Structure and properties of precipitated nickel-iron hydroxides

Abstract

Iron-substituted nickel hydroxides have been prepared by precipitation for y iron substitution rates ranging from 0.10 to 0.50. Chemical and physical studies have shown, as in the case of the homologous ‘chimie douce materials’, the presence of (1 - y)Ni 2+ and yFe 3+ ions within the slab; the compensation of the excess of positive charge mainly results from the intercalation of CO 3 2− ions in the interslab space. The IR study and the chemical analysis provide evidence for the presence of SO 4 2− ions in T d symmetry (originating from the precipitation medium) that are mainly adsorbed on the grain surface. These materials are stable in concentrated KOH solution but their ageing in such a medium induces a modification of the crystallinity as well as a spontaneous exchange of CO 3 2− ions for SO 4 2− ions.