Eu:GGG纳米荧光粉体制备及其光学特性

Preparation and Luminescent Properties of Nanocrystalline Eu:GGG Phosphor

采用液相共沉淀方法并在不同烧结温度下制得了Eu:GGG荧光粉体。用X射线衍射分析了样品的结构,计算了其晶格常数,为1.2371nm。室温下,测量了Eu:GGG的光致发射光谱、激发光谱和荧光衰减曲线。激发光谱在波长240～287nm的谱带内和393nm处有强的激发,分别来自于Eu3+-O2-间的电荷迁移态吸收和Eu3+的7F0→5L6的跃迁吸收,同时在274nm处也出现了Gd3+的8S7/2→6IJ的特征吸收。393nm激发下,591nm处的发射峰最强,对应Eu3+的5D0→7F1的磁偶极跃迁,可能由于部分Eu3+处于反演中心对称格位所致。随着烧结温度升高,Eu:GGG的发光强度增强,这可能由于随着烧结温度升高,样品晶粒尺寸变大,单位体积内被激发的Eu3+离子数增加引起,而591nm发光的荧光寿命变短,可能是由Eu3+离子的能量共振传递过程中发光被陷阱捕获所致。

Eu：GGG phosphors were prepared by coprecipitation method and sintered at different temperatures. The structure was analysed by X-ray diffraction and the lattice constant was calculated, which was 1.2371 nm. Emission, excitation spectra and fluorescence decay curve were measured at room temperature. There was a strong excitation band from 240 to 287 nm and a peak at 393 nm, and they were from the charge transfer absorption of Eu^3＋-O^2- and the ^7F0→^5L6 transition absorption of Eu^3＋ , respectively. The peak of 274 nm in the excitation spectrum was from the ^8S7/2→^6Ij transition of Gd^3＋ . Under 393 nm excitation, the strongest emission at 591 nm was from the ^5D0→^7F1 magnetic dipole transition of Eu^3＋ , maybe due to the distribution of some Eu^3＋ in the inverse symmetry sites. With the increasing of the sintered temperature, the fluorescent intensity increased, which might be the result of larger grain size with more excitated Eu^3＋ ions per unit volume. However, the fluorescence decay time at 591 nm decreased, which could be ascribed to trap capture to resonance transfer fluorescence of Eu^3 ＋ ions.