Synthesis, structure, and bonding of Sc4MgxCu15-Ga-x similar to(7.5) (x=0, 0.5). Two incommensurately modulated scandium substitution derivatives of cubic Mg2Cu6Ga5
2008 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 47, no 3, 1020-1029 p.Article in journal (Refereed) Published
The substitution of scandium for magnesium in Mg2Cu6Ga5 (Mg2Zn11-type) yields an irrational superstructure phase that includes the refined compositions, Sc4Mg0.50(2)Cu14.50(2)Ga7.61(2) and Sc4Cu14.76(2)Ga7.51(2)- These crystallize in Cmmm, a = similar to 8.31 angstrom, b = similar to 21.72 angstrom, c = -8.30 angstrom. The structures feature Sc-2 dimers, Cu-6 octahedra, a 3D CuGa (Cu12Ga2) framework, and arachno gallium-centered Cu4Ga6 icosahedra that are condensed into zigzag chains. The arrangement of these building blocks exhibits a topologic relationship to Mg2Cu6Ga5. Further studies reveal that the quaternary compound exhibits incommensurate modulations along a, with q = (0.694, 0, 0). Structure refinements with superspace group Xmmm(a00)000 led to saw-tooth modulations for two fractional or mixed sites that avoid short Cu-Ga distances. Band structure analyses reveal that the Fermi surface and bonding are sensitive to the incommensurately modulated atoms.
Place, publisher, year, edition, pages
2008. Vol. 47, no 3, 1020-1029 p.
icosahedral quasi-crystal, approximants, mg2zn11, phases, route
IdentifiersURN: urn:nbn:se:su:diva-59145DOI: 10.1021/ic701853cISI: 000252714500034OAI: oai:DiVA.org:su-59145DiVA: diva2:426296
authorCount :32011-06-232011-06-212011-06-23Bibliographically approved