Europhys. Lett.
Volume 67, Number 4, August 2004
Page(s) 607 - 613
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 August 2004
Europhys. Lett., 67 (4), pp. 607-613 (2004)
DOI: 10.1209/epl/i2004-10105-x

Structure and stability of possible new alanates

O. M. Løvvik1 and O. Swang2

1  Center for materials science and nanotechnology, University of Oslo Gaustadalléen 21, N-0349 Oslo, Norway
2  Department of Hydrocarbon Process Chemistry, SINTEF Materials and Chemistry P.O. Box 124 Blindern, N-0314 Oslo, Norway

(Received 9 February 2004; accepted in final form 11 June 2004)

Three new stable bialkalimetallic alanates are predicted by accurate density functional calculations: $\chem{K_2LiAlH_6}$, $\chem{K_2NaAlH_6}$, and $\chem{KNa_2AlH_6}$. Their detailed crystal structure has been determined by a systematic search through a large part of the probable space of crystal structures. They are thermodynamically stable at 0 $\un{K}$ compared to their monoalkali constituents by 9 to 49 $\un{kJ/mol}$ formula units. The crystal structure of the already known alanates $\chem{Li_3AlH_6}$, $\chem{Na_3AlH_6}$, $\chem{K_3AlH_6}$, and $\chem{LiNa_2AlH_6}$ were also determined, and found to be in excellent agreement with experimental data where available. The two last bialkali alanates studied, $\chem{Li_2NaAlH_6}$ and $\chem{KLi_2AlH_6}$, were found to be unstable.

61.18.-j - Other methods of structure determination.
71.20.-b - Electron density of states and band structure of crystalline solids.

© EDP Sciences 2004