Direct Synthesis of Iron Oxide Nanopowders by the Combustion Approach:  Reaction Mechanism and Properties

Solution combustion synthesis of different oxides involves a self-sustained reaction between an oxidizer (e.g., metal nitrate) and a fuel (e.g., glycine, hydrazine). The mechanism of synthesis for three major iron oxide phases, i.e., α- and γ-Fe2O3 and Fe3O4, using the combustion approach and a combination of simple precursors such as iron nitrate and oxalate, as well as different fuels, is investigated. Based on the obtained fundamental knowledge, for the first time in the literature, the above powders with well-crystalline structures and surface areas in the range 50−175 m2/g are produced using a single approach while simultaneously avoiding additional calcination procedures. It is also shown that utilizing complex fuels and complex oxidizers is an attractive methodology to control the product composition and properties.