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Title

Mg1 + xIr1 - x (x = 0, 0.037 and 0.054), a binary intermetallic compound with a new orthorhombic structure type determined from powder and single- crystal X-ray diffraction

Authors
Hlukhyy, Viktor
Pöttgen, Rainer
Published in Acta Crystallographica. B, Structural Science. 2004, vol. 60, no. 3, p. 272-281
Abstract The new binary compound Mg1 + xIr1 - x (x = 0-0.054) was prepared by melting the elements in the Mg:Ir ratio 2:3 in a sealed tantalum tube under an argon atmosphere in an induction furnace (single crystals) or by annealing coldpressed pellets of the starting composition Mg:Ir 1:1 in an autoclave under an argon atmosphere (powder sample). The structure was independently solved from high-resolution synchrotron powder and single-crystal X-ray data: Pearson symbol oC304, space group Cmca, lattice parameters from synchrotron powder data a = 18.46948 (6), b = 16.17450 (5), c = 16.82131 (5) A Ê . Mg1 + xIr1 - x is a topologically close-packed phase, containing 13 Ir and 12 Mg atoms in the asymmetric unit, and has a narrow homogeneity range. Nearly all the atoms have Frank-Kasper-related coordination polyhedra, with the exception of two Ir atoms, and this compound contains the shortest Ir-Ir distances ever observed. The solution of a rather complex crystal structure from powder diffraction, which was fully confirmed by the single-crystal method, shows the power of powder diffraction in combination with the high-resolution data and the global optimization method.
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CERNY, Radovan et al. Mg1 + xIr1 - x (x = 0, 0.037 and 0.054), a binary intermetallic compound with a new orthorhombic structure type determined from powder and single- crystal X-ray diffraction. In: Acta Crystallographica. B, Structural Science, 2004, vol. 60, n° 3, p. 272-281. https://archive-ouverte.unige.ch/unige:35518

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Deposited on : 2014-04-08

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