Materials Data on Na5Al3H14 by Materials Project

Abstract

Na5Al3H14 crystallizes in the tetragonal P4/mnc space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a body-centered cubic geometry to eight equivalent H1- atoms. All Na–H bond lengths are 2.50 Å. In the second Na1+ site, Na1+ is bonded to six H1- atoms to form distorted NaH6 octahedra that share corners with two equivalent NaH6 octahedra, corners with six AlH6 octahedra, and edges with four equivalent NaH6 octahedra. The corner-sharing octahedra tilt angles range from 38–71°. There are a spread of Na–H bond distances ranging from 2.22–2.55 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six H1- atoms to form AlH6 octahedra that share corners with four equivalent AlH6 octahedra and corners with eight equivalent NaH6 octahedra. The corner-sharing octahedra tilt angles range from 33–71°. All Al–H bond lengths are 1.75 Å. In the second Al3+ site, Al3+ is bonded to six H1- atoms to form AlH6 octahedra that share corners with two equivalent AlH6 octahedra and corners with eight equivalent NaH6 octahedra. The corner-sharing octahedra tilt angles range from 33–68°. There is four shorter (1.74 Å) and two longer (1.78 Å) Al–H bond length. There are three inequivalent H1- sites. In the first H1- site, H1- is bonded in a distorted single-bond geometry to four equivalent Na1+ and one Al3+ atom. In the second H1- site, H1- is bonded in a bent 150 degrees geometry to two Al3+ atoms. In the third H1- site, H1- is bonded to three Na1+ and one Al3+ atom to form a mixture of distorted corner and edge-sharing HNa3Al trigonal pyramids.