Cu doping induced modifications in the structural, magnetic and dielectric properties of CoFe₂O₄

Cobalt ferrites doped with Cu²⁺ ions, represented by the chemical formula Co_1−xCu_xFe₂O₄ (where x = 0.15, 0.30, 0.45, 0.60, 0.75, 0.90), are synthesized by using the sol–gel auto combustion technique. The XRD analysis indicates the establishment of a homogeneous spinel cubic phase. The average crystallite size was found in the range of 74 to 55 nm, which is a decrease due to the presence of Jahn–Teller distortion. The FESEM micrographs depict grains of nearly uniform size after the addition of Cu²⁺ ions. HRTEM micrographs show a highly crystalline structure. The outcomes derived from FTIR and Raman spectroscopy lead to additional support for the notion of a single-phase cubic arrangement. The analysis of Raman spectra demonstrated the presence of multiple vibrational modes within the specimen, thus elucidating the identification of six distinct Raman modes: 2A_2g, E_g, 3T_3g. etc. The BET analysis demonstrated a rise in the surface area from 14 m²/g to 367 m²/g. The nanocomposites demonstrated ferromagnetic characteristics, with saturation magnetization (Ms) values ranging from 73.55 to 25.44 emu/g.