不同介质里Gd_2O_3∶Eu^(3+)纳米晶中Eu^(3+)的自发辐射

The Spontaneous Radiation of Eu^(3+) in Gd_2O_3∶Eu^(3+) Nanocrystalline Surrounded by Different Media

对不同介质包围的Gd2O3∶Eu3+纳米颗粒的发光性质进行了研究。从发射光谱观察到Eu3+的4f组态内跃迁峰位受周围介质的影响不大。Gd2O3纳米颗粒中Eu3+的5D0的自发发射寿命受周围介质的局域场影响很大,主要与介质的有效折射率和纳米颗粒的填充率有关。有两种模型可以描述自发辐射寿命与周围介质的相互作用:Onsanger-实腔模型与Lorentz虚腔模型。本实验结果表明,实腔模型比较合理,而虚腔模型与实验数据偏差较大。

The optical properties of Gd2O3 ： Eu^3＋ nanoparticles immersed in different solvent were investigated The 4f intraconfigurational transition peaks are nearly not changed by the surrounding media. The spontaneous emission lifetime of ^5D0 of Eu^3＋ in Gd2O3 nanocrystalline is significantly affected by the surrounding media, mainly due to the refractive index of the media and the filling factor of the nanocrystalline. Different models predict substantially different dependences of radiative lifetime on the surrounding media. There are some measurements intended to discriminate these models have been given, and most experimental results tend to agree with the real-cavity model. Especially, recent measurements on the radiative lifetime of Eu^3＋ ion embedded in glass with varying refractive index also tend to agree with the real-cavity model in contrary to the general belief that the virtual-cavity model should be more relevant. With states of opposite parity, depends strongly on the environment and does not serve as a good examination of the real- and virtual models. To overcome the problem in 4f →4f transitions, Duan and Reid analyzed the lifetimes of 5d→f transitions of Ce^3＋ ions in hosts with different refractive indices and the results maintained the textbook virtual-cavity model. However, there was no intention to answer the questions why most other experimental results agree with the real-cavity model, and which model should be used for a given situation. The two models that describe the radiative lifetime：virtual cavity and real-cavity model, are with respect to ＂interstitial＂ and ＂substitutional＂ impurities, respectively. In our experiment, the real-cavity model is more reliable,