Reorientational Dynamics in Y(BH4)3·xNH3 (x = 0, 3, and 7): The Impact of NH3 on BH4- Dynamics
Journal article, 2024

The reorientational dynamics of Y(BH4)3·xNH3 (x = 0, 3, and 7) was studied using quasielastic neutron scattering (QENS) and neutron spin echo (NSE). The results showed that changing the number of NH3 ligands drastically alters the reorientational mobility of the BH4- anion. From the QENS experiments, it was determined that the BH4- anion performs 2-fold reorientations around the C2 axis in Y(BH4)3, 3-fold reorientations around the C3 axis in Y(BH4)3·3NH3, and either 2-fold reorientations around the C2 axis or 3-fold reorientations around the C3 axis in Y(BH4)3·7NH3. The relaxation time of the BH4- anion at 300 K decreases from 2 × 10-7 s for x = 0 to 1 × 10-12 s for x = 3 and to 7 × 10-13 s for x = 7. In addition to the reorientational dynamics of the BH4- anion, it was shown that the NH3 ligands exhibit 3-fold reorientations around the C3 axis in Y(BH4)3·3NH3 and Y(BH4)3·7NH3 as well as 3-fold quantum mechanical rotational tunneling around the same axis at 5 K. The new insights constitute a significant step toward understanding the relationship between the addition of ligands and the enhanced ionic conductivity observed in systems such as LiBH4·xNH3 and Mg(BH4)2·xCH3NH2

Author

Jakob B. Grinderslev

Aarhus University

Ulrich Häussermann

Stockholm University

Torben R. Jensen

Aarhus University

A. Faraone

National Institute of Standards and Technology (NIST)

M. Nagao

A. James Clark School of Engineering

University of Delaware

National Institute of Standards and Technology (NIST)

Maths Karlsson

Chalmers, Chemistry and Chemical Engineering, Energy and Material

Terrence J. Udovic

National Institute of Standards and Technology (NIST)

A. James Clark School of Engineering

M. S. Andersson

Uppsala University

Journal of Physical Chemistry C

1932-7447 (ISSN) 1932-7455 (eISSN)

Vol. 128 11 4431-4439

Surface/interface dynamics investigated with neutron scattering

Swedish Research Council (VR) (2016-06958), 2017-01-01 -- 2020-12-31.

Subject Categories

Physical Sciences

DOI

10.1021/acs.jpcc.4c00265

PubMed

38533240

More information

Latest update

3/30/2024