Materials Data on CaB2O9 by Materials Project
CaB2O9 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one CaB2O9 sheet oriented in the (0, 0, 1) direction. Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.34–2.81 Å. There are two inequivalent B sites. In the first B site, B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.44–1.46 Å. In the second B site, B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.45–1.48 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a distorted single-bond geometry to one Ca and one B atom. In the second O site, O is bonded in a distorted single-bond geometry to two equivalent Ca and one B atom. In the third O site, O is bonded in a distorted single-bond geometry to one Ca, one B, and one O atom. The O–O bond length is 1.63 Å. In the fourth O site, O is bonded in a bent 120 degrees geometry to one Ca and two B atoms. In the fifth O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and one B atom. In the sixth O site, O is bonded in a distorted single-bond geometry to one Ca and one B atom. In the seventh O site, O is bonded in a single-bond geometry to one Ca and one B atom. In the eighth O site, O is bonded in a single-bond geometry to one O atom. The O–O bond length is 1.24 Å. In the ninth O site, O is bonded in a bent 120 degrees geometry to two O atoms.