Effect of Co2+ substitution on the structural, terahertz and magnetic characterization of NiZn ferrites

Abstract

We present detailed studies on spinel structured Ni0.5CoxZn0.5-xFe2O4 (x = 0.1, 0.2 and 0.3), synthesized by sol-gel combustion method. In addition to the structural properties, we present optical dielectric and magnetic response of this system as a function of x. From X-ray diffraction (XRD) analysis, a single-phase formation in cubic spinel structure was confirmed with an average crystallite size (Davg) variation of 46−61 nm. X-ray diffractograms were analyzed to evaluate the lattice constant (a), X-ray density (ρx) and porosity (P) in percentage. Energy dispersive X-ray spectroscopy was used to delimit the compositional mass ratios. Terahertz time-domain spectroscopy (THz-TDS) measurements were performed to investigate the refractive index (s) of the samples at room temperature in a frequency range from 0.2 to 2.5 THz. Real and imaginary components of complex optical dielectric constant (ɛos) with the increase of Co2+ content were deduced using THz spectroscopy data. The complex optical dielectric constant for the substitution of Co2+ content at x = 0.1, 0.2 and 0.3, was determined within 5% error ~9.6+i 0.07, ~10.9+i 0.2 and ~11.7+i 0.5, respectively. The magnetic measurements were performed at a temperature range of 300−50 K using a SQUID Vibrating Sample Magnetometer (SVSM) under an applied magnetic field of ±5 Tesla. We found the highest saturation magnetization (Ms) of about 86.7 emu/g, 83.5 emu/g and 80.4 emu/g for the substitution of Co2+ content at x = 0.1, 0.2 and 0.3, respectively at room temperature.