Materials Data on LiAlCrO4 by Materials Project
LiCrAlO4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Li1+ is bonded in a 3-coordinate geometry to three O2- atoms. There are one shorter (1.96 Å) and two longer (2.04 Å) Li–O bond lengths. Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with three equivalent AlO6 octahedra, edges with two equivalent CrO6 octahedra, and edges with two equivalent AlO6 octahedra. The corner-sharing octahedra tilt angles range from 26–51°. There are a spread of Cr–O bond distances ranging from 1.86–2.05 Å. Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with three equivalent CrO6 octahedra, edges with two equivalent CrO6 octahedra, and edges with four equivalent AlO6 octahedra. The corner-sharing octahedra tilt angles range from 26–51°. There are a spread of Al–O bond distances ranging from 1.87–1.95 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to one Cr4+ and three equivalent Al3+ atoms to form OAl3Cr trigonal pyramids that share a cornercorner with one OLi2AlCr2 trigonal bipyramid, corners with two equivalent OAl3Cr trigonal pyramids, edges with two equivalent OLi2AlCr2 trigonal bipyramids, and edges with two equivalent OAl3Cr trigonal pyramids. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+ and two equivalent Cr4+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Cr4+ and two equivalent Al3+ atoms. In the fourth O2- site, O2- is bonded to two equivalent Li1+, two equivalent Cr4+, and one Al3+ atom to form distorted OLi2AlCr2 trigonal bipyramids that share a cornercorner with one OAl3Cr trigonal pyramid, edges with two equivalent OLi2AlCr2 trigonal bipyramids, and edges with two equivalent OAl3Cr trigonal pyramids.