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O: Fachverband Oberflächenphysik

O 43: Clean surfaces III

O 43.4: Vortrag

Mittwoch, 28. März 2012, 11:15–11:30, MA 043

Structure and polarity of step edges on (111) surfaces of fluorite type crystals — •Hans Hermann Pieper¹, Michael Reichling¹, and Clemens Barth² — ¹Universität Osnabrück, Germany — ²CINaM-CNRS, Marseille, France

The morphology and polarity of step edges found on CaF₂ and CeO₂ (111) is investigated by non-contact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM). The macroscopic shape of step edges strongly depends on sample preparation, however both materials exhibit type I and II facets at the nanoscale.

While type I steps are neutral, KPFM reveals a positive local charge at type II steps. Different models for the origin and the compensation of the charge are suggested. On CaF₂ the positive charge is compensated by subsurface fluorine ions on interstitial sites while for CeO₂ oxygen is released leaving behind Ce³⁺ sites located on step edges.