Ce3+∶GdLu2Al5O12/Al2O3共晶微结构及其发光性能

稀土共晶闪烁体是通过定向凝固晶体生长技术,将具有不同折射率的两相制备成具有射线探测功能的共晶材料,其中含有激活离子的闪烁体相的折射率高于基质相。在高能射线辐照下,闪烁体相将入射高能射线转换成荧光,然后,荧光在闪烁体相和基底相的界面以全反射的形式实现定向输出,从而有效提高辐射探测成像的空间分辨率。本工作采用微下降法成功生长得到φ3 mm×117.0 mm 的1.0%(原子数分数)Ce∶GdLu₂Al₅O₁₂/Al₂O₃闪烁共晶样品。通过切割抛光加工得到φ3 mm×2.0 mm的共晶薄片,并将该共晶薄片进行微观结构、能谱分析和荧光性能等表征和测试,结果表明所得到的共晶样品由Ce∶GdLuAG和Al₂O₃两晶相构成,微观结构呈现出“中国结”结构,并在生长方向呈现出一定的有序排列。荧光光谱测试表明该共晶材料存在Gd³⁺-Ce³⁺间的能量传递,具有典型的Ce³⁺辐射跃迁,其中双宽峰发射峰最强位于560 nm。此外,根据生长速率对共晶样品发射峰强、峰位以及荧光寿命影响,优化出最佳下拉生长速率为4.0 mm/min。

Microstructure and Luminescence Properties of Ce3+ Doped GdLu2Al5O12/Al2O3 Eutectic

Rare earth scintillation eutectic is a kind of radioluminescence material including two crystallographic phases with different refractive index prepared by directional solidification. The refractive index of the scintillator phase doped with active ions is higher than that of the matrix phase. Under the irradiation of high-energy rays, the scintillation light can be generated in the scintillation phase, and then the scintillation light is transmitted and output in total reflection at the interface between scintillator phase and matrix phase, thus effectively improving the spatial resolution of radiation detection imaging through directional propagation. In this work, 1.0%(atomic fraction) Ce:GdLu₂Al₅O₁₂/Al₂O₃eutectic with the size of φ3 mm×117.0 mm was successfully grown by micro-pulling-down method. The φ3 mm×2.0 mm thin eutectic slices were obtained by cutting and polishing, and then were used to be tested for microstructure, energy spectrum and fluorescence properties analysis. It is confirmed that the eutectic is composed of Ce:GdLuAG and Al₂O₃ by XRD, SEM and EDS determination. There is a certain ordered arrangement in the growth direction. The fluorescence spectra show that the eutectic material has energy transfer between Gd³⁺-Ce³⁺, and has a typical Ce³⁺ radiation transition, in which the double broad emission peak is the strongest at 560 nm. In addition, according to the effects of pulling speed on the emission peak intensity, peak position and fluorescence lifetime, the growth rate was optimized to be 4.0 mm/min.