Materials Data on Ba(As2O7)2 by Materials Project
Ba(As2O7)2 crystallizes in the orthorhombic Pmna space group. The structure is three-dimensional. Ba is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ba–O bond distances ranging from 2.83–2.89 Å. There are two inequivalent As sites. In the first As site, As is bonded to six O atoms to form AsO6 octahedra that share corners with two equivalent AsO4 tetrahedra and an edgeedge with one AsO6 octahedra. There are a spread of As–O bond distances ranging from 1.80–1.93 Å. In the second As site, As is bonded to four O atoms to form corner-sharing AsO4 tetrahedra. The corner-sharing octahedral tilt angles are 66°. There are a spread of As–O bond distances ranging from 1.72–1.75 Å. There are five inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to two As atoms. In the second O site, O is bonded in a distorted single-bond geometry to one Ba and one As atom. In the third O site, O is bonded in a distorted single-bond geometry to one Ba and one As atom. In the fourth O site, O is bonded in a water-like geometry to two equivalent As atoms. In the fifth O site, O is bonded in a distorted single-bond geometry to one Ba and one As atom.