Structural Elucidation, Morphological Properties, and Dielectric Properties of Nickel-Substituted Cobalt and Lead-Based X-Type Hexagonal Ferrites

In this work, sol-gel auto-combustion technique was employed to synthesize Pb₂Co_2-xNi_xFe₂₈O₄₆(x = 0.0, 0.4, 0.8, 1.2, 1.6, and 2) X-type hexagonal ferrites. Annealing of the samples was done at 1050 °C for 10 h. Formation of the X-type hexaferrites phase was confirmed by the XRD technique. Scanning electron microscopy was used to observe the morphology of the prepared samples. Crystallite size ranges from 15.40 to 10.10 nm. The unit cell volume was measured in the range of (2497.5-2514.1) \(\text{\AA}\). The cell volume and the lattice constants changed due to the difference in radii of the base and doping element. Distortion parameter (g) and dislocation density (δ) varied directly to site vacancies in the layers and the reordering of the lattice atoms during the transformation process. FTIR spectrum revealed the presence of particular absorption bands (metal-oxygen stretching vibration) which also confirmed the formation of hexagonal ferrites, and it was recorded in the range 600-4000 \({\mathrm{cm}}^{-1}\). Dielectric parameters exhibit frequency-dependent behavior. The dielectric constant (ɛ′), dielectric loss (ɛ″), and tan loss (tanδ) decreased abruptly at low frequency and then remained invariant up to 1.5 MHz. The higher values of the dielectric parameters recommend fabricated material a potential candidate for high-frequency applications. Dielectric constant and Q-value were found to increase with the increase in Ni content. All the samples revealed resonance peaks above 1.9 GHz which indicates the potential use of the material for EMI attenuation. The optimized dielectric nature of the prepared hexaferrites suggests the material to be useful in the manufacturing of multilayer chip inductors (MLCIs).