Chemistry, Ames Laboratory
Journal or Book Title
The phase regions around quasicrystals and approximants (QC/ACs) are rich pools for electron-poor intermetallics with novel, complex structures, and bonding patterns. The present SrAu4.30(1)In1.70(1) (1) and CaAg3.54(1)In1.88(1) (2) were synthesized through chemical tunings of the model CaAu4In2 (YCd6-Type) AC. Single crystal X-ray diffraction analyses reveals that crystal 1 has Pnma (CeCu6-type) symmetry, with a = 9.102(1) Å, b = 5.6379(9) Å, and c = 11.515(2) Å. The building block in 1 is a 19-vertex cluster Sr@Au9In4M6 (M = Au/In), which vividly mimics Ca@(Au,In)18 in Ca3Au12.4In6.1 (YCd6-type) in geometry. These clusters aggregate into one-dimensional columns extending along the b axis. Crystal 2 (P6/mmm, a = 20.660(3) Å, c = 9.410(2) Å) is closely related to Na26Cd141 (hP167) and Y13Pd40Sn31 (hP168), which are differentiated by the selective occupation of Wyckoff 1a (0 0 0) or 2d (1/3 2/3 1/2) sites by Cd or Pd. Crystal 2 adopts the Na26Cd141 structure, but the 1a site is split into two partially occupied sites. The synergistic disorder in the hexagonal tunnels along c is a major property. The valence electron count per atom (e/a) values for 1 and 2 are 1.63 and 1.74, respectively, the lowest among any other ternary phases in each system. These values are close to those of ACs in the Ca–Au–M (M = Ga, In) systems. Electronic structures for both are discussed in terms of the results of TB-LMTO-ASA calculations.
American Chemical Society
Lin, Qisheng and Corbett, John D., "Exploratory Syntheses and Structures of SrAu4.3In1.7 and CaAg3.5In1.9: Electron-Poor Intermetallics with Diversified Polyanionic Frameworks That Are Related to YCd6-Type Quasicrystal" (2011). Chemistry Publications. 972.