Low-loss Characteristics and Sustained Magneto-dielectric Behaviour of Cobalt Ferrite Nanoparticles over 1-6 GHz Frequency Range

Abstract Cobalt ferrite (CoFe2O4) nanoparticles were synthesized through the citrate precursor route. The XRD pattern confirmed the formation of a homogeneous single-phase spinel structure with an Fd3m space group. No impurities or unreacted constituents in the sample were observed. Analysis of the most prominent (311) peak of the XRD pattern revealed the crystallite size to be ∼39 nm with lattice constants and interplanar spacing as ∼8.374 A and ∼2.525 A, respectively. Other key structural parameters, such as dislocation density, strain, X-ray density, and hopping lengths, were also obtained from XRD data. Structural parameters were refined by applying the full pattern fitting of the Rietveld method using the Pseudo-Voigt function. High-resolution images obtained from SEM and TEM confirmed the morphological characteristics and crystallite size of the CoFe2O4 nanoparticles. The hysteresis loop recorded over the applied external magnetizing field of –10 kOe to +10 kOe revealed a specific saturation magnetization, specific remanent magnetization, and coercivity value of ∼64 emu/g, ∼24 emu/g, and ∼565 Oe, respectively. A remanence ratio ∼0.374 signified magnetostatic interaction between CoFe2O4 nanoparticles and confirmed their multi-domain structure and soft magnetic nature. Investigations were carried out to obtain the variations in complex dielectric permittivity, complex magnetic permeability, dielectric and magnetic loss tangents, AC conductivity, and quality factor in 1–6 GHz frequency range. The CoFe2O4 nanoparticles exhibited low dielectric and magnetic loss tangents of 10-2 and 10-3 order, along with moderate values of relative permittivity and refractive index, i.e., 4.801 and 2.3, respectively. The sustained magneto-dielectric behaviour and low-loss characteristics suggest that CoFe2O4 nanoparticles can be suitably dispersed in a dielectric matrix and used to develop efficient substrate material for improved telemetry, telecommunications and radar systems of aerospace systems operating over the 1–6 GHz frequency range.