Dielectric and ferroelectric properties of BiFeO3 ceramics sintered in different atmospheres

Pure BiFeO3 powders were successfully synthesized by microwave-hydrothermal processing, and the pellets were sintered in different atmospheres. The properties of BiFeO3 ceramic samples were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), dielectric measurements (LCR) and polarization-field hysteresis loop. The effects of different atmospheres (including air, N2, O2 and H2) on ferroelectric properties of BiFeO3 ceramics were studied in this paper. The results show that the BiFeO3 ceramics sintered in H2 and N2 atmosphere have a single-phase rhombohedra distorted perovskite structure with no trace of other impurity phases. The dielectric properties of BiFeO3 ceramics were greatly influenced by O2 and H2 atmospheres. The samples sintered in H2 atmosphere have the highest dielectric constant. Polarization-field hysteresis loops measured at room temperature indicated the samples sintered in H2 and N2 atmospheres have higher spontaneous polarization and lower breakdown field, but the ferroelectric properties of samples sintered in O2 atmospheres were poor.