On the morphology of nano-composite powder of Ni-NiO produced by solution combustion synthesis

The Ni-NiO powder was produced by solution combustion synthesis with two fuels of urea and glycine and different molar ratios of fuel to the oxidizer. The adiabatic temperatures were calculated for different molar ratios of fuel to the oxidizer. Then, the final products at any molar ratio of fuel to the oxidizer were characterized and compared to those were estimated according to the reactions' stoichiometry. The effect of different fuels, glycine and urea, and using mixed fuels were considered. Characterizations and analyses such as XRD, PSA, and FESEM were carried out to determine the compound and morphology of the products. At lower fuel to oxidizer ratio, the final product was NiO for both fuels (urea and glycine). However, with increasing the molar ratio of fuel to oxidizer, the Ni particles were synthesized adjacent to the NiO particles. Generally, the particle size of powders that were synthesized with glycine was smaller than those of urea. However, with increasing the molar ratio of fuel to oxidizer, the particle size of powders increased because of changing the composition to Ni and decreasing the adiabatic temperature. The smallest particle size was related to the sample synthesized by 75% glycine and 25% urea which was 35 nm. The morphology of Ni and NiO were compared at the different molar ratios of fuel to the oxidizer. The morphology of NiO is finer and contains more porosity.