Hydrothermal preparation of nickel hydroxide coated iron oxide particles

A novel hydrothermal coating process has been developed to deposit nickel compound over octahedral α-Fe2O3 particles of narrow size distribution (0.2–0.3 μm) by treating aqueous dispersions of the preformed cores at elevated temperatures in Ni(NO3)2/CH3COONa solutions. A study of the process parameters on the characteristics of the so prepared particles indicated that deposits containing 48.5–51.4 wt.% of nickel could be obtained at temperatures 140–200 °C and reactant concentrations (Ni(NO3)2 and CH3COONa) of 0.1–0.6 mol/l, yielding coatings composed of amorphous Ni(OH)2·H2O. The nickel hydroxide films may be formed via the hydrolysis of CH3COO− ions followed with the further interaction of OH− and Ni2+ ions.