Materials Data on BaB2O9 by Materials Project
BaB2O9 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one BaB2O9 sheet oriented in the (1, 0, 0) direction. Ba is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ba–O bond distances ranging from 2.65–3.14 Å. There are two inequivalent B sites. In the first B site, B is bonded in a trigonal planar geometry to three O atoms. There is one shorter (1.35 Å) and two longer (1.39 Å) B–O bond length. In the second B site, B is bonded in a tetrahedral geometry to four O atoms. There are a spread of B–O bond distances ranging from 1.42–1.47 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a distorted single-bond geometry to one Ba and one B atom. In the second O site, O is bonded in a single-bond geometry to one B atom. In the third O site, O is bonded in a single-bond geometry to one Ba and one B atom. In the fourth O site, O is bonded in a single-bond geometry to one Ba and one B atom. In the fifth O site, O is bonded in a single-bond geometry to one O atom. The O–O bond length is 1.23 Å. In the sixth O site, O is bonded in a distorted single-bond geometry to two equivalent Ba and one B atom. In the seventh O site, O is bonded in a single-bond geometry to one Ba and one B atom. In the eighth O site, O is bonded in a bent 120 degrees geometry to one Ba and one O atom. In the ninth O site, O is bonded in a single-bond geometry to one Ba and one B atom.