On the relationship between α-nickel hydroxide and the basic salts of nickel

α-Nickel hydroxide is isostructural with the hydroxide-rich basic salts of nickel. The anions in the basic salts are strongly grafted to the nickel hydroxide sheets, but in α-nickel hydroxide, the anions are loosely intercalated between the hydrated nickel hydroxide sheets, [Ni(OH)2 − x(H2O)x]x+. The loose intercalation causes the sheets to become disordered and leads to a turbostratic structure. In contrast, the nickel hydroxy-anion sheets in the basic salts are stacked together in a highly ordered fashion. The basic salts of nickel transform into the α-hydroxide upon ageing in a tartarate buffer, into β-hydroxide at pH 4, and into βbc (bc: badly crystallized) phase in 1 M KOH.