Lattice anharmonicity and structural evolution of LiBH4: An insight from Raman and X-ray diffraction experiments
(2009) Phase Transitions : a multinational journal — Vol. 82, n° 4, p. 344-355 (2009)
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- Authors
- Abstract
- New in situ Raman and synchrotron X-ray diffraction data (between 300 and 400 K) in conjunction with separate temperature-dependent Raman data (between 7 and 400 K) are presented. The low-frequency Raman spectra show good agreement with theoretical values obtained previously using periodic DFT calculations. The temperature-dependent spectra reveal the presence of significant anharmonicity of librational modes neither predicted theoretically nor noted in previous experiments. The splitting of the internal deformation mode 2 (of E symmetry in the free ion) decreases continuously with increasing temperature, but drops abruptly at the first-order orthorhombic to hexagonal phase transition observed at 381 K. The temperature dependence of the linewidth of the internal deformation mode 2 reveals coupling to reorientational motions of the borohydride ion in the orthorhombic phase. The thermal evolution of both crystal structure and vibration frequencies agree with the phase diagram suggested by the Landau theory.
- Affiliations
ESRF, Grenoble (France) Chimie
Citations
Hagemann, H., Filinchuk, Y., Chernyshov, D., & Van Beek, W. (2009). Lattice anharmonicity and structural evolution of LiBH4: An insight from Raman and X-ray diffraction experiments. Phase Transitions : a multinational journal, 82(4), 344-355. https://doi.org/10.1080/01411590802707688 (Original work published 2009)