The effects of temperature and composition on the structures and transport properties of UCl₃-LiCl-KCl salts were systematically investigated by using molecular dynamics simulation with a polarizable force field. In the molten salt of pure UCl₃, there exist networks of [UCl_n] (n = 6, 7, 8, …) clusters, dominated by corner-sharing, Cl-linked [UCl₈]⁵⁻. The networks became sparser with the UCl₃ concentration decreasing. The local structures of U³⁺ complexes in LiCl-KCl salts were also compared with that of typical fission products such as Sc³⁺, Y³⁺, La³⁺ and Tb³⁺. It is found that the local structures of the U³⁺ complexes in LiCl-KCl were very similar to that of La³⁺, while the U-Cl coordination bonds were less stable than that of Y-Cl, Sc-Cl, and Tb-Cl complexes. Finally, two basic transport properties, diffusion coefficient and viscosity of UCl₃-LiCl-KCl were predicted to a broader range than the previous reported data. These results help to understand the underlying mechanisms related to the pyrochemical processing for separation of trivalent uranium ions from other fission product ions in LiCl-KCl salts.

通过分子动力学模拟和极化力场，系统地研究了温度和组成对UCL ₃ -LiCl-KCl盐结构和输运性能的影响。在纯UCl ₃的熔融盐中，存在[UCl _n ]（n = 6、7、8 ...）簇的网络，这些簇以角共享，Cl相连的[UCl ₈ ] ^5−为主。随着UCl ₃浓度的降低，网络变得稀疏。还比较了LiCl-KCl盐中U ³⁺配合物的局部结构与典型裂变产物如Sc ³⁺，Y ³⁺，La ³⁺和Tb ³⁺的局部结构。。发现LiCl-KCl中U ³⁺配合物的局部结构与La ³⁺非常相似，而U-Cl配位键的稳定性低于Y-Cl，Sc-Cl和Tb -Cl配合物。最后，与以前报道的数据相比，UCL ₃ -LiCl-KCl的两个基本传输性质，扩散系数和粘度被预测为更宽的范围。这些结果有助于了解与热化学处理有关的三价铀离子与LiCl-KCl盐中其他裂变产物离子的分离机理。