Preparation and characterization of cobalt-substituted α-nickel hydroxide stable in KOH medium Part II. α-Hydroxide with a turbostratic structure

α-Turbostratic cobalted nickel hydroxides have been obtained by precipitation, with an NaOH solution, from nickel and cobalt salts. Several preparation methods have been developed in order to obtain a material containing Ni2+ and Co3+ ions. Depending on the experimental procedure, carbonate and sulfate anions are inserted between the (Ni, Co)(OH)2 slabs, in order to compensate for the excess of positive charge due to the presence of trivalent cobalt ions in the hydroxide. These materials have been characterized by chemical analysis, X-ray diffraction, TGA, and u.v.-visible spectroscopy. The resulting αCo3+ phase is stable in KOH medium if the cobalt amount is at least equal to 20%. By contrast, the αCo2+ hydroxide is spontaneously transformed to a β(II) hydroxide, whatever the cobalt amount.