Gold Network Structures in Rhombohedral and Monoclinic Sr2Au6(Au,T)3 (T= Zn, Ga). A Transition via Relaxation
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Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.
For more than 70 years, the Ames National Laboratory has successfully partnered with Iowa State University, and is unique among the 17 DOE laboratories in that it is physically located on the campus of a major research university. Many of the scientists and administrators at the Laboratory also hold faculty positions at the University and the Laboratory has access to both undergraduate and graduate student talent.
The Department of Chemistry seeks to provide students with a foundation in the fundamentals and application of chemical theories and processes of the lab. Thus prepared they me pursue careers as teachers, industry supervisors, or research chemists in a variety of domains (governmental, academic, etc).
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The Department of Chemistry was founded in 1880.
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1880-present
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- College of Liberal Arts and Sciences (parent college)
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Abstract
Quantitative syntheses, structure determinations and interpretations, and band calculations are reported for the nonstoichiometric rhombohedral (R3̅c) and monoclinic (C2/c) Sr2Au6(Au3–xTx) (T = Zn, Ga) compounds. Several different compositions of the two Sr phases were similarly refined from single crystal X-ray diffraction data as R3̅c: a ≈ 8.43 Å, c ≈ 21.85 Å, Z = 6 and C2/c: a ≈ 14.70 Å, b ≈ 8.47 Å, c ≈ 8.70 Å, β ≈ 123.2°, Z = 4. The R3̅c Zn phase is stable in the composition region x ∼ 2.5–2.9 whereas its C2/c neighbor is the major product at x ∼ 2.2–2.3. Gallium versions of both were also identified. Both R3̅c and C2/c structural types contain hexagonal-diamond-like gold superlattices stuffed with strings of interstitial Sr and disordered triangular (Au,T)3 units. The latter space group is a maximal, nonisomorphic subgroup of the former, and the decrease in interstitial radius from Ba to Sr (∼0.08 Å experimentally) evidently drives the symmetry reduction, relaxation, and small distortions, principally around the Sr sites. Au–Au bonding among the Au hexagons in the host lattices and with gold components in the triangular interstitials is dominant and reflected in their tight packing and short interatomic separations.
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This is an article from Inorganic Chemistry 52 (2013): 13623, doi: 10.1021/ic402145k. Posted with permission.