The structural evolution of graphene/Fe(110) systems upon annealing

The thermal stability and the structural evolution of graphene grown on Fe(110) has been studied upon annealing in ultra-high vacuum conditions (UHV, P <= 10(-9) mbar) and in the presence of gaseous ethylene at a pressure of similar to 10(-6) mbar by grazing incidence X-ray diffraction. It was observed that upon annealing at temperatures below 630 degrees C, graphene on Fe is thermally stable. Exposure to ethylene at these temperatures promotes the formation of graphene while inhibiting its deterioration. Annealing graphene/Fe(110) at temperatures above 630 degrees C results in a fast degradation of graphene followed by carburization of the sample, that is the irreversible formation of various iron carbides, with the most common phases being Fe3C (cementite) and Fe7C3 (Eckstrom-Adcock carbide). Annealing of the carburized sample does not result in the formation of a detectable graphitic structure.