The Syntheses of Hydrotalcite-Like Compounds and Their Structures and Physico-Chemical Properties—I: the Systems Mg2+-Al3+-NO3−, Mg2+-Al3+-Cl−, Mg2+-Al3+-ClO4−, Ni2+-Al3+-Cl− and Zn2+-Al3+-Cl−

Abstract

The basic salts of this system were prepared and their structures and physico-chemical properties were studies by electron microscopy, chemical analysis, X-ray powder diffraction, thermal analysis, i.r. absorption spectra, BET absorption, and acidity-basicity measurements. The salts were found to be new compounds analogous to hydrotalcite. They can be expressed by the formula; where M 2+ and M 3+ denote di- and trivalent cations, A− and A 2− denote mono- and divalent anions, respectively, and y = z1 + 2 z2; z1 ≫ z2. The structures consist of positively charged Cd(OH)2-like basic layers and intermediate layers formed from anions and water molecules with the solid solution of divalent cation (M 2+) and trivalent cation (M 3+) being formed in the range of 0.6 < x/(x + y) < 0.9. The anions of Cl−, NO 3− and ClO 4− are easily substituted by CO 32−. A large part of the NO 3− makes a monodentate-type bond and the ClO 4− a bridge-type bond.