Materials based on mixed aluminum and iron (III) and oxyhydroxides were prepared by the hydrothermal synthesis using urea, nitrates, or chlorides salts in different Al3+:Fe3+ molar ratios. The structural, morphological, and thermal properties of the materials were evaluated. The mixtures of Al3+ and Fe3+ nitrates led to the formation of hematite whereas, for the materials obtained from chlorides, different crystalline phases of Fe3+ were identified. For the thermal behavior, it was observed that, regardless of the anion of the precursors’ salts, the samples with composition 30%:70% (Al3+:Fe3+) stood out from the others. After calcination, the hematite phase was identified in all samples. The precursor salts and the Al3+:Fe3+ ratios reflected in differences between the samples in the evaluated properties. From the observed results, the occurrence of isomorphic substitutions of Fe3+ by Al3+ in the hematite phase was observed, which provided changes in the evaluated properties in relation to the material without the presence of Al3+.
hydrothermal synthesis; aluminum; iron; mixed oxyhydroxides; mixed oxides