Materials Data on Ca2AlFeO5 by Materials Project
Ca2FeAlO5 crystallizes in the orthorhombic Pnma 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 2.33–2.82 Å. Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with two equivalent AlO6 octahedra and corners with two equivalent FeO4 tetrahedra. The corner-sharing octahedral tilt angles are 32°. There are a spread of Fe–O bond distances ranging from 1.88–1.96 Å. Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with four equivalent AlO6 octahedra and corners with two equivalent FeO4 tetrahedra. The corner-sharing octahedral tilt angles are 10°. There is four shorter (1.91 Å) and two longer (2.06 Å) Al–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Ca2+ and two equivalent Fe3+ atoms to form distorted OCa2Fe2 tetrahedra that share corners with eight equivalent OCa4Al2 octahedra and corners with two equivalent OCa2Fe2 tetrahedra. The corner-sharing octahedra tilt angles range from 25–76°. In the second 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 OCa2Fe2 tetrahedra, edges with two equivalent OCa4Al2 octahedra, and faces with four equivalent OCa4Al2 octahedra. The corner-sharing octahedral tilt angles are 0°. In the third O2- site, O2- is bonded in a 5-coordinate geometry to three equivalent Ca2+, one Fe3+, and one Al3+ atom.