Tailoring the optical and magnetic properties of La-BaM hexaferrites by Ni substitution

We investigate the impact of Ni insertion on the structural, optical, and magnetic properties of Ba_0.8La_0.2Fe_12-xNi_xO₁₉ hexaferrites (Ni substituted La-BaM hexaferrites). Samples were prepared using the conventional co-precipitation method and sintered at 1000℃ for 4 hours to assist the crystallization process. An analysis of the structure of the samples was carried out using an x-ray diffraction (XRD) spectrometer. The M-type hexagonal structure of all the samples was confirmed using XRD spectra. The lattice parameters a and c were found to be in the ranges of 5.8925 ±0.001 nm-5.8952 ±0.001 nm and 23.2123 ±0.001 nm-23.2219 ±0.001 nm, respectively. The M-type hexagonal nature of the prepared samples was also indicated by the presence of corresponding FT-IR bands and Raman modes in the FT-IR and Raman spectra, respectively. EDX results confirmed the successful synthesis of the samples according to the required stoichiometric ratio. A UV-vis spectrometer was used to record the absorption spectra of the prepared samples in the wavelength range of 200 nm-1100 nm. The optical energy bandgap of the samples was found to be in the range of 1.21 eV-3.39 eV. The M-H loops of the samples were measured at room temperature at an applied magnetic field range of 0 kOe-60 kOe. A high saturation magnetization of 99.92 emu/g was recorded in the sample with x=0 at a microwave operating frequency of 22.2 GHz. This high value of saturation magnetization is due to the substitution of La³⁺ ions at the spin-up (12k, 2a, and 2b) sites. The Ni substitution is proven to be a potential candidate for the tuning of the optical and magnetic parameters of M-type hexaferrites. Therefore, we suggest that the prepared samples are suitable for use in magneto-optic applications.