硫化物基荧光粉的表面包覆及性能研究

Surface Coating and Characterization of Sulfide Phosphor

以硫化物为基质的荧光粉长期暴露于湿气中会缓慢发生化学反应从而降低发光特性、限制其应用。本文以正硅酸乙酯(TEOS)作为硅包膜剂,采用溶胶-凝胶法对CaS:Eu,Sm荧光粉进行表面包膜处理,获得了包覆氧化硅膜层的荧光粉。由于CaS:Eu,Sm发光粉体对酸或碱极其敏感,采用水解、包膜两步进行的工艺,先预制正硅酸乙酯的水解包膜液,再进行粉体表面包覆,并对水解工艺条件进行了讨论。对样品进行能谱分析,结果表明样品表面被包膜元素Si、O占据。包膜前、后样品浸水悬浮液的pH值曲线表明包膜后发光粉的耐水性得到较大改善,包膜后样品的上转换发光光谱峰形和峰值位置保持不变。

Alkaline earth sulfides doped with rare earth ions possess excellent up-conversion luminescence characteristic, but they are confined in application because of their poor chemical stability especially in moisture. In this paper, sol-gel method was adopted to encapsulate CaS： Eu, Sm phosphor with TEOS as silicon coating reagent. Because CaS： Eu, Sm phosphor is sensitive to acid and alkali, the two steps of hydrolyzation and encapsulation should be performed separately. The conditions of hydrolyzation process were discussed. SEM energy spectrum analysis shows that the surface of coated phosphor is mostly occupied by Si and O. PH value curves of two liquids respectively immersed with uncoated and coated phosphor indicate that the water-resistance of coated phosphor is improved greatly.