The coating of nickel compounds with copper compounds

Uniform fine particles of nickel basic carbonate were synthesized by heating, aqueous solution containing 0.08 mol dm⁻³ nickel sulfate and 0.8 mol dm⁻³ urea, at 85°C for various periods of time. These particles were then coated with copper compound by heating them in aqueous dispersion, containing urea and copper nitrate, at 85°C. The coating material was found to be amorphous and was composed of Cu₂(OH)₂CO₃. The coating mixture, when heated under similar conditions in the absence of the dispersed cores, produced greenish dispersion of the precipitated particles coating precursor solids]. The later were also amorphous in nature and had the same chemical composition Cu₂(OH)₂CO₃] as that of the coating material of the coated particles. Air-dried core, coated, and coating precursor materials were calcined at 700°C for 1 h at the heating rate of 5°C min⁻¹ in the air atmosphere, which converted them into NiO, NiO_core]/CuO_coating], and CuO, respectively. Scanning electron microscopic examination showed no sintering occurred in all these solids during the calcinations process and the particles retained their identities to a significant extent.