Exploring the impact of nickel doping on the structure and low-temperature magnetic features of cobalt nano-spinel ferrite

Tailoring the magnetic features of cobalt ferrite nanoparticles (NPs) has been achieved via varying the doping percent of nickel. The nickel-substituted cobalt ferrite NPs Ni x Co 1-x Fe 2 O 4 (0 ≤ x ≤ 1.0) are constructed by the eco-friendly coprecipitation method. The formation of a nearly cubic single-phase spinel frame is assured by the analysis of XRD data. Moreover, the Rietveld analysis based on structure refinement is implemented in this study to precisely determine the microstructural parameters and estimate the cation distribution. A linear drop-in lattice constant with boosting the Ni 2+ ion percent is acclaimed, in regard to Vegard's law. The creation of nanoparticles that are nearly spherical along with polyhedron shape and have a diameter of (about 39–45 nm) has been affirmed by utilizing high-resolution transmission electron microscopy (HRTEM). Also, the crystalline essence of the formed nanoparticles has been declared by selective area electron diffraction (SAED). The magnetic properties have been collected from the hysteresis loops and FC–ZFC curves. These curves have been tweaked as a function of low-temperature from 5 K up to 300 K and in the existence of an external magnetic field (± 70KOe). The magnetization curves revealed that CoFe 2 O 4 (NPs) correspond to the hard ferrimagnetic material, whereas NiFe 2 O 4 (NPs) matched well with identical soft ferrimagnetic material. Also, the divergence betwixt the theoretical and experimental values of the magnetic moment is well explained by the model of "Random Canting of Spins, (RCS)". In addition, a remarkable reduction is found in the recorded values of magnetic parameters by increasing Ni 2+ content and decreasing the temperature towards 5 K. These findings imply the potential of Ni 2+ ions doping in enhancing the magnetic properties of cobalt ferrite for vast magnetic applications.