Materials Data on Al2Co2O7 by Materials Project
Co2Al2O7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Co4+ sites. In the first Co4+ site, Co4+ is bonded to six O2- atoms to form distorted corner-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 55–57°. There is four shorter (1.84 Å) and two longer (1.86 Å) Co–O bond length. In the second Co4+ site, Co4+ is bonded to six O2- atoms to form distorted corner-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 55–57°. There are a spread of Co–O bond distances ranging from 1.84–1.86 Å. In the third Co4+ site, Co4+ is bonded to six O2- atoms to form distorted corner-sharing CoO6 octahedra. The corner-sharing octahedra tilt angles range from 55–57°. There is four shorter (1.84 Å) and two longer (1.86 Å) Co–O bond length. There are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Al–O bond distances ranging from 2.00–2.19 Å. In the second Al3+ site, Al3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Al–O bond distances ranging from 2.00–2.20 Å. In the third Al3+ site, Al3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Al–O bond distances ranging from 2.00–2.19 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four Al3+ atoms to form OAl4 tetrahedra that share corners with sixteen OAl4 tetrahedra and edges with six OAl2Co2 tetrahedra. In the second O2- site, O2- is bonded to two Co4+ and two Al3+ atoms to form a mixture of distorted corner and edge-sharing OAl2Co2 tetrahedra. In the third O2- site, O2- is bonded to two Co4+ and two Al3+ atoms to form a mixture of distorted corner and edge-sharing OAl2Co2 tetrahedra. In the fourth O2- site, O2- is bonded to two Co4+ and two equivalent Al3+ atoms to form a mixture of distorted corner and edge-sharing OAl2Co2 tetrahedra. In the fifth O2- site, O2- is bonded to two equivalent Co4+ and two Al3+ atoms to form a mixture of distorted corner and edge-sharing OAl2Co2 tetrahedra.