Microstructure and magnetic interactions of Co2+ substituted NiCuZn ferrites

Abstract

Nickel-Copper-Zinc ferrites are state-of-the-art dielectric materials with enhanced electromagnetic properties. Herein, we report, physicochemical and magnetic properties of Co2+ substituted NiCuZn ferrites of the series Ni0.25-xCoxCu0.30Zn0.45Fe2O4 (x = 0.00, 0.05, 0.01, 0.15, 0.20 and 0.25). The adopted synthesis method is the facile sol–gel auto combustion route with glycine as a reducing agent. X-ray diffraction (XRD) signatures revealed the cubic spinel structure, with a decrease in the lattice constant (a) due to a smaller ionic radius of Co2+ (0.72 Å) replacing Ni2+ (0.74 Å) ions. The optical properties of the ferrites are discussed in detail, viz. refractive index (η), reflectivity (R), the velocity of IR waves (v), and jump rates (J1, J2, and J). EDAX analysis indicated the elemental composition of ferrite samples as per the chosen stoichiometry. The microstructural analysis (SEM and TEM) depicts the dense microstructure with the average grain size of 38–95 nm. The samples exhibit a typical magnetic hysteresis loop at room temperature with low coercivity values confirming the soft magnetic nature. The maximum MS = 56 emu/gm was observed for the ferrite sample with x = 0.20. Temperature-dependent initial permeability at a constant frequency (1 MHz) showed the drop in the permeability values with increasing Co2+ content, whereas the values of Tc remain fairly unchanged.