Surface tension of liquid tin-oxygen alloys and relationship with surface composition by Auger electron spectroscopy

Abstract The surface tension of liquid tin has been measured at 560 K by the sessile drop method, as a function of the oxygen surface content measured on the liquid surface by AES. The surface tension values range from 598 mN/m, for a clean surface, to 535 mN/m for a surface rich in oxygen. The surface tension isotherm consists roughly of two plateaux, with a transition at a oxygen-to-tin Auger peak height ratio close to 0.2. In the oxygen poor region some LEELS experiments have been performed on liquid tin in order to examine the chemical state of the liquid surface. For the oxygen rich region, a chemical shift of the tin Auger peak has been observed (− 3.4 eV). A simple model based on the existence of oxide islands is proposed, to explain the surface tension versus oxygen concentration behaviour. The model is consistent with the experimental results obtained in the regions poor or rich in oxygen, and describes the above-mentioned surface tension transition as due to the filling of the surface with SnO islands.