Synthesis, microstructure analysis, electrical and magnetic properties of Ni0.5Mg0.5Fe2O4 – BaTiO3 Nano-composites

Abstract

Multiferroic nano-composites with chemical formula (x) Ni0.5Mg0.5Fe2O4 (NMFO) + (1-x) BaTiO3 (BTO); (x = 10, 20, 30 and 40%) were prepared via sol–gel method. XRD patterns confirmed the presence of a single cubic phase of pure NMFO and a single tetragonal phase of BTO. The crystallite size of BTO is found to be larger than that of NMFO. Moreover, the strain of the BTO phase increased, while the porosity decreased with increasing x-content. A high-resolution transmission electron microscope (HRTEM) revealed the formation of a single particle domain in the ferrite (NMFO) phase. Field emission scanning electron microscope (FESEM) demonstrated that the grain size increases with increasing x-content. The temperature dependence of D.C electrical resistivity showed a semiconducting behavior of all samples, while the resistivity decreased with increasing x-content. Electrical permittivity (e') and dielectric loss (tan δ) at low (20–105 Hz) and high (1 MHz–3 GHz) frequencies at room temperature were considered. A resonance phenomenon is observed only in the high-frequency range such that the resonant frequency shifts to a higher frequency with increasing x-content. The ferroelectric hysteresis loops (P-E) revealed that the maximum polarization (Pmax) decreased with increasing x-content. The ferromagnetic hysteresis loops (M-H), carried out using a vibrating sample magnetometer (VSM), confirmed an increase in saturation magnetization (Ms) with increasing x-content. Relative magnetic permeability (µr) as a function of temperature indicated a cooperative phenomenon between ferroelectric and ferromagnetic phases at (380–480) °C.