Materials Data on Ba2CuP2O9 by Materials Project
Ba2CuP2O9 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded in a 10-coordinate geometry to ten O atoms. There are a spread of Ba–O bond distances ranging from 2.70–3.13 Å. In the second Ba site, Ba is bonded in a 11-coordinate geometry to eleven O atoms. There are a spread of Ba–O bond distances ranging from 2.76–3.29 Å. Cu is bonded to six O atoms to form distorted CuO6 octahedra that share corners with four PO4 tetrahedra and edges with two equivalent CuO6 octahedra. There are a spread of Cu–O bond distances ranging from 1.80–2.51 Å. There are two inequivalent P sites. In the first P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with two equivalent CuO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There is two shorter (1.53 Å) and two longer (1.59 Å) P–O bond length. In the second P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with two equivalent CuO6 octahedra. The corner-sharing octahedral tilt angles are 44°. There is two shorter (1.55 Å) and two longer (1.56 Å) P–O bond length. There are seven inequivalent O sites. In the first O site, O is bonded in a distorted bent 120 degrees geometry to two Ba, one Cu, and one P atom. In the second O site, O is bonded in a distorted single-bond geometry to three Ba and one P atom. In the third O site, O is bonded in a distorted single-bond geometry to three Ba and one P atom. In the fourth O site, O is bonded in a distorted single-bond geometry to three Ba and one P atom. In the fifth O site, O is bonded in a distorted single-bond geometry to one Ba, two equivalent Cu, and one P atom. In the sixth O site, O is bonded in a distorted single-bond geometry to three equivalent Ba and one P atom. In the seventh O site, O is bonded in a distorted water-like geometry to one Ba and two equivalent Cu atoms.