Materials Data on Al4Fe2Si5O18 by Materials Project

Fe2Al4Si5O18 crystallizes in the orthorhombic Cccm space group. The structure is three-dimensional. Fe2+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share corners with two equivalent AlO4 tetrahedra, corners with four SiO4 tetrahedra, an edgeedge with one SiO4 tetrahedra, and edges with two equivalent AlO4 tetrahedra. There are four shorter (2.18 Å) and two longer (2.20 Å) Fe–O bond lengths. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with two equivalent FeO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. There is two shorter (1.73 Å) and two longer (1.79 Å) Al–O bond length. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with four SiO4 tetrahedra and edges with two equivalent FeO6 octahedra. There is two shorter (1.76 Å) and two longer (1.77 Å) Al–O bond length. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four equivalent O2- atoms to form SiO4 tetrahedra that share corners with four equivalent AlO4 tetrahedra and edges with two equivalent FeO6 octahedra. All Si–O bond lengths are 1.64 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent FeO6 octahedra, a cornercorner with one SiO4 tetrahedra, and corners with three AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. There are a spread of Si–O bond distances ranging from 1.59–1.66 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent FeO6 octahedra, a cornercorner with one SiO4 tetrahedra, and corners with three AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Si–O bond distances ranging from 1.60–1.65 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to one Al3+ and one Si4+ atom. In the second O2- site, O2- is bonded in a linear geometry to two Si4+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Fe2+, one Al3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a linear geometry to one Al3+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Fe2+, one Al3+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Fe2+, one Al3+, and one Si4+ atom.