Berlin 2012 – wissenschaftliches Programm
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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.