Title: The search for novel hydrogen storage materials: a theoretical approach

Authors: P. Vajeeston, P. Ravindran, H. Fjellvag

Addresses: Department of Chemistry, Center for Materials Science and Nanotechnology, University of Oslo, Box 1033 Blindern, N-0315 Oslo, Norway. ' Department of Chemistry, Center for Materials Science and Nanotechnology, University of Oslo, Box 1033 Blindern, N-0315 Oslo, Norway. ' Department of Chemistry, Center for Materials Science and Nanotechnology, University of Oslo, Box 1033 Blindern, N-0315 Oslo, Norway

Abstract: Density Functional Theory (DFT) is a powerful tool to predict the crystal structure of hitherto experimentally unknown phases. In this article, we demonstrate the predicting capability of DFT on the structural properties of hydrogen storage materials from different input structure models. An experimentally known structural framework is successfully reproduced for NaMgH₃ and the positional and unit-cell parameters are found to be in good agreement with the experimental findings. The crystal structure of LiMgH₃ has been predicted and this compound should have ferroelectric properties. The calculated phonon spectrum indicates that LiMgH₃ is an energetically and thermodynamically stable phase. A pressure-induced structural transition has been identified for this phase and it transforms into CaCO₃-type modification at 38 GPa.

Keywords: complex hydrides; structural investigation; hydrogen storage; high-pressure study; storage materials; density functional theory; DFT; crystal structure.

DOI: 10.1504/IJNHPA.2009.024774

International Journal of Nuclear Hydrogen Production and Applications, 2009 Vol.2 No.2, pp.137 - 147

Published online: 30 Apr 2009 *

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