X-ray scattering study of the stoichiometric recovery of the α-Fe2O3(0 0 0 1) surface

The stoichiometric recovery and accompanying changes of subsurface atomic structure of Ar ion sputtered, oxygen deficient α-Fe2O3(0 0 0 1) are studied with X-ray scattering. Although oxygen annealing up to 735 °C results in a stoichiometric top surface layer manifested as a (1 × 1) surface structure, the X-ray scattering reveals the existence of a non-stoichiometric phase in the subsurface region. The non-stoichiometric region is characterized as a remnant of Fe3O4 or γ-Fe2O3. The stoichiometric outmost surface layers act as a barrier for propagation of oxidation to underneath remnant phase. The remnant phase can be removed after annealing at a higher temperature.