Ca_2SnO_4:Tb^(3+)绿色荧光粉的制备及光致发光研究

Preparation and Luminescent Properties of a Green Ca_2SnO_4∶Tb^(3+) Phosphor

采用高温固相法合成了Ca2SnO4∶Tb3+绿色荧光粉。利用X射线衍射分析了Ca2SnO4∶Tb3+物相的形成。测量了Ca2SnO4∶Tb3+的激发和发射光谱,激发光谱由一个宽激发峰组成,研究了Tb3+浓度对样品激发光谱的影响,结果显示,随Tb3+浓度增大,宽带激发峰发生了红移。发射光谱由四个主要发射峰组成,峰值分别位于491,543,588和623nm处,Tb3+以5 D4—7 F5(543nm)跃迁发射最强,低掺杂浓度下,Tb3+的7 F6能级出现斯托克劈裂,劈裂峰(481nm处)随Tb3+浓度增加,先增强然后减弱;在发光强度方面,随Tb3+浓度的增大呈现先增大后减小的趋势,当Tb3+摩尔浓度为9%时,发光强度最大,根据Dexter理论,确定了在Ca2SnO4基质中Tb3+自身浓度猝灭机理。荧光寿命测试表明Tb3+在Ca2SnO4基质中荧光衰减平均寿命为4.4ms。

A novel green emitting phosphor,Tb3＋-doped Ca2SnO4,was prepared by the solid-state reaction.X-ray powder diffraction（XRD） analysis confirmed the formation of Ca2SnO4∶Tb3＋.Photoluminescence measurements indicated that the phosphor exhibits bright green emission at about 543 nm under UV excitation.The excitation spectra of Ca2-xTbxSnO4 appear to have a red shift with main peak from 254 to 260 nm.The emission spectra of Ca2-xTbxSnO4 have four peaks ascribed to 5D4—7FJ（where J=6,5,4,3） transitions of Tb3＋ ions.Under the condition of low Tb3＋ concentration,the 5D4—7F6 transition of Tb3＋ showed a stark energy level split to three split peaks and the peak intensity of 481nm firstly increased with increasing Tb3＋ concentration,then decreased.The dependence of luminescent intensity of Ca2SnO4∶Tb3＋ phosphor on the Tb3＋ concentration was studied,and the results show that the luminescence intensity firstly increased with increasing Tb3＋ concentration,then decreased,and reached the maximal value at 9 mol% Tb3＋.According to the Dexter theory,the authors confirmed the concentration quenching mechanism of Tb3＋ in Ca2SnO4.The fluorescence lifetime of phosphor analysis shows that the average lifetime is 4.4 ms.The results indicated that Ca2SnO4∶Tb3＋ could be a potential candidate as a green-emitting powder phosphor.