Evidence of Intermediate Hydrogen States in the Formation of a Complex Hydride
- Tohoku Univ., Sendai (Japan). Inst. for Materials Research
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical and Engineering Materials Division, Neutron Sciences Directorate
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical and Engineering Materials Division, Neutron Sciences Directorate
- Tohoku Univ., Sendai (Japan). Inst. for Materials Research; Tohoku Univ., Sendai (Japan). WPI-Advanced Inst. for Materials Research
A complex hydride (LaMg2NiH7) composed of La3+, two Mg2+, [NiH4]4– with a covalently bonded hydrogen, and three H– was formed from an intermetallic LaMg2Ni via an intermediate phase (LaMg2NiH4.6) composed of La, Mg, NiH2, NiH3 units, and H atoms at tetrahedral sites. The NiH2 and NiH3 units in LaMg2NiH4.6 were reported as precursors for [NiH4]4– in LaMg2NiH7 [Miwa et al. J. Phys. Chem. C 2016, 120, 5926–5931]. To further understand the hydrogen states in the precursors (the NiH2 and NiH3 units) and H atoms at the tetrahedral sites in the intermediate phase, LaMg2NiH4.6, we observed the hydrogen vibrations in LaMg2NiH4.6 and LaMg2NiH7 by using inelastic neutron scattering. A comparison of the hydrogen vibrations of the NiH2 and NiH3 units with that of [NiH4]4– shows that the librational modes of the NiH2 and NiH3 units were nonexistent; librational modes are characteristic modes for complex anions, such as [NiH4]4–. Furthermore, the hydrogen vibrations for the H atoms in the tetrahedral sites showed a narrower wavenumber range than that for H– and a wider range than that for typical interstitial hydrogen. The results indicated the presence of intermediate hydrogen states before the formation of [NiH4]4– and H–.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Laboratory Directed Research and Development (LDRD) Program; Japan Society for the Promotion of Science (JSPS)
- Grant/Contract Number:
- AC05-00OR22725; 16K06766; 25220911
- OSTI ID:
- 1422532
- Journal Information:
- Inorganic Chemistry, Vol. 57, Issue 2; ISSN 0020-1669
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Neutron Instruments for Research in Coordination Chemistry: Neutron Instruments for Research in Coordination Chemistry
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journal | January 2019 |
Hydrogen‐Release Reaction of a Complex Transition Metal Hydride with Covalently Bound Hydrogen and Hydride Ions
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journal | January 2019 |
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