Atomic structures of epitaxial overlayers of bcc Fe on fcc Rh surfaces

Abstract

Abstract Atomic structures of epitaxial overlayers of bcc Fe on fcc Rh(111), (001), and (102) planes have been directly observed in the field ion microscope with use of nanosecond pulsed-laser heating of the surface. The conditions of epitaxial growth of superlattice layers, both from a consideration of the surface energy and of the lattice mismatch are satisfied for this system. Thus, Fe adsorption layers are grown exitaxially on these Rh surfaces. An interesting observation is that in these overlayers, many vacancies and large voids can be observed, in great contrast to other overlayers we have also studied such as those of Rh and Mo on the Pt(111) surface where no voids have been observed. The reason for the formation of these vacancies and voids is probably because of its relatively large, 7.7%, mismatch of atom sizes of Fe and Rh.