Hydriding and dehydriding behavior of lanthanum silicides

Bohmhammel, K.; Henneberg, E.

doi:10.1016/s0167-2738(01)00774-3

Cited by 4 publications

(2 citation statements)

References 3 publications

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“…The metallic Zintl phase LaSi 2 adopts the ThSi 2 structure type, which is characterized by a trigonal prismatic surrounding of silicon atoms by lanthanum atoms and a three-dimensional silicon network ( Figure 1) [25]. The reactivity of LaSi 2 towards hydrogen was found to be very low [26].…”

Section: Introductionmentioning

confidence: 99%

Hydrogenation Properties of LnAl2 (Ln = La, Eu, Yb), LaGa2, LaSi2 and the Crystal Structure of LaGa2H0.71(2)

et al. 2019

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Many Zintl phases take up hydrogen and form hydrides. Hydrogen atoms occupy interstitial sites formed by alkali or alkaline earth metals and / or bind covalently to the polyanions. The latter is the case for polyanionic hydrides like SrTr2H2 (Tr = Al, Ga) with slightly puckered honeycomb-like polyanions decorated with hydrogen atoms. This study addresses the hydrogenation behavior of LnTr2, where the lanthanide metals Ln introduce one additional valence electron. Hydrogenation reactions were performed in autoclaves and followed by thermal analysis up to 5.0 MPa hydrogen gas pressure. Products were analyzed by powder X-ray and neutron diffraction, transmission electron microscopy, and NMR spectroscopy. Phases LnAl2 (Ln = La, Eu, Yb) decompose into binary hydrides and aluminium-rich intermetallics upon hydrogenation, while LaGa2 forms a ternary hydride LaGa2H0.71(2). Hydrogen atoms are statistically distributed over two kinds of trigonal-bipyramidal La3Ga2 interstitials with 67% and 4% occupancy, respectively. Ga-H distances (2.4992(2) Å) are considerably longer than in polyanionic hydrides and not indicative of covalent bonding. 2H solid-state NMR spectroscopy and theoretical calculations on Density Functional Theory (DFT) level confirm that LaGa2H0.7 is a typical interstitial metallic hydride.

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Section: Introductionmentioning

confidence: 99%

Hydrogenation Properties of LnAl2 (Ln = La, Eu, Yb), LaGa2, LaSi2 and the Crystal Structure of LaGa2H0.71(2)

et al. 2019

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“…LaSi reacts with hydrogen to form a hydride whose crystal structure was not known before . This work systematically investigates the oxidation of non electron‐precise Zintl phases La Tt ( Tt = Si, Ge, Sn) and Nd Tt ( Tt = Si, Ge) by hydrogen.…”

Section: Introductionmentioning

confidence: 99%

From Metallic LnTt (Ln = La, Nd; Tt = Si, Ge, Sn) to Electron‐precise Zintl Phase Hydrides LnTtH

Werwein

Auer

Kuske

et al. 2018

Zeitschrift anorg allge chemie

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LnTt (Ln = La, Nd; Tt = Si, Ge, Sn) compounds crystallize in the CrB‐ or the FeB‐structure type with 1∞[Tt2–]‐polyanionic zigzag chains and can be rationalized as Ln3+Tt2–e–. They take up hydrogen at gas pressures from 10 to 160 bar and temperatures up to 750 K. The hydrides LnTtH1–x (0.04 ≤ x ≤ 0.39) crystallize either in a hydrogen filled CrB‐structure type (ZrNiH type, C‐phase, Cmcm: LaSiD0.92(1), LaGeD0.88(1), NdSiD, NdGeD0.95(1), LaSnHx) or in a hydrogen filled FeB‐structure type (LaGeH type, P‐phase, Pnma: LaSiD0.61(3), LaGeD0.96(4), NdSiD0.88(6)). In both cases, hydrogen atoms partially fill tetrahedral Ln4 voids as proven by neutron powder diffraction. While CrB‐structure type LnTt reacts to C‐phase only, FeB‐structure type LnTt hydrogenates to mixtures of C‐ (major phase) and P‐type hydrides. Electronic structure calculations reveal the depopulation of Ln‐d states, which cause the metallic conductivity in LnTt to be the main electronic effect upon hydrogenation. They further suggest Zintl phase hydrides LnTtH to be still poor metallic conductors with a pseudo bandgap at the Fermi level. The hydrogenation reaction from LnTt to LnTtH may thus be regarded as an incomplete metal to semiconductor transition.

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Phase transitions in LaAl2-Ni and their hydrogenation properties

Zhang

Jiang

2019

Chemical Physics Letters

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Hydriding and dehydriding behavior of lanthanum silicides

Cited by 4 publications

References 3 publications

Hydrogenation Properties of LnAl2 (Ln = La, Eu, Yb), LaGa2, LaSi2 and the Crystal Structure of LaGa2H0.71(2)

Hydrogenation Properties of LnAl2 (Ln = La, Eu, Yb), LaGa2, LaSi2 and the Crystal Structure of LaGa2H0.71(2)

From Metallic LnTt (Ln = La, Nd; Tt = Si, Ge, Sn) to Electron‐precise Zintl Phase Hydrides LnTtH

Phase transitions in LaAl2-Ni and their hydrogenation properties

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