Composite surface structures formed by restructuring-type adsorption of alkali-metals on FCC metals

Recent studies of alkali-metal (AM) adsorption on fee metal surfaces, such as Cu, Ag, Au, Ni, Pd and Al, have revealed the formation of stable complex-structures involving considerable restructuring of substrate surface atoms, in contrast to adlayer formation which has been considered likely. In this review article, such structures, referred to as composite surface structures, are described in detail. In such adsorption, the restructuring occurs at room or slightly higher temperatures, whereas AM adlayers are formed at low temperatures. Recent advances in experimental techniques and theoretical calculations have made it possible to determine complicated composite surface structures. In restructuring-type adsorption, substrate surface atoms are replaced, migrated and rearranged to form ordered composite surface structures in collaboration with AM atoms. Thermal activation is required for the formation of the composite surface structures. We have classified the composite surface structures into nine groups based on the fcc low-index planes (001), (110) and (111). In each class a notation is used to identify and, we name each structural group. From the notation, AM coverages in the structural groups can be obtained. Structural parameters of each group are summarized in tables. Conditions and reasons for the formation of the composite surface structures are described. Similar composite surface structures are formed by deposition of metals other than AM in four groups, and their structures are compared with AM induced ones. Common features of the composite surface structures are summarized in the final section.