(1. 江西理工大學(xué) 資源與環(huán)境工程學(xué)院，贛州 341000；
2. 五礦稀土集團廣西礦業(yè)有限公司，南寧 530022；
3. 濰坊龍達鋅業(yè)有限公司，濰坊 262100；
4. 江西理工大學(xué) 建筑與設(shè)計學(xué)院，贛州 341000；
5. 中國礦業(yè)大學(xué)(北京) 化學(xué)與環(huán)境工程學(xué)院，北京 100083)
摘 要: 采用Material studio的DMol3模塊研究了La3+、Ce3+、Pr3+、Nd3+四種離子的水合物Re3+(H2O)n (n=1~12)，分析了幾何優(yōu)化后的構(gòu)型的幾何結(jié)構(gòu)、結(jié)合能、前線軌道、電荷、振動情況。結(jié)果表明：La3+、Ce3+、Pr3+、Nd3+四種輕稀土離子第一水化層的最小水合數(shù)分別為4、6、7、7；在相同水合數(shù)條件下，Re—O的平均鍵長大小順序為La＞Ce＞Pr＞Nd，Re3+(H2O)10的Re—O平均鍵長約為2.6 ？，輕稀土離子水合物的水化層半徑約為3.22~3.59 ？。輕稀土離子的水化反應(yīng)為放熱反應(yīng)，當水分子配位數(shù)相同時，結(jié)合能大小順序為La＞Ce＞Pr＞Nd。電荷分析結(jié)果顯示，水合反應(yīng)過程中稀土離子得到電子，當?shù)谝凰瘜犹顫M后，Re3+(H2O)n性質(zhì)逐漸趨于穩(wěn)定，Re離子的電荷量在2e左右。前線軌道分析結(jié)果顯示，不同于離子半徑的變化，四種稀土離子自身的硬度大小順序為La＞Nd＞P＞Ce。模擬的La3+(H2O)n的紅外光譜顯示，隨著水分子數(shù)量的增加，Vsym和Vasym峰發(fā)生藍移；當n大于10時，Vsym和Vasym峰不再發(fā)生藍移，說明第一水化層外的水分子沒有與La離子發(fā)生反應(yīng)。
關(guān)鍵字: 稀土；離子水合物；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
