锕系固体氧化物中杂质效应的电子结构计算研究

Solid state actinide oxides have been considered as the most concerned solid state actinide-based compounds mainly due to their importance in the scientific research and practical application in the context of nuclear fuel and chemical corrosion. Available reports focus on the stoichiometric actinide oxides; however, the impurities effects that cannot be avoided in the actual conditions have been rarely reported. Owing to the potential dangerousness in handling the radioactive materials and the scarcity of high-quaility actinide samples, the direct microscopic-structure characterization and analysis on actinide-based materials are extremely difficult. A possible solution to the understanding of the behaviors of impurities and their effects on actinide-based materials is the use of advanced electronic structure calculation methods. In the present work, we will conduct the calculations on the geometric configuration and occupied site, electronic state, energetics, chemical bonding, thermodynamics and kinetics of impurities in actinide oxides by using hybrid density functional theory. Other methods such as DFT+U and dynamic mean-field theory (DMFT) are selected for comparison. According to the calculation results, the influences of impurities on actinide oxides and the trends of impurities behaviors in the oxides are expected to be obtained. Moreover, the roles of impurities in the actinide oxides in the actual conditions could be discussed in detail. By combining the theoretical results with the available experimental findings, the impurities effects in actinide oxides could be reasonably evaluated and predicted. Therefore, some valuable theoretical instructions could be provided for the practical applications of actinide-based materials.

锕系氧化物因在化学腐蚀及核燃料领域的重要性而成为最受关注的固态锕系化合物。已有的研究集中在化学计量比锕系氧化物体系，而对于实际条件下无法避免的杂质效应问题的研究则较少报道。鉴于锕系材料的潜在危险性以及高质量样品稀缺等限制因素，直接针对锕系材料的微观结构表征和分析非常困难，先进的电子结构计算方法有利于理解锕系氧化物中杂质原子行为以及它们对材料性质的影响。本项目将以杂化密度泛函理论计算方法为主，以DFT+U和DMFT等强关联电子体系第一性原理计算方法为辅，研究锕系氧化物中杂质原子的结构和占位、电子态、能量学、成键特征、热力学和动力学等，获得杂质原子对锕系氧化物性质的影响程度以及杂质原子行为的规律性认识，深入探讨杂质原子在锕系氧化物实际使用条件下的作用机制，结合相关实验研究成果，合理评价和预测锕系氧化物中的杂质效应，为锕系材料的实际使用提供若干重要的理论指导原则。

准确理解锕系氧化物的缺陷性质对锕系材料的应用非常重要。众所周知，锕系材料毒性和放射性非常强，这使得其实验表征非常困难，实验数据缺乏。由此，发展锕系材料缺陷性质的第一性原理计算方法非常重要。本项目以杂化密度泛函理论计算方法为主，以DFT+U和DMFT等强关联电子体系第一性原理计算方法为辅，研究锕系氧化物中杂质原子的结构和占位、电子态、能量学、成键特征、热力学和动力学等，获得杂质原子对锕系氧化物性质的影响程度以及杂质原子行为的规律性认识，深入探讨杂质原子在锕系氧化物实际使用条件下的作用机制，结合相关实验研究成果，合理评价和预测锕系氧化物中的杂质效应，获得缺陷性质的基本规律、氧化态的确定方法以及锕系材料氧化态的基本规律，为锕系材料的实际使用提供若干重要的理论指导原则。