以NH_3·H_2O-NH_4HCO_3混合溶液为复合沉淀剂,制备了LaAlO_3∶Eu~(3+)纳米晶体.通过X射线衍射、扫描电镜和透射电镜对产物进行了表征,用荧光光度计测试了样品的三维荧光光谱、激发光谱和发射光谱.结果表明:前驱沉淀物经800 ℃焙烧处理2 h,制备出球型形貌,颗粒分散性好、尺寸约为40 nm的立方相LaAlO_3纳米晶.由三维荧光光谱确定了LaAlO_3∶Eu~(3+)的最佳监测波长和激发波长,在395 nm波长光的激发下观察到纳米LaAlO_3 中Eu~(3+)的591 nm (~5D_(0-7)~F_1)和613 nm (~5D_(0-)~7F_2)特征发射谱,磁偶极跃迁~5D_(0-7)~F_1的发射峰强度要比电偶极跃迁~5D_(0-)~7F_2更强,而且这种趋势随着焙烧温度的升高明显增强,说明由该法制备的纳米LaAlO_3中Eu~(3+)离子占据的位置具有高的对称性.
The LaAlO_3:Eu~(3+) nanocrystals were prepared by the complex precipitation processing us-ing NH_3'H_2O-NH_4HCO_3 mixture as complex precipitant. The material was characterized by XRD, SEM and TEM techniques. Three dimension spectra, emission and excitation spectra have been measured. The results indicate that the LaAlO_3:Eu~(3+) nanocrystals were in spheric phase with good dispersion, by annealing at 800 ℃ for 2 h. The crystal size is about 40 ran. The luminescent prop-erties of Eu~(3+) in the LaAlO_3 nanocrystals have been measured by 3D, including optimal emission and excitation wavelength. In emission spectrum the hand at 591 nm and 613 nm are corresponding to ~5D_(0-)~7F_1 and~ 5D_(0-)~7F_2 transition of Eu~(3+) ions. The intensity of the ~5D_(0-)~7F_1 transition is bigger than the ~5D_(0-)~7F_2 transition. With increasing in annealing temperature this trend is increased obviously. This phenomenon shows that the Eu~(3+) ion in the LaAlO_3 nanocrystals is symmetrical.
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