Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1609099 | Journal of Alloys and Compounds | 2015 | 5 Pages |
Abstract
To study the effects of partial halide anion substitution on the reorientational motion of [BH4]â anions in NaBH4, we have measured the 1H and 11B NMR spectra and spin-lattice relaxation rates in the cubic solid solutions Na(BH4)0.5Cl0.5 and Na(BH4)0.5I0.5 over broad ranges of temperature (8-324 K) and the resonance frequency (14-90 MHz). For both solid solutions, the measured 1H spin-lattice relaxation rates are governed by reorientations of BH4 groups, and the experimental data can be satisfactorily described by the model with a Gaussian distribution of the activation energies. The average values of the activation energies derived from the 1H spin-lattice relaxation data are 192 ± 7 meV for Na(BH4)0.5Cl0.5 and 120 ± 3 meV for Na(BH4)0.5I0.5. At a given temperature, the reorientational jump rates are found to increase in the order of Na(BH4)0.5Cl0.5-NaBH4-Na(BH4)0.5I0.5, in agreement with the quasielastic neutron scattering (QENS) results. This trend correlates with the lattice expansion reflecting the increase in the size of the corresponding anions (in the order of Clâ-[BH4]â-Iâ).
Related Topics
Physical Sciences and Engineering
Materials Science
Metals and Alloys
Authors
R.V. Skoryunov, O.A. Babanova, A.V. Soloninin, A.V. Skripov, N. Verdal, T.J. Udovic,