Electrical conduction mechanism of cobalt-modified MnFe2O4 ferrites nanoparticles

This study correlates the structural, electrical, and magnetic properties of Mn1-xCoₓFe₂O₄ (MCFO) (0 ≤ x ≤ 1) nanoparticles. The ferrites were synthesized via the hydrothermal method at 160 °C for 10 hours. Structural characterization was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). XRD and FTIR analysis confirmed the formation of a single-phase cubic spinel structure, and the mean crystallite size was 33 ±1 nm and 14 ±1 nm. To investigate the magnetic behavior, a comprehensive analysis at room temperature and 2.5 K, including SQUID magnetometry for zero-field-cooled/field-cooled (ZFC/FC) measurements and M(H) curves, as well as ferromagnetic resonance (FMR) analysis, was conducted. The electrical properties of the ferrites were studied using complex impedance spectroscopy (CIS), which was performed as a function of frequency at different temperatures. Complex impedance analysis allowed the separation of grain and grain-boundary resistances. The variations in grain and grain-boundary conductivities with increasing temperature support the material's semiconducting behavior. The results show that grain boundaries play a critical role in determining electrical behavior by influencing charge-carrier transport and polarization mechanisms. At high frequencies, grain boundaries facilitate charge accumulation at interfaces, thus enhancing electrical properties. Most importantly, the main finding is that the electrical properties of MCFO can be precisely tuned by controlling microstructural parameters, grain size, and porosity through the synthesis method. This tunability enables the optimization of dielectric properties and guides the selection of optimal compositions for advanced technological applications.