Materials Data on Ba17Al3O7 by Materials Project
Ba17Al3O7 crystallizes in the tetragonal P4_2/ncm space group. The structure is two-dimensional and consists of two Ba17Al3O7 sheets oriented in the (0, 0, 1) direction. there are seven inequivalent Ba sites. In the first Ba site, Ba is bonded in a 3-coordinate geometry to three O atoms. There are two shorter (2.73 Å) and one longer (2.82 Å) Ba–O bond lengths. In the second Ba site, Ba is bonded in a 2-coordinate geometry to two equivalent O atoms. Both Ba–O bond lengths are 2.90 Å. In the third Ba site, Ba is bonded in a 3-coordinate geometry to one Al and two O atoms. The Ba–Al bond length is 3.45 Å. There are one shorter (2.94 Å) and one longer (3.07 Å) Ba–O bond lengths. In the fourth Ba site, Ba is bonded in a single-bond geometry to one O atom. The Ba–O bond length is 2.71 Å. In the fifth Ba site, Ba is bonded in a distorted single-bond geometry to one Al and one O atom. The Ba–Al bond length is 3.71 Å. The Ba–O bond length is 2.87 Å. In the sixth Ba site, Ba is bonded in a 5-coordinate geometry to three O atoms. There are two shorter (3.08 Å) and one longer (3.22 Å) Ba–O bond lengths. In the seventh Ba site, Ba is bonded in a 3-coordinate geometry to three O atoms. There are two shorter (2.72 Å) and one longer (2.84 Å) Ba–O bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded to four O atoms to form corner-sharing AlO4 tetrahedra. There is three shorter (1.79 Å) and one longer (1.84 Å) Al–O bond length. In the second Al site, Al is bonded in a 8-coordinate geometry to eight Ba atoms. There are three inequivalent O sites. In the first O site, O is bonded in a distorted trigonal bipyramidal geometry to three Ba and two equivalent Al atoms. In the second O site, O is bonded in a distorted single-bond geometry to five Ba and one Al atom. In the third O site, O is bonded in a 1-coordinate geometry to five Ba and one Al atom.