LiF-BeF2熔盐微观结构及扩散特性的分子动力学研究  

Molecular dynamics investigation on microstructure and diffusion properties of LiF-BeF molten salt

作　　者：贺国达 汤睿[1,2] 段学志 谢雷东[1] 傅杰[1,2] 戴建兴 钱渊[1,2] 王建强[1,2,5] HE Guoda;TANG Rui;DUAN Xuezhi;XIE Leidong;FU Jie;DAI Jianxing;QIAN Yuan;WANG Jianqiang(Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China;Key Laboratory of Interfacial Physics and Technology,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China;Dalian National Laboratory for Clean Energy,Chinese Academy of Sciences,Dalian 116023,Liaoning,China)

机构地区：[1]中国科学院上海应用物理研究所,上海201800 [2]中国科学院微观界面物理与探测重点实验室,上海201800 [3]中国科学院大学,北京100049 [4]华东理工大学化学工程联合国家重点实验室,上海200237 [5]中国科学院洁净能源创新研究院,辽宁大连116023

出　　处：《化工学报》2020年第8期3565-3574,F0003,共11页CIESC Journal

基　　金：中国科学院战略性先导科技专项(XDA02010000,XDA21000000);中国科学院青年人才专项(Y929021031)。

摘　　要：LiF-BeF2熔盐作为熔盐堆的冷却剂及核燃料溶剂近年来备受关注,其扩散行为与核燃料的相容性和结构材料的腐蚀性密切相关。采用Car-Parrinello分子动力学模拟研究了LiF-BeF2熔盐的微观结构及基于此结构的扩散行为。研究结果表明Be2+具有较强的络合能力,易形成中性网络聚合体,且其数量随温度的增加而减少;液态LiF-BeF2熔盐中除了包含聚合体,还包含游离的F^-、Li^+、BeF3^-和BeF4^2-,而非完全游离的F^-、Li^+和Be^2+。基于此微观结构获得的自扩散系数及电导率与实验结果吻合较好,且电导率随温度变化符合Arrhenius模型,而不是目前文献认为的无限稀释溶液的线性模型。LiF-BeF2 molten salt has been paid much attention in recent years as a coolant and nuclear fuel solvent for molten salt reactor,and its diffusion behavior is closely related to the compatibility of nuclear fuel and the corrosion of structural materials.In this paper,Car-Parrinello molecular dynamics simulation was used to investigate the microstructure and diffusion behavior of LiF-BeF2 melts.The results show that Be2+has a strong complexation ability to form neutral clusters,and its number decreases with the increase of temperature.Liquid LiF-BeF2 consists of neutral clusters and free F^-,Li^+,BeF3^-and BeF4^2-,rather than completely free F^-,Li^+and Be^2+.The self-diffusion coefficient and conductivity obtained based on this microstructure are in good agreement with the experimental results,and the change of conductivity with temperature conforms to the Arrhenius model,rather than the linear model of infinitely diluted solutions considered in the literature.

关 键 词：LiF-BeF2熔盐 分子模拟 微观结构 扩散 电导率 

分 类 号：O645.4[理学—物理化学]