Nonstoichiometry on $TiO2$(110) and $Cu–TiO2$ interfaces

A number of reconstructions have been observed on the (110) surface of $TiO2$ in the rutile modification that accommodates oxygen deficiency. We present atomically resolved scanning tunneling microscope images that describe a new reconstruction with $(3×2)$ symmetry. A model for the observed reconstruction is discussed where this symmetry is achieved by removing $1/3$ or $2/3$ of the oxygen in the bridging oxygen rows such that a shift in position of missing oxygen by one lattice space vector along the [001] direction occurs in every second row. This structure contrasts those reported previously in which entire rows are modified or removed. Furthermore, nanometer-sized Cu islands on $TiO2$(110) surfaces fabricated by vapor deposition onto $TiO2$ at 200 °C were studied by conventional and high-resolution transmission electron microscopy (TEM). Our TEM studies show that Cu forms faceted islands (40 nm in width) on the surface with the orientation relationship given by $Cu{110}∥TiO2(110)$ and $Cu〈001〉∥TiO2[11̄0].$ The orientation relationship differs from that resulting from room temperature deposition onto stoichiometric surfaces.