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

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 = z 1 + 2 z 2 ; z 1 ≫ z 2 . 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 3 2− . A large part of the NO 3 − makes a monodentate-type bond and the ClO 4 − a bridge-type bond.