Improved magneto-dielectric properties in Co substituted Cr ferrites for miniaturized antenna applications

Abstract

The composition Cr(Fe1-xCox)2O4 with x = 0.0, 0.1, 0.5, and 0.9 has been synthesized using the solid-state reaction method followed by the double sintering technique of pre-sintering at 800 ◦C and sintering at 1332 ◦C.
The structure and cationic distribution in the studied samples obtained by the Rietveld refinement of X-ray
diffraction (XRD) patterns confirm a mixed spinel cubic structure of Fd3m space group, with a reduction in
impurity phase (α-Fe2O3) as Co2 + substitution increases. In addition, the scanning electron microscopy (SEM) of
these samples indicates a decrease in grain size and porosities with higher Co content. The magnetic hysteresis
measurement by a vibrating sample magnetometer (VSM) reveals that Co2+ substitution at Fe3+ enhances the
magnetic properties, with maximum saturation magnetization (Ms) of ∼ 4.03 × 10− 2 μB/F.U and coercivity (Hc)
of ~102.1 Oe observed for x = 0.5. In addition, the frequency-dependent permeability (μ) improves with Co
doping in Cr ferrite, and dielectric studies exhibit reduced loss tangent (tanδ) and enhanced dielectric quality
factor (Qε). Finally, the matching impedance becomes stable across a broad frequency range (3 kHz to 7 MHz)
with Z/η0 ≈ 0.75, resulting in the Co-substituted Cr ferrites as promising materials for miniaturized antenna
applications including superior magneto-dielectric performance and eco-friendly composition