title: Structurally complex cobalt intermetallics grown from liquid aluminum: Co19Al45Si(10-x) (x = 0.13) and Co5Al14Si2.
abstract: The cobalt aluminum silicides Co19Al45Si(10-x) (x = 0.13) and Co5Al14Si2 were synthesized in liquid aluminum and characterized by single-crystal X-ray diffraction. Co19Al45Si(10-x) (x = 0.13) crystallizes in the monoclinic space group C2/c with lattice parameters a = 19.991(2) A, b = 19.143(2) A, c = 12.8137(15) A, beta = 123.583(2) degrees. Co5Al14Si2 adopts the orthorhombic space group Pnma with cell parameters a = 13.8948(19) A, b = 23.039(3) A, c = 7.3397(10) A. Both structures are exceptionally complex with the Co2Si2 rhombus being a common building motif. The coordination environments of cobalt atoms resemble those of the transition metals in typical quasi-crystal approximants. Co5Al14Si2 shows oxidation resistance in air up to 1000 degrees C by forming a dense-packed Al2O3 layer on the surface of the crystal.
authors.affiliation: Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Xiuni
authors.initials: X
authors.lastname: Wu
authors.forename: Susan
authors.initials: S
authors.lastname: Latturner
authors.forename: Mercouri G
authors.initials: MG
authors.lastname: Kanatzidis