Multivalent metal tetrahydroborides of Al, Sc, Y, Ti, and Zr

作者：Lodziana Zbigniew^*

来源：Physical Review B, 2010, 81(14): 144108.

DOI：10.1103/PhysRevB.81.144108

Metal tetrahydroborates remain interesting materials as potential hydrogen storage media. While overcoming large thermodynamic stability of uni- and divalent metal borohydrides may still be challenging, very little information is available about tetrahydroborates of tri- or tetravalent metal cations. Here, we analyze basic thermodynamic and electronic properties of borohydrides of Al, Sc, Y, Ti, and Zr by means of extensive density functional calculations. We show that solid phases of these compounds can range from ionic-like structures for Y (BH4)(3) to the molecular ones of Al(BH4)(3) and Zr(BH4)(4). These compounds are thermodynamically unstable at room temperature with respect to their decomposition into boron and hydrogen. Their stability is explained through the experimentally observed formation of diborane being a necessary step in the decomposition path. This points out that the kinetic factors are important for analysis of the metal borohydrides stability.

• 出版日期2010-4-1