纳米Gd2O3:Eu3+中Judd-Ofelt参数的实验确定

报道用Judd-Ofelt理论研究立方相纳米晶Gd2O3:Eu3+材料在77K下的光谱性质.以几乎不受周围晶场环境影响的5D0→7F1跃迁为参考，利用5D0→7F2和5D0→7F4跃迁，从实验上确定强度参数Ωλ(λ＝2，4).发现纳米Gd2O3:Eu3+材料晶场强度参数Ωλ随纳米晶粒径的变化而改变,与体材料相比有显著的不同.随微晶粒径减小，发射能级5D0的寿命变短、量子效率降低.这是因为微晶粒径越小，量子限域效应越强，表体比越大，在无序体调制的表面上表面缺陷作用增强而引起的.对电荷(Eu3+-O2-)迁移态和多声子过程另外两种无辐射通道也进行讨论.关键词：纳米Gd2O3:Eu3+强度参数辐射与无辐射弛豫量子效率

Judd-Ofelt parameters determined experimentally for nanoparticles Gd2O3:Eu3+

The spectral properties of nanoparticles Gd2O3:Eu3+ have been investigated by using Judd Ofelt theory at 77K. Intensity parameters Ωλ(λ＝2，4) were calculated using the experimental data of 5D0→7F2 and 5D0→7F4 transitions by taking the magnetic dipole transition 5D0→7F1 as reference. The intensity of the transition is almost completely unaffected by the local environment. It is indicated that intensity parameter Ωλ changes with the variation of diameter of nanoparticles Gd2O3:Eu3+,dramatically different from that of the bulk material.With decreasing diameter of the nanoparticles Gd2O3:Eu3+ from 135 to 15nm,the quantum efficiency of the emitting level 5D0 reduces from 23.6% to 4.6%. The smaller the diameter of nanoparticles Gd2O3:Eu3+, the bigger the ratio of surface to volume and the more the surface defect.It is the enhancing of the non radiation channels that results in the decrease of the quantum efficiency. The other two non radiation channels, charge (Eu3+-O2-) transfer state and multiphonon nonradiative re excitaton, were also studied.