Materials Data on Ca2Al2O5 by Materials Project

Abstract

Ca2Al2O5 crystallizes in the orthorhombic Ima2 space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.81 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with four equivalent AlO6 octahedra and corners with two equivalent AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 9°. There are a spread of Al–O bond distances ranging from 1.90–2.08 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with two equivalent AlO6 octahedra and corners with two equivalent AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 36°. There are a spread of Al–O bond distances ranging from 1.76–1.81 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Ca2+ and two equivalent Al3+ atoms to form distorted OCa4Al2 octahedra that share corners with two equivalent OCa4Al2 octahedra, corners with four equivalent OCa2Al2 tetrahedra, edges with two equivalent OCa4Al2 octahedra, and faces with four equivalent OCa4Al2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second O2- site, O2- is bonded to two equivalent Ca2+ and two equivalent Al3+ atoms to form distorted OCa2Al2 tetrahedra that share corners with eight equivalent OCa4Al2 octahedra and corners with two equivalent OCa2Al2 tetrahedra. The corner-sharing octahedra tilt angles range from 19–83°. In the third O2- site, O2- is bonded in a 5-coordinate geometry to three equivalent Ca2+ and two Al3+ atoms.