Surface termination of hematite at environmental oxygen pressures: Experimental surface phase diagram

A. Barbier (1) , A. Stierle , N. Kasper , M.-J. Guittet , J. Jupille (2)

1 SPCSI - Service de Physique et de Chimie des Surfaces et Interfaces
2 INSP - Institut des Nanosciences de Paris

We provide an experimental surface phase diagram (surface termination versus chemical oxygen potential) of alpha-Fe2O3(0001) using a natural single crystal surface. In a partial reduction reoxidation cycle, we observe a sequence from oxygen-, to ferryl-, and again oxygen-terminated surfaces, in better agreement with recent density functional theory in the generalized gradient approximation calculations than with calculations taking into account on-site Fe 3d Coulomb repulsion. The nonreversible change in surface termination is accompanied by the formation of basal twins, which act as a sink for the extra Fe ions during the surface transformation processes.

Domaines: Matière Condensée [cond-mat]

A. Barbier, A. Stierle, N. Kasper, M.-J. Guittet, J. Jupille. Surface termination of hematite at environmental oxygen pressures: Experimental surface phase diagram. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2007, 75 (23), pp.233406. ⟨10.1103/PhysRevB.75.233406⟩. ⟨hal-01293288⟩