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- Title
Ternary aurides RE<sub>4</sub>Mg<sub>3</sub>Au<sub>10</sub> (RE=Y, Nd, Sm, Gd–Dy) and their silver analogues.
- Authors
Block, Theresa; Johnscher, Michael; Linsinger, Stefan; Ch. Rodewald, Ute; Pöttgen, Rainer
- Abstract
The ternary aurides RE4Mg3Au10 (RE=Y, Nd, Sm, Gd–Dy) and their silver analogues were synthesized by induction melting of the elements in sealed niobium tubes. These intermetallic phases were characterized by powder X-ray diffraction. They crystallize with the Ca4In3Au10-type structure, which, from a geometrical point of view, is a ternary ordered version of Zr7Ni10 with the rare earth and magnesium atoms ordering on the four crystallographically independent zirconium sites. The structures of crystals from three differently prepared gadolinium samples were refined from single-crystal X-ray diffractometer data: Cmca, a=1366.69(3), b=998.07(4), c=1005.54(3) pm, wR2=0.0332, 1234 F2 values, 46 variables for Gd4.43Mg2.57Au10, a=1378.7(1), b=1005.3(1), c=1011.2(1) pm, wR2=0.0409, 1255 F2 values, 48 variables for Gd5.50Mg1.50Au10, and a=1350.2(5), b=995.5(1), c=1009.3(1) pm, wR2=0.0478, 1075 F2 values, 48 variables for Gd5.61Mg1.39Au10. All crystals show substantial Mg/Gd mixing on two sites. The gold atoms form a pronounced two-dimensional substructure with Au–Au distances of 278 to 297 pm in Gd4.43Mg2.57Au10. These gold blocks are condensed via magnesium atoms (278–315 pm Mg–Au). The gadolinium atoms fill larger cavities within the three-dimensional networks. The magnesium vs. gadolinium site preference is a consequence of the different coordination numbers of the cation sites. All phases show homogeneity ranges RE4+xMg3–xAg10 and RE4+xMg3–xAu10. The influence of the synthesis conditions is briefly discussed.
- Subjects
MELTING; NIOBIUM; X-ray diffraction; MAGNESIUM; ZIRCONIUM
- Publication
Zeitschrift für Naturforschung B: A Journal of Chemical Sciences, 2015, Vol 70, Issue 2, p135
- ISSN
0932-0776
- Publication type
Article
- DOI
10.1515/znb-2014-0225