Tuning Plasma Properties for Controlled Ni Nanoparticle Synthesis through Pulsed Laser Ablation

This study methodically investigates the correlation between plasma parameters and the structural properties of Ni nanoparticles synthesized using pulsed laser ablation in liquid (PLAL) at varying laser energies (600 - 900 mJ). Optical emission spectroscopy (OES) revealed that increasing laser energy enhanced plasma ionization with electron temperature (Te) rising from 0.262 to 0.334 eV, and electron density (ne) increased from 5.00×1018 to 5.63×1018 cm⁻³ through intensified collisional excitation. Plasma parameters directly influenced the variation in crystallite size and morphology, demonstrating that higher plasma temperatures and densities enhance nanoparticle growth and crystallinity. The X-ray diffraction (XRD) analysis revealed the formation of both metallic Ni and NiO phases, with crystallite size increasing from 17.3 to 25.6 nm as energy increases. Field emission scanning electron microscopy (FE-SEM) showed that as the plasma energy increased, the size of the nanoparticles grew from 28.29 to 48.73 nm at 600 mJ and from 46.71 to 66.