Control of the size of nanoparticles by spark discharge with an atomizer and a bubbler

Abstract

We propose a simple method to control the size of nanoparticle generated by spark discharge. Nanoparticle characteristics are of importance for numerous applications. Property control can lead to desired applications. The spark discharge method can generate nanoparticles of high purity with ease. A pin-to-plate type spark discharge-nanoparticle generator (SDG) solely created approximately 1.3×108 metal particles/cm3 of geometric mean diameter (GMD) of 20.4 nm. Instead of pure gas, ethanol vapor and droplets from an atomizer were introduced into the SDG. The GMD was increased to 40.0 nm similar to the size of particles generated from the atomizer. The differences in discharge voltage and frequency were too small to change nanoparticle characteristics. To investigate this phenomenon, a bubbler replaced the atomizer and various solvents were used such as ethanol, methanol, and water. The GMD was reduced to 14.6 nm when the methanol bubbler was used. Organic solvent decreased GMD with decreased number concentration, while water did not contribute to the change in particle size. This suggests that vapor from the bubbler suppresses homogeneous nucleation while droplets from the atomizer induce heterogeneous nucleation. This research can be applied to nanoparticle control techniques for production processes.Copyright © 2022 American Association for Aerosol Research