Bonding in Zintl phase hydrides: Density functional calculations for SrAlSiH, SrAl2 H2, SrGa2 H2, and BaGa2 H2

We investigate the bonding characteristics of SrAlSiH, SrAl2 H2, SrGa2 H2, and BaGa2 H2 using density functional calculations. The mixed bonding characteristic of other families of Zintl phases is found, with the formation of covalent s p2 bonds in the Al/Ga/Al-Si planes of the various compounds. On the other hand the Sr and Ba atoms occur as divalent cations, while the H is anionic. The results indicate that insulating SrSiAlH may be a switchable ferroelectric.