title: Covalent bonds in AlMnSi icosahedral quasicrystalline approximant
abstract: Electron density distributions were obtained using the maximum entropy method with synchrotron radiation powder data. In the metallic Al12Re, metallic bonding was observed for the icosahedral Al12 cluster with central Re atom. In the nonmetallic alpha-AlMnSi 1/1 approximant, covalent bonds were found in the electron density distribution of the Mackay icosahedral cluster without central atom. Rather than the Hume-Rothery mechanism, the covalency of Al (Si) icosahedron and that between Al (Si) and Mn atoms is considered to be the origin of the pseudogap and nonmetallic behavior of alpha-AlMnSi.
authors.affiliation: Department of Materials Science, the University of Tokyo, 113-8656, Japan.
authors.initials: K
authors.lastname: Kirihara
authors.initials: T
authors.lastname: Nakata
authors.initials: M
authors.lastname: Takata
authors.initials: Y
authors.lastname: Kubota
authors.initials: E
authors.lastname: Nishibori
authors.initials: K
authors.lastname: Kimura
authors.initials: M
authors.lastname: Sakata