Determination of a (4 × 4) structure formed on a Cu(0 0 1) surface by adsorption of calcium

Hisashi Yoshida, Shougo Higashi, Tetsuroh Shirasawa, Seigi Mizuno, Hiroshi Tochihara, Xiangdong Liu, Fumio Komori

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    1 Citation (Scopus)


    The adsorption of calcium (Ca) atoms on a Cu(0 0 1) surface has been studied by low-energy electron diffraction (LEED) at 130, 300 and 400 K. It is found that a (4 × 4) was the only LEED pattern appeared at 400 K while a quasi-hexagonal structure was formed in a wide range of submonolayer coverage at 130 K. At 300 K, the (4 × 4) LEED spots were broad and weak. The (4 × 4) structure formed at 400 K was determined by a tensor LEED I-V analysis. It is a new-type of surface alloys consisting of five substitutional Ca atoms, nine surface Cu atoms, and two atomic vacancies in the unit cell. In spite of a quite large size-difference between Ca (3.94 Å) and Cu (2.55 Å) atoms, all Ca atoms are located at the substitutional sites. Among surface alloys so far reported, the atomic size ratio between Cu and Ca in the (4 × 4), 1.54, is the largest. Optimized structural parameters reveal that large lateral displacements of surface Cu atoms, being enabled by the appearance of the vacancies, allow the formation of the (4 × 4) structure.

    Original languageEnglish
    Pages (from-to)659-663
    Number of pages5
    JournalSurface Science
    Issue number4
    Publication statusPublished - Feb 15 2009

    All Science Journal Classification (ASJC) codes

    • Condensed Matter Physics
    • Surfaces and Interfaces
    • Surfaces, Coatings and Films
    • Materials Chemistry


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