水热法制备LaF_3∶Ce,Tb纳米荧光粉及发光性质研究

Hydrothermal Preparation and Luminescence of LaF_3∶Ce, Tb Nano-Sized Phosphor

利用水热法制备了LaF3∶Ce,Tb纳米荧光粉,分别用XRD,TEM和发光光谱等测试手段对粉末的物相、形貌、发光性质进行了研究。XRD和TEM结果表明所得的纳米荧光粉粒度均匀、结晶完好,呈规则的六边形形状,颗粒平均尺寸为30nm,掺入Ce3+和Tb3+,杂质后晶格结构没有变化。发光光谱的测试表明Ce3+呈现其宽带发射;Tb3+呈现其特征绿色发射,最强峰位于544nm处。Ce3+的掺入有效敏化了Tb3+的发光,通过进一步光谱分析证实了在LaF3∶Ce,Tb体系中存在Ce3+→Tb3+的能量传递过程。当Ce3+和Tb3+掺杂摩尔浓度分别为35mol%和5mol%时具有最强荧光发射。制备的样品无需煅烧即可获得比体相材料高2倍的荧光,也高于优化条件下煅烧样品的荧光。

Green-emitting LaF3 ： Ce, Tb phosphor nanoparticles were synthesized by a simple hydrotherlnal method and characterized by XRD, TEM and fluorescence spectra. The prepared samples had a hexagonal shape, fine size （30 nm）, and high brightness under ultraviolet, and the structure of LaF3 remained unchanged after being doped with Ce^3＋ and Tb^3＋ ions. The blue Ce^3＋ emission centered at 261 nm is efficiently quenched in the samples of LaF3 ： C,e, Tb, in which the dominant emission is in the green at 544 nm, originating from the doped Tb^3＋ ions＇ transition of sD4 to 7Fs. Excitation spectra of the LaF3 ： Ce, Tb,observed at 544 nm, consist of both contributions from Ce^3＋ and Tb^3＋ ions. There is energy transfer of Ce^3＋→Tb^3＋ in this systern. The energy transfer mechanism was discussed. Above all, the phosphor nanoparticles have high photoluminescence intensity even without any calcination, about twice that of bulk materials prepared by high temperature solid synthesis, and the intensity is also stronger than calcined phosphor nanoparticles.