Optimization of room temperature multiferroic properties and magnetoelectric coupling effect in MnO2 doped BiFeO3−Bi0.5K0.5TiO3 ceramics

Abstract

Abstract The 0.6BiFeO3–0.4Bi0.5K0.5TiO3 + x mol% MnO2 ceramics (BFKT–xMn, x = 0, 2.5, 5, 7.5 and 10) have been successfully synthesized via a conventional solid-state reaction method. All the ceramics possess a morphotropic phase boundary formed by rhombohedral and tetragonal phases. A room temperature magnetoelectric (ME) coupling coefficient of 30.12 mV cm−1 Oe−1 is observed for the first time in the undoped BFKT ceramic. The appropriate addition of MnO2 can optimize the electrical insulation and ferroelectricity of BFKT ceramic due to the decreased densities of impurity and grain boundary, and thus enhance the magnetoelectric coupling effect significantly. The BFKT–2.5Mn ceramic exhibits a high remanent polarization of 36.2 μC/cm2 at a maximum electric field of 70 kV/cm and a high ME coupling coefficient of 42.56 mV cm−1 Oe−1 as well. Meanwhile, the leakage current density of the BFKT–2.5Mn ceramic maintains at a low value of 1.83 × 10−8 A/cm2 (at a maximum electric field of 45 kV/cm). These characteristics indicate the BFKT–2.5Mn ceramic has potential applications in multifunctional devices as lead-free multiferroic materials.