Microstructure of precipitated Au nanoclusters in TiO2

Gold nanoclusters dispersed in single crystal TiO2 (110) have been formed by 2MeV Au2+ implantation to anion fluence of 1 x 10(17) cm(-2) at 300 K and 975 K followed by annealing at 1275 K for 10 hours. The morphological features, size and crystallographic orientation of the An nanoclusters with respect to the TiO2 matrix have been investigated using conventional transmission electron microscopy and electron diffractions. In particular, the interface structure between the An nanoclusters and TiO2 was investigated. Atomic structural model of interface between An and TiO2 was established based on high-resolution transmission electron microscopy (HRTEM) imaging and HRTEM image simulations. Two types of orientation relationship can be identified, Au<110>//TiO2[001] and Au {111}//TiO2(200), and Au<110>//TiO2[001] and Au {111}//TiO2(110). Au clusters are faceted along Au {112} and Au {111} or Au {220} and Au {002} planes. The precipitated Au clusters show extensive (111) twins. These orientation relationships are the same for Au clusters grown on TiO2 (110) surface, indicating that lowering interfacial energy to be a governing factor for setting the orientation relationship.