DOI: 10.17188/1751054
title: Materials Data on Al6CO7 by Materials Project

description: Al4O4CAl2O3 crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three Al2O3 sheets oriented in the (0, 0, 1) direction and three Al4O4C sheets oriented in the (0, 0, 1) direction. In each Al2O3 sheet, there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form distorted AlO6 octahedra that share corners with three equivalent AlO4 tetrahedra and edges with six equivalent AlO6 octahedra. There are three shorter (1.87 Å) and three longer (2.16 Å) Al–O bond lengths. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with three equivalent AlO6 octahedra and corners with six equivalent AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. There is one shorter (1.72 Å) and three longer (1.86 Å) Al–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Al3+ atoms. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three equivalent Al3+ atoms. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three equivalent Al3+ atoms. In each Al4O4C sheet, there are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six AlC3O tetrahedra and edges with six equivalent AlO6 octahedra. There are three shorter (1.93 Å) and three longer (2.09 Å) Al–O bond lengths. In the second Al3+ site, Al3+ is bonded to three equivalent C4- and one O2- atom to form AlC3O tetrahedra that share corners with three equivalent AlO6 octahedra and corners with nine AlC3O tetrahedra. The corner-sharing octahedral tilt angles are 66°. All Al–C bond lengths are 1.86 Å. The Al–O bond length is 2.13 Å. In the third Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with three equivalent AlO6 octahedra and corners with six equivalent AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. There is one shorter (1.79 Å) and three longer (1.83 Å) Al–O bond length. In the fourth Al3+ site, Al3+ is bonded to one C4- and three equivalent O2- atoms to form corner-sharing AlCO3 tetrahedra. The Al–C bond length is 1.94 Å. All Al–O bond lengths are 1.84 Å. C4- is bonded to four Al3+ atoms to form CAl4 tetrahedra that share corners with three equivalent OAl4 tetrahedra and corners with six equivalent CAl4 tetrahedra. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to four Al3+ atoms to form OAl4 tetrahedra that share corners with three equivalent CAl4 tetrahedra, corners with six equivalent OAl4 tetrahedra, corners with three equivalent OAl4 trigonal pyramids, and edges with three equivalent OAl4 trigonal pyramids. In the second O2- site, O2- is bonded to four Al3+ atoms to form a mixture of distorted edge and corner-sharing OAl4 trigonal pyramids. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three equivalent Al3+ atoms. In the fourth O2- site, O2- is bonded in a trigonal non-coplanar geometry to three equivalent Al3+ atoms.