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M. Setvin, M. Wagner, M. Schmid, G. Parkinson, U. Diebold:
"Surface point defects on bulk oxides: atomically-resolved scanning probe microscopy";
Chemical Society Reviews, 46 (2017), 1772 - 1784.

Metal oxides are abundant in nature and they are some of the most versatile materials for applications
ranging from catalysis to novel electronics. The physical and chemical properties of metal oxides are
dramatically influenced, and can be judiciously tailored, by defects. Small changes in stoichiometry
introduce so-called intrinsic defects, e.g., atomic vacancies and/or interstitials. This review gives an
overview of using Scanning Probe Microscopy (SPM), in particular Scanning Tunneling Microscopy (STM),
to study the changes in the local geometric and electronic structure related to these intrinsic point
defects at the surfaces of metal oxides. Three prototypical systems are discussed: titanium dioxide
(TiO2), iron oxides (Fe3O4), and, as an example for a post-transition-metal oxide, indium oxide (In2O3).
Each of these three materials prefers a different type of surface point defect: oxygen vacancies, cation
vacancies, and cation adatoms, respectively. The different modes of STM imaging and the promising
capabilities of non-contact Atomic Force Microscopy (nc-AFM) techniques are discussed, as well as the
capability of STM to manipulate single point defects.