绿色发光材料NaLa(MoO_4)_2:Tb^(3+)的微波辅助溶胶-凝胶法制备及其性质

Preparation of NaLa(MoO_4)_2:Tb^(3+) Green Phosphor by a Microwave-Assisted Sol-Gel Method and Its Luminescent Properties

采用微波辅助溶胶-凝胶法制备了系列绿色发光粉NaLa31-x(MoO4)2:Tb+x(x=0.02,0.1,0.15)。用X射线粉末衍射仪和荧光分光光度计等分析和表征所合成样品的物相结构和发光性质。结果表明:所合成的NaLa(MoO4)2:Tb3+晶体结构与NaLa(MoO4)2相似,属四方晶系结构;样品的激发光谱为位于250~350 nm的1个宽带,最大激发峰位于300 nm处;发射光谱由一系列尖峰组成,最强的发射峰位于544 nm处,归属于Tb3+的5D4-7F5跃迁。NaLa(MoO4)2:Tb3+的发光强度随Tb3+掺杂浓度的增加逐渐加强,当Tb3+浓度为10 mol%时发光强度最大,而后随Tb3+浓度的增加而降低,发生浓度猝灭。根据Dexter能量共振理论,该浓度猝灭系Tb3+的电偶极-电偶极的相互作用所致。通过含氧酸根阴离子(SO2-4)的掺杂有效提高了NaLa(MoO4)2:Tb3+体系的发光亮度。

A series of green-emitting phosphors NaLa1-x（MoO4）2：Tb3＋x（x=0.02, 0.1, 0.15） were prepared by a microwave-assisted sol-gel method. X-ray diffraction and fluorescence spectrophotometer were used to analyze the phase structure and luminescent properties of as-synthesized phosphors, respectively. The results show that NaLa（MoO4）2：Tb3＋ phosphors possess a tetragonal crystal structure similar to that of NaLa（MoO4）2. The excitation spectrum of NaLa（MoO4）2：Tb3＋is a broad band between 250 nm and 350 nm, and the main peak is at 300 nm. The emission spectrum is composed of a series of sharp lines. The main emission peak is at 544 nm, which is ascribed to the transition of 5D4–7F5. The luminescent intensity of Na La（MoO4）2：Tb3＋ increases with the increase of Tb3＋ content, and reaches the maximum when the content of Tb3＋ is 10 mol%, and then decreases with the further increase of Tb3＋ content. The concentration quenching is caused by the interaction of electric dipole-electric dipole of Tb3＋ according to the Dexter theory. Moreover, the luminescent intensity of NaLa（MoO4）2：Tb3＋ can be greatly enhanced with incorporation of SO2-4.