Syntheses and Structure of Gd3Rh1.940(7)In4 |
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Authors: | Ute Ch Rodewald Mar’yana Lukachuk Rolf-Dieter Hoffmann and Rainer P?ttgen |
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Institution: | (1) Institut f?r Anorganische und Analytische Chemie, Westf?lische Wilhelms-Universit?t M?nster, Corrensstrasse 30, 48149 M?nster, Germany; |
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Abstract: | The gadolinium–rhodium–indide Gd3Rh1.940(7)In4 was prepared by arc-melting of the elements and subsequent annealing in a corundum crucible in a sealed silica tube. Gd3Rh1.940(7)In4 adopts the hexagonal Lu3Co1.87In4 type, space group
P`6]P{\bar 6}
, a = 781.4(5), c = 383.8(3) pm, wR2 = 0.0285, BASF = 0.375(1) (merohedric twinning via a twofold axis (xx0)), 648 F2 values, 22 variables. The structure is derived from the well known ZrNiAl type through an ordering of rhodium and indium
atoms on the Ni2 sites. The Rh/In ordering forces a reduction of the space group symmetry from
P`6]62mP{\bar 6}62m
to
P`6]P{\bar 6}
, leading to merohedric twinning for the investigated crystal. The Rh1 site has an occupancy of only 94.0(7)%. The investigated
crystal had a composition Gd3Rh1.940(7)In4. The main geometrical motif are three types of centered, tricapped trigonal prisms, i.e., Rh1In26Gd3], Rh2Gd6In23], and In1Gd6In23]. The shortest interatomic distances occur for Rh–In (276–296 pm) followed by In–In (297 pm). Together, the rhodium and indium
atoms build up a three-dimensional Rh1.940(7)In4] network, in which the gadolinium atoms fill slightly distorted pentagonal channels. The crystal chemistry of Gd3Rh1.940(7)In4 is discussed on the basis of a group-subgroup scheme. |
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