On the Oxygen Transport Mechanism in Titanium Thin Films under Irradiation by Molecular Water Ions

The behavior of oxygen atoms in (0.5 – 1.0) mm thick Ti films is investigated under high-flux, low-energy molecular water ion irradiation. The anomalously deep penetration of oxygen without formation of new compounds observable by XRD has been registered after 10 min of irradiation at room temperature using Auger Electron spectroscopy analysis. The mechanism driving oxygen atoms from the surface into the bulk is discussed. It is based on the results of experimental studies of surface topography and assumption that the surface energy increases under ion irradiation, and relaxation processes minimizing the surface energy initiate the atomic redistribution on the surface and in the bulk. Two processes minimizing the surface free energy are considered: (i) the mixing of atoms on the surface, and (ii) the annihilation of surface vacancies by the atoms transported from the bulk to the surface. DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3822