Synthesis and multiferroic properties of high-purity CoFe2O4–BiFeO3 nanocomposites

•CFO-BFO nanocomposites were synthesized using a combination of hydrothermal/citric acid sol-gel method.•X-ray diffraction analysis shows the crystallinity and the high purity of the nanocomposites.•Magnetic properties analysis suggests the presence of dipolar interaction between CFO and BFO.•Electrical properties analysis indicates the leaky behavior of the samples.•Magnetoelectric property measurement shows the magnetic field control of electric polarization in the nanocomposites. CoFe2O4–BiFeO3 (CFO–BFO) nanocomposites of three different molar ratios (CFO:BFO = 2:2, 1.5:2, and 1:2) were synthesized by a combination hydrothermal/citric acid sol-gel method. This methodology allowed us to synthesize high-purity crystalline nanocomposites at a lower calcination temperature of 450 °C. Transmission electron microscopy (TEM) images revealed that the CFO and BFO nanocrystals are inter-embedded in each other. Room-temperature magnetic characterizations showed that the sintered sample of the 2:2 ratio had a high magnetization value of 40.5 emu/g at 20 kOe. The values of magnetization and coercivity indicated the presence of dipolar interaction between CFO and BFO. The electric-polarization change (ΔP) was estimated to be ~295 μC/m2 at a magnetic field strength of ~30 kOe at room temperature, although the polarization-electric field (P–E) loop measurements indicated that all of the samples manifested leaky behavior. The results presented herein offer a means of reliable magnetic-field control of electric polarization in high-purity multiferroic CFO–BFO nanocomposites.