Crystal structure, impedance, and multiferroic property of SrZrO3 and MnO2 modified 0.725BiFeO3−0.275BaTiO3 ceramics

SrZrO3 modified and SrZrO3+MnO2 co-modified 0.725BiFeO3−0.275BaTiO3:xSrZrO3+yMnO2 (BF-BT:xSZ+yMnO2, x, y = 0-0.075) multiferroic ceramics were prepared and the structure, resistance and multiferroic properties were comparatively investigated. SZ plays a more dominant role than MnO2 in making a phase transition from rhombohedral to pseudocubic around x = 0.02, y = 0, which implies that SZ has formed solid solution with BF-BT whereas most Mn cations may have not entered into lattice of host but exist as second phase isolated particles. The modifications have complex effects on impedance spectra but the SZ-induced MPB has significantly increased resistance. As a result, such modifications show great effects on multiferroics. Briefly, the rhombohedral-pseudocubic morphotropic phase boundary composition shows peak ferroelectricity with remanent polarization of 8.2 μC/cm2 and switchable remanent magnetization of 0.22 emu/g. Then the ferroelectricity and magnetism weaken slightly with increasing SZ contents. However, the introduction of MnO2 results in monotonously suppressed ferroelectricity but enhanced magnetization. These results not only provide promising multiferroic material with switchable polarization and magnetization at room temperature, but also may stimulate further work on co-modified BF-BT solid solutions with optimized multiferroic properties.