Superparamagnetic cobalt-substituted copper zinc ferrialuminate: synthesis, morphological, magnetic and dielectric properties investigation

The cobalt-substituted copper zinc ferrite (Cu 0.3 Zn 0.7− x Co x FeAlO 4 , CZC ferrite) was chemically synthesized by the sol−gel methodology. The phase identification, crystal structure change confirmation, morphology analysis, and magnetic evolution of samples have been studied. The X-ray diffraction and vibrating sample magnetometer (VSM) were used for structural and magnetic studies of the prepared CZC ferrite samples. The cation distribution carried out from X-ray analysis confirms the occupancy of Fe 3+ , Zn 2+ and Cu 2+ on tetrahedral sites and Fe 3+ , Cu 2+ , Al 3+ and Co 2+ on octahedral sites in the crystal lattice. The spherical-shaped nanoparticles of 22−32 nm were observed from TEM images, and the nanocrystallinity of particles was confirmed from HRTEM. Hysteresis curves of the CZC demonstrate modifications in coercivity, magnetization and magnetic remanence with Co 2+ ions doping in CZC systems. All the samples show soft magnetic behavior. For x = 0.3, lower values of H c and M r indicate super-paramagnetic nature. The dielectric behavior of CZC system was analyzed with frequency variation of real and imaginary portion of dielectric constant. The effects of multi-elementals like Cu, Zn, Co, and Al on ferrite are studied in this paper. The transition of ferrite from ferrimagnetic to superparamagnetic is observed in this study. Highlights The cobalt-substituted copper zinc ferrite was prepared by the sol−gel auto-combustion method. The cobalt-substituted copper zinc shows transition from ferrimagnetic to superparamagnetic. The coercivity and remanence approaches very low values, showing superparamagnetic nature of the sample.