Structural, dielectric, magnetic and magnetoelectric properties of (x) Bi0.5Na0.5TiO3-(1 − x) Ni0.2Co0.8Fe2O4 composites

Abstract

Magnetoelectric composites (x) Bi0.5Na0.5TiO3-(1 − x) Ni0.2Co0.8Fe2O4 (x = 0.0, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, and 1.0) were synthesized using a solid-state reaction method. The x-ray diffraction studies confirm the existence of rhombohedral Bi0.5Na0.5TiO3 (BNT) and mixed spinel Ni0.2Co0.8Fe2O4 (NCFO) phases without any intermediate phase. The microstructure and surface morphology were studied using a field-emission scanning electron microscope. The relative permittivity (ε′) and dielectric loss (tanδ) are measured as a function of frequency in the frequency range 100 Hz–1 MHz at room temperature and found to decrease rapidly in low-frequency regime and remain nearly constant in high-frequency regime. The magnetization-magnetic field (M-H) hysteresis loops have been measured to see the response of the magnetic field on the NCFO phase in the composites. The saturation and remnant magnetization are observed to decrease with increasing BNT content in the composite. The magnetoelectric (ME) voltage coefficient, αME was measured as a function of the applied DC magnetic field. The highest value of αME = 7.538 mV cm−1 Oe was obtained for the 60%BNT–40%NCFO bulk composite, which is attributed to the enhanced mechanical coupling between the phases. This is a promising result compared to other BNT-based composites. The addition of BNT and NCFO enhances the ME properties of these composites.