Materials Data on Ba3TaOF9 by Materials Project

BaTaF8Ba2OF crystallizes in the orthorhombic C222_1 space group. The structure is two-dimensional and consists of two Ba2OF sheets oriented in the (0, 1, 0) direction and two BaTaF8 sheets oriented in the (0, 1, 0) direction. In each Ba2OF sheet, there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 4-coordinate geometry to two equivalent O2- and two equivalent F1- atoms. Both Ba–O bond lengths are 2.57 Å. Both Ba–F bond lengths are 2.59 Å. In the second Ba2+ site, Ba2+ is bonded in a 4-coordinate geometry to two equivalent O2- and two equivalent F1- atoms. Both Ba–O bond lengths are 2.59 Å. Both Ba–F bond lengths are 2.57 Å. O2- is bonded to four Ba2+ atoms to form OBa4 tetrahedra that share corners with four equivalent OBa4 tetrahedra and edges with four equivalent FBa4 tetrahedra. F1- is bonded to four Ba2+ atoms to form FBa4 tetrahedra that share corners with four equivalent FBa4 tetrahedra and edges with four equivalent OBa4 tetrahedra. In each BaTaF8 sheet, Ba2+ is bonded in a 7-coordinate geometry to seven F1- atoms. There are a spread of Ba–F bond distances ranging from 2.40–2.88 Å. Ta5+ is bonded in a pentagonal bipyramidal geometry to seven F1- atoms. There are a spread of Ta–F bond distances ranging from 1.94–2.02 Å. There are five inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted single-bond geometry to one Ba2+ and one Ta5+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Ta5+ atom. In the third F1- site, F1- is bonded in a 1-coordinate geometry to one Ba2+ and one Ta5+ atom. In the fourth F1- site, F1- is bonded in a distorted linear geometry to one Ba2+ and one Ta5+ atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one Ba2+ atom.