Nuclear magnetic resonance study of the rotational motion and the phase transition in LiBH4
(2008) Journal of Physical Chemistry C — Vol. 112, n° 47, p. 18701-18705 (2008)
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- Abstract
- To study the rotational motion of BH4 tetrahedra in LiBH 4, we have measured the 1H and 11B nuclear magnetic resonance spectra and spin-lattice relaxation rates in this compound over wide ranges of temperature (92-424 K) and resonance frequency (14-90 MHz for 1H and 14-28 MHz for 11B). In the low-temperature (orthorhombic) phase of LiBH4, our spin-lattice relaxation results are consistent with a coexistence of two types of the rotational motion of BH4 tetrahedra with the activation energies of 0.182 ± 0.003 eV and 0.251 ± 0.004 eV. For both types of motions, the jump rates of the reorientations reach the values of the order of 1011 s-1 near the upper limit of the temperature range of the orthorhombic phase stability (T0 ≈381 K). In the high-temperature (hexagonal) phase, both the 1H and 11B spin-lattice relaxation rates are governed by an additional low-frequency fluctuation process (with the characteristic rate of the order of 107 s-1 just above T0) due to the translational diffusion of Li ions. © 2008 American Chemical Society.
- Affiliations
ESRF, Grenoble (France) Chimie
Citations
Skripov, A. V., Soloninin, A. V., Filinchuk, Y., & Chernyshov, D. (2008). Nuclear magnetic resonance study of the rotational motion and the phase transition in LiBH4. Journal of Physical Chemistry C, 112(47), 18701-18705. https://doi.org/10.1021/jp806705q (Original work published 2008)