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Werwein A, Maaß F, Dorsch LY, Janka O, Pöttgen R, Hansen TC, Kimpton J, Kohlmann H. Hydrogenation Properties of Laves Phases LnMg 2 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb). Inorg Chem 2017; 56:15006-15014. [PMID: 29166003 DOI: 10.1021/acs.inorgchem.7b02319] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The hydrogenation properties of Laves phases LnMg2 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb) were investigated by thermal analysis, X-ray, synchrotron, and neutron powder diffraction. At 14.0 MPa hydrogen gas pressure and 393 K, PrMg2 and NdMg2 take up hydrogen and form the colorless, ternary hydrides PrMg2H7 (P41212, a = 632.386(6) pm, c = 945.722(11) pm) and NdMg2H7 (P41212, a = 630.354(9) pm, c = 943.018(16) pm). The crystal structures were refined by the Rietveld method from neutron powder diffraction data on the deuterides (PrMg2D7, P41212, a = 630.56(2) pm, c = 943.27(3) pm; NdMg2D7, P41212, a = 628.15(2) pm, c = 940.32(3) pm) and shown to be isotypic to LaMg2D7. The LaMg2D7 type of hydrides decompose at 695 K (La), 684 K (Ce), 684 K (Pr), 672 K (Nd), and 639 K (Sm) to lanthanide hydrides and magnesium. The Laves phase EuMg2 forms a hydride EuMg2Hx of black color. Its crystal structure (P212121, a = 664.887(4) pm, b = 1136.993(7) pm, c = 1069.887(7) pm) is closely related to the hexagonal Laves phase (MgZn2 type) of the hydrogen-free parent intermetallic. GdMg2 and TbMg2 form hydrides GdMg2Hx with orthorhombic unit cells (a = 1282.7(4) pm, b = 572.5(2) pm, c = 881.7(2) pm) and TbMg2Hx (a = 617.8(3) pm, b = 1045.8(8) pm, c = 997.1(5) pm), presumably also with a distorted MgZn2 type of structure. CeMg2H7 and NdMg2H7 are paramagnetic with effective magnetic moments of 2.49(1) μB and 3.62(1) μB, respectively, in good agreement with the calculated magnetic moments of the free trivalent rare-earth cations (μcalc(Ce3+) = 2.54 μB; μcalc(Nd3+) = 3.62 μB).
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Affiliation(s)
- Anton Werwein
- Department of Inorganic Chemistry, Leipzig University , Johannisallee 29, 04103 Leipzig, Germany
| | - Florian Maaß
- Department of Inorganic Chemistry, Leipzig University , Johannisallee 29, 04103 Leipzig, Germany
| | - Leonhard Y Dorsch
- Department of Inorganic Chemistry, Leipzig University , Johannisallee 29, 04103 Leipzig, Germany
| | - Oliver Janka
- Institut für Anorganische und Analytische Chemie, Universität Münster , Corrensstrasse 30, 48149 Münster, Germany
| | - Rainer Pöttgen
- Institut für Anorganische und Analytische Chemie, Universität Münster , Corrensstrasse 30, 48149 Münster, Germany
| | - Thomas C Hansen
- Institut Laue-Langevin , 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Justin Kimpton
- Australian Synchrotron , 800 Blackburn Road, Clayton, Melbourne, Australia
| | - Holger Kohlmann
- Department of Inorganic Chemistry, Leipzig University , Johannisallee 29, 04103 Leipzig, Germany
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Paul-Boncour V, Parker SF, Hagemann H, Filipek SM, Wierzbicki R, Latroche M. YMn2Hx and RMn2−yFeyH6 (R = Y, Er) studied by Raman, infrared and inelastic neutron scattering spectroscopies. Faraday Discuss 2011; 151:307-14; discussion 385-97. [DOI: 10.1039/c0fd00019a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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