Synthesis of magnesium ferrite by combustion of glycine-nitrate gel: the influence of reagents on the gel-precursor and the microstructure of nanopowders

In this study, the influence of initial reagents on the phase composition and morphology of magnesium ferrite obtained by combustion of glycine-nitrate gel was investigated. The local environment of iron ions in the gel-precursor was studied in detail using FT-IR, XANES- and EXAFS- spectroscopy. It has been established that in the gel-precursor obtained by dissolving metals (Mg, Fe) in dilute nitric acid, binuclear Fe(III) complexes are formed, while in a similar gel-precursor obtained from crystalline hydrates of nitrates of the corresponding metals, trinuclear Fe(III) complexes predominate. Combustion of a gel consisting of binuclear Fe(III) complexes leads to the formation of nanocrystalline magnesium ferrite powder, characterized by a unimodal particle size distribution.