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The Hydrogenation of the Zintl Phase NdGa Studied by in situ Neutron Diffraction
Author(s) -
Auer Henry,
Nedumkandathil Reji,
Häussermann Ulrich,
Kohlmann Holger
Publication year - 2019
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201800459
Subject(s) - neutron diffraction , hydrogen , zintl phase , crystallography , chemistry , lattice constant , gallium , interstitial defect , diffraction , materials science , crystal structure , doping , organic chemistry , physics , optics , optoelectronics
The hydrogenation of the Zintl phase NdGa was studied by in situ neutron powder diffraction. We find a compositional range of 0.1 < x < 0.8 in NdGaH 1+ x . Hydrogen atoms are located in two different positions, in HNd 4 tetrahedra, and close to the polyanionic chains. For the latter, the Ga–H distance in NdGaH 1.66 is quite long (ca. 200 pm) with a trigonal bipyramidal Nd 3 Ga 2 surrounding of hydrogen atoms. Hydrogen poor NdGaH <1 phases as known for similar systems were not observed. The changing hydrogen content shows no measureable effect on the unit cell volume, but on lattice parameter ratios. Superstructures occur for 0.53 < x < 0.66 and 0.73 < x < 0.8, leading to a doubling or tripling of the lattice parameter a . They are probably caused by partial hydrogen ordering. The threefold superstructure contains a 1 ∞ [(Ga–H–Ga–H–Ga) 6– ] moiety with hydrogen bridging two gallium chains.