Deterioration of structural integrity and ferromagnetic transformation due to the emergence of traces of Alpha-hematite (α-Fe2O3) secondary phase in magnesia-enriched nickel ferrite spinel nanoparticles.

MgNi ferrite nanoparticles were prepared successfully via wet sol-gel route using the nitrates of proposed elements i.e. Mg, Ni and iron were used as precursors with citric acid as fuel. The prepared materials were annealed at a temperature of 900∘C to achieve the best properties. To know structural, morphological, elastic and magnetic properties, the synthesized nanoparticles were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscope (HRTEM), vibrating sample magnetometer (VSM), FTIR spectroscopy and Raman spectroscopy. The results of XRD, FTIR and Raman spectroscopy patterns are indicative of formation of ferrite nanoparticles and the structural studies confirm the inverse-spinel structure with crystallite size 35–61 nm. The formation of spinel ferrite structure is confirmed by absorption bands corresponds to vibration of tetrahedral site-A and by absorption bands corresponds to the octahedral site-B. Crystallite size calculations were carried out using WilliamFson-Hall plot. Rietveld refinement was applied to assure the crystal structure and allied parameters. The magnetic analysis of the prepared samples was carried out by VSM indicates that the nanoparticles exhibited superparamagnetic behavior having high magnetic saturation (M S) and negligible coercivity (H C). The elastic and magnetic properties through absorption bands found degraded at higher magnesium compositions. [Display omitted] • High-Magnesium MgNi ferrite nanoparticles posses elastic stability. • Traces of alpha hematite phase detected in high-magnesium composition. • Magnetic field strength increased. • MgNi ferrites exhibit ferromagnetic characteristics. [ABSTRACT FROM AUTHOR]