Effect of lanthanum (La) substitution on the magnetic and electrical properties of nickel ferrites: an investigation of its doping concentrations

The structural, morphological, magnetic, and dielectric properties of lanthanum substituted nickel ferrite (NiLa x Fe2−x O4) nanoparticles have been reported in this article. The amount of lanthanum substitution in NiLa x Fe2−x O4 sample was varied from x = 0.025 to 0.125. The nanocrystalline Ni–La ferrites were synthesized using a solution combustion reaction (SCR) method. The orthorhombic crystal system of space group Pnma (62) is shown as the single-phase in all samples through structural investigation utilizing an X-ray diffraction (XRD) pattern. The observed trend indicates a positive correlation between the concentration of La and the corresponding rise in the predicted crystallite size values, which range from 60.5 nm to 65.2 nm. The nanoscale of the surface morphology has been confirmed by the utilisation of field emission scanning electron microscopy (FESEM). Energy dispersive X-ray (EDAX) mapping provides the compositional evidence for the prepared Ni–La ferrites. In addition, X-ray photoelectron spectroscopy (XPS) determines the ionic state of the individual atoms present in these samples. It reveals that there are no changes in the ionic state of the parent component atoms by substituting La. EDAX and XPS evidence the purity of prepared NiLa x Fe2−x O4 samples without any other impurity elements. By regulating the composition of dopants, this research can substantiate the superparamagnetic characteristics of ferrites. The paramagnetic nature of lanthanum atoms involves in reducing the coercivity value. The dielectric measurement on NiLa x Fe2−x O4 samples reveals that La3+ substitution effectively influence the electro-transport properties.