Magnetic field and cetyltrimethylammonium bromide assisted hydrothermal synthesis of cobalt ferrite nanorods for UHF applications

In this study, investigates the formation of cobalt ferrite via the hydrothermal process using two distinct approaches. The first approach involved adding cetyltrimethylammonium bromide (CTAB) as a surfactant to the cobalt ferrite, while in the second, a magnetic field was applied to the cobalt ferrite without the surfactant. X-ray diffraction (XRD) patterns of all CoFe₂O₄ samples reveal a spinel phase without impurities. Magnetic field-assisted cobalt ferrite exhibits higher crystallinity than CTAB-assisted cobalt ferrite. The samples' Fourier transform infrared (FT-IR) spectra show absorption bands at 580 cm −1 and 408 cm −1 , corresponding to M-O (M = Fe 3+ , Co 2+ ) stretching vibrations of tetrahedral and octahedral spinel sites, respectively. Field emission scanning electron microscopy images show that the application of a magnetic field and the addition of CTAB influence ferrite morphology, producing nanorods and nanofibres. Magnetisation analysis indicates that the saturation magnetisation of cobalt ferrites values between 50 and 55 emu/g, reflecting the influence of shape anisotropy of the ferrites. The complex permittivity, permeability, and reflection loss of cobalt ferrites were investigated over the frequency range of 1.0 MHz to 3.6 GHz. The ferromagnetic resonance of cobalt ferrite nanofibers occurs in the frequency range of 1.0-2.0 GHz. The synthesized cobalt ferrites also exhibit a reflection loss ranging from −33 to −17 dB.