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Pronounced matrix effect in YbMo2Al4-type Ca(AuxZn2-x)Au-4 (x=0.09-0.89)

TitlePronounced matrix effect in YbMo2Al4-type Ca(AuxZn2-x)Au-4 (x=0.09-0.89)
Publication TypeJournal Article
Year of Publication2014
AuthorsMishra, T, Lin, QS, Corbett, JD
JournalJournal of Solid State Chemistry
Volume218
Pagination103-108
Date Published10
Type of ArticleArticle
ISBN Number0022-4596
Accession NumberWOS:000339987000016
Keywordsapproximants, au-ga system, ba, Bonding, ca, Ca-Au-Zn system, chemistry, Coloring, icosahedral quasi-crystal, Intermetallic compounds, Matrix effect, phases, sn, X-ray diffraction
Abstract

Electron-poor polar intermetallics Ca(AuxZn2-x)Au-4 have been synthesized through fusion of stoichiometric metals in sealed tantalum tubes at 800 degrees C and annealing at 400 degrees C for one week. Single crystal X-ray diffraction analyses reveal that this phase belongs to the YbMo2Al4-type structure (I4/mmm, Pearson symbol tI14), a approximate to 6.943-7.017 angstrom, c approximate to 5.278-5.286 angstrom, z = 2, with homogeneous composition range of x=0.09(1)-0.89(1). The structure exhibits a three-dimensional framework of (Au-8)(1/2) featuring square and octagonal channels extending in c, in which Ca and the infinite linear chains of [(Au,Zn)(2)](1/2) are located, respectively. Mulliken population analyses demonstrate that Zn prefers to form the linear chains in the whole homogeneous composition range, consistent with experimental observations. Crystal orbital Hamilton population (COHP) analyses reveal that the channel-to-chain Au-Zn contact has strong bonding interactions regardless of its large interatomic distance (similar to 2.85 angstrom), a signature of pronounced matrix effect. The last mentioned effect in YbMO2Al4-type structures is expected in case the linear chains are defined by small size atoms. Published by Elsevier Inc.

DOI10.1016/j.jssc.2014.06.019
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