Effect of mechanical milling on structural, dielectric and magnetic properties of BaTiO3-Ni0.5Co0.5Fe2O4 multiferroic nanocomposites

The coexistence of ferroelectricity and ferromagnetism has triggered great interest in multiferroic materials. Multiferroic with strong room temperature magnetoelectric (ME) coupling can provide a platform for future technologies. In this paper, we have investigated the effect of mechanical milling on the properties of multiferroic nanocomposites synthesized by mixing barium titanate (BaTiO3) (BT) and nickel cobalt ferrite (Ni0.5Co0.5Fe2O4) (NCF). This process has resulted into reliable disposal of a given quantity of NCF nanoparticles in BT grid and composite samples of different particle sizes (< 500 nm) have been obtained by varying the duration of ball-milling for 12, 24, and 48 h. The presence of NCF within BT powder has been confirmed by X-ray Diffraction (XRD) and magnetization measurements (MH). Structural analysis was performed by using Reitveld refinement method that shows that the tetragonality of BaTiO3 structure get reduced in submicron range. Variations in ferroelectric and dielectric properties with reduction in particle size/milling duration have been studied by P-E loop tracer and Impedance analyzer. The dielectric constant value of 400 has been observed for BT-NCFO that increases to 9.7 K for composite sample ball mill at 48 h whereas remnant polarization increases to 4.2 C/cm(2). These composites with high dielectric constant that changes with temperature and particles size find application in energy storage devices, sensor and memory devices.