Structure of a (0001) Surface of an Ilmenite (FeTiO3) Single Crystal Following Argon ion Sputtering and Annealing in Oxygen Partial Pressures

R. A. Fellows Department of Earth Sciences, Manchester University, Manchester M13 9PL, UK

robert.fellows@man.ac.uk

A. R. Lennie Department of Earth Sciences, Manchester University, Manchester M13 9PL, UK

D. J. Vaughan Department of Earth Sciences, Manchester University, Manchester M13 9PL, UK

G. Thornton Department of Chemistry, Manchester University, Manchester M13 9PL, UK, and Interdisciplinary Research Centre in Surface Science, University of Liverpool, Liverpool L69 3BX, UK

The structure and composition of a (0001) surface of an ilmenite (FeTiO3) single crystal has been studied using low energy electron diffraction (LEED) and Auger electron microscopy (AES), in preparation for scanning tunneling microscopy (STM) studies. Following cycles of argon ion bombardment and annealing at 1127K (850°C) under ultra high vacuum (UHV)
conditions, examination of the (0001) basal plane using LEED showed a trigonal pattern consistent with that expected for a bulk termination of ilmenite. Similar results were also observed following annealing at 1127K (850°C) in oxygen partial pressures of either 1.0 x 10-7, 1.0 x 10-6 or 1.0 x 10-5 mbars. Auger electron spectra showed the presence of Fe, Ti and O. Surface structure models for the (0001) plane of ilmenite, consistent with the LEED data, will be presented. Following similar conditions of preparation, the (0001) surface of isostructural hematite (Fe2O3) shows reduction to a (111) magnetite (Fe3O4) termination.

These observations of surface behaviour in the Fe-Ti-O system are consistent with bulk properties of these phases in magmatic systems.