Materials Data on MgAlH5 by Materials Project

Abstract

MgAlH5 crystallizes in the orthorhombic C222_1 space group. The structure is three-dimensional. Mg2+ is bonded to six H1- atoms to form MgH6 octahedra that share corners with four equivalent MgH6 octahedra, corners with four equivalent AlH6 octahedra, and an edgeedge with one AlH6 octahedra. The corner-sharing octahedra tilt angles range from 41–57°. There are a spread of Mg–H bond distances ranging from 1.86–2.02 Å. Al3+ is bonded to six H1- atoms to form AlH6 octahedra that share corners with two equivalent AlH6 octahedra, corners with four equivalent MgH6 octahedra, and an edgeedge with one MgH6 octahedra. The corner-sharing octahedra tilt angles range from 41–57°. There are a spread of Al–H bond distances ranging from 1.68–1.79 Å. There are three inequivalent H1- sites. In the first H1- site, H1- is bonded in a bent 150 degrees geometry to one Mg2+ and one Al3+ atom. In the second H1- site, H1- is bonded in a trigonal planar geometry to two equivalent Mg2+ and one Al3+ atom. In the third H1- site, H1- is bonded in a bent 120 degrees geometry to two equivalent Al3+ atoms.