Revealing a Surface Alloying-to-Dealloying Transition of Bi on Ag(110)

Surface alloys of bismuth on noble-metal surfaces garnered great attention due to their unique properties. Despite the extensive research, the intricacies of the surface alloy formation process and structural evolution of Bi on (110) metal surfaces have yet to be fully explored. Here, employing scanning tunneling microscopy, we observed a surface alloying-to-dealloying transition during the growth of Bi on Ag(110). Initially, at a coverage of θ ≤ 0.5 ML, the deposited Bi atoms are embedded into the topmost layer of Ag(110), forming a c-(2 × 2) AgBi surface alloy that is similar to the Sb/Ag(110) system. With increasing coverage (θ ≥ 0.5 ML), the surface alloy undergoes partial dealloying and evolves into diatomic nanostripes. After reaching up to 0.75 ML, it undergoes complete dealloying and transforms into penta-atomic nanostripes. With further deposition of bismuth, a new stripe-chain structure emerges, characterized by one-dimensional atomic chains, which ultimately remains stable. Additionally, we propose possible atomic structural models for each phase, with the corresponding calculated coverages aligning well with experimental observations. This study is significant for enhancing the understanding of the characteristics of surface alloys.