Materials Data on Al3CrO6 by Materials Project
CrAl3O6 is Ilmenite-like structured and crystallizes in the monoclinic Pc space group. The structure is three-dimensional. Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with two equivalent CrO6 octahedra, corners with seven AlO6 octahedra, edges with three AlO6 octahedra, and a faceface with one AlO6 octahedra. The corner-sharing octahedra tilt angles range from 49–62°. There are a spread of Cr–O bond distances ranging from 1.98–2.04 Å. There are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share a cornercorner with one CrO6 octahedra, corners with eight AlO6 octahedra, an edgeedge with one CrO6 octahedra, edges with two equivalent AlO6 octahedra, and a faceface with one CrO6 octahedra. The corner-sharing octahedra tilt angles range from 43–62°. There are a spread of Al–O bond distances ranging from 1.85–2.03 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent CrO6 octahedra, corners with seven AlO6 octahedra, an edgeedge with one AlO6 octahedra, edges with two equivalent CrO6 octahedra, and a faceface with one AlO6 octahedra. The corner-sharing octahedra tilt angles range from 43–62°. There are a spread of Al–O bond distances ranging from 1.87–2.00 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form distorted AlO6 octahedra that share corners with four equivalent CrO6 octahedra, corners with five AlO6 octahedra, edges with three AlO6 octahedra, and a faceface with one AlO6 octahedra. The corner-sharing octahedra tilt angles range from 49–59°. There are a spread of Al–O bond distances ranging from 1.89–2.04 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Cr3+ and two Al3+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Cr3+ and three Al3+ atoms. In the third O2- site, O2- is bonded to four Al3+ atoms to form distorted OAl4 trigonal pyramids that share corners with eight OAl4 trigonal pyramids and an edgeedge with one OAl3Cr trigonal pyramid. In the fourth O2- site, O2- is bonded to one Cr3+ and three Al3+ atoms to form a mixture of distorted edge and corner-sharing OAl3Cr trigonal pyramids. In the fifth O2- site, O2- is bonded to one Cr3+ and three Al3+ atoms to form distorted OAl3Cr trigonal pyramids that share corners with six OAl4 trigonal pyramids and an edgeedge with one OAl3Cr trigonal pyramid. In the sixth O2- site, O2- is bonded in a distorted see-saw-like geometry to one Cr3+ and three Al3+ atoms.