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Deuterium ordering in Laves-phase deuteride YFe2D4.2

Paul-Boncour, V.
Proffen, Th.
Published in Journal of solid state chemistry. 2009, vol. 182, no. 7, p. 1907-1912
Abstract The structure of Laves-phase deuteride YFe2D4.2 has been investigated by synchrotron and neutron (ToF) powder diffraction experiments between 60 and 370 K. Below 323 K, YFe2D4.2 crystallizes in a fully ordered, monoclinic structure (s.g. Pc, Z=8, a=5.50663(4), b=11.4823(1), c=9.42919(6) Å, β=122.3314(5)°, V=503.765(3) Å3 at 290 K) containing 4 yttrium, 8 iron and 18 deuterium atoms. Most D–D distances are, within the precision of the diffraction experiment, longer than 2.1 Å; the shortest ones are of 1.96 Å. Seven of eight iron atoms are coordinated by deuterium in a trigonal bipyramid, similar to that in TiFeD1.95−2. The eighth iron atom is coordinated by deuterium in a tetrahedral configuration. The coordination of iron by deuterium, and the iron-deuterium distances point to the importance of the directional bonding between iron and deuterium atoms. The lowering of crystal symmetry due to deuterium ordering occurs at much higher temperature than the magnetic ordering, and is therefore one of the parameters that are at the origin of the magnetic transition at lower temperatures.
Keywords Laves-phaseDeuterium orderingPowder diffraction
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Research group Groupe Cerny
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ROPKA, Joanna et al. Deuterium ordering in Laves-phase deuteride YFe2D4.2. In: Journal of solid state chemistry, 2009, vol. 182, n° 7, p. 1907-1912. doi: 10.1016/j.jssc.2009.04.033 https://archive-ouverte.unige.ch/unige:35434

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Deposited on : 2014-04-08

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