FORMATION OF TIB2 COATINGS AT ROOM-TEMPERATURE BY DYNAMIC ION MIXING

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