Abstract
•The NSF, NEF & CSF samples are prepared by citrate-gel autocombustion method.•X-ray diffraction patterns cubic spinel structure.•The FTIR spectra confirmed the cubic spinel structure by locating A and B-sites.•ZFC & FC curves revealed the superparamagnetic nature of nanoparticle.•CSF attributes the soft magnetic behaviour for soft magnets manufacturing industrial applications.
The Er/Sm-substituted nickel ferrite and Sm-substituted cobalt ferrite nanomaterials were synthesized via citrate-gel autocombustion technique. The diffraction pattern revealed the formation of cubic spinel structure. In addition, the structural parameters such as lattice constant (a), average crystallite size (D) and X-ray density (ρx) were also evaluated. The surface morphology was analyzed using field emission scanning electron microscope (FESEM) and transmission electron microscopes (TEM). Besides, the low temperature magnetic properties were studied using magnetization versus temperature (M−T) & magnetic field (M−H) curves. The obtained results attributed that the NiSm0.1Fe1.9O4 (NSF) and NiEr0.1Fe1.9O4 (NEF) samples exhibited the superparamagnetic property pertaining almost zero value of coercivity (Hc) and remanence (Mr) at 5 K & 300 K. Moreover, the superparamagnetic property was evidenced by zero-field cooled (ZFC) and field cooled (FC) curves. Interestingly, the CoSm0.1Fe1.9O4 (CSF) sample performed the soft magnetic behavior with increase of temperature from 5 to 300 K by possessing certain numerical values of Hc and Mr.