Influence of volume fraction on magnetodielectric effect in CoFe2O4–Ba0.8Sr0.2TiO3 multiferroic fluids

The multiferroic fluids use an external field to rotate the magnetization/polarization direction of the multiferroic particles to form a chain structure with a clamping effect, which is expected to achieve the enhanced magnetodielectric effect. In this paper, CoFe2O4–Ba0.8Sr0.2TiO3 multiferroic fluids were successfully prepared by ball milling method. The effects of volume fraction (0.1%, 0.5%, 1%, 2%, and 5%) on the magnetodielectric effect were systematically investigated. The analysis of X-ray diffraction patterns confirms that both CoFe2O4 and Ba0.8Sr0.2TiO3 particles were prepared in the pure phase. With the increase of the volume fraction, the dielectric properties and magnetodielectric effect increase slightly. When the volume fraction is 5%, the multiferroic fluids have a maximum ɛr of 6.44 at 100 Hz. Under the action of a 74.65 mT magnetic field, the maximum dielectric constant is 8.57, with the maximum magnetodielectric coefficient of 27.1%. Under the discontinuous magnetic field, the “switching effect” was also found. Moreover, the C–V curve demonstrates the nonlinear dielectric properties of multiferroic fluids.