Formation of polycrystalline BaTixOy compounds in barium implanted TiO2

Barium (Ba2+) ions of 280 and 30 keV energies were implanted at room temperature in TiO2 rutile single crystals with a total fluence of 1.2 × 1017ions cm−2 and subsequently thermally annealed up to 1150°C in O2 flow or in air during 1 h. Some samples were post-implanted with oxygen (O+) ions of 45 and 30 keV energies. The annealing effects in the implanted layer were investigated by Rutherford Backscattering Spectrometry in channeling geometry, X-ray diffraction at glancing incidence and Transmission Electron Microscopy. The thermal treatments performed at 1150°C lead to the formation of two new phases: (a) BaTi4O9 obtained after annealing in air, (b) BaTi4O9 and BaTi2O5 after annealing in O2 flow. The oxygen post-irradiation seems to modify mainly the epitaxial relation between the new phases and the matrix.