GdAlO3∶Tb3+-Al2O3有序共晶生长及其微结构研究

两相有序共晶材料由于具有不同折射率的两晶相呈现有序排列,可降低荧光在共晶材料内部的散射而实现导光功能,可被应用于高分辨探测成像器件中。本工作根据定向凝固原理,用微下降法生长技术制备得到了直径为3 mm的GdAlO₃∶Tb³⁺-Al₂O₃两相有序共晶。通过SEM和元素分析,探究了GdAlO₃∶Tb³⁺-Al₂O₃共晶内部的微结构,结果显示,所得共晶中GdAlO₃∶Tb³⁺晶相均匀有序地分布于基质Al₂O₃晶相中,GdAlO₃∶Tb³⁺晶相直径的大小受生长速率的影响,速率越快,直径越小。所制备得到的GdAlO₃∶Tb³⁺-Al₂O₃有序共晶在X射线辐照下发射出明亮的绿色荧光,并在GdAlO₃∶Tb³⁺晶相中定向传播,有望被用作X射线探测成像材料,提高探测器的空间分辨率。

Growth and Microstructure of Ordered Eutectics GdAlO3:Tb3+-Al2O3

Binary ordered eutectic materials which have two separated crystallographic phases with different refractive index can reduce light scattering and possess light guiding properties, which may be used in high spatial resolution imaging detectors. In this work, the ordered eutectics GdAlO₃:Tb³⁺-Al₂O₃ with a diameter of 3 mm were grown by micro-pulling-down method according to directionally solidified principle. The internal structure of obtained eutectics was determined by SEM and elemental analysis. It was found that the GdAlO₃:Tb³⁺ crystal fibers were well aligned in the matrix Al₂O₃ crystallographic phase and the diameter of GdAlO₃:Tb³⁺ crystal fibers can be adjusted by pulling-down speed during crystal growth process. The faster the pulling-down speed is, the smaller the crystal fiber becomes. At the same time, the radioluminescence properties of GdAlO₃:Tb³⁺-Al₂O₃ eutectic samples were determined. The GdAlO₃:Tb³⁺ crystal fibers can convert X-rays to green lights and the emitted green lights are transported along the fiber direction by total reflection mode, which can overcome resolution reduction caused by light scattering and have potential application for X-ray detection.