Microcosmic analysis on dielectric and magnetic properties of Fe(CrxFe2−x)O4 spinel ferrite ceramics via the value of x

A series of ferrite ceramics with the chemical formula Fe(Cr x Fe 2− x )O 4 ( x = 1.5, 1.6, 1.7, 1.8, 1.9) were synthesized using the solid-state reaction method. Rietveld refinement of the x-ray diffraction patterns confirmed the formation of a pure cubic spinel structure, with the lattice parameters decreasing as the Cr 3+ content ( x ) increased. Raman spectroscopy revealed the splitting of the A 1 g ${{{\mathrm{A}}}_{1{\mathrm{g}}}}$ vibrational mode into two distinct bands at 670 and 710 cm −1 that were attributed to the symmetric stretching vibrations of Fe 2+ –O and Fe 3+ –O bonds, respectively. This supports a mixed spinel-type cation distribution in which Cr 3+ and a fraction of Fe 2+ ions occupy octahedral sites, whereas Fe 3+ and the remaining Fe 2+ ions occupy tetrahedral sites. With increasing chromium content, the dielectric constant and loss tangent both decreased. Magnetic measurements showed a reduction in the remnant magnetization and coercivity. Furthermore, the samples demonstrate behavior that tends toward a superparamagnetic response. This study systematically established the relationship between the Cr/Fe ratio and the resulting structural, dielectric, and magnetic properties, underscoring the important role played by cation distribution in tuning the material properties of these ferrite ceramics.