(1. 江西理工大学 资源与环境工程学院，赣州 341000；
2. 五矿稀土集团广西矿业有限公司，南宁 530022；
3. 潍坊龙达锌业有限公司，潍坊 262100；
4. 江西理工大学 建筑与设计学院，赣州 341000；
5. 中国矿业大学(北京) 化学与环境工程学院，北京 100083)
摘 要: 采用Material studio的DMol3模块研究了La3+、Ce3+、Pr3+、Nd3+四种离子的水合物Re3+(H2O)n (n=1~12)，分析了几何优化后的构型的几何结构、结合能、前线轨道、电荷、振动情况。结果表明：La3+、Ce3+、Pr3+、Nd3+四种轻稀土离子第一水化层的最小水合数分别为4、6、7、7；在相同水合数条件下，Re—O的平均键长大小顺序为La＞Ce＞Pr＞Nd，Re3+(H2O)10的Re—O平均键长约为2.6 ？，轻稀土离子水合物的水化层半径约为3.22~3.59 ？。轻稀土离子的水化反应为放热反应，当水分子配位数相同时，结合能大小顺序为La＞Ce＞Pr＞Nd。电荷分析结果显示，水合反应过程中稀土离子得到电子，当第一水化层填满后，Re3+(H2O)n性质逐渐趋于稳定，Re离子的电荷量在2e左右。前线轨道分析结果显示，不同于离子半径的变化，四种稀土离子自身的硬度大小顺序为La＞Nd＞P＞Ce。模拟的La3+(H2O)n的红外光谱显示，随着水分子数量的增加，Vsym和Vasym峰发生蓝移；当n大于10时，Vsym和Vasym峰不再发生蓝移，说明第一水化层外的水分子没有与La离子发生反应。
关键字: 稀土；离子水合物；密度泛函；Material studio
（1. School of Resource and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China;
2. Guangxi Mining Co., Ltd., China Minmetals Rare Earth Group Co., Ltd., Nanning 530022, China;
3. Weifang Longda Zinc Industry Co. Ltd., Weifang 262100, China;
4. School of Architecture and Design, Jiangxi University of Science and Technology, Ganzhou 341000, China;
5. School of Chemical and Environmental Engineering, China University of Mining & Technology, Beijing 100083, China）
Abstract:DMol3 module of Material Studio was used to study the hydrate Re3+(H2O)n(n=1-12) of four kinds of light rare earth ion coordination water quantities of La, Ce, Pr and Nd. The geometric structure, binding energy, frontier molecular orbital, charge and vibration of the geometrically optimized configuration were analyzed. The results show that the minimum hydration number of the first hydration layer of La3+, Ce3+, Pr3+and Nd3+ are 4, 6, 7 and 7, respectively, which can contain up to 10 water molecules. The order of average Re—O bond length is La＞Ce＞Pr＞Nd, the average Re—O bond length of Re3+(H2O)10 is about 2.6 ？, and the hydration layer width of light rare earth ionic hydrate is about 3.22-3.59 ？. The hydration reaction of light rare earth ions is exothermic. When the coordination number of water molecules is the same, the order of binding energy is La＞Ce＞Pr＞Nd. Charge analysis results show that rare earth ions gain electrons in the hydration reaction. When the first hydration layer is filled, the properties of Re3+(H2O)n gradually become stable, and the charge of Re ions is around 2e. The results of frontier molecular orbital analysis show that, different from the change of ion radius, the hardness sequence of the four rare earth ions is La＞Nd＞Pr＞Ce. The simulated infrared spectra of La3+(H2O)n reveal that, with the increase of the number of water molecules, the Vsym and Vasym peaks show blue shift. When n is greater than 10, the Vsym and Vasym peaks show no blue shift, indicating that the water molecules outside the first hydration layer will not react with La ions.
Key words: rare earth; ionic hydrate; density functional; Material studio
