Materials Data on AlCr3O8 by Materials Project
Cr3AlO8 is trigonal omega-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Cr+4.33+ is bonded to six O2- atoms to form CrO6 octahedra that share edges with two equivalent AlO6 octahedra and edges with four equivalent CrO6 octahedra. There is four shorter (1.93 Å) and two longer (1.96 Å) Cr–O bond length. Al3+ is bonded to six equivalent O2- atoms to form AlO6 octahedra that share edges with six equivalent CrO6 octahedra. All Al–O bond lengths are 1.93 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to three equivalent Cr+4.33+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cr+4.33+ and one Al3+ atom.