Journal of Physics and Chemistry of Solids, cilt.193, 2024 (SCI-Expanded)
In this study, it was aimed to obtain copper-substituted nickel ferrite nanoparticles, which are advantageous for use in energy storage devices such as batteries and supercapacitors that provide high energy storage capability with their high dielectric behavior, by co-precipitation method. Nickel ferrite nanoparticles in the form of CuxNi1-xFe2O4 containing copper substitution at ratios for x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 were synthesized. X-ray diffraction Method (XRD) was used to analyze the spinel structure, the purity phase, and the crystalline size of the nanoparticles. Field Emission Scanning Electron Microscopy (FE-SEM), and Fourier Transform Infrared (FTIR) Spectroscopy were also performed to investigate the particle size, morphological distribution, and the functional groups of the samples. The structural analyses confirmed the successfully produced single-phase pure cubic spinel nickel ferrite and copper-substituted nickel ferrites with nanometer-scale particle distribution. The Impedance Spectroscopy technique was used for the characterization of the dielectric properties of the samples. Frequency-dependent complex dielectric, impedance, modulus, and alternating current (AC) conductivity mechanisms of the copper-doped nickel ferrite nanoparticles (CuxNi1-xFe2O4) were determined. The results showed that copper-induced nickel ferrite nanoparticles display a promising dielectric material consisting of grains and grain boundaries which are confirmed by Maxwell-Wagner interface-type polarization, which is in agreement with Koop's theory. Furthermore, a remarkable enhancement is obtained on the dielectric parameters of copper-induced nickel ferrites for x = 0.2, and it is seen that this is a critical value on the doping ratio. In addition, the dielectric parameters decreased between x = 0.2–0.8 ratios but still showed higher values than pure nickel ferrites, confirming that nickel ferrites have a tunable dielectric behavior depending on the stoichiometric copper doping ratios. Therefore, this may make them a promising dielectric medium for further studies in various electronic device applications.