The structure of the rutile TiO_2(110) surface and Ni/TiO_2 nanoislands

High resolution scanning tunnelling microscopy of TiO_2(110)-p(1 x 1) reveals alternate rows of O and Ti atoms, where the contrast is due to topographic and electronic effects, respectively. Annealing in vacuum promotes a surface reconstruction consisting of isolated, narrow, long, straight rows on top of the (1 x 1) surface, best described by an added Ti_2O_3 row model. A dense array of rows creates an inert (1 x 2) reconstruction, with straight [001] anti-phase boundaries (APBs) and meandering [1-bar10] APBs. Imaging these reconstructions is possible only at positive sample bias. Stronger heating causes crystallographic shear (CS). Straight half-height steps, > 500 A in length appear on the surface in the [11-bar1], [1-bar11], [1-bar12] and [11-bar2] directions, implying CS on #left brace#132#right brace# planes. Ni grows on TiO_2(110) in the Volmer-Weber mode between 295-495 K. At sub-monolayer coverage, equiaxed Ni nanoclusters form predominantly at down-steps. Imaging is dominated by topographic contrast and is possible for all sample biases. Equiaxed crystalline Ni clusters of 40-50 A diameter are seen at #approx# 1 ML. Some have a preferred epitaxy, and for > 2 ML Ni the orientation relation is identified as (110)_N_i parallel (110)_T_i_O_2, [1-bar10]_N_i [001]_T_i_O_2, which minimises the average mismatch. ''Hut''-shaped crystallites develop, elongated in the TiO_2 [001] direction with long #left brace#111#right brace# facets and short facets, possibly of #left brace#100#right brace#-type. Annealing causes the huts to grow in volume up to a maximum value after which a transition to a different stable shape may occur. Exposure to the atmosphere causes the Ni islands to oxidise. Subsequent heating in UHV regenerates the Ni clusters, but with a different epitaxial relation. (author)Available from British Library Document Supply Centre-DSC:D210162 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo