Formation of TiB2 coatings at room temperature by dynamic ion mixing

We have deposited crystalline TiB2 coatings of stoichiometric composition at room temperature by dynamic ion mixing (DIM). The film deposition was obtained by ion beam sputtering of a composite TiB2 +B target using an intense Ar+ ion beam with energy 1.2 keV and the growing films were continuously bombarded with 320 keV Xe2+ ions. The chemical composition analysis was carried out by means of both Rutherford backscattering spectroscopy (RBS) and X-ray photoelectron spectroscopy (XPS). Complementary information on the microstructural state was deduced from transmission electron microscopy (TEM) observations on cross-sectional samples and by X-ray photoelectron spectroscopy (XPS). Results using both techniques are in complete agreement, indicating that the internal structure of the films corresponds to the hexagonal TiB2 phase. The XPS analysis shows that an important amount of oxygen is present in the very first surface layers, but after sputter cleaning only TiB2 was detected. Radiation-induced crystallization and grain growth appear correlated with the displacement damage produced by the high-energy heavy ion bombardment.