The Effect of Annealing on Crystallite Size of Green Synthesized Nickel Oxide Nanoparticles Using Azadirachta Indica and Aegle Marmelos Leaves

The green synthesis method of nanoparticles is becoming increasingly popular worldwide due to its cost-effectiveness, promptness, and environmental friendliness. This work highlights the straightforward and time-efficient synthesis of nickel oxide nanoparticles (NiO NPs) utilizing leaf extracts from Azadirachta indica [AI] and Aegle marmelos [AM] leaves. Phytochemicals such as flavanoids and terpenoids found in A. Indica leaves, as well as phytochemicals like flavonoids, tannins, and coumarins in A. marmelos leaves, serve as capping and reducing agents to stabilize the nanoparticles. X-ray diffraction has been used to characterize the structure of the NiO NPs samples annealed at 400 °C and further annealed at 500, 600, and 800 °C temperatures. A comparative analysis of NiO nanoparticles prepared with these two distinct leaf extracts is performed in the present work. The impact of annealing temperature on phase, average crystallite size, and dislocation density of nanoparticles is also examined. The pure phase of NiO NPs is detected at an annealing temperature of 800 °C in both instances. The average crystallite sizes of 26.2 and 35.4 nm are obtained using leaf extract samples from A. Indica and A. marmelos, respectively. The A. Indica leaf extract is more effective for preparing NiO NPs than the A. marmelos leaf extract.