Microstructure of Co-doped TiO2(110) rutile by ion implantation

Co-doped rutile TiO2 was synthesized by injecting Co ions into single crystal rutile TiO2 using high energy ion implantation. Microstructures of the implanted specimens were studied in detail using high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray spectroscopy, electron diffraction, and HRTEM image simulations. The spatial distribution and conglomeration behavior of the implanted Co ions, as well as the point defect distributions induced by ion implantation, show strong dependences on implantation conditions. Uniform distribution of Co ions in the rutile TiO2 lattice was obtained by implanting at 1075 K with a Co ion fluence of 1.25x1016 Co/cm2. Implanting at 875 K leads to the formation of Co metal clusters. The precipitated Co metal clusters and surrounding TiO2 matrix exhibit the orientation relationships Co<110> parallel TiO2[001] and Co{111} parallel TiO2(110). A structural model representing the interface between Co metal clusters and TiO2 is developed based on HRTEM imaging and image simulations