Lightest borohydride probed by synchrotron X-ray diffraction: Experiment calls for a new theoretical revision
(2008) Journal of Physical Chemistry C — Vol. 112, n° 28, p. 10579-10584 (2008)
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- Abstract
- A combination of synchrotron X-ray diffraction techniques have been applied to resolve ambiguities between experimental and theoretical studies of LiBH4 and to reveal its complex structural evolution as a function of temperature. Crystal structures of the low- and high-temperature polymorphs of LiBH4 have been determined from diffraction on single-crystals. In contrast to recent theoretical conjectures, we find that the high-temperature structure is hexagonal, space group P63mc. Experimental data suggest a nearly isotropic disorder of the rigid tetrahedral BH4 groups as one of the factors stabilizing the hexagonal structure. Tetrahedral BH 4 anions are undistorted and geometrically very similar in both polymorphs. The first order phase transition at 381 K is preceded by highly anisotropic lattice expansion and is accompanied by a negative volume change. Disorder phenomena and strong lattice anharmonicity, being ignored, lead to the failure of theoretical predictions of the structural stability of LiBH 4 published so far. © 2008 American Chemical Society.
- Affiliations
ESRF, Grenoble (France) Chimie
Citations
Filinchuk, Y., Chernyshov, D., & Cerny, R. (2008). Lightest borohydride probed by synchrotron X-ray diffraction: Experiment calls for a new theoretical revision. Journal of Physical Chemistry C, 112(28), 10579-10584. https://doi.org/10.1021/jp8025623 (Original work published 2008)