Materials Data on Ba(AlGe)2 by Materials Project

Abstract

BaAl2Ge2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ba is bonded in a 3-coordinate geometry to nine Al and seven Ge atoms. There are a spread of Ba–Al bond distances ranging from 3.44–3.90 Å. There are a spread of Ba–Ge bond distances ranging from 3.34–3.67 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to five equivalent Ba and four Ge atoms to form a mixture of distorted corner, edge, and face-sharing AlBa5Ge4 tetrahedra. There are a spread of Al–Ge bond distances ranging from 2.56–2.62 Å. In the second Al site, Al is bonded to four equivalent Ba and four Ge atoms to form distorted AlBa4Ge4 tetrahedra that share corners with fourteen AlBa5Ge4 tetrahedra, edges with two equivalent AlBa4Ge4 tetrahedra, and faces with eight AlBa5Ge4 tetrahedra. There are three shorter (2.60 Å) and one longer (2.61 Å) Al–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 7-coordinate geometry to three equivalent Ba and four Al atoms. In the second Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Ba and four Al atoms.