Materials Data on Ba3Cr2O8 by Materials Project
Ba3Cr2O8 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.64–2.98 Å. In the second Ba2+ site, Ba2+ is bonded to six equivalent O2- atoms to form distorted BaO6 cuboctahedra that share corners with six equivalent CrO4 tetrahedra. All Ba–O bond lengths are 2.80 Å. Cr5+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with three equivalent BaO6 cuboctahedra. There is one shorter (1.71 Å) and three longer (1.74 Å) Cr–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to one Ba2+ and one Cr5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to four Ba2+ and one Cr5+ atom.