Preparation of palladium nanoparticles and a grain-size determining equation of pulsed wire discharge in N<inf>2</inf>, Ar, and He ambient gasses

Pulsed wire discharge (PWD) is one of the many nanoparticle preparation methods known for its high efficiency and high production rate. Particle size is controlled by gas pressure and input energy. However, the effect of ambient gas species on particle size is not well known. In this study, single-phase palladium (Pd) nanoparticles were prepared in N2, Ar, and He ambient gasses by PWD. The mean diameter of the prepared particles in Ar was smaller than those of the other nanoparticles because of the low ionization energy required to form an alternate current path and the partial wire evaporation. A novel equation for estimating the average grain size was proposed. By comparing the estimated and measured mean diameters, the validity of the equation was shown.