Materials Data on Al9Fe2Si4HO24 by Materials Project

Abstract

Fe2Al9Si4HO24 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Fe2+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with eleven AlO6 octahedra. The corner-sharing octahedra tilt angles range from 56–72°. There are a spread of Fe–O bond distances ranging from 2.05–2.10 Å. There are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four equivalent SiO4 tetrahedra, and edges with four AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–1.96 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four equivalent SiO4 tetrahedra, and edges with four AlO6 octahedra. There is four shorter (1.92 Å) and two longer (1.94 Å) Al–O bond length. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with three equivalent FeO4 tetrahedra, corners with three equivalent SiO4 tetrahedra, and edges with four AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.85–2.05 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four equivalent SiO4 tetrahedra, and edges with four equivalent AlO6 octahedra. There is two shorter (1.82 Å) and four longer (2.01 Å) Al–O bond length. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with eight AlO6 octahedra. The corner-sharing octahedra tilt angles range from 50–55°. There are a spread of Si–O bond distances ranging from 1.64–1.66 Å. H1+ is bonded in a linear geometry to two equivalent O2- atoms. Both H–O bond lengths are 1.40 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded to one Fe2+ and three Al3+ atoms to form distorted OAl3Fe trigonal pyramids that share corners with five OAl2FeH tetrahedra, a cornercorner with one OAl3Fe trigonal pyramid, and an edgeedge with one OAl2FeH tetrahedra. In the second O2- site, O2- is bonded to one Fe2+, two equivalent Al3+, and one H1+ atom to form distorted OAl2FeH tetrahedra that share corners with five OAl2FeH tetrahedra, a cornercorner with one OAl3Fe trigonal pyramid, and an edgeedge with one OAl3Fe trigonal pyramid. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two Al3+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one Si4+ atom. In the seventh O2- site, O2- is bonded to one Fe2+ and three Al3+ atoms to form distorted OAl3Fe tetrahedra that share corners with five OAl2FeH tetrahedra and corners with two equivalent OAl3Fe trigonal pyramids.