Stoichiometry, Structure, and Electronic Properties of Fe_2O3 (Hematite) (0001)
Abstract
Despite the importance of metal oxides for several profitable industrial processes, good quality studies of surface geometries of these systems are scarce. Experiments are very complicated, and in theoretical studies substantial difficulties arise because the interesting metal oxides involve 3d transition metals as well as oxygen which implies significant charge transfer, a highly corrugated electron density, strong electrostatic fields, and even magnetism. In fact, good-quality super-cell calculations for such systems only became possible by recent improvements of the computational method (we use density-functional theory (DFT) and the FP-LAPW approach). The structure of Fe_2O3 (0001) can be described in terms of a stacking of layers: O_3-Fe-Fe-O_3-Fe-Fe- \cdots. Our theoretical results reveal several unexpected properties. For example, we find huge surface relaxations (55 %) and we predict unusual magnetic properties and the presence of two domains on the surface: one being O3 terminated, the other being Fe-O3 \cdots terminated. We show how the surface stoichiometry and structure depend on the O2 partial pressure of the environment. The DFT-GGA results are compared to STM measurements.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1998
- Bibcode:
- 1998APS..MAR.U1909W