Materials Data on Ba3W2O9 by Materials Project
Ba3W2O9 crystallizes in the trigonal R-3c space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with six equivalent BaO12 cuboctahedra, corners with four equivalent WO6 octahedra, faces with eight equivalent BaO12 cuboctahedra, and faces with four equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 6–29°. There are a spread of Ba–O bond distances ranging from 2.87–3.09 Å. W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with six equivalent BaO12 cuboctahedra, faces with six equivalent BaO12 cuboctahedra, and a faceface with one WO6 octahedra. There is three shorter (1.85 Å) and three longer (2.11 Å) W–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted L-shaped geometry to four equivalent Ba2+ and two equivalent W6+ atoms. In the second O2- site, O2- is bonded in a distorted single-bond geometry to four equivalent Ba2+ and one W6+ atom.