乳状液膜法制备硫氧化物超细X射线发光粉

Preparation of Oxysulfide X-Ray Phosphor Fine Particles Using Emulsion Liquid Membrane System

采用乳状液膜法制备了颗粒均匀的Gd-Tb草酸盐微粒,将草酸盐粒子放在硫气气氛下焙烧后得到Gd2O2S∶Tb超细X射线发光粉。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、红外(IR)光谱、光致发光(PL)光谱和X射线激发发光光谱(XEL)对微晶进行了表征。结果表明,900℃下焙烧后的粒子显示了单一的六角形Gd2O2S晶相,与传统固相法相比,有效降低了焙烧温度。根据谢乐公式,估算一次粒径为29nm,初级粒子尺寸较小,这在一定程度上可以提高成像系统的空间分辨率。从SEM照片来看,粒子显示了一定的团聚性,但团聚尺寸<5μm,为超细X射线发光粉。同时,在254nm紫外光和X射线激发下,Gd2O2S∶Tb发光粉都显示出Tb3+的特征发射峰,并且通过分析红外光谱对样品发光性能的影响作了详细的讨论。

Gd oxysulfide X-ray phosphors fine particles doped with Tb were prepared by using an emulsion liquid membrane (ELM, W/O/W emulsion) system. The rare-earth ions (Gd 3+ and Tb 3+ ) were extracted from the external water phase and stripped into internal water phase to make precursor composite oxalate particles. Gd2O2S∶Tb fine particles were obtained via a solid-gas reaction in sulfur atmosphere of the precursor oxalate particles. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectra and X-ray excited luminescence (XEL) spectra. The results indicate that the samples show the pure hexagonal gadolinium oxysulfide phases. Diameter of the particle calculated by Scherer formulation is around 29 nm and the agglomerate size is 1～3 μm. Meanwhile, PL spectra and XEL spectra both show the characteristic emission of rare earth activation ions (Tb 3+ ), though their luminescence principles are different.