Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (09): 2088-2094.doi: 10.3866/PKU.WHXB20110923


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

LIU Jiao, YAO Ping, NI Zhe-Ming, LI Yuan, SHI Wei   

  1. Laboratory of Advanced Catalytic Materials, College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032, P. R. China
  • Received:2011-05-09 Revised:2011-07-08 Published:2011-08-26
  • Contact: NI Zhe-Ming

Abstract: We propose a periodic interaction model for the layered double hydroxides, CuxMg3-xAl-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 Cu2+ d orbital and also exists in the unfilled Mg2+ 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 Cu2+ 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 Cu2+ 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.

Key words: Layered double hydroxide, Jahn-Teller effect, Density functional theory, Binding energy, Mulliken population


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