Quantitative effects of fuel on the synthesis of Ni/NiO particles using a microwave-induced solution combustion synthesis in air atmosphere

Microwave-induced solution combustion process for the synthesis of Ni and NiO powders were described. The exothermic redox reaction and the heat evolved from the reaction completely convert the precursors into their corresponding products at temperatures below 400 °C in an oxidizing atmosphere. The characteristics of synthesized powders were investigated with types and amounts of fuel. Nickel particles were directly synthesized through solution combustion synthesis with fuel-rich (Φe = 0.65) composition in air atmosphere without further reducing calcinations process. In the fuel-lean composition range (Φe > 1) and stoichiometric composition (Φe = 1), only NiO phase crystallized from the precursor mixture without forming any intermediate phases. Primary crystallite size of the as-synthesized Ni and NiO were about 30 nm.