Preparation and multiferroic properties of Bi0.8La0.2FeO3-CoFe2O4 ceramics

Composite multiferroics usually show larger magnetoelectric effect, which is important for actual application, than their single-phase counterparts. Here, (1−x)BiFeO3-xCoFe2O4 and (1−x)Bi0.8La0.2FeO3-xCoFe2O4 (x=0.1, 0.2, and 0.3) multiferroic composite ceramics were prepared. The former system shows low resistivity, which prevents the intrinsic ferroelectric measurements, whereas for the later system, the composition with x=0.1 shows well saturated polarization-electric field hysteresis loop at room temperature, the measured remnant polarization is 13.4 μC/cm2. However, for the compositions with x=0.2 and 0.3, the measured loops show negative curvature near saturation, which is attributed to the decreased resistivity. Further magnetic measurements reveal that at low temperature, 0.9Bi0.8La0.2FeO3−0.1CoFe2O4 shows ferromagnetic nature whereas at high temperature antiferroelectric-like nature, which is discussed based on comparing its magnetic response with that of pure Bi0.8La0.2FeO3 and CoFe2O4 ceramics. These results may be helpful for further understanding, and designing, new multiferroic composites.