Model for the Formation Energies of Alanates and Boranates

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• 作者：Michiel J. van Setten ; Gilles A. de Wijs ; Geert Brocks
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：July 5, 2007
• 年：2007
• 卷：111
• 期：26
• 页码：9592 - 9594
• 全文大小：71K
• 年卷期：v.111,no.26(July 5, 2007)
• ISSN：1932-7455

文摘

We develop a simple model for the formation energies (FEs) of alkali and alkaline earth alanates and boranates,based upon ionic bonding between metal cations and AlH₄^- or BH₄^- anions. The FEs agree well with valuesobtained from first principles calculations and with experimental FEs. The model shows that details of thecrystal structure are relatively unimportant. The small size of the BH₄^- anion causes a strong bonding in thecrystal, which makes boranates more stable than alanates. Smaller alkali or alkaline earth cations do not givean increased FE. They involve a larger ionization potential that compensates for the increased crystal bonding.