Structural, microstructural, electromagnetic and magnetoelectric properties of (1 − y) [Ba0.85Ca0.15Zr0.1Ti0.9O3] + (y) [Ni0.92Co0.03Mn0.05Cu0.05Fe1.95−xAlxO4] composites

Abstract

In the present study, polycrystalline (1 − y) [Ba0.85Ca0.15Zr0.1Ti0.9O3] (BCZTO) + (y) [Ni0.92Co0.03Mn0.05Cu0.05Fe1.95−xAlxO4] (NCMCFAlxO) (where x = 0, 0.1, 0.3, 0.5, 0.7, 0.9 and y = 0.5) composites were synthesized via solid state reaction route. The samples were characterized through the standard techniques. X-ray diffraction (XRD) analysis revealed the successful formation of the BCZTO–NCMCFAlxO composites without any extra phases and diffusion. The lattice parameter of BCZTO and NCMCFAlxO decreases as the concentration of Al3+ increases. SEM analysis reveals that the microstructure exhibits nonuniform grain size distribution with Al3+ concentration. The dispersion of dielectric constant is well consistent with Maxwell–Wagner interfacial polarization and the dielectric constant decreases as the concentration of Al3+ ions increases due to the difference of ionic radii. The electrical conductivity is due to the small polaron hopping according to Austin–Mott model. The decrement in saturation magnetization with increasing Al3+ concentration because exchange interactions is weakened through the substitution of Fe3+ by Al3+ ions. Permeability decreases with Al3+ concentration and exhibits good frequency stability over the entire measured frequency domain. The magnetoelectric coupling coefficient decreases as the concentration of Al3+ increases at both sintering temperatures which is due to the variation of grain size. The maximum magnetoelectric voltage coefficient of 0.72 V Oe−1 cm−1 was obtained for the pristine composite at 1373 K.