Synthesis and room-temperature multiferroic properties of lead-free Bi4Ti3O12/NiFe2O4 nanocomposite films

Lead-free Bi4Ti3O12/NiFe2O4 nanocomposite films have been prepared via sol-gel spin-coating route. The successful phase formation of orthorhombic Bi4Ti3O12 and cubic NiFe2O4 has been confirmed using x-ray diffraction without any detectable extra phase. The scanning electron microscopy with EDS measurement reveals homogeneous and dense growth of both phases accompanied by clear interface between the two layers. The loop of magnetization versus magnetic field indicates the ferromagnetic properties at room temperature with saturation magnetization of ~257.48 emu/cm3, coercive field of ~121 Oe and remnant magnetization of ~57.03 emu/cm3. Room-temperature ferroelectric behavior is also obtained along with the good fatigue endurance properties and low leakage current density. The frequency dependence of dielectric constant displays the monotonous decreasing tendency with low dielectric loss. Moreover, evident magnetodielectric behavior is achieved in the nanocomposite films at room temperature. The coexistence of ferromagnetic and ferroelectric behavior including the appearance of magnetodielectric effect proves the room-temperature multiferroic properties in Bi4Ti3O12/NiFe2O4 nanocomposite films, which makes the films meaningful as the lead-free multiferroic systems for device applications at room temperature.