The composition and structure of oxide films grown on the (110) crystal face of iron

Epitaxial oxide layers of Fe₃O₄‐like composition and symmetry have grown on Fe(110) crystals exposed to oxygen gas. The epitaxial relationship between the oxide and the Fe(110) substrate is elucidated and the orientation of the oxide film has been explained in terms of the close registry between the Fe(110) and Fe₃O₄(111) crystal lattices. Both the structure and composition of the iron oxide epitaxies are a function of substrate temperature and oxygen pressure, and oxide formation has been observed over only part of the temperature–pressure range investigated. While oxide surfaces with Fe₂O₃‐like composition have been observed, they are disordered and are only approximately one monolayer in thickness.