Transition metal oxides play an important role in technological applications such as catalytic chemistry, gas sensing and metal-ceramic bonding. The structure on surfaces was directly responsible for variations in surface chemical reactivity. Consequently many oxide surfaces were the focus of scanning tunnelling microscopy investigations, especially TiO2 which was considered to be an ideal test case for transition metal oxides. The local geometric and electronic structures of TiO2 single crystals were characterized by scanning tunnelling microscopy and spatially resolved tunnelling spectroscopy in ultra-high vacuum. In addition to the (1 x 1) reconstruction, a new structure with (3 x 2) symmetry was examined. Atomically resolved scanning tunnelling microscopic images and low-energy electron diffraction revealed details that were used to develop geometrical models for the reconstructed surfaces. Scanning tunnelling spectroscopy data revealed, that for the (3 x 2) symmetry, scanning tunnelling microscopy appeared to have imaged Ti.

Atomic-Scale Structures of Ceramic Surfaces - Reconstructions of TiO2 (110). Wagner, M., Bonnell, D.A., Rühle, M.: Applied Physics A, 1998, 66[1], S1165-70