Effect of annealing duration on the structural, optical and magnetic properties of NiO/NiFe₂O₄ nanocomposites

Abstract

The impact of annealing time on the structural, optical, and magnetic characteristics of NiO/NiFe2O4 nanocomposites (NCs) was examined after successful synthesis via a straightforward economical wet chemical method. X-ray diffraction (XRD) characterization reveals the presence of cubic NiO as the predominant phase along with the minor phase fraction of NiFe2O4. Slight growth in the crystallite size from 38.96 to 40.25 nm is noticed with the rise of annealing duration. The suppression of intensity of the 2M Raman mode of NiO matrix confirms the decreasing trend of antiferromagnetic (AFM) correlations with the elevation of annealing time. The band gap of the samples increased from 3.38 to 3.98 eV upon increasing the annealing duration. The samples showed strong emissions in the UV region along with other visible emissions. The CIE chromatographic image of the samples indicated the shift of colour emission from blue to the near green region with increasing annealing time. Magnetization data suggests the presence of weak ferromagnetic feature in the background of the AFM NiO matrix at 300 K. The remanent magnetization of the samples increased slightly from ∼0.23 to 0.27 emu g−1 with increasing annealing duration along with perseverance of exchange bias (EB) in all samples at room temperature.