铜镁铝三元水滑石的姜-泰勒效应  

Jahn-Teller Effect of Cu-Mg-Al Layered Double Hydroxides

作　　者：刘娇[1] 姚萍[1] 倪哲明[1] 李远[1] 施炜[1] 

机构地区：[1]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

出　　处：《物理化学学报》2011年第9期2088-2094,共7页Acta Physico-Chimica Sinica

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.We propose a periodic interaction model for the layered double hydroxides, CuxMg3-xAI-LDHs （x=0-3）. Based on density functional theory, the geometries of CuxMg3-xAl-LDHs（x=0-3） were optimized using the CASTEP program. The Jahn-Teller effect and the stability were investigated by analyzing the geometric parameters, electronic arrangement, hydrogen-bonding, charge populations, and binding energies. The results show that the Jahn-Teller effect exists in the unfilled Cu^2＋ d orbital and also exists in the unfilled Mg^2＋ p orbital. The two orbitals affect the Jahn-Teller distortion of the metal ions. In CuxMg3-xAl- LDHs（x=0-3）, both aluminum and magnesium exist in stabilized octahedral forms. With an increase of Cu^2＋ in the layer the octahedral of copper changes from a flat configuration to a stable elongated configuration and the Jahn-Teller stabilization energy of the system gradually increases. In general, with an increase of Cu^2＋ in the layer the distortion caused by the Jahn-Teller effect weakens hydrogen-bonding and the electrostatic interactions between the host layer and the guest. The absolute value of the binding energy decreases and the chemical stability of the system decreases as well. This allows us to theoretically understand the Jahn-Teller effect better for the synthesis of copper-containing LDHs.

关 键 词：水滑石 姜-泰勒效应 密度泛函理论 结合能Mulliken布居 

分 类 号：O641.4[理学—物理化学]