Investigating samarium doping effects on the structural, morphological, optical and dielectric properties of zinc cobalt ferrites: A detailed insight

In this study, Samarium-substituted zinc cobalt ferrites [Zn_0.5Co_0.5Sm_xFe_2-xO₄, (0.0 ≤ x ≤ 0.2; step 0.02)] were prepared using the simple co-precipitation technique. XRD analysis with Rietveld refinement confirmed a single-phase spinel cubic structure, with lattice constants ranging from 8.39 to 8.43 Å and 8.385 to 8.420 Å, respectively. Crystallite sizes, determined via Scherrer's and Williamson-Hall methods, ranged between 29.16 - 34.09 nm and 35.2–52.6 nm, respectively. SEM results revealed spherical nanoparticles ranging from 0.28 to 0.38 μm, determined using ImageJ software. FTIR spectra showed metal oxide absorption peaks at 430 cm⁻¹ and 529 cm⁻¹, confirming the presence of a cubic spinel phase. UV–visible analysis indicated a decreasing energy band gap from 2.91 to 2.76 eV with increasing rare earth (RE) Sm³⁺ substitution. The dielectric constant has a maximum value at higher frequencies ranging from 0.5 to 3.2 GHz, while AC conductivity reached a maximum of 0.025 (Ω cm)⁻¹. The electric modulus increased steadily with frequency. Such improved properties make these materials potential candidates for high frequency devices, actuators and energy storage systems applications.