We present atomic-scale structures of reconstructed phases of oxygen-defici
ent TiO2(110) observed by non-contact atomic force microscopy. This techniq
ue provided atomic structure of the surface terminated with added Ti2O3 row
s including single oxygen atom vacancies. We successfully observed not only
half steps along [(1) over bar 12] caused by crystallographic shear planes
belonging to {132} family but also novel half steps along [001]. On the ba
sis of the idea that the half step formation has close relations with both
the CS formation and diffusion of segregated impurities, we propose a struc
tural model for half steps along [001]. (C) 2000 Elsevier Science B.V. All
rights reserved.