Enhancement of coercivity in polybenzoxazine/CoxMg1−xFe2O4 nanoferrite composites: Synthesis and characterization

In this research, we synthesize composites of CoxMg1−xFe2O4 (0 ≤ x ≤ 1) spinel nano-ferrites and polybenzoxazine (PBZ) and characterize their structural, optical, and magnetic properties. The magnetic nanoparticles are fabricated using the chemical co-precipitation method. The benzoxazine (BZ) monomer is synthesized by Mannich condensation reaction using aniline, paraformaldehyde, and phenol. Specific weights of the ferrite particles and BZ monomer are then mixed and thermally treated to produce the composites. X-ray diffraction (XRD) ensures that the desired spinel phase is formed. Moreover, the average crystallite size calculated from the XRD data ranges from 5.3 to 15.5 nm, which shows a fair degree of agreement with the transmission electron microscope images. Energy dispersive x-ray spectroscopy has confirmed the chemical composition of the samples. Fourier transform infrared characterization has been used to confirm the formation of BZ and PBZ. The magnetic properties at room temperature are evaluated using a vibrating sample magnetometer. Increasing the cobalt content has increased the saturation magnetization (Ms) significantly in the ferrite samples while creating composites with PBZ decreased the Ms values. We find that the coercivity (Hc) of the composites has increased more than that of the bare ferrite particles. The optical properties are evaluated by ultraviolet–visible spectrophotometry (UV–Vis) analysis, where it is found that the optical bandgap increases with an increase in the Mg component. Higher retention of the magnetic properties in the composite, especially coercivity (Hc), shows potential for applications that require high magnetic properties in combination with structural flexibility.