Structure‐Dependent Electrical and Magnetic Properties of Iron Oxide Composites

Abstract

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 (Fe 3 O 4magnetite with Fe 2 O 3hematite), 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, Fe 21.34 O 32 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 δ plot. The inherent ferromagnetism of Fe 3 O 4 reveals to be retained in composite samples.