On the Relationship Between Surface Reconstructions and Step Edge Stability on BaTiO3 (001)
The step orientations on four BaTiO3 (001) surfaces were quantified from Scanning Tunneling Microscopy images in order to determine the relationship between surface reconstructions and step stability. The (1x1), c(2x2), (√5x√5) R26.6°, and (√13x√13) R33.7° surface reconstructions are compared. A well-known procedure that renders non-polar and low energy surface energies is applied to consider model step face structures, taking into account for the first time the adatoms of the surface reconstruction. A comparison of the number of steps with two crystallographically equivalent step face structures but different reconstruction termination shows that the surface adatoms affect the stability of steps. Except for the (1x1) surface Ti adatoms influence the choice of crystallographic direction of the step edge in all the surfaces mentioned above. The observed step edge directions are in accordance with general energetic principles where the facets exposed are most favorable surface planes in the cubic system.