Structure-Dependent Electrical and Magnetic Properties of Iron Oxide Composites

The physical and chemical properties of polymorphs of iron oxides are utilized for electronic, energy, and biomedical applications. To design a functional material with arresting interplay at the interfaces and boundaries between polymorphs of iron oxide (Fe3O4 - magnetite with Fe2O3 - hematite), two different approaches of synthesis are adopted, namely, mechanical mixing and in situ growth. Unlike mechanically mixed composites, the in situ-synthesized composites show the development of a highly distinct non-stoichiometric, Fe21.34O32 phase at the boundary. The atomically diffused composition at boundary is found to govern the fourfold increase in conductivity. By varying the ratio of constituent iron oxide polymorphs, the dielectric constant can be tuned and is found to be highly frequency dependent with minimum loss in tan delta plot. The inherent ferromagnetism of Fe3O4 reveals to be retained in composite samples