Morphological impact of low-energy Xe+ irradiation on polycrystalline titanium targets

Abstract

Low energy (1-keV) Xe+ irradiation at different incidence angles (α) has been performed on pure polycrystalline Ti pellets at room temperature. The ion current was set between 110 and 200 μA cm−2 (ion flux ∼ 7-12 ×1014 ions cm−2 s−1). Changes of the surface morphology were characterized ex-situ with scanning electron microscopy and atomic force microscopy. Ion bombardment induces a significant surface roughening, with a complex morphology due to the polycrystalline nature of the targets. For α ≤ 60°, ripple nanostructures appear within a long-range roughening. The ripple domains present a short-range order, with no orientation coherence between different domains or with respect to the ion beam. For α = 70°, large pillar-like structures appear aligned with respect to the ion beam. Finally, at gracing incidence (α = 80°), a smooth surface emerges with shallow ripples oriented parallel to the ion beam. The observed features can be interpreted as the result from the interplay between transport and erosion mechanisms, which are modulated by the initial material microstructure (grain and crystal size). Finally, the surfaces become more hydrophobic after ion irradiation, which can be exploited for biomedical applications.