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

The impact of Ni insertion on structural, optical, and magnetic properties of Ba0.8La0.2Fe12-xNixO19 hexaferrites (Ni substituted La-BaM hexaferrites) is investigated. The samples were prepared using the conventional co-precipitation method and sintered at 1000 oC for 4 hours to assist the crystallization process. The analysis of the structure of the samples was carried out using X-ray diffraction (XRD) spectrometer. The M-type hexagonal structure of all the samples was confirmed from the XRD spectra. The lattice parameters 'a' and 'c' are found in the range 5.8925 ±0.001 - 5.8952 ±0.001 nm and 23.2123 ±0.001 - 23.2219 ±0.001 nm, respectively. The M-type hexagonal nature of the prepared samples is also indicated by the presence of corresponding FT-IR bands and Raman modes in the FT-IR and Raman spectra, respectively. The EDX results confirmed the successful synthesis of the samples according to the required stoichiometric ratio. UV-vis spectrometer was used to record the absorption spectra of the prepared samples in the wavelength range 200 – 1100 nm. The optical energy band gap of the samples were found in the range 1.21 – 3.39 eV. The M-H loops of the samples were measured at room temperature in the applied magnetic field range 0 – 60 KOe. A high saturation magnetization of 99.92 emu/g was recorded in the sample with x = 0 and with microwave operating frequency 22.2 GHz. This high value of saturation magnetization is due to the substitution of La3+ ions at spin-up (12k, 2a, and 2b) sites. The Ni substitution is proved to be a potential candidate to tune the optical and magnetic parameters of M-type hexaferrites. Therefore, the prepared samples are suggested for applications in magneto-optic applications.