Materials Data on Al5O8 by Materials Project
Al5O8 is beta indium sulfide-like structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. there are three inequivalent Al sites. In the first Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra, corners with three equivalent AlO4 tetrahedra, and edges with five AlO6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are a spread of Al–O bond distances ranging from 1.82–1.97 Å. In the second Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with six equivalent AlO6 octahedra, corners with three equivalent AlO4 tetrahedra, and edges with three equivalent AlO6 octahedra. The corner-sharing octahedral tilt angles are 48°. There is three shorter (1.87 Å) and three longer (2.00 Å) Al–O bond length. In the third Al site, Al is bonded to four O atoms to form corner-sharing AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–61°. All Al–O bond lengths are 1.82 Å. There are four inequivalent O sites. In the first O site, O is bonded in a distorted T-shaped geometry to three equivalent Al atoms. In the second O site, O is bonded to four Al atoms to form a mixture of distorted corner and edge-sharing OAl4 tetrahedra. In the third O site, O is bonded in a distorted T-shaped geometry to three Al atoms. In the fourth O site, O is bonded to four Al atoms to form a mixture of distorted corner and edge-sharing OAl4 tetrahedra.