant. The influence of B ions and annealing temperature on luminescent properties of phosphors has been studied using fluorescence spectrum, X-ray diffraction and IR spectrum. The phosphors showed prominent luminescent in red. When heated up to 500 ℃, the emission spectrum showed six characteristic emission peaks, due to the electronic transition of ^5D0→^7FJ （J=0, 1, 2, 3, 4）for Eu^3＋ respectively and the electronic transition of ^5D0→^7F1 was splited two peaks. When B ions were introduced to the Eu doped samples ,the red Eu^3＋ emission was enhanced remarkably. This is because Si-O-B bonds were formed in the luminescent materials, and the symmetry of network was breached. Annealing changed the network structure and reduced the content of-OH and water, which benefits intensity of emission from Eu^3＋. The intensity of emission from Eu3＋ quenches with increasing of annealing （up to 850℃） for probability during the annealing process ,the rare earth ions may migrate and form clusters. The clustering process makes the local concentration of Eu very high and causes serious fluorescence quenching. XRD results show that the phosphor is in amorphous phase.