稀土掺杂萤石结构卤化物晶体团簇结构研究  

Cluster Structure of Rare Earth Doped Fluorite Halide Crystals

作　　者：马凤凯 张振[2] 姜大朋 张中晗[2] 李真 寇华敏[2] 陈振强[1] 苏良碧[2] MA Fengkai;ZHANG Zhen;JIANG Dapeng;ZHANG Zhonghan;LI Zhen;KOU Huamin;CHEN Zhenqiang;SU Liangbi(Department of Optoelectronic Engineering,Jinan University,Guangzhou 510632,China;The State Key Lab of High Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 201899,China)

机构地区：[1]暨南大学理工学院光电工程系,广州510632 [2]中国科学院上海硅酸盐研究所高性能陶瓷与超微结构国家重点实验室,上海201899

出　　处：《人工晶体学报》2023年第7期1219-1235,共17页Journal of Synthetic Crystals

基　　金：国家重点研发计划(2022YFB3605702);国家自然科学基金(61925508,61905289);中科院稳定支持基础研究领域青年团队计划(YSBR-024);上海市科学技术委员会项目(20520750200);中国科学院“一带一路”国际合作项目(121631KYSB20200039);广东省重点领域研发计划(2020B090922006);广州市科技计划(202201010427)。

摘　　要：稀土掺杂萤石卤化物在国民经济、国防建设等领域发挥着不可替代的作用。萤石卤化物特殊的晶体结构导致稀土离子团聚,目前针对稀土离子团聚的系统研究还比较少。本文以稀土掺杂萤石卤化物为研究对象,采用第一性原理计算系统研究了从稀土离子单体到高阶团簇的结构特征、演变规律、联系及其影响因素。研究发现,稀土离子单体中心1|0|0|11(C_(4v))和1|0|0|12(C_(3v))稳定性随离子半径变化而改变,且不同晶体的变化趋势不同,与晶格畸变分析结果一致。晶格畸变与库仑作用相互耦合决定了电荷补偿间隙卤离子的占位倾向性,即C_(4v)和C_(3v)中心的相对稳定性。此外,共价效应使得PbF_(2)和SrCl_(2)晶体单体中心结构及其稳定性与CaF 2、SrF_(2)和BaF 2不同。研究还揭示了晶体离子性和晶胞尺寸对单体中心能量差斜率的影响。文中还研究了稀土离子高阶团簇的结构,其稳定性演变规律与单体中心相对应。本文提出了高阶团簇相对稳定性判据,为新型稀土掺杂萤石卤化物的探索、筛选和研发提供指导,有望进一步拓展其应用范围。Rare earth doped fluorite halides play important roles in the fields of economy,national defense,and so on.The trivalent rare earth ions easily cluster in fluorite halides due to the special crystal structure.However,the systematic investigation into the aggregation of rare earth ions is rarely reported.In this work,the cluster structure characteristics,evolution patterns and their connections,as well as the influencing factors were systematically studied.It is found that the stabilities of 1|0|0|11(C_(4v))and 1|0|0|12(C_(3v))rare earth monomers vary with the ionic radius,and the trends are different in different matrix crystals,which are consistent with the analysis of lattice distortion.The coupling of lattice distortion and coulomb interactions determines the site occupations of charge compensation interstitial halide ions,i.e.the relative stabilities of C_(4v) and C_(3v) center.Additionally,the covalent effect makes the monomer structures of rare earth doped PbF_(2) and SrCl_(2) are different from that of CaF 2,SrF_(2)and BaF 2.The study also reveals the relationship of energy difference slopes of monomers with crystal ionicity and cell size.The structures of high-order rare earth clusters were also studied and its evolutions are intimately related with that of monomer centers.The criterion of relative stabilities in high-order clusters is proposed,which provides a guideline for the exploration,screening and development of new rare earth doped fluorite halides,and its application scope is highly expected to be extended.

关 键 词：萤石卤化物晶体 稀土离子团簇 结构演变 晶格畸变 高阶团簇 

分 类 号：O734[理学—晶体学] O641