A study of preparing silver iodide nanocolloid by electrical spark discharge method and its properties

This study employed an electric discharge machine (EDM) and the Electrical Spark Discharge Method (ESDM) to prepare silver iodide nanocolloid (AgINC). Povidone–iodine (PVP-I) was dissolved in deionized water to create a dielectric fluid. Silver material was melted using the high temperature generated by an electric arc, and the peeled-off material was reacted with PVP-I to form AgI nanoparticles (AgINPs). Six discharge pulse wave parameter combinations (Ton–Toff) were employed, and the resultant particle size and suspension of the prepared samples were examined. The results revealed that AgINPs were successfully created using the ESDM. When Ton–Toff was set at 90–90 μs, the zeta potential of the AgINC was − 50.3 mV, indicating excellent suspension stability. The AgINC particle size was 16 nm, verifying that the parameters yielded AgINPs with the smallest particle size distribution and highest zeta potential. Ultraviolet–visible spectrum analyser was performed to analyse the samples, and the spectra indicated that the characteristic wavelength was 420 nm regardless of the Ton–Toff values. X-ray diffraction analysis determined that the AgINPs exhibited two crystal structures, namely β-AgI and Ag. Transmission electron microscopy was performed and revealed that the particles were irregularly shaped and that some of the larger particles had aggregated. The crystal structure was determined to be a mixture of Ag and β-AgI, with a lattice spacing of 0.235 nm and 0.229 nm, respectively. The lattice spacing of the Ag was 0.235 nm. X-ray diffraction analysis indicated that the prepared AgINC were composed of only Ag and I; no additional chemical elements were detected.