Chemistry, Ames Laboratory
Journal or Book Title
Exploratory syntheses in the M−Au−Ge (M = Ca, Yb) systems have led to the discovery of two cleanly separated non-stoichiometric phases M3Au∼14.4Ge∼4.6 (I) and M3.25Au∼12.7Ge∼5.3 (II). Single crystal X-ray studies reveal that both (space group Im3̅) feature body-centered-cubic packing of five-shell multiply endohedral clusters that resemble those in the parent YCd6 (= Y3Cd18) and are akin to approximate phases in other quasicrystal systems. However, differences resulting from various disorders in these are distinctive. The innermost cluster in the M3Au∼14.4Ge∼4.6 phase (I) remains a disordered tetrahedron, as in the YCd6 parent. In contrast, its counterpart in the electron-richer M3.25Au∼12.7Ge∼5.3 phase (II) is a “rattling” M atom. The structural differentiations between I and II exhibit strong correlations between lattice parameters, cluster sizes, particular site occupancies, and valence electron counts.
American Chemical Society
Lin, Qisheng and Corbett, John D., "M3(Au,Ge)19 and M3.25(Au,Ge)18 (M = Ca, Yb): Distinctive Phase Separations Driven by Configurational Disorder in Cubic YCd6-type Derivatives" (2010). Chemistry Publications. 969.