Materials Data on Ho3Al2(Ni3H4)2 by Materials Project

Abstract

Ho3Al2(Ni3H4)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Ho sites. In the first Ho site, Ho is bonded in a 4-coordinate geometry to four equivalent H atoms. All Ho–H bond lengths are 2.11 Å. In the second Ho site, Ho is bonded in a 5-coordinate geometry to five H atoms. There are one shorter (2.10 Å) and four longer (2.11 Å) Ho–H bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a distorted bent 120 degrees geometry to two equivalent Al and two equivalent H atoms. Both Ni–Al bond lengths are 2.44 Å. Both Ni–H bond lengths are 1.65 Å. In the second Ni site, Ni is bonded in a 2-coordinate geometry to two equivalent Al and three H atoms. Both Ni–Al bond lengths are 2.56 Å. There are a spread of Ni–H bond distances ranging from 1.68–2.02 Å. Al is bonded in a distorted linear geometry to six Ni and two equivalent H atoms. Both Al–H bond lengths are 1.99 Å. There are four inequivalent H sites. In the first H site, H is bonded to three Ho and one Al atom to form HHo3Al tetrahedra that share corners with two equivalent HHo2Ni4 octahedra, corners with four equivalent HHo3Al tetrahedra, and edges with three equivalent HHo3Al tetrahedra. The corner-sharing octahedral tilt angles are 49°. In the second H site, H is bonded in a 4-coordinate geometry to four Ni atoms. In the third H site, H is bonded to four equivalent Ni atoms to form edge-sharing HNi4 tetrahedra. In the fourth H site, H is bonded to two equivalent Ho and four equivalent Ni atoms to form HHo2Ni4 octahedra that share corners with eight equivalent HHo3Al tetrahedra and edges with two equivalent HNi4 tetrahedra.