Effects of Sulfur Adsorption on Surface Tension of Liquid Copper

We investigated the effects of temperature and sulfur adsorption on the surface tension of liquid copper using the oscillating droplet method in combination with electromagnetic levitation. At low temperatures, the surface tension of liquid copper decreased with increasing sulfur activity due to sulfur adsorption. However, at high temperatures, the surface tension approached that of pure state value of liquid copper regardless of the sulfur activity owing to the exothermic nature of sulfur adsorption. This led to an initial increase followed by a decrease in the surface tension with increasing temperature. We successfully described the surface tension of liquid copper as a function of temperature and sulfur activity using the Szyszkowski equation. Additionally, we estimated the enthalpy and entropy changes associated with sulfur adsorption on liquid copper.