Structural and Magnetic Characterization of Nickel Nanoparticles Synthesized through Chemical Routes

This study presents the magnetic properties of clusters of ultrafine nickel nanoparticles synthesized through an aqueous chemical reduction technique. The morphology and microstructure of the synthesized nanostructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The XRD results indicate that the nickel nanoparticles exhibit a polycrystalline face-centered cubic (FCC) structure with a particle size of 16 nm. The magnetic properties were investigated using a vibrating sample magnetometer (VSM) at different temperatures (80 K, 150 K, 300 K, and 400 K). The hysteresis loop confirms the ferromagnetic behaviour of the nickel nanoparticles. Samples grown under specific conditions exhibit a systematic change in saturation magnetization (Ms) and coercive field (H_C) with increasing temperature. The variation in saturation magnetization may be attributed to a decrease in particle size with temperature, resulting in an increased area-to-volume ratio.

The coercivity of the prepared nanoparticles demonstrates an increasing trend with decreasing temperature. Micromagnetic simulations using mumax3 were performed to explore the temperature dependency of nickel nanoparticles, and the results validate that coercivity decreases with an increase in temperature.