Materials Data on Yb19(Mg4H27)2 by Materials Project

Abstract

Yb19Mg8H54 crystallizes in the cubic Im-3 space group. The structure is three-dimensional. Mg is bonded to six H atoms to form MgH6 octahedra that share corners with three equivalent MgH6 octahedra and a faceface with one YbH12 cuboctahedra. The corner-sharing octahedral tilt angles are 36°. There is three shorter (1.94 Å) and three longer (1.99 Å) Mg–H bond length. There are three inequivalent Yb sites. In the first Yb site, Yb is bonded in a 8-coordinate geometry to eight H atoms. There are a spread of Yb–H bond distances ranging from 2.23–2.45 Å. In the second Yb site, Yb is bonded in a distorted q6 geometry to ten H atoms. There are a spread of Yb–H bond distances ranging from 2.32–2.46 Å. In the third Yb site, Yb is bonded to twelve equivalent H atoms to form YbH12 cuboctahedra that share faces with eight equivalent MgH6 octahedra. All Yb–H bond lengths are 2.44 Å. There are four inequivalent H sites. In the first H site, H is bonded in a distorted see-saw-like geometry to four Yb atoms. In the second H site, H is bonded to four Yb atoms to form a mixture of edge and corner-sharing HYb4 tetrahedra. In the third H site, H is bonded to one Mg and three Yb atoms to form distorted HYb3Mg tetrahedra that share corners with sixteen HYb4 tetrahedra and edges with four HYb3Mg tetrahedra. In the fourth H site, H is bonded to two equivalent Mg and two Yb atoms to form distorted HYb2Mg2 tetrahedra that share corners with fourteen HYb4 tetrahedra and edges with seven HYb2Mg2 tetrahedra.