Ag+掺杂的立方相Y2O3:Eu纳米晶体粉末发光强度研究

采用化学自燃烧法制备了不同Ag⁺掺杂浓度的Y₂O₃:Eu纳米晶体粉末样品(［Y³⁺］∶［Eu³⁺］∶［Ag⁺］=99∶1∶X，X=0—3.5×10^-2)，以及通过退火处理得到了相应的体材料.根据X射线衍射谱确定所得纳米和体材料样品均为纯立方相.实验表明在纳米尺寸样品中随着Ag离子浓度的增加，荧光发射强度随之增加，当X=2×10^-2时达到最大值，其发光强度比X=0时提高了近50%.当Ag离子浓度继续增加，样品发光强度保持不变.在相应的体材料样品中则没有观察到此现象.通过对各样品的发射光谱，激发光谱，X射线衍射图谱，透射电镜(TEM)照片和荧光衰减曲线的研究，分析了引起纳米样品荧光强度变化的原因是由于Ag离子与表面悬键氧结合，从而使这一无辐射通道阻断，使发光中心Eu³⁺的量子效率提高；Ag⁺的引入所带来的另一个效应是使激发更为有效.这两方面原因使发光效率得到了提高.

Luminescence intensity of Ag+ doped Y2O3:Eu nanocrystals

Eu³⁺ doped Y₂O₃ nanocrystalline and bulk powders with small content of Ag⁺ were prepared by chemical self-combustion. An interesting phenomenon was observed: with an increase in Ag⁺ content the luminescent intensity of the nanosized crystal is enhanced at first and then maintains a stable level; however for the bulk powder there is no obvious change in the luminescent intensity when the Ag⁺ content is varied. The morphology and crystal structure were characterized by transmission electron microscopy (TEM) and X-ray Diffraction (XRD), respectively. Emission spectra were measured for nano- and bulk samples. The fluorescence decay curves for all the samples, including nanosized and bulk ones, either with or without Ag⁺, were measured. It is found that the lifetime for the nanosized sample with Ag⁺ is longer than that without Ag⁺, and the lifetime for the bulk sample has no change. From these experimental results wecome to the conclusion that the Ag⁺ ion may link with a surfice O^2-, which has a free bond, then the surfice unsaturated dangling bonds can be eliminated. The elimination of surfice dangling bonds may cause the increase of luminescence efficiency of Eu³⁺ doped nanosized Y₂O₃.