Journal of Inorganic Materials

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Hydrothermal Synthesis Nano Mg-Al LDHs and its Formation Mechanism

WANG Yong-Zai

  

  1. (Center of Analysis and Testing, Shan Dong University of Technology, Zibo 255049, China)
  • Received:2006-12-26 Revised:2007-02-11 Published:2008-01-20 Online:2008-01-20

Abstract: Nano Mg-Al LDHs were prepared by a hydrothermal method in one step. Effects of precursors, alkalinity of the starting solution, temperature and time on phase purity and crystallite sizes of Mg-Al LDHs were systematically investigated. Reaction products were characterized by powder XRD and SEM. Crystallite sizes of Mg-Al LDHs were determined by the X-ray whole powder pattern fitting method. The optimal parameters for preparing Mg-Al LDHs are keeping the ratio of MgO:Al(OH)3:Na2CO3=2:1:1
at 140℃ for 4h to 10h. The formation mechanism proposed for Mg-Al LDHs is dissociationprecipitiationcrystal growth. The reactant type and hydrothermal conditions may influence the dissociation rate of the precursors, nucleation and growth rates of Mg-Al LDHs, as well as phase combination and crystallite sizes of the reaction products.

Key words: nano crystallites, Mg-Al LDHs, hydrothermal synthesis, whole powder pattern fitting, formation mechanism

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