Carbon Combustion Synthesis of Ferrites: Synthesis and Characterization

Submicrometer powders of Mn−Zn and Ni−Zn ferrites have been produced by carbon combustion synthesis of oxides (CCSO). The self-propagating temperature front had a maximum temperature of a up to 1300 °C and moved at a velocity 3.5 mm/s. Solid-state interactions between the precursors and crystal growth of the crystalline spinel ferrites started in the early period of the combustion and continued in the postcombustion zone. The crystalline Ni 0.35 Zn 0.65 Fe 2 O 4 and Mn 0.25 Zn 0.75 Fe 2 O 4 ferrites formed using reactant mixtures containing up to 40% carbon and did not require further calcination to get complete conversion. The product particle size increased with increasing carbon content in the reactants mixture and oxygen concentrations. At least twice the amount of required stoichiometric oxygen was needed to generate a stable combustion front and form pure spinel ferrite structure. The emission of carbon dioxide increased the porosity and friability of the products. The synthesized ferrites had soft magnetic properties which compared well with those obtained by other synthesis methods.