紫外激发的LiCaPO_4:Eu~(2+)蓝色发光粉的发光特性

采用高温固相法合成了LiCaPO4:Eu2+蓝色发光粉,并对其发光特性进行了研究。该发光粉发射峰值位于470nm,属于Eu2+的4f65d1→4f的特征跃迁发射,与结构相似的LiSrPO4:Eu2+和NaBaPO4:Eu2+相比其峰值有明显红移。Eu2+在LiCaPO4晶体中可被250～440nm光有效激发,这与紫外发光二极管的发射光谱(350～410nm)匹配。考察了Eu2+的掺杂浓度对发光强度的影响,最佳掺杂摩尔分数为5%,摩尔分数超过5%后发生猝灭现象。浓度猝灭机理为电多极-电多极的交互作用。LiCaPO4:Eu2+是适合UV-LED管芯激发的白光发光二极管用高亮度蓝色发光粉。

Optical Properties of Eu2+-activated Blue-emitting Phosphor LiCaPO4 under Ultraviolet Excitation

A novel blue-emitting phosphor LiCaPO4 : Eu2+ for LEDs was prepared by high temperature solid-state reaction and its luminescent properties were investigated. The emission spectrum shows a single intense band centered at 470 nm, which corresponds to the 4f65d1→4f7 transition of Eu2+. Comparing with LiSrPO4 : Eu2+ and NaBaPO4 : Eu2+, the emission spectrum shows a red shift obviously. It is caused by the decrease of cationic radii which change the degree of Eu2+ energy splitting and affect the electron cloud expansion. The excitation spectrum is a broad band extending in 250~440 nm, which matches the emission of ultraviolet light-emitting diodes (UV-LEDs) well. The effect of doped Eu2+ content on the emission intensity of LiCaPO4 : Eu2+ was also investigated. Different Eu2+ contents have little effort on the emission spectrum, but the emission intensity shows a great different. The emission intensity is enhanced with the increase of the Eu2+ content, and the optimal doping content is 5%. Concentration quenching occurs when the Eu2+ content is beyond 5%, as a result of multipole-multipole interaction. The LiCaPO4 : Eu2+ phosphor is a potential blue-emitting phosphor for white-emitting LEDs.