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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on K3AlH6 by Materials Project

K3AlH6 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to eight H1- atoms to form distorted KH8 hexagonal bipyramids that share corners with four equivalent KH8 hexagonal bipyramids, edges with six equivalent KH8 hexagonal bipyramids, and edges with four equivalent AlH6 octahedra. There are four shorter (2.60 Å) and four longer (2.95 Å) K–H bond lengths. In the second K1+ site, K1+ is bonded in a linear geometry to two equivalent H1- atoms. Both K–H bond lengths are 2.69 Å. Al3+ is bonded to six H1- atoms to form AlH6 octahedra that share edges with eight equivalent KH8 hexagonal bipyramids. There is four shorter (1.73 Å) and two longer (1.93 Å) Al–H bond length. There are two inequivalent H1- sites. In the first H1- site, H1- is bonded in a distorted trigonal planar geometry to two equivalent K1+ and one Al3+ atom. In the second H1- site, H1- is bonded to five K1+ and one Al3+ atom to form a mixture of distorted edge and corner-sharing HK5Al octahedra. The corner-sharing octahedra tilt angles range from 0–15°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3AlH6 by Materials Project

K3AlH6 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six H1- atoms to form KH6 octahedra that share corners with six equivalent AlH6 octahedra. The corner-sharing octahedra tilt angles range from 21–25°. There are a spread of K–H bond distances ranging from 2.57–2.59 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight H1- atoms. There are a spread of K–H bond distances ranging from 2.71–3.03 Å. Al3+ is bonded to six H1- atoms to form AlH6 octahedra that share corners with six equivalent KH6 octahedra. The corner-sharing octahedra tilt angles range from 21–25°. There is four shorter (1.78 Å) and two longer (1.79 Å) Al–H bond length. There are three inequivalent H1- sites. In the first H1- site, H1- is bonded in a 1-coordinate geometry to four K1+ and one Al3+ atom. In the second H1- site, H1- is bonded in a 1-coordinate geometry to four K1+ and one Al3+ atom. In the third H1- site, H1- is bonded in a 4-coordinate geometry to three K1+ and one Al3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KAlH4 by Materials Project

KAlH4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 6-coordinate geometry to six H1- atoms. There are a spread of K–H bond distances ranging from 2.66–2.89 Å. Al3+ is bonded in a tetrahedral geometry to four H1- atoms. There is two shorter (1.63 Å) and two longer (1.64 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 two equivalent K1+ and one Al3+ atom. In the second H1- site, H1- is bonded in a distorted single-bond geometry to one K1+ and one Al3+ atom. In the third H1- site, H1- is bonded in a distorted linear geometry to one K1+ and one Al3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3AlH6 by Materials Project

K3AlH6 crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to seven H1- atoms. There are a spread of K–H bond distances ranging from 2.56–2.90 Å. In the second K1+ site, K1+ is bonded in a 5-coordinate geometry to three H1- atoms. There are two shorter (2.53 Å) and one longer (2.63 Å) K–H bond lengths. In the third K1+ site, K1+ is bonded in a 7-coordinate geometry to seven H1- atoms. There are a spread of K–H bond distances ranging from 2.52–3.00 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six H1- atoms to form edge-sharing AlH6 octahedra. There is two shorter (1.68 Å) and four longer (1.96 Å) Al–H bond length. In the second Al3+ site, Al3+ is bonded to six H1- atoms to form edge-sharing AlH6 octahedra. There is two shorter (1.66 Å) and four longer (1.97 Å) Al–H bond length. There are six inequivalent H1- sites. In the first H1- site, H1- is bonded in a single-bond geometry to three K1+ and one Al3+ atom. In the second H1- site, H1- is bonded to five K1+ atoms to form a mixture of distorted edge and corner-sharing HK5 square pyramids. In the third H1- site, H1- is bonded in a distorted trigonal non-coplanar geometry to one K1+ and two equivalent Al3+ atoms. In the fourth H1- site, H1- is bonded to five K1+ atoms to form a mixture of distorted edge and corner-sharing HK5 trigonal bipyramids. In the fifth H1- site, H1- is bonded in a distorted single-bond geometry to two equivalent K1+ and one Al3+ atom. In the sixth H1- site, H1- is bonded in a distorted water-like geometry to one K1+ and two equivalent Al3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KAlH4 by Materials Project

KAlH4 crystallizes in the tetragonal I4_1/a space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight equivalent H1- atoms. There are four shorter (2.71 Å) and four longer (2.78 Å) K–H bond lengths. Al3+ is bonded in a tetrahedral geometry to four equivalent H1- atoms. All Al–H bond lengths are 1.63 Å. H1- is bonded in a distorted single-bond geometry to two equivalent K1+ and one Al3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KAlH3 by Materials Project

KAlH3 is (Cubic) Perovskite structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. K is bonded to twelve equivalent H atoms to form KH12 cuboctahedra that share corners with twelve equivalent KH12 cuboctahedra, faces with six equivalent KH12 cuboctahedra, and faces with eight equivalent AlH6 octahedra. All K–H bond lengths are 2.82 Å. Al is bonded to six equivalent H atoms to form AlH6 octahedra that share corners with six equivalent AlH6 octahedra and faces with eight equivalent KH12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. All Al–H bond lengths are 1.99 Å. H is bonded to four equivalent K and two equivalent Al atoms to form a mixture of distorted edge, corner, and face-sharing HK4Al2 octahedra. The corner-sharing octahedra tilt angles range from 0–60°.

36 MATERIALS SCIENCE↗