文摘
Monodispersed nickel(II) particles were achieved by ageing aqueous solutions of NiSO4·6H2O in the presence of urea, at 90°C for 3.5 h. Working up this colloidal dispersion led to a green powder with the stoichiometry 5[Ni3(OH)5(NCO)]·[NiCO3]·[H2O]. This mixed salt was characterised by extensive spectroscopic investigations and chemical–physical analyses. The nickel intermediate was further thermally decomposed at various temperatures, under both aerobic and anaerobic conditions, and gave black mono dispersed particles of Ni(II) and Ni(III) oxides. The phase transformations were studied in detail and the oxidation products (NiO and NiO(OH)) were characterised.