A Study of Vacuum Arc Deposition Parameters and Their Effect on the Structural and Optical Properties of NiO Nanoparticles

NiO nanoparticles have been synthesized in a low-pressure arc discharge plasma at a gas mixture pressure in the chamber of 70 Pa, using argon as a plasma gas. The nanoparticles were deposited on a substrate at temperatures of 300, 400, 500, and 600 K. The deposition time was 30 min. X-ray diffraction characterization showed that the synthesized NiO nanoparticles were polycrystalline at all of the deposition temperatures. The nanoparticles ranged in size from 3.2 to 32.7 nm. We have studied the optical properties of the synthesized nanoparticles. The results demonstrate that their band gap decreases linearly with increasing nanoparticle size, ranging from 2.91 to 1.93 eV.