Materials Data on Ba4Ta2O9 by Materials Project

Abstract

Ba4Ta2O9 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. there are three inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Ba–O bond distances ranging from 2.84–3.31 Å. In the second Ba2+ site, Ba2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.73 Å) and three longer (2.79 Å) Ba–O bond lengths. In the third Ba2+ site, Ba2+ is bonded to six equivalent O2- atoms to form distorted BaO6 octahedra that share corners with six equivalent TaO6 octahedra. The corner-sharing octahedral tilt angles are 26°. All Ba–O bond lengths are 2.67 Å. Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with three equivalent BaO6 octahedra and a faceface with one TaO6 octahedra. The corner-sharing octahedral tilt angles are 26°. There are three shorter (1.91 Å) and three longer (2.17 Å) Ta–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to four Ba2+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+ and one Ta5+ atom.