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First-principles study on thermodynamical stability of metal borohydrides: Aluminum borohydride Al(BH4)3

Kazutoshi Miwa·Nobuko Ohba·Yuko Nakamori·Shin-ichi Towata·Andreas Zuttel·Shin-ichi Orimo
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Abstract

The thermodynamical stability of ${\rm Al(BH_4)_3}$ has been investigated using first-principles calculations based on density functional theory. The heats of formation are obtained to be -132 and $-131 {\rm kJ/mol}$ without the zero-point energy corrections for $α$- and $β$-${\rm Al(BH_4)_3}$, respectively, which are made up of discrete molecular ${\rm Al(BH_4)_3}$ units. It is predicted correctly that the $α$ phase is more stable than the $β$ phase. The energy difference between the solid phases and the isolated molecule is only about 10 kJ/mol. An analysis of the electronic structure also suggests the weak interaction between ${\rm Al(BH_4)_3}$ molecules in the solid phases. It is confirmed that ${\rm Al(BH_4)_3}$ obeys the linear relationship between the heat of formation and the Pauling electronegativity of the cation, which has been proposed in our previous study [Nakamori {\it et al.}, Phys. Rev. B {\bf 74}, 045126 (2006)].

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Kazutoshi Miwa, Nobuko Ohba, Yuko Nakamori, Shin-ichi Towata, Andreas Zuttel, Shin-ichi Orimo. 2006-10-31. First-principles study on thermodynamical stability of metal borohydrides: Aluminum borohydride Al(BH4)3. https://arxiv.org/abs/cond-mat/0610853

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