Novel magnetoelectric ceramic composites by control of the interface reactions in Fe2O3@BaTiO3 core-shell structures

In the present work, composite ceramics of ferroelectric BaTiO3 (BT) with magnetic alpha Fe2O3 were prepared from powders synthesized by two different methods: (a) core-shell powders of Fe2O3@BT and (b) Fe2O3-BT composites from mixed powders with the same composition. The M(H) loops at room temperature show a "wasp-waisted" character, with multiple components, determined as result of the formation of magnetic phases with contrasting coercivities (hard BaFe12O19 and soft Ba12Ti28Fe15O84 phases) in different ratios, as indicated by the magnetic first-order-reversal curves analysis. The core-shell composite ceramics generally showed slightly improved dielectric properties and smaller conductivity. The high field properties of composite ceramics show a strong nonlinearity in both cases, together with a reduction of zero field permittivity, making from these composites possible tunable materials interesting for applications. Their multifunctional character is enhanced by the presence of a complex magnetic character with soft/hard components. (c) 2014 AIP Publishing LLC.