title: Unraveling the atomic structure of ultrafine iron clusters.
abstract: Unraveling the atomic structures of ultrafine iron clusters is critical to understanding their size-dependent catalytic effects and electronic properties. Here, we describe the stable close-packed structure of ultrafine Fe clusters for the first time, thanks to the superior properties of graphene, including the monolayer thickness, chemical inertness, mechanical strength, electrical and thermal conductivity. These clusters prefer to take regular planar shapes with morphology changes by local atomic shuffling, as suggested by the early hypothesis of solid-solid transformation. Our observations differ from observations from earlier experimental study and theoretical model, such as icosahedron, decahedron or cuboctahedron. No interaction was observed between Fe atoms or clusters and pristine graphene. However, preferential carving, as observed by other research groups, can be realized only when Fe clusters are embedded in graphene. The techniques introduced here will be of use in investigations of other clusters or even single atoms or molecules.
authors.affiliation: Institute of Applied Mechanics, Zhejiang University, Hangzhou 310027, China.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Wang
authors.forename: Kun
authors.initials: K
authors.lastname: Li
authors.forename: Yingbang
authors.initials: Y
authors.lastname: Yao
authors.forename: Qingxiao
authors.initials: Q
authors.lastname: Wang
authors.forename: Yingchun
authors.initials: Y
authors.lastname: Cheng
authors.forename: Udo
authors.initials: U
authors.lastname: Schwingenschlögl
authors.forename: Xi Xiang
authors.initials: XX
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Yang