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 (3X2) 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 degrees 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}parallel to TiO2(110) and Cu[001]parallel to TiO2[1(1) over bar 0]. The orientation relationship differs from that resulting from room temperature deposition onto stoichiometric surfaces. (C) 1998 American Vacuum Society.