Impact of Cu-substitution on the dielectric properties and electronic structure of cobalt nanoferrites

This work studied the dielectric characteristics and electronic structure of cobalt nanoferrites with Cu substitutions. Here, Cu_xCo_1–xFe₂O₄ (0.0 ≤ x ≤ 1.0, in step x = 0.2) (CCFO) series was synthesized by utilizing the sol–gel self-combustion process. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and an impedance analyzer were used to analyze each sample. FTIR Spectroscopy has confirmed the existence of one absorption band due to Fe–O interaction. Further nitrate group, the bending vibrations of H–O–H and carbonyl group were identified at 1380–1418 cm⁻¹, 1533–1581 cm⁻¹, and 2312–2360 cm⁻¹. Several vibrational modes were found in the material, which revealed three different Raman modes: E_g, T_2g, and A_1g. The elemental chemical states of CCFO nanoparticles were investigated employing XPS and exhibited the Fe, Co, and Cu atoms valence states are Fe³⁺, Co²⁺, Cu²⁺, and Cu⁺. Adding Cu²⁺ ions to these ferrites increased the metal oxide bonds and decreased the relative oxygen vacancy. The dielectric behavior of the proposed series is evaluated with frequencies between 100 Hz and 1 MHz, and the findings are then described in terms of the dielectric constant. As the frequency increased, the dielectric constant dropped and at more significant frequencies, it became constant. The results of the dielectric properties revealed that interfacial polarization causes the typical Maxwell–Wagner type dielectric dispersion. The study indicates that these materials may be used to manufacture microwave antennas to decrease energy losses and other purposes. It shows that distinct copper concentrations in cobalt ferrite nanoparticles could successfully alter their electronic and dielectric properties.