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A quasielastic and inelastic neutron scattering study of the alkaline and alkaline-earth borohydrides LiBH 4 and Mg(BH 4 ) 2 and the mixture LiBH 4 + Mg(BH 4 ) 2

Silvi, Luca; Zhao-Karger, Zhirong; Röhm, Eva; Fichtner, Maximilian; Petry, Winfried; Lohstroh, Wiebke

Abstract:
Quasielastic neutron scattering was used to investigate the low energy transfer dynamics of the complex borohydrides Mg(BH₄)₂ in the α- and β-modifications, LiBH₄ in the low and high temperature crystal structure, and an 1 : 1 molar mixture of LiBH₄ + α-Mg(BH₄)₂. All investigated compounds show a rich dynamic behaviour below an energy range of ΔE = 10 meV with the superposition of rotational dynamics of the constituent [BH₄]¯ anions and low lying lattice modes. For Mg(BH₄)₂, the rotational diffusion of the [BH₄] units was found to be much more activated in the metastable β-polymorph compared to the α-phase, and the low lying lattice modes are even softer in the former crystal structure. In Mg(BH₄)₂, the structural phase transition is mainly governed by the lattice dynamics, while alkaline LiBH₄ exhibits a transition of the [BH₄] rotations around the phase transition temperature. Ball milled LiBH₄ + α-Mg(BH₄)₂ remains a physical mixture of the parent compounds and each component retains its characteristic dynamic signature up to the melting temperature.

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Verlagsausgabe §
DOI: 10.5445/IR/1000104440
Veröffentlicht am 19.12.2019
Originalveröffentlichung
DOI: 10.1039/c8cp04316g
Scopus
Zitationen: 3
Web of Science
Zitationen: 4
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Nanotechnologie (INT)
Helmholtz-Institut Ulm (HIU)
Post Lithium Storage (POLiS)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2019
Sprache Englisch
Identifikator ISSN: 1463-9076, 1463-9084
KITopen-ID: 1000104440
HGF-Programm 37.01.01 (POF III, LK 01)
Fundamentals and Materials
Erschienen in Physical chemistry, chemical physics
Band 21
Heft 2
Seiten 718–728
Vorab online veröffentlicht am 04.12.2018
Nachgewiesen in Web of Science
Scopus
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