Influence of Chromium on Structural, Morphological, Dielectric and Magnetic Properties of M-Type Calcium–Barium Hexagonal Ferrites for Technological Applications

In this work, M-type hexagonal ferrite nanoparticles having the composition ${\mathrm{\text{Ca}}}_{0.25}{\mathrm{\text{Ba}}}_{0.75}{\mathrm{\text{Cr}}}_x{\mathrm{\text{Fe}}}_{12-2x}{\mathrm{\text{O}}}_{19}$, where $x=(0.0,0.05,0.10,0.15,0.20)$ were fabricated by the sol–gel auto-combustion technique. The influence of chromium doping on structural, dielectric and magnetic characteristics was examined. XRD powder analysis revealed the geometry of single-phase hexaferrite with P63/mmc space group. The magnetoplumbite hexagonal structure was revealed by the X-ray diffraction analysis. Crystallite size, $a$ & $c$ lattice parameters, bulk density, X-ray density, cell volume and porosity were assessed. Crystallite size ranged from 39.54nm to 42.91nm. The X-ray density and bulk density were enhanced while porosity was decreased with the substitution of ${\mathrm{\text{Cr}}}^{3+}$cation. The morphology of the fabricated materials was inspected by the SEM analysis, which displays uniformly scattered particles with hexagonal platelet shape. The value of the dielectric constant is high in the low-frequency regime, and it decreases with increasing frequency. The dielectric constant decreased appreciably with the increase of ${\mathrm{\text{Cr}}}^{3+}$. Such observed dielectric and magnetic features are useful for different technological applications like microwave absorbers, voltage-controlled, dielectric resonators and recording media.