ハイドロタルサイト型層状化合物 M(II)_<1-x>In_x(OH)_2(NO_3)_xnH_2O(M=Ni, Mg, Co, Ca) の合成

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Hydrotalcite (HT) type layered compounds [M(II) _<1-x> In_x (OH)_2(NO_3)_x nH_2O] with varying M(II) were synthesized and characterized by various methods. Preparations were done by coprecipitation and by adsorption. HT type compounds can be synthesized in the cases of M(II) = Ni^<2+> at pH=7, Mg^<2+> at pH=10, Co^<2+> at pH=7 and Ca^<2+> at pH=12 but not in the cases of M(II) =Cu^<2+> Zn^<2+> Mn^<2+> and Sr^<2+> The basal spacings of the HT type compounds range from 8.O to 8.7Å. That of Ca-In HT compound (8.7Å) expanded to 10.2Å in R.H.= 100%, while it shrank to 7.9Å in R.H. =0%, reversibly. The Ca/In ratio was around 2/1 and the NO^-_3 concentration was smaller than the ideal value due to a partial substitution of CO^<2->_3. Crystallinity of the M(II)-In HT compounds was poor except for the Ca-In HT. It is probably due to the large ionic radius of In^<3+> compared with those of the M(II) cations except for Ca^<2+>. Formation of M(II)-M(III) HT compounds was found to be almost restricted to the cases for M(II) and M(III) cations where M(II) (OH)_2 has a CdI_2 type layer structure and the coordination polyhedra of M(III) cations in hydroxides are octahedra.
日本粘土学会の論文
1994-07-07