碘化铵脱水法制备闪烁晶体用高纯无水SrI2/EuI2

As a superior scintillator, SrI2:Eu has promising prospects in various applications such as nuclear identification, safety inspection, and medical detection. However, difficulty in preparing high purity anhydrous SrI2 and EuI2, which are essential raw materials for SrI2:Eu crystal growth, and the high cost of doing so, severely prohibited the development and application of this material. Therefore, an efficient but low-cost method to prepare anhydrous SrI2 and EuI2 is of great importance and urgency to SrI2:Eu crystal. In this project, a new method, i.e. the ammonium iodide route, is proposed to prepare anhydrous SrI2 and EuI2. This method is based on the hypothesis that the coordination between NH4I and Sr or Eu ions could restrict the hydrolysis of the hydrates during the dehydration and therefore reduce the yield of deleterious oxide impurity, which helps obtain high purity products. To verify the hypothesis, this project will investigate the composition, structure and the stability of the intermediate complex, and try to understand the mechanism how NH4I restrains the hydrolysis of the hydrates from the point of coordination chemistry. We will also study the behavior of the oxide impurity, including its existing form, yield condition and transformation during the preparation, which will provide useful information on how to control or eliminate the oxide impurity. The final goal of this project is to obtain high purity anhydrous SrI2 and EuI2 qualified for scintillation crystal growth.

SrI2:Eu是一种性能极为优异的闪烁晶体材料，在核素甄别、安全检查、医学探测等领域具有广阔的应用前景。但SrI2:Eu晶体生长用高纯无水SrI2、EuI2原料的制备困难和高昂成本，严重阻碍了该晶体的发展和应用。本项目针对这一问题，提出采用碘化铵脱水法进行高纯无水SrI2、EuI2的制备，利用NH4I与Sr、Eu离子的配位作用，抑制SrI2、EuI2在脱水过程中的水解反应和有害氧化物杂质的生成，以实现其低成本高纯化制备。本项目拟对该法的具体反应机理进行深入研究，确定中间配合物的组成、结构及其稳定存在条件，结合配位化学分析，阐明NH4I对SrI2、EuI2水解反应的抑制机理；通过杂质分析，探明氧杂质等关键有害杂质在制备过程中的赋存状态、生成条件和转化路径，为无水SrI2、EuI2中氧杂质的有效控制和去除提供理论依据，最终制备出可满足闪烁晶体生长需求的高纯无水SrI2和EuI2。

SrI2:Eu是一种性能极为优异的闪烁晶体材料，但晶体生长用高纯无水SrI2、EuI2原料的制备困难和高昂成本阻碍了该晶体的发展和应用。本项目针对这一问题，提出采用碘化铵脱水法进行高纯无水SrI2、EuI2的制备，利用NH4I与Sr、Eu离子的配位作用，抑制SrI2、EuI2在脱水过程中的水解反应和有害氧化物杂质的生成，以实现其低成本高纯化制备。本项目主要进行了以下三个方面的研究：.（1）碘化铵脱水法制备无水SrI2、EuI2 的反应机理研究：研究了SrI2、EuI2水合物在常温下的存在形式及其在脱水过程的物相转化过程，对比研究了SrI2、EuI2水合物与NH4I混合脱水过程与单独脱水的异同，揭示了NH4SrI3、NH4Eu2I5中间配合物的存在及其对于水解反应的抑制作用，探明了SrI2、EuI2水解、氧化的主要机理。.（2）无水SrI2、EuI2 的碘化铵脱水法制备工艺研究：结合上述机理研究，建立了SrI2、EuI2的碘化铵脱水法制备工艺，重点考察了脱水温度、碘化铵用量、真空度、气氛条件、脱氨温度等对SrI2、EuI2产品质量的影响，成功实现了纯度99.99%、氧含量低于50ppm的高纯无水SrI2、EuI2的制备。.（3）无水SrI2、EuI2杂质行为规律及纯化技术研究：对无水SrI2、EuI2中的各种杂质进行了表征分析，重点考察了氧杂质的存在形式、生成条件及转化规律，考察了区熔提纯、化学除氧、熔体老化等方法对SrI2、EuI2的提纯效果，成功获得了可满足单晶生长需求的高纯无水SrI2、EuI2 产品。.本项目共计发表学术论文3篇（另有1篇文章在审），申请发明专利4项，圆满完成了各项计划研究任务，达到了预期研究目标。本项目为高纯无水SrI2、EuI2的工业化制备提供了有益参考，有望为SrI2:Eu晶体的生长提供坚实的原材料支撑，并有力促进该晶体的发展和应用。