Influence of composition ratio on structural, optical and magnetic properties of NiFe<inf>2</inf>O<inf>4</inf>/(1−x)MnO−xCoO composites

Abstract

NiFe2O4 and NiFe2O4/[(1−x)MnO−xCoO] (x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) samples were produced utilizing co-precipitation procedure. The possibility of formed samples with a single phase or nanocomposite in NiFe2O4/[(1−x)MnO−xCoO] system was studied using search match program X’Pert HighScore Plus. The structural and microstructural parameters of each sample were obtained applying Rietveld analysis. The compositions and morphologies of the samples were explored using Energy-dispersive X-ray analysis, scanning electron microscope images and transmission electron microscope techniques. The linear and nonlinear optical characteristics of the samples with different composition (x) were investigated using UV–vis diffuse reflectance spectra. The optical bandgap value of NiFe2O4 (NFO) reduced regularly from 1.59 to 1.43 eV in the sample with x = 0.1 (single phase structure). In the samples with the composite structures, the optical band gap reduced irregularly attained its lowest value (1.13 eV) for the sample with x = 0.9. NFO showed superparamagnetic nature while other samples displayed good ferromagnetic characteristics. The saturation magnetization values for pure NFO and samples with x = 0.0, 0.5 and 1.0 are 38.1, 29.7, 26.81 and 22.34 emu/gm, respectively. The remanence (Mr) and magnetic squareness (Mr/Ms) values of NFO (3.47 emu/g, 0.09) were reduced to (0.55 emu/g, 0.02) upon doping with Mn ions only, while both enhanced to (7.13 emu/g, 0.27) when Co3O4 entered the matrix. The coercivity was decreased when NFO doped with Mn only, while it increased as Co3O4 existed in addition to the Mn ions.