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1、物理化学学报(WuliHuaxueXuebao)2088ActaPhys.-Chim.Sin.2011,27(9),2088-2094September[Article]www.whxb.pku.edu.cn铜镁铝三元水滑石的姜-泰勒效应*刘娇姚萍倪哲明李远施炜(浙江工业大学化学工程与材料学院,先进催化材料实验室,杭州310032)摘要:采用密度泛函理论(DFT),用CASTEP程序模块,对类水滑石(CuxMg3-xAl-LDHs,x=0-3)周期性模型进行几何全优化,通过分析各体系的结构参数、电子排布、氢键、Mulliken电荷布居、结合能,总结出体系中的姜-泰勒效应和结构稳定性
2、规律.结果表明,姜-泰勒效应不仅存在于d轨道未排满的Cu2+中,在p轨道未排满的Mg2+中也可能存在,且未饱和的d、p轨道共同影响着金属离子姜-泰勒畸变的大小.在CuxMg3-xAl-LDHs(x=0-3)中,铝八面体和镁八面体分别以稳定的拉长的八面体形式存在.而随着Cu2+的增加,铜八面体逐渐从压扁的八面体向稳定的拉长的八面体形式转变,体系获得了逐渐增多的姜-泰勒稳定化能.总体上,随着Cu2+的增加,体系中姜-泰勒效应导致的畸变使主客体间的氢键和静电作用力均有减弱趋势,且体系的结合能绝对值逐渐减小,故体系稳定性下降.这有助于从理论上进一步认识含铜水滑石的姜-泰勒效应.关键词:水滑
3、石;姜-泰勒效应;密度泛函理论;结合能;Mulliken布居中图分类号:O641Jahn-TellerEffectofCu-Mg-AlLayeredDoubleHydroxides*LIUJiaoYAOPingNIZhe-MingLIYuanSHIWei(LaboratoryofAdvancedCatalyticMaterials,CollegeofChemicalEngineeringandMaterialsScience,ZhejiangUniversityofTechnology,Hangzhou310032,P.R.China)Abstract:Weproposeaperi
4、odicinteractionmodelforthelayereddoublehydroxides,CuxMg3-xAl-LDHs(x=0-3).Basedondensityfunctionaltheory,thegeometriesofCuxMg3-xAl-LDHs(x=0-3)wereoptimizedusingtheCASTEPprogram.TheJahn-Tellereffectandthestabilitywereinvestigatedbyanalyzingthegeometricparameters,electronicarrangement,hydrogen-bo
5、nding,chargepopulations,andbindingenergies.TheresultsshowthattheJahn-TellereffectexistsintheunfilledCu2+dorbitalandalsoexistsintheunfilledMg2+porbital.ThetwoorbitalsaffecttheJahn-Tellerdistortionofthemetalions.InCuxMg3-xAl-LDHs(x=0-3),bothaluminumandmagnesiumexistinstabilizedoctahedralforms.Wi
6、thanincreaseofCu2+inthelayertheoctahedralofcopperchangesfromaflatconfigurationtoastableelongatedconfigurationandtheJahn-Tellerstabilizationenergyofthesystemgraduallyincreases.Ingeneral,withanincreaseofCu2+inthelayerthedistortioncausedbytheJahn-Tellereffectweakenshydrogen-bondingandtheelectrost
7、aticinteractionsbetweenthehostlayerandtheguest.Theabsolutevalueofthebindingenergydecreasesandthechemicalstabilityofthesystemdecreasesaswell.ThisallowsustotheoreticallyunderstandtheJahn-Tellereffectbetterforthesynthesisofcopper-containin
