Hydrogen dynamics in the low temperature phase of LiBH4 probed by quasielastic neutron scattering

Arndt Remhof; Andreas Züttel; Timmy Ramirez-Cuesta; Victoria García-Sakai; Bernhard Frick

doi:10.1016/j.chemphys.2013.07.017

Hydrogen dynamics in the low temperature phase of LiBH₄ probed by quasielastic neutron scattering

Arndt Remhof, Andreas Züttel, Timmy Ramirez-Cuesta, Victoria García-Sakai, Bernhard Frick

Research output: Contribution to journal › Article › peer-review

10 Scopus citations

Abstract

LiBH₄ contains 18.5 wt% hydrogen and undergoes a structural phase transition (orthorhombic → hexagonal) at 381 K which is associated with a large increase in hydrogen and lithium solid-state mobility. We investigated the hydrogen dynamics in the low temperature phase of LiBH ₄ by quasielastic neutron scattering, including a new kind of inelastic fixed window scan (IFWS). In the temperature range from 175 to 380 K the H-dynamics is dominated by thermally activated rotational jumps of the [BH₄]^- anion around the c3 axis with an activation energy of about 162 meV. In agreement with earlier NMR data, a second type of thermally activated motion with an activation energy of about 232 meV could be identified using the IFWS. The present study of hydrogen dynamics in LiBH₄ illustrates the feasibility of using IFWS on neutron backscattering spectrometers as a probe of localised motion.

Original language	English
Pages (from-to)	18-21
Number of pages	4
Journal	Chemical Physics
Volume	427
DOIs	https://doi.org/10.1016/j.chemphys.2013.07.017
State	Published - Dec 12 2013

Funding

Financial support by a Grant from Switzerland through the Swiss Contribution to the enlarged European Union is gratefully acknowledged.

Keywords

Dynamics
Energy Materials
Hydrogen Storage
Lithium borohydride
Quasielastic Neutron Scattering
Reorientations

Access to Document

10.1016/j.chemphys.2013.07.017

Cite this

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title = "Hydrogen dynamics in the low temperature phase of LiBH4 probed by quasielastic neutron scattering",

abstract = "LiBH4 contains 18.5 wt\% hydrogen and undergoes a structural phase transition (orthorhombic → hexagonal) at 381 K which is associated with a large increase in hydrogen and lithium solid-state mobility. We investigated the hydrogen dynamics in the low temperature phase of LiBH 4 by quasielastic neutron scattering, including a new kind of inelastic fixed window scan (IFWS). In the temperature range from 175 to 380 K the H-dynamics is dominated by thermally activated rotational jumps of the [BH4]- anion around the c3 axis with an activation energy of about 162 meV. In agreement with earlier NMR data, a second type of thermally activated motion with an activation energy of about 232 meV could be identified using the IFWS. The present study of hydrogen dynamics in LiBH4 illustrates the feasibility of using IFWS on neutron backscattering spectrometers as a probe of localised motion.",

keywords = "Dynamics, Energy Materials, Hydrogen Storage, Lithium borohydride, Quasielastic Neutron Scattering, Reorientations",

author = "Arndt Remhof and Andreas Z{\"u}ttel and Timmy Ramirez-Cuesta and Victoria Garc{\'i}a-Sakai and Bernhard Frick",

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T1 - Hydrogen dynamics in the low temperature phase of LiBH4 probed by quasielastic neutron scattering

AU - Remhof, Arndt

AU - Züttel, Andreas

AU - Ramirez-Cuesta, Timmy

AU - García-Sakai, Victoria

AU - Frick, Bernhard

PY - 2013/12/12

Y1 - 2013/12/12

N2 - LiBH4 contains 18.5 wt% hydrogen and undergoes a structural phase transition (orthorhombic → hexagonal) at 381 K which is associated with a large increase in hydrogen and lithium solid-state mobility. We investigated the hydrogen dynamics in the low temperature phase of LiBH 4 by quasielastic neutron scattering, including a new kind of inelastic fixed window scan (IFWS). In the temperature range from 175 to 380 K the H-dynamics is dominated by thermally activated rotational jumps of the [BH4]- anion around the c3 axis with an activation energy of about 162 meV. In agreement with earlier NMR data, a second type of thermally activated motion with an activation energy of about 232 meV could be identified using the IFWS. The present study of hydrogen dynamics in LiBH4 illustrates the feasibility of using IFWS on neutron backscattering spectrometers as a probe of localised motion.

AB - LiBH4 contains 18.5 wt% hydrogen and undergoes a structural phase transition (orthorhombic → hexagonal) at 381 K which is associated with a large increase in hydrogen and lithium solid-state mobility. We investigated the hydrogen dynamics in the low temperature phase of LiBH 4 by quasielastic neutron scattering, including a new kind of inelastic fixed window scan (IFWS). In the temperature range from 175 to 380 K the H-dynamics is dominated by thermally activated rotational jumps of the [BH4]- anion around the c3 axis with an activation energy of about 162 meV. In agreement with earlier NMR data, a second type of thermally activated motion with an activation energy of about 232 meV could be identified using the IFWS. The present study of hydrogen dynamics in LiBH4 illustrates the feasibility of using IFWS on neutron backscattering spectrometers as a probe of localised motion.

KW - Dynamics

KW - Energy Materials

KW - Hydrogen Storage

KW - Lithium borohydride

KW - Quasielastic Neutron Scattering

KW - Reorientations

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