Evolution of structural and magnetic properties of nickel oxide nanoparticles: Influence of annealing ambient and temperature

Abstract Nickel oxide (NiO) nanoparticles (NPs) are synthesized using the sol-gel method. The effect of annealing atmosphere type, including air, O 2 and annealing temperature ( T A ) on the structural, morphological and magnetic properties of NiO NPs was investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) analysis. For this purpose, NiO NPs are annealed at 400, 500, 600, 700 and 800 °C. The magnetic properties of the NPs change as a result of increasing crystallite size in terms of T A in both atmospheres. These variations are different according to the type of the annealing atmosphere. At lower temperatures ( T A 2 atmosphere have higher crystallinity, larger lattice constant, and lower magnetization and coercivity. At higher temperatures, the structural and magnetic properties of the samples in both atmospheres are more similar.