Materials Data on Al3CrO6 by Materials Project

Abstract

CrAl3O6 is Ilmenite-like structured and crystallizes in the trigonal R3 space group. The structure is three-dimensional. Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with nine AlO6 octahedra, edges with three equivalent AlO6 octahedra, and a faceface with one AlO6 octahedra. The corner-sharing octahedra tilt angles range from 49–62°. There are three shorter (1.99 Å) and three longer (2.04 Å) Cr–O bond lengths. There are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with three equivalent CrO6 octahedra, corners with six equivalent AlO6 octahedra, edges with three equivalent AlO6 octahedra, and a faceface with one CrO6 octahedra. The corner-sharing octahedra tilt angles range from 44–62°. There is three shorter (1.86 Å) and three longer (2.03 Å) Al–O bond length. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with nine AlO6 octahedra, edges with three equivalent CrO6 octahedra, and a faceface with one AlO6 octahedra. The corner-sharing octahedra tilt angles range from 44–58°. There is three shorter (1.89 Å) and three longer (2.00 Å) Al–O bond length. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with three equivalent AlO6 octahedra, corners with six equivalent CrO6 octahedra, edges with three equivalent AlO6 octahedra, and a faceface with one AlO6 octahedra. The corner-sharing octahedra tilt angles range from 49–58°. There is three shorter (1.90 Å) and three longer (1.97 Å) Al–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to one Cr3+ and three Al3+ atoms to form a mixture of distorted corner and edge-sharing OAl3Cr trigonal pyramids. In the second O2- site, O2- is bonded in a distorted see-saw-like geometry to one Cr3+ and three Al3+ atoms.