Study of Sm³⁺-doped Ni–Zn ferrites synthesized by solid-state reaction: Correlation between structural, magnetic, and dielectric properties

Ni0.6Zn0.4SmxFe2 −xO4 (NZSFO, x = 0.00–0.08) ceramics were prepared by solid-state reaction to correlate their structural, magnetic and dielectric properties. All samples crystallize in the cubic spinel structure and a few weak reflections remain unindexed; bulk density rises from 3.60 to 3.83 g/cm 3 and porosity falls from 34.2% to 32.8%. Saturation magnetization increases fourfold, from 9.14 to 37.26 emu/g, at x = 0.06 and drops to 13.0 emu/g at x = 0.08; the initial permeability is also highest at x = 0.06. The dielectric constant at 1 kHz decreases from 63 (x = 0.00) to 41 (x = 0.06), and tanδE at 1 MHz decreases from 0.065 to 0.043 (0.036 at x = 0.08), following Maxwell–Wagner interfacial polarization. The magnetization gain is attributed to reduced Yafet–Kittel spin canting, and the lower loss to reduced Fe 2+ /Fe 3+ hopping, more resistive grain boundaries, and densification. The x = 0.06 composition offers the best magnetic response combined with low dielectric loss.