微波场作用下La_2O_2S∶Tb绿色荧光粉的快速合成及其发光特性

Rapid Synthesis of Green-emitting Phosphor La_2O_2S∶Tb by the Microwave Radiation Method and Its Luminescent Properties

采用微波法快速合成了La2O2S：Tb绿色荧光粉。用X射线粉末衍射（XRD）、扫描电镜（SEM）、荧光分光光度计等对合成产物的结构、形貌以及发光特性进行了研究。结果表明，材料的晶体结构为六方晶系，与La2O2S的相同。颗粒的形貌多为六边形，分散性很好，尺寸在2μm左右。发射光谱由498nm、547nm、590nm、624nm等一系列窄带发射峰组成，归属于Tb^3＋从^5D4到^7FJ（J=0～6）的跃迁。主发射峰位于547nm，对应于^5D4→^7F5的能级跃迁，导致一种绿光发射。研究发现Tb的掺杂浓度对样品主发射峰的发光强度有着很重要的影响，在7％（摩尔分数）时达到最大，继续增加Tb的浓度，发光强度反而降低。

La2O2S ： Tb, green-emitting phosphors were synthesized in microwave field. Reaction time was only 20min. The crystal structure,morphology and luminescence properties of as-synthesized La2O2S ： Tb were investigated by x-ray diffraction, SEM and fluorescence spectrophotometer respectively. The results show that the crystal structure of as-synthesized La2O2S ： Tb is hexagonal,which is similar to that of La2O2S. The particles of as-synthesized phosphor are basically hexagonal in shape, and dispersing well. The emission spectrum is composed by a series of sharp peaks ,located at 498nm, 547nm, 590nm, 624nm respectively. These emission peaks are ascribed to Tb^3＋ transition from ^5D4 to ^7FJ （J= 0-6）. The main emission peak is at 547nm （^5D4→＆7F5）, which results in a green-emitting. It is also found that the molar ratio of Tb^3＋ plays a very important role in the emission spectrum. When the molar ratio of Tb^3＋ is 7%, the green emitting becomes strongest. Further increasing the molar ratio of Tb^3＋, the green emitting becomes weak.