讨论了不同的Mg、Al源为起始反应物、反应温度、时间和碱度对水热合成Mg-Al水滑石物相组成和晶粒度的影响. 用XRD、SEM对合成产物进行了表征, 用X射线全谱拟合法计算了Mg-Al水滑石晶粒度. 以MgO和Al(OH)3为起始反应物, Mg/Al=2,在140℃反应4～10h, 可以制备出高结晶度的单相纳米晶Mg-Al水滑石. Mg-Al水滑石的形成机理可概括为: 水解反应-沉淀成核-晶粒长大. 反应物类型及合成条件会影响前驱物的水解速率和水解程度, 进而影响晶体成核和生长速率,控制物相的组成和晶粒度大小.
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.
参考文献
| [1] | Cavani F, Trifiro F, Vaccari A. Catal. Today, 1991, 11: 173-301. [2] Khan A I, O’Hare D. J. Mater. Chem., 2002, 12: 3191-3198. [3] Newman S P, Jones W. New J. Chem., 1998. 105-115. [4] Trifiro F, Vaccari A. Comprehensive Supramolecular Chemistry, Pergamon, Oxford, 1996, 7: 251-291. [5] Aramendia M A, Borau V, Jimenez C, et al. J. Solid State Chem., 2002, 168: 156-161. [6] Hickey L, Kloprogge J T, Frost R L. J. Mater. Sci., 1999, 35: 4347-4355. [7] Labajos F M, Rives V, Ulibarri M A. J. Mater. Sci., 1992, 27: 1546-1552. [8] Rao M M, Reddy B R, Jayalakshmi M V, et al. Mater. Research Bull., 2005, 40: 347-359. [9] Zhao Yun, Li Feng, Zhang Rui, et al. Chem. Mater., 2002, 14: 4286-4291. [10] 冯 桃, 李殿卿, 段 雪．无机化学学报, 2002, 18 (11): 1156-1160. [11] Xu Zhi-Ping, Lu Guo-Qing. Chem. Mater., 2005, 17: 1055-1062. [12] Bruker AXS, DIFFRACplus TOPAS P, Version 2.1. 2003, 6. BRUKER AXS GmbH, West Germany. [13] Labajos F M, Rives V, Ulibarri M A. J. Mater. Sci., 1992, 27: 1546-1552. [14] Rao M M, Reddy B R, Jayalakshmi M V, et al. Mater. Res. Bull., 2005, 40: 347-359. [15] Oh J-M, Hwang S-H, Choy J-H. Solid State Ionics, 2002, 151: 285-291. |
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