Apatite-forming ability of hydrothermally deposited rutile nano-structural arrays with exposed {101} facets on Ti foil

Highly ordered TiO2 nano-pillar arrays were deposited on the Ti foils by a hydrothermal method, using aqueous solutions of TiOSO4. The vertical nano-pillars with diameters in tens of nanometers strongly attached on the Ti foil and densely covered the whole surface. The structural studies clearly showed that the nano-pillars were pure tetragonal rutile TiO2 phase. [001] was the preferential growth direction. Based on the experimental results, a model for the in situ deposition of TiO2 with high-energy facet exposed is given. The growth mechanism was interpreted in terms of the lattice matching between the growing nano-structural titania and Ti, and the thermodynamic stability of the rutile lattice planes. The obtained TiO2 crystallographic plane with high energy induced apatite nucleation in less than 1 day and exhibited good in vitro bioactivity.