中文摘要：

采用十六烷基三甲基溴化铵（CTAB）辅助水热法制备了LaF3∶Tb3＋,Ce3＋纳米晶,研究了pH,Ce3＋/Tb3＋和反应时间对样品荧光性能的影响。XRD分析表明,样品的主衍射峰与标准卡片（JCPDS 32-0483）的衍射峰相似,属于六方相晶系,其主衍射峰随掺杂稀土离子浓度增大略有偏移,说明掺杂稀土离子与基质晶格中的La3＋发生部分的同晶取代。电镜结果显示,样品颗粒是平均晶粒尺寸在20~50nm内且结晶度高的纳米晶体。在样品的激发光谱中,较强的激发峰位于250nm,归属于铈离子能级的4f→5d跃迁。在250nm光激发下,样品均在490nm有较弱的蓝光发射（电偶极跃迁5 D4→7 F6）和543nm有较强的绿光发射（磁偶极跃迁5 D4→7 F5）。随着Ce3＋/Tb3＋的摩尔比值增大,其荧光强度先增强后减弱,在nCe3＋/nTb3＋=4时样品的绿光发射最强。溶液pH能影响LaF3∶Tb3＋,Ce3＋纳米晶的色纯度和发光强度,其中pH为9时样品的绿色纯度最好,而pH为7时其绿光发射最强。增加水热反应时间有助于提高样品的色纯度和增强绿光发射。

英文摘要：

LaF3∶Tb3＋,Ce3＋nanocrystals were prepared with hydrothermal method with the help of cetyltrimethyl ammonium bromide（CTAB）.The effects of pH values of the solution,Ce3＋/Tb3＋ratio value and reaction time on the luminescent properties were investigated.XRD analysis shows that the as-prepared samples possess hexagonal phase and their main diffraction peaks of samples are similar to the standard card（JCPDS 32-0483）.Compared with pure LaF3,the main diffraction peaks of the doped samples have a slight shift,showing existing isomorphous substitution between La3＋and the doped rare earth ions in parent lattice of LaF3.It is found from TEM results that the as-prepared samples have good crystallinity and their average grain sizes change in the range of 20~50nm.The excitation spectra indicate that the stronger excitation spectrum peaks exist at 250 nm,which is assigned to the transition of 4f→5dfrom Ce3＋.When activated at 250 nm,all LaF3∶Tb3＋,Ce3＋nanocrystals possess weak blue emission at 490nm（electric dipole transition,5 D4→7 F6）and good green emission at 543nm（magnetic dipole transition,5 D4→7 F5）.As the Ce3＋/Tb3＋ratio increases,the fluorescence intensities increase at first and then weaken,and reach the strongest green emission at nCe3＋/nTb3＋ =4.The pH values have some influence on the colors and intensities of the LaF3∶Tb3＋,Ce3＋nanocrystals.The sample prepared at pH 9presents the best color,while the one at pH 7exhibits the strongest green emission.Besides,increasing reaction time is helpful to improve color purity of sample and enhance its green emission.