Study of magnetic and magnetoelectric properties of some perovskite-spinel composites

Abstract

The perovskite-spinel composites were synthesized and their various properties were investigated for technological applications. Various (1-y) Ba0.60-xCaxSr0.40Zr0.25Ti0.75O3 + y (Li0.50Fe0.50)0.40Ni0.30Zn0.18Cu0.12Fe2O4 composites were synthesized by conventional solid state reaction method. The structural properties were studied by using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrum (EDS). XRD confirms the phase formation and crystallinity of the composites and assures that spinel and perovskite can coexist in the composite without any reaction. Average grain size was measured by linear intercept method and found to increase with addition of spinel in the composites. The presence and relative proportion of constituent elements were confirmed by EDS. The magnetic properties were investigated by using vibrating sample magnetometer (VSM). The VSM spectra show that saturation magnetization increases with the concentration of spinel in the composites. Impedance analyzer was used to study the variation of initial permeability, relative quality factor, dielectric constant, and dissipation factor at room temperature as a function of frequency. Permeability spectra show that it increases with increase of ferrite in the composite. The dielectric constant shows dispersion in the lower frequency range which is attributed to Maxwell-Wagner dispersion. The ac conductivity was also calculated and linearity of log (ζac) vs log (ω2) confirms that the electrical conduction in these composites is mainly due to small polaron hopping. The magnetoelectric (ME) voltage coefficient was measured as a function of applied dc magnetic field and found to increase with increment of magnetic field. The maximum ME coefficient was obtained 1158 mV/cm-Oe for x=0.20 and y=0.20 which confirms the utility of present composites in multifunctional devices.